2 * doc.c - Contains the short and long descriptions of all the documentation
3 * sections in the Glk spec, as well as the GtkDoc comments for symbols
4 * defined only in glk.h.
9 * @short_description: How to terminate a Glk program cleanly
10 * @include: libchimara/glk.h
12 * A Glk program usually ends when the end of the glk_main() function is
13 * reached. You can also terminate it earlier.
17 * SECTION:glk-interrupt
18 * @short_description: Specifying an interrupt handler for cleaning up critical
20 * @include: libchimara/glk.h
22 * Most platforms have some provision for interrupting a program —
23 * <keycombo action="simul"><keycap function="command">command</keycap>
24 * <keycap>period</keycap></keycombo> on the Macintosh, <keycombo
25 * action="simul"><keycap function="control">control</keycap><keycap>C</keycap>
26 * </keycombo> in Unix, possibly a window manager item, or other possibilities.
27 * This can happen at any time, including while execution is nested inside one
28 * of your own functions, or inside a Glk library function.
30 * If you need to clean up critical resources, you can specify an interrupt
36 * @short_description: Yielding time to the operating system
37 * @include: libchimara/glk.h
39 * Many platforms have some annoying thing that has to be done every so often,
40 * or the gnurrs come from the voodvork out and eat your computer.
42 * Well, not really. But you should call glk_tick() every so often, just in
43 * case. It may be necessary to yield time to other applications in a
44 * cooperative-multitasking OS, or to check for player interrupts in an infinite
50 * @short_description: Basic types used in Glk
51 * @include: libchimara/glk.h
53 * For simplicity, all the arguments used in Glk calls are of a very few types.
56 * <term>32-bit unsigned integer</term>
57 * <listitem><para>Unsigned integers are used wherever possible, which is
58 * nearly everywhere. This type is called #glui32.</para></listitem>
61 * <term>32-bit signed integer</term>
62 * <listitem><para>This type is called #glsi32. Rarely used.</para>
66 * <term>References to library objects</term>
67 * <listitem><para>These are pointers to opaque C structures; each library
68 * will use different structures, so you can not and should not try to
69 * manipulate their contents. See <link
70 * linkend="chimara-Opaque-Objects">Opaque Objects</link>.</para></listitem>
73 * <term>Pointer to one of the above types</term>
74 * <listitem><para>Pointer to a structure which consists entirely of the
75 * above types.</para></listitem>
78 * <term><type>unsigned char</type></term>
79 * <listitem><para>This is used only for Latin-1 text characters; see
80 * <link linkend="chimara-Character-Encoding">Character Encoding</link>.
84 * <term>Pointer to <type>char</type></term>
85 * <listitem><para>Sometimes this means a null-terminated string; sometimes
86 * an unterminated buffer, with length as a separate #glui32 argument. The
87 * documentation says which.</para></listitem>
90 * <term>Pointer to <type>void</type></term>
91 * <listitem><para>When nothing else will do.</para></listitem>
97 * SECTION:glk-opaque-objects
98 * @short_description: Complex objects in Glk
99 * @include: libchimara/glk.h
101 * Glk keeps track of a few classes of special objects. These are opaque to your
102 * program; you always refer to them using pointers to opaque C structures.
104 * Currently, these classes are:
107 * <term>Windows</term>
108 * <listitem><para>Screen panels, used to input or output information.
112 * <term>Streams</term>
113 * <listitem><para>Data streams, to which you can input or output text.
115 * <note><para>There are file streams and window streams, since you can
116 * output data to windows or files.</para></note>
120 * <term>File references</term>
121 * <listitem><para>Pointers to files in permanent storage.</para>
122 * <note><para>In Unix a file reference is a pathname; on the Mac, an
123 * <type>FSSpec</type>. Actually there's a little more information included,
124 * such as file type and whether it is a text or binary file.</para></note>
128 * <term>Sound channels</term>
129 * <listitem><para>Audio output channels.</para>
130 * <note><para>Not all Glk libraries support sound.</para></note>
136 * Note that there may be more object classes in future versions of the Glk API.
139 * When you create one of these objects, it is always possible that the creation
140 * will fail (due to lack of memory, or some other OS error.) When this happens,
141 * the allocation function will return %NULL instead of a valid pointer. You
142 * should always test for this possibility.
144 * %NULL is never the identifier of any object (window, stream, file reference,
145 * or sound channel). The value %NULL is often used to indicate <quote>no
146 * object</quote> or <quote>nothing</quote>, but it is not a valid reference. If
147 * a Glk function takes an object reference as an argument, it is illegal to
148 * pass in %NULL unless the function definition says otherwise.
150 * The <filename class="headerfile">glk.h</filename> file defines types
151 * #winid_t, #strid_t, #frefid_t, #schanid_t to store references. These are
152 * pointers to struct #glk_window_struct, #glk_stream_struct,
153 * #glk_fileref_struct, and #glk_schannel_struct respectively. It is, of course,
154 * illegal to pass one kind of pointer to a function which expects another.
157 * This is how you deal with opaque objects from a C program. If you are using
158 * Glk through a virtual machine, matters will probably be different. Opaque
159 * objects may be represented as integers, or as VM objects of some sort.
160 * </para></note></para>
162 * <refsect2 id="chimara-Rocks"><!-- Indeed it does. -->
163 * <title>Rocks</title>
165 * Every one of these objects (window, stream, file reference, or sound channel)
166 * has a <quote>rock</quote> value. This is simply a 32-bit integer value which
167 * you provide, for your own purposes, when you create the object.
169 * <note><para>The library — so to speak — stuffs this value under a
170 * rock for safe-keeping, and gives it back to you when you ask for it.
172 * <note><para>If you don't know what to use the rocks for, provide 0 and forget
173 * about it.</para></note>
175 * <refsect2 id="chimara-Iterating-Through-Opaque-Objects">
176 * <title>Iteration Through Opaque Objects</title>
178 * For each class of opaque objects, there is an iterate function, which you can
179 * use to obtain a list of all existing objects of that class. It takes the form
181 * CLASSid_t glk_CLASS_iterate(CLASSid_t obj, glui32 *rockptr);
183 * ...where <code><replaceable>CLASS</replaceable></code> represents one of the
184 * opaque object classes.
187 * So, at the current time, these are the functions glk_window_iterate(),
188 * glk_stream_iterate(), glk_fileref_iterate(), and glk_schannel_iterate().
189 * There may be more classes in future versions of the spec; they all behave
193 * Calling <code>glk_<replaceable>CLASS</replaceable>_iterate(%NULL, r)</code>
194 * returns the first object; calling
195 * <code>glk_<replaceable>CLASS</replaceable>_iterate(obj, r)</code> returns
196 * the next object, until there aren't any more, at which time it returns %NULL.
199 * The @rockptr argument is a pointer to a location; whenever
200 * <code>glk_<replaceable>CLASS</replaceable>_iterate()</code> returns an
201 * object, the object's rock is stored in the location <code>(*@rockptr)</code>.
202 * If you don't want the rocks to be returned, you may set @rockptr to %NULL.
205 * You usually use this as follows:
207 * obj = glk_CLASS_iterate(NULL, NULL);
209 * /* ...do something with obj... *<!-- -->/
210 * obj = glk_CLASS_iterate(obj, NULL);
215 * If you create or destroy objects inside this loop, obviously, the results are
216 * unpredictable. However it is always legal to call
217 * <code>glk_<replaceable>CLASS</replaceable>_iterate(obj, r)</code> as long as
218 * @obj is a valid object id, or %NULL.
221 * The order in which objects are returned is entirely arbitrary. The library
222 * may even rearrange the order every time you create or destroy an object of
223 * the given class. As long as you do not create or destroy any object, the rule
224 * is that <code>glk_<replaceable>CLASS</replaceable>_iterate(obj, r)</code> has
225 * a fixed result, and iterating through the results as above will list every
226 * object exactly once.
232 * SECTION:glk-gestalt
233 * @short_description: Testing Glk's capabilities
234 * @include: libchimara/glk.h
236 * The <quote>gestalt</quote> mechanism (cheerfully stolen from the Mac OS) is a
237 * system by which the Glk API can be upgraded without making your life
238 * impossible. New capabilities (graphics, sound, or so on) can be added without
239 * changing the basic specification. The system also allows for
240 * <quote>optional</quote> capabilities — those which not all Glk library
241 * implementations will support — and allows you to check for their
242 * presence without trying to infer them from a version number.
244 * The basic idea is that you can request information about the capabilities of
245 * the API, by calling the gestalt functions.
249 * SECTION:glk-character-input
250 * @short_description: Waiting for a single keystroke
251 * @include: libchimara/glk.h
253 * You can request that the player hit a single key. See <link
254 * linkend="chimara-Character-Input-Events">Character Input Events</link>.
256 * If you use the basic text API, the character code which is returned can be
257 * any value from 0 to 255. The printable character codes have already been
258 * described. The remaining codes are typically control codes: <keycombo
259 * action="simul"><keycap function="control">control</keycap>
260 * <keycap>A</keycap></keycombo> to <keycombo action="simul"><keycap
261 * function="control">control</keycap><keycap>Z</keycap></keycombo> and a few
264 * There are also a number of special codes, representing special keyboard
265 * keys, which can be returned from a char-input event. These are represented
266 * as 32-bit integers, starting with 4294967295 (0xFFFFFFFF) and working down.
267 * The special key codes are defined in the <filename
268 * class="headerfile">glk.h</filename> file. They include one code for <keycap
269 * function="enter">return</keycap> or <keycap function="enter">enter</keycap>,
270 * one for <keycap function="delete">delete</keycap> or <keycap
271 * function="backspace">backspace</keycap>, twelve function keys, and one code
272 * for any key which has no Latin-1 or special code. The full list of key codes
275 * Various implementations of Glk will vary widely in which characters the
276 * player can enter. The most obvious limitation is that some characters are
277 * mapped to others. For example, most keyboards return a <keycombo
278 * action="simul"><keycap function="control">control</keycap><keycap>I</keycap>
279 * </keycombo> code when the <keycap function="tab">tab</keycap> key is
280 * pressed. The Glk library, if it can recognize this at all, will generate a
281 * <keysym>%keycode_Tab</keysym> event (value 0xFFFFFFF7) when this occurs.
282 * Therefore, for these keyboards, no keyboard key will generate a <keycombo
283 * action="simul"><keycap function="control">control</keycap><keycap>I</keycap>
284 * </keycombo> event (value 9.) The Glk library will probably map many of the
285 * control codes to the other special keycodes.
288 * On the other hand, the library may be very clever and discriminate between
289 * <keycap>tab</keycap> and <keycombo action="simul"><keycap
290 * function="control">control</keycap><keycap>I</keycap></keycombo>. This is
291 * legal. The idea is, however, that if your program asks the player to
292 * <quote><computeroutput>press the <keycap function="tab">tab</keycap>
293 * key</computeroutput></quote>, you should check for a
294 * <keysym>%keycode_Tab</keysym> event as opposed to a <keycombo
295 * action="simul"><keycap function="control">control</keycap>
296 * <keycap>I</keycap></keycombo> event.
299 * Some characters may not be enterable simply because they do not exist.
302 * Not all keyboards have a <keycap function="home">home</keycap> or <keycap
303 * function="end">end</keycap> key. A pen-based platform may not recognize
304 * any control characters at all.
307 * Some characters may not be enterable because they are reserved for the
308 * purposes of the interface. For example, the Mac Glk library reserves the
309 * <keycap function="tab">tab</keycap> key for switching between different Glk
310 * windows. Therefore, on the Mac, the library will never generate a
311 * <keysym>%keycode_Tab</keysym> event or a <keycombo action="simul">
312 * <keycap function="control">control</keycap><keycap>I</keycap></keycombo>
316 * Note that the linefeed or <keycombo action="simul"><keycap
317 * function="control">control</keycap><keycap>J</keycap></keycombo>
318 * character, which is the only printable control character, is probably not
319 * typable. This is because, in most libraries, it will be converted to
320 * <keysym>%keycode_Return</keysym>. Again, you should check for
321 * <keysym>%keycode_Return</keysym> if your program asks the player to
322 * <quote><computeroutput>press the <keycap function="enter">return</keycap>
323 * key</computeroutput></quote>.
327 * The <keycap function="delete">delete</keycap> and <keycap
328 * function="backspace">backspace</keycap> keys are merged into a single
329 * keycode because they have such an astonishing history of being confused in
330 * the first place... this spec formally waives any desire to define the
331 * difference. Of course, a library is free to distinguish <keycap
332 * function="delete">delete</keycap> and <keycap
333 * function="backspace">backspace</keycap> during line input. This is when it
334 * matters most; conflating the two during character input should not be a
338 * You can test for this by using the %gestalt_CharInput selector.
341 * Glk porters take note: it is not a goal to be able to generate every
342 * single possible key event. If the library says that it can generate a
343 * particular keycode, then game programmers will assume that it is
344 * available, and ask players to use it. If a <keysym>%keycode_Home</keysym>
345 * event can only be generated by typing <keycombo action="seq"><keycap
346 * function="escape">escape</keycap><keycombo action="simul"><keycap
347 * function="control">control</keycap><keycap>A</keycap></keycombo>
348 * </keycombo>, and the player does not know this, the player will be lost
349 * when the game says <quote><computeroutput>Press the <keycap
350 * function="home">home</keycap> key to see the next
351 * hint.</computeroutput></quote> It is better for the library to say that it
352 * cannot generate a <keysym>%keycode_Home</keysym> event; that way the game
353 * can detect the situation and ask the user to type <keycap>H</keycap>
357 * Of course, it is better not to rely on obscure keys in any case. The arrow
358 * keys and <keycap function="enter">return</keycap> are nearly certain to be
359 * available; the others are of gradually decreasing reliability, and you
360 * (the game programmer) should not depend on them. You must be certain to
361 * check for the ones you want to use, including the arrow keys and <keycap
362 * function="enter">return</keycap>, and be prepared to use different keys in
363 * your interface if %gestalt_CharInput says they are not available.
369 * @short_description: Changing the case of strings
370 * @include: libchimara/glk.h
372 * Glk has functions to manipulate the case of both Latin-1 and Unicode strings.
373 * One Latin-1 lowercase character corresponds to one uppercase character, and
374 * vice versa, so the Latin-1 functions act on single characters. The Unicode
375 * functions act on whole strings, since the length of the string may change.
379 * SECTION:glk-normalize
380 * @short_description: Combining characters
381 * @include: libchimara/glk.h
383 * Comparing Unicode strings is difficult, because there can be several ways to
384 * represent a piece of text as a Unicode string. For example, the one-character
385 * string <quote>è</quote> (an accented <quote>e</quote>) will be
386 * displayed the same as the two-character string containing <quote>e</quote>
387 * followed by Unicode character 0x0300 (COMBINING GRAVE ACCENT). These strings
388 * should be considered equal.
390 * Therefore, a Glk program that accepts line input should convert its text to a
391 * normalized form before parsing it. These functions offer those conversions.
392 * The algorithms are defined by the Unicode spec (chapter 3.7) and <ulink
393 * url="http://www.unicode.org/reports/tr15/">Unicode Standard Annex
398 * SECTION:glk-window-opening
399 * @short_description: Creating new windows and closing them
400 * @include: libchimara/glk.h
402 * You can open a new window using glk_window_open() and close it again using
403 * glk_window_close().
407 * SECTION:glk-window-constraints
408 * @short_description: Manipulating the size of a window
409 * @include: libchimara/glk.h
411 * There are library functions to change and to measure the size of a window.
415 * SECTION:glk-window-types
416 * @short_description: Blank, pair, text grid, text buffer, and graphics windows
417 * @include: libchimara/glk.h
419 * A technical description of all the window types, and exactly how they behave.
423 * SECTION:glk-echo-streams
424 * @short_description: Creating a copy of a window's output
425 * @include: libchimara/glk.h
427 * Every window has an associated window stream; you print to the window by
428 * printing to this stream. However, it is possible to attach a second stream to
429 * a window. Any text printed to the window is also echoed to this second
430 * stream, which is called the window's <quote>echo stream.</quote>
432 * Effectively, any call to glk_put_char() (or the other output commands) which
433 * is directed to the window's window stream, is replicated to the window's echo
434 * stream. This also goes for the style commands such as glk_set_style().
436 * Note that the echoing is one-way. You can still print text directly to the
437 * echo stream, and it will go wherever the stream is bound, but it does not
438 * back up and appear in the window.
440 * An echo stream can be of any type, even another window's window stream.
443 * This would be somewhat silly, since it would mean that any text printed to
444 * the window would be duplicated in another window. More commonly, you would
445 * set a window's echo stream to be a file stream, in order to create a
446 * transcript file from that window.
449 * A window can only have one echo stream. But a single stream can be the echo
450 * stream of any number of windows, sequentially or simultaneously.
452 * If a window is closed, its echo stream remains open; it is not automatically
456 * Do not confuse the window's window stream with its echo stream. The window
457 * stream is <quote>owned</quote> by the window, and dies with it. The echo
458 * stream is merely temporarily associated with the window.
461 * If a stream is closed, and it is the echo stream of one or more windows,
462 * those windows are reset to not echo anymore. (So then calling
463 * glk_window_get_echo_stream() on them will return %NULL.)
467 * SECTION:glk-window-other
468 * @short_description: Miscellaneous functions for windows
469 * @include: libchimara/glk.h
471 * This section contains functions for windows that don't fit anywhere else.
476 * @short_description: Waiting for events
477 * @include: libchimara/glk.h
479 * As described in <link linkend="chimara-Your-Programs-Main-Function">Your
480 * Program's Main Function</link>, all player input is handed to your program by
481 * the glk_select() call, in the form of events. You should write at least one
482 * event loop to retrieve these events.
486 * SECTION:glk-character-input-events
487 * @short_description: Events representing a single keystroke
488 * @include: libchimara/glk.h
490 * You can request character input from text buffer and text grid windows. See
491 * %evtype_CharInput. There are separate functions for requesting Latin-1 input
492 * and Unicode input; see %gestalt_Unicode.
496 * SECTION:glk-line-input-events
497 * @short_description: Events representing a line of user input
498 * @include: libchimara/glk.h
500 * You can request line input from text buffer and text grid windows. See
501 * %evtype_LineInput. There are separate functions for requesting Latin-1 input
502 * and Unicode input; see %gestalt_Unicode.
506 * SECTION:glk-mouse-events
507 * @short_description: Events representing a mouse click
508 * @include: libchimara/glk.h
510 * On some platforms, Glk can recognize when the mouse (or other pointer) is
511 * used to select a spot in a window. You can request mouse input only in text
512 * grid windows and graphics windows.
514 * A window can have mouse input and character/line input pending at the same
517 * If the player clicks in a window which has a mouse input event pending,
518 * glk_select() will return an event whose type is %evtype_MouseInput. Again,
519 * once this happens, the request is complete, and you must request another if
520 * you want further mouse input.
522 * In the event structure, @win tells what window the event came from.
524 * In a text grid window, the @val1 and @val2 fields are the x and y coordinates
525 * of the character that was clicked on.
526 * <note><para>So @val1 is the column, and @val2 is the row.</para></note>
527 * The top leftmost character is considered to be (0,0).
529 * In a graphics window, they are the x and y coordinates of the pixel that was
530 * clicked on. Again, the top left corner of the window is (0,0).
533 * Most mouse-based idioms define standard functions for mouse hits in text
534 * windows — typically selecting or copying text. It is up to the
535 * library to separate this from Glk mouse input. The library may choose to
536 * select text when it is clicked normally, and cause Glk mouse events when
537 * text is control-clicked. Or the other way around. Or it may be the
538 * difference between clicking and double-clicking. Or the library may
539 * reserve a particular mouse button, on a multi-button mouse. It may even
540 * specify a keyboard key to be the "mouse button", referring to wherever the
541 * mouse cursor is when the key is hit. Or some even more esoteric positioning
542 * system. You need only know that the user can do it, or not.
545 * However, since different platforms will handle this issue differently, you
546 * should be careful how you instruct the player in your program. Do not tell
547 * the player to <quote>double-click</quote>, <quote>right-click</quote>, or
548 * <quote>control-click</quote> in a window. The preferred term is <quote>to
549 * touch the window</quote>, or a spot in the window.
552 * Goofy, but preferred.
557 * SECTION:glk-timer-events
558 * @short_description: Events sent at fixed intervals
559 * @include: libchimara/glk.h
561 * You can request that an event be sent at fixed intervals, regardless of what
562 * the player does. Unlike input events, timer events can be tested for with
563 * glk_select_poll() as well as glk_select().
565 * It is possible that the library does not support timer events. You can check
566 * this with the %gestalt_Timer selector.
570 * SECTION:glk-streams
571 * @short_description: Input and output abstractions
572 * @include: libchimara/glk.h
574 * All character output in Glk is done through streams. Every window has an
575 * output stream associated with it. You can also write to files on disk; every
576 * open file is represented by an output stream as well.
578 * There are also input streams; these are used for reading from files on disk.
579 * It is possible for a stream to be both an input and an output stream.
582 * Player input is done through line and character input events, not streams.
583 * This is a small inelegance in theory. In practice, player input is slow and
584 * things can interrupt it, whereas file input is immediate. If a network
585 * extension to Glk were proposed, it would probably use events and not
586 * streams, since network communication is not immediate.
589 * It is also possible to create a stream that reads or writes to a buffer in
592 * Finally, there may be platform-specific types of streams, which are created
593 * before your program starts running.
596 * For example, a program running under Unix may have access to standard input
597 * as a stream, even though there is no Glk call to explicitly open standard
598 * input. On the Mac, data in a Mac resource may be available through a
599 * resource-reading stream.
602 * You do not need to worry about the origin of such streams; just read or write
603 * them as usual. For information about how platform-specific streams come to
604 * be, see <link linkend="chimara-Startup-Options">Startup Options</link>.
606 * A stream is opened with a particular file mode, see the
607 * <code>filemode_</code> constants below.
609 * For information on opening streams, see the discussion of each specific type
610 * of stream in <link linkend="chimara-The-Types-of-Streams">The Types of
611 * Streams</link>. Remember that it is always possible that opening a stream
612 * will fail, in which case the creation function will return %NULL.
614 * Each stream remembers two character counts, the number of characters printed
615 * to and read from that stream. The write-count is exactly one per
616 * glk_put_char() call; it is figured before any platform-dependent character
620 * For example, if a newline character is converted to
621 * linefeed-plus-carriage-return, the stream's count still only goes up by
622 * one; similarly if an accented character is displayed as two characters.
625 * The read-count is exactly one per glk_get_char_stream() call, as long as the
626 * call returns an actual character (as opposed to an end-of-file token.)
628 * Glk has a notion of the <quote>current (output) stream</quote>. If you print
629 * text without specifying a stream, it goes to the current output stream. The
630 * current output stream may be %NULL, meaning that there isn't one. It is
631 * illegal to print text to stream %NULL, or to print to the current stream when
634 * If the stream which is the current stream is closed, the current stream
640 * @short_description: Printing to streams
641 * @include: libchimara/glk.h
643 * You can print Latin-1 and Unicode characters, null-terminated strings, or
644 * buffers to any stream. The characters will be converted into the appropriate
645 * format for that stream.
650 * @short_description: Reading from streams
651 * @include: libchimara/glk.h
653 * You can read Latin-1 or Unicode characters, buffers, or whole lines from any
654 * stream. The characters will be converted into the form in which you request
659 * SECTION:glk-closing-streams
660 * @short_description: Closing streams and retrieving their character counts
661 * @include: libchimara/glk.h
663 * When you close a Glk stream, you have the opportunity to examine the
664 * character counts — the number of characters written to or read from the
669 * SECTION:glk-stream-positions
670 * @short_description: Moving the read/write mark
671 * @include: libchimara/glk.h
673 * You can set the position of the read/write mark in a stream.
676 * Which makes one wonder why they're called <quote>streams</quote> in the
677 * first place. Oh well.
683 * @short_description: Changing the appearance of printed text
684 * @include: libchimara/glk.h
686 * You can send style-changing commands to an output stream. After a style
687 * change, new text which is printed to that stream will be given the new style,
688 * whatever that means for the stream in question. For a window stream, the text
689 * will appear in that style. For a memory stream, style changes have no effect.
690 * For a file stream, if the machine supports styled text files, the styles may
691 * be written to the file; more likely the style changes will have no effect.
693 * Styles are exclusive. A character is shown with exactly one style, not a
694 * subset of the possible styles.
697 * Note that every stream and window has its own idea of the <quote>current
698 * style.</quote> Sending a style command to one window or stream does not
702 * Except for a window's echo stream; see <link
703 * linkend="chimara-Echo-Streams">Echo Streams</link>.
706 * The styles are intended to distinguish meaning and use, not formatting. There
707 * is no standard definition of what each style will look like. That is left up
708 * to the Glk library, which will choose an appearance appropriate for the
709 * platform's interface and the player's preferences.
711 * There are currently eleven styles defined. More may be defined in the future.
713 * Styles may be distinguished on screen by font, size, color, indentation,
714 * justification, and other attributes. Note that some attributes (notably
715 * justification and indentation) apply to entire paragraphs. If possible and
716 * relevant, you should apply a style to an entire paragraph — call
717 * glk_set_style() immediately after printing the newline at the beginning of
718 * the text, and do the same at the end.
721 * For example, %style_Header may well be centered text. If you print
722 * <quote>Welcome to Victim (a short interactive mystery)</quote>, and only the
723 * word <quote>Victim</quote> is in the %style_Header, the center-justification
724 * attribute will be lost. Similarly, a block quote is usually indented on both
725 * sides, but indentation is only meaningful when applied to an entire line or
726 * paragraph, so block quotes should take up an entire paragraph. Contrariwise,
727 * %style_Emphasized need not be used on an entire paragraph. It is often used
728 * for single emphasized words in normal text, so you can expect that it will
729 * appear properly that way; it will be displayed in italics or underlining,
730 * not center-justified or indented.
734 * Yes, this is all a matter of mutual agreement between game authors and game
735 * players. It's not fixed by this specification. That's natural language for
741 * SECTION:glk-stylehints
742 * @short_description: Setting style hints
743 * @include: libchimara/glk.h
745 * There are no guarantees of how styles will look, but you can make
748 * Initially, no hints are set for any window type or style. Note that having no
749 * hint set is not the same as setting a hint with value 0.
751 * These functions do <emphasis>not</emphasis> affect
752 * <emphasis>existing</emphasis> windows. They affect the windows which you
753 * create subsequently. If you want to set hints for all your game windows, call
754 * glk_stylehint_set() before you start creating windows. If you want different
755 * hints for different windows, change the hints before creating each window.
758 * This policy makes life easier for the interpreter. It knows everything about
759 * a particular window's appearance when the window is created, and it doesn't
760 * have to change it while the window exists.
763 * Hints are hints. The interpreter may ignore them, or give the player a choice
764 * about whether to accept them. Also, it is never necessary to set hints. You
765 * don't have to suggest that %style_Preformatted be fixed-width, or
766 * %style_Emphasized be boldface or italic; they will have appropriate defaults.
767 * Hints are for situations when you want to <emphasis>change</emphasis> the
768 * appearance of a style from what it would ordinarily be. The most common case
769 * when this is appropriate is for the styles %style_User1 and %style_User2.
771 * There are currently ten style hints defined. More may be defined in the
774 * Again, when passing a style hint to a Glk function, any value is actually
775 * legal. If the interpreter does not recognize the stylehint value, it will
778 * This policy allows for the future definition of style hints without breaking
784 * SECTION:glk-style-measure
785 * @short_description: Finding out how the library displays your style hints
786 * @include: libchimara/glk.h
788 * You can suggest the appearance of a window's style before the window is
789 * created; after the window is created, you can test the style's actual
790 * appearance. These functions do not test the style hints; they test the
791 * attribute of the style as it appears to the player.
793 * Note that although you cannot change the appearance of a window's styles
794 * after the window is created, the library can. A platform may support dynamic
795 * preferences, which allow the player to change text formatting while your
796 * program is running.
798 * Changes that affect window size (such as font size changes) will be
799 * signalled by an %evtype_Arrange event. However, more subtle changes (such
800 * as text color differences) are not signalled. If you test the appearance of
801 * styles at the beginning of your program, you must keep in mind the
802 * possibility that the player will change them later.
807 * SECTION:glk-stream-types
808 * @short_description: Window, memory, and file streams
809 * @include: libchimara/glk.h
811 * <refsect2 id="chimara-Window-Streams"><title>Window Streams</title>
813 * Every window has an output stream associated with it. This is created
814 * automatically, with %filemode_Write, when you open the window. You get it
815 * with glk_window_get_stream(). Window streams always have rock value 0.
817 * A window stream cannot be closed with glk_stream_close(). It is closed
818 * automatically when you close its window with glk_window_close().
820 * Only printable characters (including newline) may be printed to a window
821 * stream. See <link linkend="chimara-Character-Encoding">Character
825 * <refsect2 id="chimara-Memory-Streams"><title>Memory Streams</title>
827 * You can open a stream which reads from or writes to a space in memory. See
828 * glk_stream_open_memory() and glk_stream_open_memory_uni(). When opening a
829 * memory stream, you specify a buffer to which the stream's output will be
830 * written, and its length @buflen.
832 * When outputting, if more than @buflen characters are written to the stream,
833 * all of them beyond the buffer length will be thrown away, so as not to
834 * overwrite the buffer. (The character count of the stream will still be
835 * maintained correctly. That is, it will count the number of characters written
836 * into the stream, not the number that fit into the buffer.)
838 * If the buffer is %NULL, or for that matter if @buflen is zero, then
839 * <emphasis>everything</emphasis> written to the stream is thrown away. This
840 * may be useful if you are interested in the character count.
842 * When inputting, if more than @buflen characters are read from the stream, the
843 * stream will start returning -1 (signalling end-of-file.) If the buffer is
844 * %NULL, the stream will always return end-of-file.
846 * The data is written to the buffer exactly as it was passed to the printing
847 * functions (glk_put_char(), etc.); input functions will read the data exactly
848 * as it exists in memory. No platform-dependent cookery will be done on it.
851 * You can write a disk file in text mode, but a memory stream is effectively
852 * always in binary mode.
855 * Whether reading or writing, the contents of the buffer are undefined until
856 * the stream is closed. The library may store the data there as it is written,
857 * or deposit it all in a lump when the stream is closed. It is illegal to
858 * change the contents of the buffer while the stream is open.
861 * <refsect2 id="chimara-File-Streams"><title>File Streams</title>
863 * You can open a stream which reads from or writes to a disk file. See
864 * glk_stream_open_file() and glk_stream_open_file_uni().
866 * The file may be written in text or binary mode; this is determined by the
867 * file reference you open the stream with. Similarly, platform-dependent
868 * attributes such as file type are determined by the file reference. See <link
869 * linkend="chimara-File-References">File References</link>.
875 * SECTION:glk-stream-other
876 * @short_description: Miscellaneous functions for streams
877 * @include: libchimara/glk.h
879 * This section includes functions for streams that don't fit anywhere else.
883 * SECTION:glk-fileref
884 * @short_description: A platform-independent way to refer to disk files
885 * @include: libchimara/glk.h
887 * You deal with disk files using file references. Each fileref is an opaque C
888 * structure pointer; see <link linkend="chimara-Opaque-Objects">Opaque
891 * A file reference contains platform-specific information about the name and
892 * location of the file, and possibly its type, if the platform has a notion of
893 * file type. It also includes a flag indication whether the file is a text file
897 * Note that this is different from the standard C I/O library, in which you
898 * specify text or binary mode when the file is opened.
901 * A fileref does not have to refer to a file which actually exists. You can
902 * create a fileref for a nonexistent file, and then open it in write mode to
905 * You always provide a usage argument when you create a fileref. The usage
906 * indicates the file type and the mode (text or binary.) It must be the
907 * logical-or of a file-type constant and a mode constant. These values are used
908 * when you create a new file, and also to filter file lists when the player is
909 * selecting a file to load.
911 * In general, you should use text mode if the player expects to read the file
912 * with a platform-native text editor; you should use binary mode if the file is
913 * to be read back by your program, or if the data must be stored exactly. Text
914 * mode is appropriate for %fileusage_Transcript; binary mode is appropriate for
915 * %fileusage_SavedGame and probably for %fileusage_InputRecord. %fileusage_Data
916 * files may be text or binary, depending on what you use them for.
920 * SECTION:glk-fileref-types
921 * @short_description: Four different ways to create a file reference
922 * @include: libchimara/glk.h
924 * There are four different functions for creating a fileref, depending on how
925 * you wish to specify it. Remember that it is always possible that a fileref
926 * creation will fail and return %NULL.
930 * SECTION:glk-fileref-other
931 * @short_description: Miscellaneous functions for file references
932 * @include: libchimara/glk.h
934 * This section includes functions for file references that don't fit anywhere
939 * SECTION:glk-image-resources
940 * @short_description: Graphics in Glk
941 * @include: libchimara/glk.h
943 * In accordance with this modern age, Glk provides for a modicum of graphical
944 * flair. It does not attempt to be a complete graphical toolkit. Those already
945 * exist. Glk strikes the usual uncomfortable balance between power,
946 * portability, and ease of implementation: commands for arranging pre-supplied
947 * images on the screen and intermixed with text.
949 * Graphics is an optional capability in Glk; not all libraries support
950 * graphics. This should not be a surprise.
952 * Most of the graphics commands in Glk deal with image resources. Your program
953 * does not have to worry about how images are stored. Everything is a resource,
954 * and a resource is referred to by an integer identifier. You may, for example,
955 * call a function to display image number 17. The format, loading, and
956 * displaying of that image is entirely up to the Glk library for the platform
959 * Of course, it is also desirable to have a platform-independent way to store
960 * sounds and images. Blorb is the official resource-storage format of Glk. A
961 * Glk library does not have to understand Blorb, but it is more likely to
962 * understand Blorb than any other format.
965 * Glk does not specify the exact format of images, but Blorb does. Images in
966 * a Blorb archive must be PNG or JPEG files. More formats may be added if
967 * real-world experience shows it to be desirable. However, that is in the
968 * domain of the Blorb specification. The Glk spec, and Glk programming, will
972 * At present, images can only be drawn in graphics windows and text buffer
973 * windows. In fact, a library may not implement both of these possibilities.
974 * You should test each with the %gestalt_DrawImage selector if you plan to use
975 * it. See <link linkend="chimara-Testing-for-Graphics-Capabilities">Testing for
976 * Graphics Capabilities</link>.
980 * SECTION:glk-graphics-windows
981 * @short_description: Drawing graphics in graphics windows
982 * @include: libchimara/glk.h
984 * A graphics window is a rectangular canvas of pixels, upon which you can draw
985 * images. The contents are entirely under your control. You can draw as many
986 * images as you like, at any positions — overlapping if you like. If the
987 * window is resized, you are responsible for redrawing everything. See <link
988 * linkend="wintype-Graphics">Graphics Windows</link>.
991 * Note that graphics windows do not support a full set of object-drawing
992 * commands, nor can you draw text in them. That may be available in a future
993 * Glk extension. For now, it seems reasonable to limit the task to a single
994 * primitive, the drawing of a raster image. And then there's the ability to
995 * fill a rectangle with a solid color — a small extension, and
996 * hopefully no additional work for the library, since it can already clear
997 * with arbitrary background colors. In fact, if glk_window_fill_rect() did
998 * not exist, an author could invent it — by briefly setting the
999 * background color, erasing a rectangle, and restoring.
1002 * If you call glk_image_draw() or glk_image_draw_scaled() in a graphics window,
1003 * @val1 and @val2 are interpreted as X and Y coordinates. The image will be
1004 * drawn with its upper left corner at this position.
1006 * It is legitimate for part of the image to fall outside the window; the excess
1007 * is not drawn. Note that these are signed arguments, so you can draw an image
1008 * which falls outside the left or top edge of the window, as well as the right
1011 * There are a few other commands which apply to graphics windows.
1015 * SECTION:glk-graphics-text
1016 * @short_description: Drawing graphics inside or beside text
1017 * @include: libchimara/glk.h
1019 * A text buffer is a linear text stream. You can draw images in-line with this
1020 * text. If you are familiar with HTML, you already understand this model. You
1021 * draw images with flags indicating alignment. The library takes care of
1022 * scrolling, resizing, and reformatting text buffer windows.
1024 * If you call glk_image_draw() or glk_image_draw_scaled() in a text buffer
1025 * window, @val1 gives the image alignment. The @val2 argument is currently
1026 * unused, and should always be zero.
1028 * The two <quote>margin</quote> alignments require some care. To allow proper
1029 * positioning, images using %imagealign_MarginLeft and %imagealign_MarginRight
1030 * must be placed at the beginning of a line. That is, you may only call
1031 * glk_image_draw() (with these two alignments) in a window, if you have just
1032 * printed a newline to the window's stream, or if the window is entirely empty.
1033 * If you margin-align an image in a line where text has already appeared, no
1034 * image will appear at all.
1036 * Inline-aligned images count as <quote>text</quote> for the purpose of this
1039 * You may have images in both margins at the same time.
1041 * It is also legal to have more than one image in the same margin (left or
1042 * right.) However, this is not recommended. It is difficult to predict how text
1043 * will wrap in that situation, and libraries may err on the side of
1048 * SECTION:glk-graphics-testing
1049 * @short_description: Checking whether the library supports graphics
1050 * @include: libchimara/glk.h
1052 * Before calling Glk graphics functions, you should use the gestalt selector
1053 * %gestalt_Graphics. To test for additional capabilities, you can also use the
1054 * %gestalt_DrawImage and %gestalt_GraphicsTransparency selectors.
1058 * SECTION:glk-sound-channels
1059 * @short_description: Creating new sound channels and closing them
1060 * @include: libchimara/glk.h
1062 * Sounds in Glk are played through sound channels. Sound channels are another
1063 * type of opaque object, like windows, streams, and file references.
1067 * SECTION:glk-playing-sounds
1068 * @short_description: Producing noise
1069 * @include: libchimara/glk.h
1071 * These functions play the actual sounds through the sound channels.
1075 * SECTION:glk-sound-other
1076 * @short_description: Miscellaneous functions for sound channels
1077 * @include: libchimara/glk.h
1079 * This section includes functions for sound channels that don't fit anywhere
1084 * SECTION:glk-sound-testing
1085 * @short_description: Checking whether the library supports sound
1086 * @include: libchimara/glk.h
1088 * Before calling Glk sound functions, you should use the %gestalt_Sound
1089 * selector. To test for additional capabilities, you can use the
1090 * %gestalt_SoundMusic, %gestalt_SoundVolume, and %gestalt_SoundNotify
1095 * SECTION:glk-creating-hyperlinks
1096 * @short_description: Printing text as a hyperlink
1097 * @include: libchimara/glk.h
1099 * Some games may wish to mark up text in their windows with hyperlinks, which
1100 * can be selected by the player — most likely by mouse click. Glk allows
1101 * this in a manner similar to the way text styles are set.
1103 * Hyperlinks are an optional capability in Glk.
1107 * SECTION:glk-accepting-hyperlinks
1108 * @short_description: Generating and catching hyperlink navigation events
1109 * @include: libchimara/glk.h
1111 * When you request a hyperlink event in a window, you will receive a hyperlink
1112 * event when the player clicks on a hyperlink.
1116 * SECTION:glk-hyperlinks-testing
1117 * @short_description: Checking whether the library supports hyperlinks
1118 * @include: libchimara/glk.h
1120 * Before calling Glk hyperlink functions, you should use the gestalt selectors
1121 * %gestalt_Hyperlinks and %gestalt_HyperlinkInput.
1126 * @short_description: Getting the current time from the system clock
1127 * @include: libchimara/glk.h
1129 * You can get the current time, either as a Unix timestamp (seconds since 1970)
1130 * or as a broken-out structure of time elements (year, month, day, hour,
1133 * The system clock is not guaranteed to line up with timer events (see <link
1134 * linkend="chimara-Timer-Events">Timer Events</link>). Timer events may be
1135 * delivered late according to the system clock.
1139 * SECTION:glk-clock-conversions
1140 * @short_description: Converting from timestamps to date structures and back
1141 * @include: libchimara/glk.h
1143 * This section describes functions for converting timestamps to more
1144 * human-readable date structures and back.
1148 * SECTION:glk-clock-testing
1149 * @short_description: Checking whether the library supports the clock functions
1150 * @include: libchimara/glk.h
1152 * Before calling Glk date and time functions, you should use the following
1157 * SECTION:dispatch-interrogating
1158 * @short_description: Finding out what functions the Glk library exports
1159 * @include: libchimara/glk.h, libchimara/gi_dispa.h
1161 * These are the ancilliary functions that let you enumerate.
1165 * SECTION:dispatch-dispatching
1166 * @short_description: Dispatching the call to the Glk library
1167 * @include: libchimara/glk.h, libchimara/gi_dispa.h
1169 * The function gidispatch_call() invokes a function from the Glk library.
1173 * SECTION:dispatch-prototypes
1174 * @short_description: Querying Glk function prototypes
1175 * @include: libchimara/glk.h, libchimara/gi_dispa.h
1177 * There are many possible ways to set up a #gluniversal_t array, and it's
1178 * illegal to call gidispatch_call() with an array which doesn't match the
1179 * function. Furthermore, some references are passed in, some passed out, and
1180 * some both. How do you know how to handle the argument list?
1182 * One possibility is to recognize each function selector, and set up the
1183 * arguments appropriately. However, this entails writing special code for each
1184 * Glk function; which is exactly what we don't want to do.
1186 * Instead, you can call gidispatch_prototype().
1190 * SECTION:dispatch-library-functions
1191 * @short_description: Platform-dependent dispatch layer functions
1192 * @include: libchimara/glk.h, libchimara/gi_dispa.h
1194 * Ideally, the three layers — program, dispatch layer, Glk library
1195 * — would be completely modular; each would refer only to the layers
1196 * beneath it. Sadly, there are a few places where the library must notify the
1197 * program that something has happened. Worse, these situations are only
1198 * relevant to programs which use the dispatch layer, and then only some of
1201 * Since C is uncomfortable with the concept of calling functions which may not
1202 * exist, Glk handles this with call-back function pointers. The program can
1203 * pass callbacks in to the library; if it does, the library will call them, and
1204 * if not, the library doesn't try.
1206 * These callbacks are optional, in the sense that the program may or may not
1207 * set them. However, any library which wants to interoperate with the dispatch
1208 * layer must <emphasis>allow</emphasis> the program to set them; it is the
1209 * program's choice. The library does this by implementing
1210 * <code>set_registry functions</code> — the functions to which the
1211 * program passes its callbacks.
1214 * Even though these callbacks and the functions to set them are declared in
1215 * <filename class="headerfile">gi_dispa.h</filename>, they are not defined in
1216 * <filename>gi_dispa.c</filename>. The dispatch layer merely coordinates
1217 * them. The program defines the callback functions; the library calls them.
1222 * SECTION:blorb-program
1223 * @short_description: How to use the Blorb layer in your program
1224 * @include: libchimara/glk.h, libchimara/gi_blorb.h
1226 * If you wish your program to load its resources from a Blorb file, you need to
1227 * find and open that file in your startup code. (See <link
1228 * linkend="chimara-Startup-Options">Startup Options</link>.) Each platform will
1229 * have appropriate functions available for finding startup data. Be sure to
1230 * open the file in binary mode, not text mode. Once you have opened the file as
1231 * a Glk stream, pass it to giblorb_set_resource_map().
1233 * If you do not call giblorb_set_resource_map() in your startup code, or if it
1234 * fails, the library is left to its own devices for finding resources. Some
1235 * libraries may try to load resources from individual files —
1236 * <filename>PIC1</filename>, <filename>PIC2</filename>,
1237 * <filename>PIC3</filename>, and so on. (See the Blorb specification for more
1238 * on this approach.) Other libraries will not have any other loading mechanism
1239 * at all; no resources will be available.
1243 * SECTION:blorb-layer
1244 * @short_description: The platform-independent functions in the Blorb layer
1245 * @include: libchimara/glk.h, libchimara/gi_blorb.h
1247 * These are the functions which are implemented in
1248 * <filename>gi_blorb.c</filename>. They will be compiled into the library, but
1249 * they are the same on every platform. In general, only the library needs to
1250 * call these functions. The Glk program should allow the library to do all the
1251 * resource handling.
1255 * SECTION:blorb-errors
1256 * @short_description: Error codes returned by the Blorb layer functions
1257 * @include: libchimara/glk.h, libchimara/gi_blorb.h
1259 * All Blorb layer functions, including giblorb_set_resource_map(), return the
1260 * following error codes.
1264 * SECTION:glkext-startup
1265 * @short_description: Parsing startup options
1266 * @include: libchimara/glk.h, libchimara/glkstart.h
1268 * This section describes an extension to Glk for parsing command-line startup
1269 * options. It was written by Andrew Plotkin for the Glk libraries CheapGlk and
1272 * When you compile a Glk program, you may define a function called
1273 * <function>glkunix_startup_code()</function>, and an array
1274 * <code>glkunix_arguments[]</code>. These set up various Unix-specific options
1275 * used by the Glk library. There is a sample
1276 * <quote><filename>glkstart.c</filename></quote> file included in this package;
1277 * you should modify it to your needs.
1279 * |[ extern glkunix_argumentlist_t glkunix_arguments[]; ]|
1281 * The <code>glkunix_arguments[]</code> array is a list of command-line
1282 * arguments that your program can accept. The library will sort these out of
1283 * the command line and pass them on to your code.
1287 * SECTION:glkext-unix
1288 * @short_description: Unix-specific functions
1289 * @include: libchimara/glk.h, libchimara/glkstart.h
1291 * This section describes an extension to Glk for various Unix functions. It was
1292 * written by Andrew Plotkin for the Glk libraries CheapGlk and GlkTerm.
1294 * You can put other startup code in glkunix_startup_code(). This should
1295 * generally be limited to finding and opening data files. There are a few Unix
1296 * Glk library functions which are convenient for this purpose.
1300 * SECTION:glkext-garglk
1301 * @short_description: Gargoyle extensions to Glk
1302 * @include: libchimara/glk.h, libchimara/garglk.h
1304 * This section describes various extensions to Glk that were written for the
1305 * popular interpreter <ulink
1306 * url="http://www.ccxvii.net/gargoyle/">Gargoyle</ulink> by Tor Andersson (now
1307 * maintained by Ben Cressey).
1309 * These functions mostly serve to close the gap between Glk's input/output
1310 * capabilities and what some interpreters expect. For example,
1311 * garglk_set_zcolors() displays the colors defined in the Z-machine standard,
1312 * and garglk_set_story_name() can be used to give the host program a hint
1313 * about what to display in the title bar of its window.
1316 /*---------------- TYPES AND CONSTANTS FROM GLK.H ----------------------------*/
1321 * A 32-bit unsigned integer type, used wherever possible in Glk.
1327 * A 32-bit signed integer type, rarely used.
1331 * GLK_MODULE_UNICODE:
1333 * If this preprocessor symbol is defined, so are the core Unicode functions and
1334 * constants (see %gestalt_Unicode). If not, not.
1340 * If you are writing a C program, there is an additional complication. A
1341 * library which does not support graphics may not implement the graphics
1342 * functions at all. Even if you put gestalt tests around your graphics calls,
1343 * you may get link-time errors. If the <filename
1344 * class="headerfile">glk.h</filename> file is so old that it does not declare
1345 * the graphics functions and constants, you may even get compile-time errors.
1347 * To avoid this, you can perform a preprocessor test for the existence of
1348 * %GLK_MODULE_IMAGE. If this is defined, so are all the functions and constants
1349 * described in this section. If not, not.
1352 * To be extremely specific, there are two ways this can happen. If the
1353 * <filename class="headerfile">glk.h</filename> file that comes with the
1354 * library is too old to have the graphics declarations in it, it will of
1355 * course lack %GLK_MODULE_IMAGE as well. If the <filename
1356 * class="headerfile">glk.h</filename> file is recent, but the library is old,
1357 * the definition of %GLK_MODULE_IMAGE should be removed from <filename
1358 * class="headerfile">glk.h</filename>, to avoid link errors. This is not a
1359 * great solution. A better one is for the library to implement the graphics
1360 * functions as stubs that do nothing (or cause run-time errors). Since no
1361 * program will call the stubs without testing %gestalt_Graphics, this is
1369 * If you are writing a C program, there is an additional complication. A
1370 * library which does not support sound may not implement the sound functions at
1371 * all. Even if you put gestalt tests around your sound calls, you may get
1372 * link-time errors. If the <filename class="headerfile">glk.h</filename> file
1373 * is so old that it does not declare the sound functions and constants, you may
1374 * even get compile-time errors.
1376 * To avoid this, you can perform a preprocessor test for the existence of
1377 * %GLK_MODULE_SOUND. If this is defined, so are all the functions and constants
1378 * described in this section. If not, not.
1382 * GLK_MODULE_HYPERLINKS:
1384 * If you are writing a C program, you can perform a preprocessor test for the
1385 * existence of %GLK_MODULE_HYPERLINKS. If this is defined, so are all the
1386 * functions and constants described in this section. If not, not.
1390 * GLK_MODULE_UNICODE_NORM:
1392 * If this preprocessor symbol is defined, so are the Unicode normalization
1393 * functions (see %gestalt_UnicodeNorm). If not, not.
1397 * GLK_MODULE_DATETIME:
1399 * If you are writing a C program, you can perform a preprocessor test for the
1400 * existence of %GLK_MODULE_DATETIME. If this is defined, so are all the
1401 * functions and data types described in this section.
1405 * GLK_MODULE_LINE_ECHO:
1407 * If this preprocessor symbol is defined, so is glk_set_echo_line_event(). If
1412 * GLK_MODULE_LINE_TERMINATORS:
1414 * If this preprocessor symbol is defined, so is
1415 * glk_set_terminators_line_event(). If not, not.
1421 * Opaque structure representing a Glk window. It has no user-accessible
1428 * Opaque structure representing an input or output stream. It has no
1429 * user-accessible members.
1435 * Opaque structure representing a file reference. It has no user-accessible
1442 * Opaque structure representing a sound channel. It has no user-accessible
1449 * For an example of the gestalt mechanism, consider the selector
1450 * %gestalt_Version. If you do
1453 * res = glk_gestalt(gestalt_Version, 0);
1455 * <code>res</code> will be set to a 32-bit number which encodes the version of
1456 * the Glk spec which the library implements. The upper 16 bits stores the major
1457 * version number; the next 8 bits stores the minor version number; the low 8
1458 * bits stores an even more minor version number, if any.
1461 * So the version number 78.2.11 would be encoded as 0x004E020B.
1464 * The current Glk specification version is 0.7.2, so this selector will return
1469 * res = glk_gestalt_ext(gestalt_Version, 0, NULL, 0);
1471 * does exactly the same thing. Note that, in either case, the second argument
1472 * is not used; so you should always pass 0 to avoid future surprises.
1476 * gestalt_CharInput:
1478 * If you set <code>ch</code> to a character code, or a special code (from
1479 * 0xFFFFFFFF down), and call
1482 * res = glk_gestalt(gestalt_CharInput, ch);
1484 * then <code>res</code> will be %TRUE (1) if that character can be typed by
1485 * the player in character input, and %FALSE (0) if not. See <link
1486 * linkend="chimara-Character-Input">Character Input</link>.
1490 * gestalt_LineInput:
1492 * If you set <code>ch</code> to a character code, and call
1495 * res = glk_gestalt(gestalt_LineInput, ch);
1497 * then <code>res</code> will be %TRUE (1) if that character can be typed by the
1498 * player in line input, and %FALSE (0) if not. Note that if <code>ch</code> is
1499 * a nonprintable Latin-1 character (0 to 31, 127 to 159), then this is
1500 * guaranteed to return %FALSE. See <link linkend="chimara-Line-Input">Line
1505 * gestalt_CharOutput:
1507 * If you set <code>ch</code> to a character code (Latin-1 or higher), and call
1510 * res = glk_gestalt_ext(gestalt_CharOutput, ch, &len, 1);
1512 * then <code>res</code> will be one of %gestalt_CharOutput_CannotPrint,
1513 * %gestalt_CharOutput_ExactPrint, or %gestalt_CharOutput_ApproxPrint (see
1516 * In all cases, <code>len</code> (the #glui32 value pointed at by the third
1517 * argument) will be the number of actual glyphs which will be used to represent
1518 * the character. In the case of %gestalt_CharOutput_ExactPrint, this will
1519 * always be 1; for %gestalt_CharOutput_CannotPrint, it may be 0 (nothing
1520 * printed) or higher; for %gestalt_CharOutput_ApproxPrint, it may be 1 or
1521 * higher. This information may be useful when printing text in a fixed-width
1525 * As described in <link linkend="chimara-Other-API-Conventions">Other API
1526 * Conventions</link>, you may skip this information by passing %NULL as the
1527 * third argument in glk_gestalt_ext(), or by calling glk_gestalt() instead.
1530 * This selector will always return %gestalt_CharOutput_CannotPrint if
1531 * <code>ch</code> is an unprintable eight-bit character (0 to 9, 11 to 31, 127
1535 * Make sure you do not get confused by signed byte values. If you set a
1536 * <quote><type>signed char</type></quote> variable <code>ch</code> to 0xFE,
1537 * the small-thorn character (þ), it will wind up as -2. (The same is
1538 * true of a <quote><type>char</type></quote> variable, if your compiler
1539 * treats <quote><type>char</type></quote> as signed!) If you then call
1540 * |[ res = glk_gestalt(gestalt_CharOutput, ch); ]|
1541 * then (by the definition of C/C++) <code>ch</code> will be sign-extended to
1542 * 0xFFFFFFFE, which is not a legitimate character, even in Unicode. You
1544 * |[ res = glk_gestalt(gestalt_CharOutput, (unsigned char)ch); ]|
1548 * Unicode includes the concept of non-spacing or combining characters, which
1549 * do not represent glyphs; and double-width characters, whose glyphs take up
1550 * two spaces in a fixed-width font. Future versions of this spec may
1551 * recognize these concepts by returning a <code>len</code> of 0 or 2 when
1552 * %gestalt_CharOutput_ExactPrint is used. For the moment, we are adhering to
1553 * a policy of <quote>simple stuff first</quote>.
1558 * gestalt_CharOutput_CannotPrint:
1560 * When the %gestalt_CharOutput selector returns this for a character, the
1561 * character cannot be meaningfully printed. If you try, the player may see
1562 * nothing, or may see a placeholder.
1566 * gestalt_CharOutput_ApproxPrint:
1568 * When the %gestalt_CharOutput selector returns this for a character, the
1569 * library will print some approximation of the character. It will be more or
1570 * less right, but it may not be precise, and it may not be distinguishable from
1571 * other, similar characters. (Examples:
1572 * <quote><computeroutput>ae</computeroutput></quote> for the one-character
1573 * <quote>æ</quote> ligature,
1574 * <quote><computeroutput>e</computeroutput></quote> for
1575 * <quote>è</quote>, <quote><computeroutput>|</computeroutput></quote>
1576 * for a broken vertical bar (¦).)
1580 * gestalt_CharOutput_ExactPrint:
1582 * When the %gestalt_CharOutput selector returns this for a character, the
1583 * character will be printed exactly as defined.
1587 * gestalt_MouseInput:
1589 * You can test whether mouse input is supported with the %gestalt_MouseInput
1591 * |[ res = glk_gestalt(gestalt_MouseInput, windowtype); ]|
1592 * This will return %TRUE (1) if windows of the given type support mouse input.
1593 * If this returns %FALSE (0), it is still legal to call
1594 * glk_request_mouse_event(), but it will have no effect, and you will never get
1601 * You can test whether the library supports timer events:
1602 * |[ res = glk_gestalt(gestalt_Timer, 0); ]|
1603 * This returns %TRUE (1) if timer events are supported, and %FALSE (0) if they
1610 * Before calling Glk graphics functions, you should use the following gestalt
1614 * res = glk_gestalt(gestalt_Graphics, 0);
1616 * This returns 1 if the overall suite of graphics functions is available. This
1617 * includes glk_image_draw(), glk_image_draw_scaled(), glk_image_get_info(),
1618 * glk_window_erase_rect(), glk_window_fill_rect(),
1619 * glk_window_set_background_color(), and glk_window_flow_break(). It also
1620 * includes the capability to create graphics windows.
1622 * If this selector returns 0, you should not try to call these functions. They
1623 * may have no effect, or they may cause a run-time error. If you try to create
1624 * a graphics window, you will get %NULL.
1628 * gestalt_DrawImage:
1630 * This selector returns 1 if images can be drawn in windows of the given type.
1631 * If it returns 0, glk_image_draw() will fail and return %FALSE (0). You should
1632 * test %wintype_Graphics and %wintype_TextBuffer separately, since libraries
1633 * may implement both, neither, or only one.
1639 * You can test whether the library supports sound:
1642 * res = glk_gestalt(gestalt_Sound, 0);
1644 * This returns 1 if the overall suite of sound functions is available. This
1645 * includes glk_schannel_create(), glk_schannel_destroy(),
1646 * glk_schannel_iterate(), glk_schannel_get_rock(), glk_schannel_play(),
1647 * glk_schannel_play_ext(), glk_schannel_stop(), glk_schannel_set_volume(), and
1648 * glk_sound_load_hint().
1650 * If this selector returns 0, you should not try to call these functions. They
1651 * may have no effect, or they may cause a run-time error.
1655 * gestalt_SoundVolume:
1657 * You can test whether the library supports setting the volume of sound
1661 * res = glk_gestalt(gestalt_SoundVolume, 0);
1663 * This selector returns 1 if the glk_schannel_set_volume() function works. If
1664 * it returns zero, glk_schannel_set_volume() has no effect.
1668 * gestalt_SoundNotify:
1670 * You can test whether the library supports sound notification events:
1673 * res = glk_gestalt(gestalt_SoundNotify, 0);
1675 * This selector returns 1 if the library supports sound notification events. If
1676 * it returns zero, you will never get such events.
1680 * gestalt_Hyperlinks:
1682 * You can test whether the library supports hyperlinks:
1685 * res = glk_gestalt(gestalt_Hyperlinks, 0);
1687 * This returns 1 if the overall suite of hyperlinks functions is available.
1688 * This includes glk_set_hyperlink(), glk_set_hyperlink_stream(),
1689 * glk_request_hyperlink_event(), glk_cancel_hyperlink_event().
1691 * If this selector returns 0, you should not try to call these functions. They
1692 * may have no effect, or they may cause a run-time error.
1696 * gestalt_HyperlinkInput:
1698 * You can test whether hyperlinks are supported with the
1699 * %gestalt_HyperlinkInput selector:
1700 * |[ res = glk_gestalt(gestalt_HyperlinkInput, windowtype); ]|
1701 * This will return %TRUE (1) if windows of the given type support hyperlinks.
1702 * If this returns %FALSE (0), it is still legal to call glk_set_hyperlink() and
1703 * glk_request_hyperlink_event(), but they will have no effect, and you will
1704 * never get hyperlink events.
1708 * gestalt_SoundMusic:
1710 * You can test whether music resources are supported:
1711 * |[ res = glk_gestalt(gestalt_SoundMusic, 0); ]|
1712 * This returns 1 if the library is capable of playing music sound resources. If
1713 * it returns 0, only sampled sounds can be played.
1715 * <quote>Music sound resources</quote> means MOD songs — the only music
1716 * format that Blorb currently supports. The presence of this selector is, of
1717 * course, an ugly hack. It is a concession to the current state of the Glk
1718 * libraries, some of which can handle AIFF but not MOD sounds.
1723 * gestalt_GraphicsTransparency:
1725 * This returns 1 if images with alpha channels can actually be drawn with the
1726 * appropriate degree of transparency. If it returns 0, the alpha channel is
1727 * ignored; fully transparent areas will be drawn in an implementation-defined
1730 * The JPEG format does not support transparency or alpha channels; the PNG
1738 * The basic text functions will be available in every Glk library. The Unicode
1739 * functions may or may not be available. Before calling them, you should use
1740 * the %gestalt_Unicode and %gestalt_UnicodeNorm gestalt selectors.
1744 * res = glk_gestalt(gestalt_Unicode, 0);
1746 * This returns 1 if the core Unicode functions are available. If it returns 0,
1747 * you should not try to call them. They may print nothing, print gibberish, or
1748 * cause a run-time error. The Unicode functions include
1749 * glk_buffer_to_lower_case_uni(), glk_buffer_to_upper_case_uni(),
1750 * glk_buffer_to_title_case_uni(), glk_put_char_uni(), glk_put_string_uni(),
1751 * glk_put_buffer_uni(), glk_put_char_stream_uni(), glk_put_string_stream_uni(),
1752 * glk_put_buffer_stream_uni(), glk_get_char_stream_uni(),
1753 * glk_get_buffer_stream_uni(), glk_get_line_stream_uni(),
1754 * glk_request_char_event_uni(), glk_request_line_event_uni(),
1755 * glk_stream_open_file_uni(), glk_stream_open_memory_uni().
1757 * If you are writing a C program, there is an additional complication. A
1758 * library which does not support Unicode may not implement the Unicode
1759 * functions at all. Even if you put gestalt tests around your Unicode calls,
1760 * you may get link-time errors. If the
1761 * <filename class="headerfile">glk.h</filename> file is so old that it does not
1762 * declare the Unicode functions and constants, you may even get compile-time
1765 * To avoid this, you can perform a preprocessor test for the existence of
1766 * %GLK_MODULE_UNICODE.
1770 * gestalt_UnicodeNorm:
1774 * res = glk_gestalt(gestalt_UnicodeNorm, 0);
1776 * This code returns 1 if the Unicode normalization functions are available. If
1777 * it returns 0, you should not try to call them. The Unicode normalization
1778 * functions include glk_buffer_canon_decompose_uni() and
1779 * glk_buffer_canon_normalize_uni().
1781 * The equivalent preprocessor test for these functions is
1782 * %GLK_MODULE_UNICODE_NORM.
1786 * gestalt_LineInputEcho:
1789 * res = glk_gestalt(gestalt_LineInputEcho, 0);
1792 * This returns 1 if glk_set_echo_line_event() is supported, and 0 if it is not.
1794 * Remember that if it is not supported, the behavior is always the default,
1795 * which is line echoing <emphasis>enabled</emphasis>.
1800 * gestalt_LineTerminators:
1803 * res = glk_gestalt(gestalt_LineTerminators, 0);
1806 * This returns 1 if glk_set_terminators_line_event() is supported, and 0 if it
1811 * gestalt_LineTerminatorKey:
1814 * res = glk_gestalt(gestalt_LineTerminatorKey, ch);
1817 * This returns 1 if the keycode @ch can be passed to
1818 * glk_set_terminators_line_event(). If it returns 0, that keycode will be
1819 * ignored as a line terminator. Printable characters and %keycode_Return will
1827 * res = glk_gestalt(gestalt_DateTime, 0);
1830 * This returns 1 if the overall suite of system clock functions, as described
1831 * in this chapter, is available.
1833 * If this selector returns 0, you should not try to call these functions. They
1834 * may have no effect, or they may cause a run-time error.
1837 * Glk timer events are covered by a different selector. See %gestalt_Timer.
1844 * No event. This is a placeholder, and glk_select() never returns it.
1850 * An event that repeats at fixed intervals. See <link
1851 * linkend="chimara-Timer-Events">Timer Events</link>.
1857 * A keystroke event in a window. See <link
1858 * linkend="chimara-Character-Input-Events">Character Input Events</link>.
1860 * If a window has a pending request for character input, and the player hits a
1861 * key in that window, glk_select() will return an event whose type is
1862 * %evtype_CharInput. Once this happens, the request is complete; it is no
1863 * longer pending. You must call glk_request_char_event() or
1864 * glk_request_char_event_uni() if you want another character from that window.
1866 * In the event structure, @win tells what window the event came from. @val1
1867 * tells what character was entered; this will be a character code, or a special
1868 * keycode. (See <link linkend="chimara-Character-Input">Character
1869 * Input</link>.) If you called glk_request_char_event(), @val1 will be in
1870 * 0..255, or else a special keycode. In any case, @val2 will be 0.
1876 * A full line of input completed in a window. See <link
1877 * linkend="chimara-Line-Input-Events">Line Input Events</link>.
1879 * If a window has a pending request for line input, the player can generally
1880 * hit the <keycap>enter</keycap> key (in that window) to complete line input.
1881 * The details will depend on the platform's native user interface.
1883 * When line input is completed, glk_select() will return an event whose type is
1884 * %evtype_LineInput. Once this happens, the request is complete; it is no
1885 * longer pending. You must call glk_request_line_event() if you want another
1886 * line of text from that window.
1888 * In the event structure, @win tells what window the event came from. @val1
1889 * tells how many characters were entered. @val2 will be 0 unless input was
1890 * ended by a special terminator key, in which case @val2 will be the keycode
1891 * (one of the values passed to glk_set_terminators_line_event()).
1893 * The characters themselves are stored in the buffer specified in the original
1894 * glk_request_line_event() or glk_request_line_event_uni() call.
1897 * There is no null terminator or newline stored in the buffer.
1900 * It is illegal to print anything to a window which has line input pending.
1903 * This is because the window may be displaying and editing the player's
1904 * input, and printing anything would make life unnecessarily complicated for
1910 * evtype_MouseInput:
1912 * A mouse click in a window. See <link
1913 * linkend="chimara-Mouse-Input-Events">Mouse Input Events</link>.
1919 * An event signalling that the sizes of some windows have changed.
1921 * Some platforms allow the player to resize the Glk window during play. This
1922 * will naturally change the sizes of your windows. If this occurs, then
1923 * immediately after all the rearrangement, glk_select() will return an event
1924 * whose type is %evtype_Arrange. You can use this notification to redisplay the
1925 * contents of a graphics or text grid window whose size has changed.
1928 * The display of a text buffer window is entirely up to the library, so you
1929 * don't need to worry about those.
1932 * In the event structure, @win will be %NULL if all windows are affected. If
1933 * only some windows are affected, @win will refer to a window which contains
1934 * all the affected windows. @val1 and @val2 will be 0.
1937 * You can always play it safe, ignore @win, and redraw every graphics and
1941 * An arrangement event is guaranteed to occur whenever the player causes any
1942 * window to change size, as measured by its own metric.
1945 * Size changes caused by you — for example, if you open, close, or
1946 * resize a window — do not trigger arrangement events. You must be
1947 * aware of the effects of your window management, and redraw the windows that
1952 * It is possible that several different player actions can cause windows to
1953 * change size. For example, if the player changes the screen resolution, an
1954 * arrangement event might be triggered. This might also happen if the player
1955 * changes his display font to a different size; the windows would then be
1956 * different <quote>sizes</quote> in the metric of rows and columns, which is
1957 * the important metric and the only one you have access to.
1960 * Arrangement events, like timer events, can be returned by glk_select_poll().
1961 * But this will not occur on all platforms. You must be ready to receive an
1962 * arrangement event when you call glk_select_poll(), but it is possible that it
1963 * will not arrive until the next time you call glk_select().
1966 * This is because on some platforms, window resizing is handled as part of
1967 * player input; on others, it can be triggered by an external process such as
1975 * An event signalling that graphics windows must be redrawn.
1977 * On platforms that support graphics, it is possible that the contents of a
1978 * graphics window will be lost, and have to be redrawn from scratch. If this
1979 * occurs, then glk_select() will return an event whose type is %evtype_Redraw.
1981 * In the event structure, @win will be %NULL if all windows are affected. If
1982 * only some windows are affected, @win will refer to a window which contains
1983 * all the affected windows. @val1 and @val2 will be 0.
1986 * You can always play it safe, ignore @win, and redraw every graphics window.
1989 * Affected windows are already cleared to their background color when you
1990 * receive the redraw event.
1992 * Redraw events can be returned by glk_select_poll(). But, like arrangement
1993 * events, this is platform-dependent. See %evtype_Arrange.
1995 * For more about redraw events and how they affect graphics windows, see <link
1996 * linkend="wintype-Graphics">Graphics Windows</link>.
2000 * evtype_SoundNotify:
2002 * On platforms that support sound, you can request to receive an
2003 * %evtype_SoundNotify event when a sound finishes playing. See <link
2004 * linkend="chimara-Playing-Sounds">Playing Sounds</link>.
2010 * On platforms that support hyperlinks, you can request to receive an
2011 * %evtype_Hyperlink event when the player selects a link. See <link
2012 * linkend="chimara-Accepting-Hyperlink-Events">Accepting Hyperlink
2018 * @type: the event type
2019 * @win: the window that spawned the event, or %NULL
2020 * @val1: information, the meaning of which depends on the type of event
2021 * @val2: more information, the meaning of which depends on the type of event
2023 * The event structure is self-explanatory. @type is the event type. The window
2024 * that spawned the event, if relevant, is in @win. The remaining fields contain
2025 * more information specific to the event.
2027 * The event types are described below. Note that %evtype_None is zero, and the
2028 * other values are positive. Negative event types (0x80000000 to 0xFFFFFFFF)
2029 * are reserved for implementation-defined events.
2035 * Represents any key that has no Latin-1 or special code.
2041 * Represents the <keycap function="left">left arrow</keycap> key.
2047 * Represents the <keycap function="right">right arrow</keycap> key.
2053 * Represents the <keycap function="up">up arrow</keycap> key.
2059 * Represents the <keycap function="down">down arrow</keycap> key.
2065 * Represents the <keycap function="enter">return</keycap> or <keycap
2066 * function="enter">enter</keycap> keys.
2072 * Represents the <keycap function="delete">delete</keycap> or <keycap
2073 * function="backspace">backspace</keycap> keys.
2079 * Represents the <keycap function="escape">escape</keycap> key.
2085 * Represents the <keycap function="tab">tab</keycap> key.
2091 * Represents the <keycap function="pageup">page up</keycap> key.
2097 * Represents the <keycap function="pagedown">page down</keycap> key.
2103 * Represents the <keycap function="home">home</keycap> key.
2109 * Represents the <keycap function="end">end</keycap> key.
2115 * Represents the <keycap>F1</keycap> key.
2121 * Represents the <keycap>F2</keycap> key.
2127 * Represents the <keycap>F3</keycap> key.
2133 * Represents the <keycap>F4</keycap> key.
2139 * Represents the <keycap>F5</keycap> key.
2145 * Represents the <keycap>F6</keycap> key.
2151 * Represents the <keycap>F7</keycap> key.
2157 * Represents the <keycap>F8</keycap> key.
2163 * Represents the <keycap>F9</keycap> key.
2169 * Represents the <keycap>F10</keycap> key.
2175 * Represents the <keycap>F11</keycap> key.
2181 * Represents the <keycap>F12</keycap> key.
2187 * The style of normal or body text. A new window or stream always starts with
2188 * %style_Normal as the current style.
2194 * Text which is emphasized.
2198 * style_Preformatted:
2200 * Text which has a particular arrangement of characters.
2202 * This style, unlike the others, does have a standard appearance; it will
2203 * always be a fixed-width font. This is a concession to practicality. Games
2204 * often want to display maps or diagrams using character graphics, and this is
2205 * the style for that.
2212 * Text which introduces a large section. This is suitable for the title of an
2213 * entire game, or a major division such as a chapter.
2219 * Text which introduces a smaller section within a large section.
2221 * In a Colossal-Cave-style game, this is suitable for the name of a room (when
2222 * the player looks around.)
2229 * Text which warns of a dangerous condition, or one which the player should pay
2236 * Text which notifies of an interesting condition.
2238 * This is suitable for noting that the player's score has changed.
2245 * Text which forms a quotation or otherwise abstracted text.
2251 * Text which the player has entered. You should generally not use this style at
2252 * all; the library uses it for text which is typed during a line-input request.
2253 * One case when it is appropriate for you to use %style_Input is when you are
2254 * simulating player input by reading commands from a text file.
2260 * This style has no particular semantic meaning. You may define a meaning
2261 * relevant to your own work, and use it as you see fit.
2267 * Another style available for your use.
2272 * @readcount: Number of characters read from the stream.
2273 * @writecount: Number of characters printed to the stream, including ones that
2276 * If you are interested in the character counts of a stream (see <link
2277 * linkend="chimara-Streams">Streams</link>), then you can pass a pointer to
2278 * #stream_result_t as an argument of glk_stream_close() or glk_window_close().
2279 * The structure will be filled with the stream's final character counts.
2285 * A constant representing all window types, which may be used as the @wintype
2286 * argument in glk_stylehint_set().
2292 * A pair window is completely filled by the two windows it contains. It
2293 * supports no input and no output, and it has no size.
2295 * You cannot directly create a pair window; one is automatically created
2296 * every time you split a window with glk_window_open(). Pair windows are
2297 * always created with a rock value of 0.
2299 * You can close a pair window with glk_window_close(); this also closes every
2300 * window contained within the pair window.
2302 * It is legal to split a pair window when you call glk_window_open().
2308 * A blank window is always blank. It supports no input and no output. (You
2309 * can call glk_window_get_stream() on it, as you can with any window, but
2310 * printing to the resulting stream has no effect.) A blank window has no
2311 * size; glk_window_get_size() will return (0,0), and it is illegal to set a
2312 * window split with a fixed size in the measurement system of a blank window.
2315 * A blank window is not the same as there being no windows. When Glk starts
2316 * up, there are no windows at all, not even a window of the blank type.
2321 * wintype_TextBuffer:
2323 * A text buffer window contains a linear stream of text. It supports output;
2324 * when you print to it, the new text is added to the end. There is no way for
2325 * you to affect text which has already been printed. There are no guarantees
2326 * about how much text the window keeps; old text may be stored forever, so
2327 * that the user can scroll back to it, or it may be thrown away as soon as it
2328 * scrolls out of the window.
2331 * Therefore, there may or may not be a player-controllable scroll bar or
2332 * other scrolling widget.
2335 * The display of the text in a text buffer is up to the library. Lines will
2336 * probably not be broken in the middles of words — but if they are, the
2337 * library is not doing anything illegal, only ugly. Text selection and copying
2338 * to a clipboard, if available, are handled however is best on the player's
2339 * machine. Paragraphs (as defined by newline characters in the output) may be
2343 * You should not, in general, fake this by printing spaces before each
2344 * paragraph of prose text. Let the library and player preferences handle
2345 * that. Special cases (like indented lists) are of course up to you.
2348 * When a text buffer is cleared (with glk_window_clear()), the library will do
2349 * something appropriate; the details may vary. It may clear the window, with
2350 * later text appearing at the top — or the bottom. It may simply print
2351 * enough blank lines to scroll the current text out of the window. It may
2352 * display a distinctive page-break symbol or divider.
2354 * The size of a text buffer window is necessarily imprecise. Calling
2355 * glk_window_get_size() will return the number of rows and columns that would
2356 * be available <emphasis>if</emphasis> the window was filled with
2357 * <quote>0</quote> (zero) characters in the <quote>normal</quote> font.
2358 * However, the window may use a non-fixed-width font, so that number of
2359 * characters in a line could vary. The window might even support
2360 * variable-height text (say, if the player is using large text for emphasis);
2361 * that would make the number of lines in the window vary as well.
2363 * Similarly, when you set a fixed-size split in the measurement system of a
2364 * text buffer, you are setting a window which can handle a fixed number of rows
2365 * (or columns) of <quote>0</quote> characters. The number of rows (or
2366 * characters) that will actually be displayed depends on font variances.
2368 * A text buffer window supports both character and line input, but not mouse
2371 * In character input, there will be some visible signal that the window is
2372 * waiting for a keystroke. (Typically, a cursor at the end of the text.) When
2373 * the player hits a key in that window, an event is generated, but the key is
2374 * <emphasis>not</emphasis> printed in the window.
2376 * In line input, again, there will be some visible signal. It is most common
2377 * for the player to compose input in the window itself, at the end of the text.
2378 * (This is how IF story input usually looks.) But it's not strictly required.
2379 * An alternative approach is the way MUD clients usually work: there is a
2380 * dedicated one-line input window, outside of Glk's window space, and the user
2381 * composes input there.
2384 * If this approach is used, there will still be some way to handle input from
2385 * two windows at once. It is the library's responsibility to make this
2386 * available to the player. You only need request line input and wait for the
2390 * By default, when the player finishes his line of input, the library will
2391 * display the input text at the end of the buffer text (if it wasn't there
2392 * already.) It will be followed by a newline, so that the next text you print
2393 * will start a new line (paragraph) after the input.
2395 * If you call glk_cancel_line_event(), the same thing happens; whatever text
2396 * the user was composing is visible at the end of the buffer text, followed by
2399 * However, this default behavior can be changed with the
2400 * glk_set_echo_line_event() call. If the default echoing is disabled, the
2401 * library will <emphasis>not</emphasis> display the input text (plus newline)
2402 * after input is either completed or cancelled. The buffer will end with
2403 * whatever prompt you displayed before requesting input. If you want the
2404 * traditional input behavior, it is then your responsibility to print the text,
2405 * using the Input text style, followed by a newline (in the original style).
2411 * A text grid contains a rectangular array of characters, in a fixed-width
2412 * font. Its size is the number of columns and rows of the array.
2414 * A text grid window supports output. It maintains knowledge of an output
2415 * cursor position. When the window is opened, it is filled with blanks (space
2416 * characters), and the output cursor starts in the top left corner —
2417 * character (0,0). If the window is cleared with glk_window_clear(), the window
2418 * is filled with blanks again, and the cursor returns to the top left corner.
2420 * When you print, the characters of the output are laid into the array in
2421 * order, left to right and top to bottom. When the cursor reaches the end of a
2422 * line, or if a newline (0x0A) is printed, the cursor goes to the beginning of
2423 * the next line. The library makes <emphasis>no</emphasis> attempt to wrap
2424 * lines at word breaks. If the cursor reaches the end of the last line, further
2425 * printing has no effect on the window until the cursor is moved.
2428 * Note that printing fancy characters may cause the cursor to advance more
2429 * than one position per character. (For example, the <quote>æ</quote>
2430 * ligature may print as two characters.) See <link
2431 * linkend="chimara-Output">Output</link>, for how to test this situation.
2434 * You can set the cursor position with glk_window_move_cursor().
2436 * When a text grid window is resized smaller, the bottom or right area is
2437 * thrown away, but the remaining area stays unchanged. When it is resized
2438 * larger, the new bottom or right area is filled with blanks.
2441 * You may wish to watch for %evtype_Arrange events, and clear-and-redraw your
2442 * text grid windows when you see them change size.
2445 * Text grid window support character and line input, as well as mouse input (if
2446 * a mouse is available.)
2448 * Mouse input returns the position of the character that was touched, from
2451 * <alt>(width-1,height-1)</alt>
2452 * <mathphrase>(width - 1, height - 1)</mathphrase>
2456 * Character input is as described in the previous section.
2458 * Line input is slightly different; it is guaranteed to take place in the
2459 * window, at the output cursor position. The player can compose input only to
2460 * the right edge of the window; therefore, the maximum input length is
2462 * <alt>(windowwidth - 1 - cursorposition)</alt>
2463 * <mathphrase>(windowwidth - 1 - cursorposition)</mathphrase>
2465 * . If the maxlen argument of glk_request_line_event() is smaller than this,
2466 * the library will not allow the input cursor to go more than maxlen characters
2467 * past its start point.
2470 * This allows you to enter text in a fixed-width field, without the player
2471 * being able to overwrite other parts of the window.
2474 * When the player finishes his line of input, it will remain visible in the
2475 * window, and the output cursor will be positioned at the beginning of the
2476 * <emphasis>next</emphasis> row. Again, if you glk_cancel_line_event(), the
2477 * same thing happens. The glk_set_echo_line_event() call has no effect in grid
2484 * A graphics window contains a rectangular array of pixels. Its size is the
2485 * number of columns and rows of the array.
2487 * Each graphics window has a background color, which is initially white. You
2488 * can change this; see <link
2489 * linkend="chimara-Graphics-in-Graphics-Windows">Graphics in Graphics
2492 * When a graphics window is resized smaller, the bottom or right area is
2493 * thrown away, but the remaining area stays unchanged. When it is resized
2494 * larger, the new bottom or right area is filled with the background color.
2497 * You may wish to watch for %evtype_Arrange events, and clear-and-redraw your
2498 * graphics windows when you see them change size.
2501 * In some libraries, you can receive a graphics-redraw event (%evtype_Redraw)
2502 * at any time. This signifies that the window in question has been cleared to
2503 * its background color, and must be redrawn. If you create any graphics
2504 * windows, you <emphasis>must</emphasis> handle these events.
2507 * Redraw events can be triggered when a Glk window is uncovered or made
2508 * visible by the platform's window manager. On the other hand, some Glk
2509 * libraries handle these problem automatically — for example, with a
2510 * backing store — and do not send you redraw events. On the third hand,
2511 * the backing store may be discarded if memory is low, or for other reasons
2512 * — perhaps the screen's color depth has changed. So redraw events are
2513 * always a possibility, even in clever libraries. This is why you must be
2514 * prepared to handle them.
2516 * However, you will not receive a redraw event when you create a graphics
2517 * window. It is assumed that you will do the initial drawing of your own
2518 * accord. You also do not get redraw events when a graphics window is
2519 * enlarged. If you ordered the enlargement, you already know about it; if the
2520 * player is responsible, you receive a window-arrangement event, which covers
2524 * For a description of the drawing functions that apply to graphics windows,
2525 * see <link linkend="chimara-Graphics-in-Graphics-Windows">Graphics in Graphics
2528 * Graphics windows support no text input or output.
2530 * Not all libraries support graphics windows. You can test whether Glk graphics
2531 * are available using the gestalt system. In a C program, you can also test
2532 * whether the graphics functions are defined at compile-time. See <link
2533 * linkend="chimara-Testing-for-Graphics-Capabilities">Testing for Graphics
2534 * Capabilities</link>.
2537 * As with all windows, you should also test for %NULL when you create a
2545 * When calling glk_window_open() with this @method, the new window will be
2546 * to the left of the old one which was split.
2552 * When calling glk_window_open() with this @method, the new window will be
2553 * to the right of the old one which was split.
2559 * When calling glk_window_open() with this @method, the new window will be
2560 * above the old one which was split.
2566 * When calling glk_window_open() with this @method, the new window will be
2567 * below the old one which was split.
2573 * When calling glk_window_open() with this @method, the new window will be
2574 * a fixed size. (See glk_window_open()).
2578 * winmethod_Proportional:
2580 * When calling glk_window_open() with this @method, the new window will be
2581 * a given proportion of the old window's size. (See glk_window_open()).
2587 * When calling glk_window_open() with this @method, it specifies that there
2588 * should be a visible window border between the new window and its sibling.
2589 * (This is a hint to the library.)
2593 * winmethod_NoBorder:
2595 * When calling glk_window_open() with this @method, it specifies that there
2596 * should not be a visible window border between the new window and its sibling.
2597 * (This is a hint to the library; you might specify NoBorder between two
2598 * graphics windows that should form a single image.)
2604 * Any other kind of file (preferences, statistics, arbitrary data.)
2608 * fileusage_SavedGame:
2610 * A file which stores game state.
2614 * fileusage_Transcript:
2616 * A file which contains a stream of text from the game (often an echo stream
2621 * fileusage_InputRecord:
2623 * A file which records player input.
2627 * fileusage_TextMode:
2629 * The file contents will be transformed to a platform-native text file as they
2630 * are written out. Newlines may be converted to linefeeds or
2631 * linefeed-plus-carriage-return combinations; Latin-1 characters may be
2632 * converted to native character codes. When reading a file in text mode, native
2633 * line breaks will be converted back to newline (0x0A) characters, and native
2634 * character codes may be converted to Latin-1.
2637 * Line breaks will always be converted; other conversions are more
2638 * questionable. If you write out a file in text mode, and then read it back
2639 * in text mode, high-bit characters (128 to 255) may be transformed or lost.
2641 * <note><title>Chimara</title>
2643 * Text mode files in Chimara are in UTF-8, which is GTK+'s native file
2649 * fileusage_BinaryMode:
2651 * The file contents will be stored exactly as they are written, and read back
2652 * in the same way. The resulting file may not be viewable on platform-native
2653 * text file viewers.
2657 * fileusage_TypeMask:
2659 * Bitwise AND this value with a file usage argument to find whether the file
2660 * type is %fileusage_SavedGame, %fileusage_Transcript, %fileusage_InputRecord,
2661 * or %fileusage_Data.
2670 * Corresponds to mode <code>"w"</code> in the stdio library, using fopen().
2680 * Corresponds to mode <code>"r"</code> in the stdio library, using fopen().
2685 * filemode_ReadWrite:
2687 * Both an input and an output stream.
2690 * Corresponds to mode <code>"r+"</code> in the stdio library, using fopen().
2695 * filemode_WriteAppend:
2697 * An output stream, but the data will added to the end of whatever already
2698 * existed in the destination, instead of replacing it.
2701 * Confusingly, %filemode_WriteAppend cannot be mode <code>"a"</code>, because
2702 * the stdio spec says that when you open a file with mode <code>"a"</code>,
2703 * then fseek() doesn't work. So we have to use mode <code>"r+"</code> for
2704 * appending. Then we run into the <emphasis>other</emphasis> stdio problem,
2705 * which is that <code>"r+"</code> never creates a new file. So
2706 * %filemode_WriteAppend has to <emphasis>first</emphasis> open the file with
2707 * <code>"a"</code>, close it, reopen with <code>"r+"</code>, and then fseek()
2708 * to the end of the file. For %filemode_ReadWrite, the process is the same,
2709 * except without the fseek() — we begin at the beginning of the file.
2716 * In glk_stream_set_position(), signifies that @pos is counted in characters
2717 * after the beginning of the file.
2723 * In glk_stream_set_position(), signifies that @pos is counted in characters
2724 * after the current position (moving backwards if @pos is negative.)
2730 * In glk_stream_set_position(), signifies that @pos is counted in characters
2731 * after the end of the file. (@pos should always be zero or negative, so that
2732 * this will move backwards to a position within the file.
2736 * stylehint_Indentation:
2738 * How much to indent lines of text in the given style. May be a negative
2739 * number, to shift the text out (left) instead of in (right). The exact metric
2740 * isn't precisely specified; you can assume that +1 is the smallest indentation
2741 * possible which is clearly visible to the player.
2745 * stylehint_ParaIndentation:
2747 * How much to indent the first line of each paragraph. This is in addition to
2748 * the indentation specified by %stylehint_Indentation. This too may be
2749 * negative, and is measured in the same units as %stylehint_Indentation.
2753 * stylehint_Justification:
2755 * The value of this hint must be one of the constants
2756 * %stylehint_just_LeftFlush, %stylehint_just_LeftRight (full justification),
2757 * %stylehint_just_Centered, or %stylehint_just_RightFlush.
2763 * How much to increase or decrease the font size. This is relative; 0 means the
2764 * interpreter's default font size will be used, positive numbers increase it,
2765 * and negative numbers decrease it. Again, +1 is the smallest size increase
2766 * which is easily visible.
2768 * The amount of this increase may not be constant. +1 might increase an
2769 * 8-point font to 9-point, but a 16-point font to 18-point.
2776 * The value of this hint must be 1 for heavy-weight fonts (boldface), 0 for
2777 * normal weight, and -1 for light-weight fonts.
2781 * stylehint_Oblique:
2783 * The value of this hint must be 1 for oblique fonts (italic), or 0 for normal
2788 * stylehint_Proportional:
2790 * The value of this hint must be 1 for proportional-width fonts, or 0 for
2795 * stylehint_TextColor:
2797 * The foreground color of the text. This is encoded in the 32-bit hint value:
2798 * the top 8 bits must be zero, the next 8 bits are the red value, the next 8
2799 * bits are the green value, and the bottom 8 bits are the blue value. Color
2800 * values range from 0 to 255.
2802 * So 0x00000000 is black, 0x00FFFFFF is white, and 0x00FF0000 is bright red.
2807 * stylehint_BackColor:
2809 * The background color behind the text. This is encoded the same way as
2810 * %stylehint_TextColor.
2814 * stylehint_ReverseColor:
2816 * The value of this hint must be 0 for normal printing (%stylehint_TextColor on
2817 * %stylehint_BackColor), or 1 for reverse printing (%stylehint_BackColor on
2818 * %stylehint_TextColor).
2820 * Some libraries may support this hint but not the %stylehint_TextColor and
2821 * %stylehint_BackColor hints. Other libraries may take the opposite tack;
2822 * others may support both, or neither.
2827 * stylehint_just_LeftFlush:
2829 * A value for %stylehint_Justification representing left-justified text.
2833 * stylehint_just_LeftRight:
2835 * A value for %stylehint_Justification representing fully justified text.
2839 * stylehint_just_Centered:
2841 * A value for %stylehint_Justification representing centered text.
2845 * stylehint_just_RightFlush:
2847 * A value for %stylehint_Justification representing right-justified text.
2851 * imagealign_InlineUp:
2853 * The image appears at the current point in the text, sticking up. That is, the
2854 * bottom edge of the image is aligned with the baseline of the line of text.
2858 * imagealign_InlineDown:
2860 * The image appears at the current point, and the top edge is aligned with the
2861 * top of the line of text.
2865 * imagealign_InlineCenter:
2867 * The image appears at the current point, and it is centered between the top
2868 * and baseline of the line of text. If the image is taller than the line of
2869 * text, it will stick up and down equally.
2873 * imagealign_MarginLeft:
2875 * The image appears in the left margin. Subsequent text will be displayed to
2876 * the right of the image, and will flow around it — that is, it will be
2877 * left-indented for as many lines as it takes to pass the image.
2879 * <warning><para>Margin images are not implemented yet.</para></warning>
2883 * imagealign_MarginRight:
2885 * The image appears in the right margin, and subsequent text will flow around
2888 * <warning><para>Margin images are not implemented yet.</para></warning>
2893 * @year: The full (four-digit) year
2894 * @month: The month number, ranging from 1-12, 1 is January
2895 * @day: The day of the month, ranging from 1-31
2896 * @weekday: The day of the week, ranging from 0-6, 0 is Sunday
2897 * @hour: The hour of the day, ranging from 0-23
2898 * @minute: The minute of the hour, ranging from 0-59
2899 * @second: The second of the minute, ranging from 0-59; may be 60 during a leap
2901 * @microsec: The fraction of the second in microseconds, ranging from 0-999999
2903 * This structure represents a human-readable date in a specific timezone.
2908 * @high_sec: The most significant 32 bits of the timestamp in seconds.
2909 * @low_sec: The least significant 32 bits of the timestamp in seconds.
2910 * @microsec: The fraction of the timestamp, in microseconds, ranging from
2913 * This structure represents the Unix timestamp, i.e. the number of seconds
2914 * since January 1, 1970.
2917 /*---------- TYPES, FUNCTIONS AND CONSTANTS FROM GI_DISPA.H ------------------*/
2920 * gidispatch_count_classes:
2922 * Returns the number of opaque object classes used by the library. You will
2923 * need to know this if you want to keep track of opaque objects as they are
2924 * created; see <link linkend="gidispatch-set-object-registry">Opaque Object
2927 * As of Glk API 0.7.0, there are four classes: windows, streams, filerefs, and
2928 * sound channels (numbered 0, 1, 2, and 3 respectively.)
2930 * Returns: Number of opaque object classes used by the library.
2934 * gidispatch_get_class:
2935 * @index: Unique integer index of the class.
2937 * Returns a structure describing an opaque class that the library exports.
2938 * @index can range from 0 to <inlineequation><mathphrase>N -
2939 * 1</mathphrase><alt>N - 1</alt></inlineequation>, where N is the value
2940 * returned by gidispatch_count_classes().
2942 * Returns: A #gidispatch_intconst_t structure describing the class.
2946 * gidispatch_count_intconst:
2948 * Returns the number of integer constants exported by the library.
2950 * Returns: Number of integer constants exported by the library.
2954 * gidispatch_get_intconst:
2955 * @index: Unique integer index of the integer constant.
2957 * Returns a structure describing an integer constant which the library exports.
2958 * These are, roughly, all the constants defined in the <filename
2959 * class="headerfile">glk.h</filename> file. @index can range from 0 to
2960 * <inlineequation><mathphrase>N - 1</mathphrase><alt>N -
2961 * 1</alt></inlineequation>, where N is the value returned by
2962 * gidispatch_count_intconst().
2964 * Returns: A #gidispatch_intconst_t structure describing the integer constant.
2968 * gidispatch_intconst_t:
2969 * @name: Symbolic name of the integer constant.
2970 * @val: Value of the integer constant.
2972 * This structure simply contains a string and a value. The string is a
2973 * symbolic name of the value, and can be re-exported to anyone interested in
2974 * using Glk constants.
2977 * In the current <filename>gi_dispa.c</filename> library, these structures
2978 * are static and immutable, and will never be deallocated. However, it is
2979 * safer to assume that the structure may be reused in future
2980 * gidispatch_get_intconst() calls.
2985 * gidispatch_count_functions:
2987 * Returns the number of functions exported by the library.
2989 * Returns: Number of functions exported by the library.
2993 * gidispatch_get_function:
2994 * @index: Unique integer index of the function.
2996 * Returns a structure describing a Glk function. @index can range from 0 to
2997 * <inlineequation><mathphrase>N - 1</mathphrase><alt>N -
2998 * 1</alt></inlineequation>, where N is the value returned by
2999 * gidispatch_count_functions().
3002 * Again, it is safest to assume that the structure is only valid until the
3003 * next gidispatch_get_function() or gidispatch_get_function_by_id() call.
3006 * Returns: A #gidispatch_function_t structure describing the function.
3010 * gidispatch_function_t:
3011 * @id: Dispatch selector of the function.
3012 * @fnptr: Pointer to the function.
3013 * @name: Name of the function, without the <code>glk_</code> prefix.
3015 * The @id field is a selector — a numeric constant used to refer to the
3016 * function in question. @name is the function name, as it is given in the
3017 * <filename class="headerfile">glk.h</filename> file, but without the
3018 * <quote><code>glk_</code></quote> prefix. And @fnptr is the address of the
3022 * This is included because it might be useful, but it is not recommended. To
3023 * call an arbitrary Glk function, you should use gidispatch_call().
3026 * See <link linkend="chimara-Table-of-Selectors">Table of Selectors</link> for
3027 * the selector definitions. See <link
3028 * linkend="chimara-Dispatching">Dispatching</link> for more about calling Glk
3029 * functions by selector.
3033 * gidispatch_get_function_by_id:
3036 * Returns a structure describing the Glk function with selector @id. If there
3037 * is no such function in the library, this returns %NULL.
3040 * Again, it is safest to assume that the structure is only valid until the
3041 * next gidispatch_get_function() or gidispatch_get_function_by_id() call.
3044 * Returns: a #gidispatch_function_t structure, or %NULL.
3049 * @funcnum: Selector of the function to call.
3050 * @numargs: Length of @arglist.
3051 * @arglist: List of arguments to pass to the function.
3053 * @funcnum is the function number to invoke; see <link
3054 * linkend="chimara-Table-of-Selectors">Table of Selectors</link>. @arglist is
3055 * the list of arguments, and @numargs is the length of the list.
3057 * The arguments are all stored as #gluniversal_t objects.
3058 * </para><refsect3 id="chimara-Basic-Dispatch-Types"><title>Basic Dispatch
3059 * Types</title><para>
3060 * Numeric arguments are passed in the obvious way — one argument per
3061 * #gluniversal_t, with the @uint or @sint field set to the numeric value.
3062 * Characters and strings are also passed in this way — #char<!---->s in
3063 * the @uch, @sch, or @ch fields (depending on whether the #char is signed) and
3064 * strings in the @charstr field. Opaque objects (windows, streams, etc) are
3065 * passed in the @opaqueref field (which is <code>void*</code>, in order to
3066 * handle all opaque pointer types.)
3068 * However, pointers (other than C strings), arrays, and structures complicate
3069 * life. So do return values.
3070 * </para></refsect3>
3071 * <refsect3 id="chimara-References"><title>References</title><para>
3072 * A reference to a numeric type or object reference — that is,
3073 * <code>#glui32*</code>, <code>#winid_t*</code>, and so on — takes
3074 * <emphasis>one or two</emphasis> #gluniversal_t objects. The first is a flag
3075 * indicating whether the reference argument is %NULL or not. The @ptrflag field
3076 * of this #gluniversal_t should be %FALSE (0) if the reference is %NULL, and
3077 * %TRUE (1) otherwise. If %FALSE, that is the end of the argument; you should
3078 * not use a #gluniversal_t to explicitly store the %NULL reference. If the flag
3079 * is %TRUE, you must then put a #gluniversal_t storing the base type of the
3082 * For example, consider a hypothetical function, with selector
3083 * <code>0xABCD</code>:
3085 * void glk_glomp(glui32 num, winid_t win, glui32 *numref, strid_t *strref);
3092 * glk_glomp(5, mainwin, &value, &gamefile);
3095 * To perform this through gidispatch_call(), you would do the following:
3097 * gluniversal_t arglist[6];
3098 * arglist[0].uint = 5;
3099 * arglist[1].opaqueref = mainwin;
3100 * arglist[2].ptrflag = TRUE;
3101 * arglist[3].uint = value;
3102 * arglist[4].ptrflag = TRUE;
3103 * arglist[5].opaqueref = gamefile;
3104 * gidispatch_call(0xABCD, 6, arglist);
3105 * value = arglist[3].uint;
3106 * gamefile = arglist[5].opaqueref;
3109 * Note that you copy the value of the reference arguments into and out of
3110 * @arglist. Of course, it may be that
3111 * <function>glk_glomp()</function> only uses these as pass-out
3112 * references or pass-in references; if so, you could skip copying in or out.
3114 * For further examples:
3116 * glk_glomp(7, mainwin, NULL, NULL);
3118 * gluniversal_t arglist[4];
3119 * arglist[0].uint = 7;
3120 * arglist[1].opaqueref = mainwin;
3121 * arglist[2].ptrflag = FALSE;
3122 * arglist[3].ptrflag = FALSE;
3123 * gidispatch_call(0xABCD, 4, arglist);
3127 * glk_glomp(13, NULL, NULL, &gamefile);
3129 * gluniversal_t arglist[5];
3130 * arglist[0].uint = 13;
3131 * arglist[1].opaqueref = NULL;
3132 * arglist[2].ptrflag = FALSE;
3133 * arglist[3].ptrflag = TRUE;
3134 * arglist[4].opaqueref = gamefile;
3135 * gidispatch_call(0xABCD, 5, arglist);
3136 * gamefile = arglist[4].opaqueref;
3140 * glk_glomp(17, NULL, &value, NULL);
3142 * gluniversal_t arglist[5];
3143 * arglist[0].uint = 17;
3144 * arglist[1].opaqueref = NULL;
3145 * arglist[2].ptrflag = TRUE;
3146 * arglist[3].uint = value;
3147 * arglist[4].ptrflag = FALSE;
3148 * gidispatch_call(0xABCD, 5, arglist);
3149 * value = arglist[3].uint;
3152 * As you see, the length of @arglist depends on how many of the reference
3153 * arguments are %NULL.
3154 * </para></refsect3>
3155 * <refsect3 id="chimara-Structures"><title>Structures</title><para>
3156 * A structure pointer is represented by a single @ptrflag, possibly followed by
3157 * a sequence of #gluniversal_t objects (one for each field of the structure.)
3158 * Again, if the structure pointer is non-%NULL, the @ptrflag should be %TRUE
3159 * and be followed by values; if not, the @ptrflag should be %NULL and stands
3162 * For example, the function glk_select() can be invoked as follows:
3165 * gluniversal_t arglist[5];
3166 * arglist[0].ptrflag = TRUE;
3167 * gidispatch_call(0x00C0, 5, arglist);
3168 * ev.type = arglist[1].uint;
3169 * ev.win = arglist[2].opaqueref;
3170 * ev.val1 = arglist[3].uint;
3171 * ev.val2 = arglist[4].uint;
3174 * Since the structure passed to glk_select() is a pass-out reference (the entry
3175 * values are ignored), you don't need to fill in <code>arglist[1..4]</code>
3176 * before calling gidispatch_call().
3179 * Theoretically, you would invoke <code>#glk_select(%NULL)</code> by setting'
3180 * <code>arglist[0].ptrflag</code> to %FALSE, and using a one-element @arglist
3181 * instead of five-element. But it's illegal to pass %NULL to glk_select(). So
3182 * you cannot actually do this.
3183 * </para></note></para></refsect3>
3184 * <refsect3 id="chimara-Arrays"><title>Arrays</title><para>
3185 * In the Glk API, an array argument is always followed by a numeric argument
3186 * giving the array's length. These two C arguments are a single logical
3187 * argument, which is represented by <emphasis>one or three</emphasis>
3188 * #gluniversal_t objects. The first is a @ptrflag, indicating whether the
3189 * argument is %NULL or not. The second is a pointer, stored in the @array
3190 * field. The third is the array length, stored in the @uint field. And again,
3191 * if the @ptrflag is %NULL, the following two are omitted.
3193 * For example, the function glk_put_buffer() can be invoked as follows:
3197 * glk_put_buffer(buf, len);
3199 * gluniversal_t arglist[3];
3200 * arglist[0].ptrflag = TRUE;
3201 * arglist[1].array = buf;
3202 * arglist[2].uint = len;
3203 * gidispatch_call(0x0084, 3, arglist);
3206 * Since you are passing a C char array to gidispatch_call(), the contents will
3207 * be read directly from that. There is no need to copy data into @arglist, as
3208 * you would for a basic type.
3210 * If you are implementing a VM whose native representation of char arrays is
3211 * more complex, you will have to do more work. You should allocate a C char
3212 * array, copy your characters into it, make the call, and then free the array.
3215 * glk_put_buffer() does not modify the array passed to it, so there is no
3216 * need to copy the characters out.
3217 * </para></note></para></refsect3>
3218 * <refsect3 id="chimara-Return-Values"><title>Return Values</title><para>
3219 * The return value of a function is not treated specially. It is simply
3220 * considered to be a pass-out reference argument which may not be %NULL. It
3221 * comes after all the other arguments of the function.
3223 * For example, the function glk_window_get_rock() can be invoked as follows:
3227 * rock = glk_window_get_rock(win);
3229 * gluniversal_t arglist[3];
3230 * arglist[0].opaqueref = win;
3231 * arglist[1].ptrflag = TRUE;
3232 * gidispatch_call(0x0021, 3, arglist);
3233 * rock = arglist[2].uint;
3235 * </para></refsect3><para>
3240 * @uint: Stores a #glui32.
3241 * @sint: Stores a #glsi32.
3242 * @opaqueref: Stores a #winid_t, #strid_t, #frefid_t, or #schanid_t.
3243 * @uch: Stores an #unsigned #char.
3244 * @sch: Stores a #signed #char.
3245 * @ch: Stores a #char with the default signedness.
3246 * @charstr: Stores a null-terminated string.
3247 * @unicharstr: Stores a zero-terminated string of #glui32 values representing
3248 * Unicode characters.
3249 * @array: Stores a pointer to an array, and should be followed by another
3250 * #gluniversal_t with the array length stored in the @uint member.
3251 * @ptrflag: If %FALSE, represents an opaque reference or array that is %NULL,
3252 * in which case it represents the entire argument. If %TRUE, should be followed
3253 * by another #gluniversal_t with the pointer in its @opaqueref or @array field.
3255 * This is a union, encompassing all the types that can be passed to Glk
3260 * gidispatch_prototype:
3261 * @funcnum: A selector for the function to be queried.
3263 * This returns a string which encodes the proper argument list for the given
3264 * function. If there is no such function in the library, this returns %NULL.
3266 * The prototype string for the <function>glk_glomp()</function>
3267 * function described above would be: <code>"4IuQa&Iu&Qb:"</code>. The
3268 * <code>"4"</code> is the number of arguments (including the return value, if
3269 * there is one, which in this case there isn't.) <code>"Iu"</code> denotes an
3270 * unsigned integer; <code>"Qa"</code> is an opaque object of class 0 (window).
3271 * <code>"&Iu"</code> is a <emphasis>reference</emphasis> to an unsigned
3272 * integer, and <code>"&Qb"</code> is a reference to a stream. The colon at
3273 * the end terminates the argument list; the return value would follow it, if
3276 * Note that the initial number (<code>"4"</code> in this case) is the number of
3277 * logical arguments, not the number of #gluniversal_t objects which will be
3278 * passed to gidispatch_call(). The <function>glk_glomp()</function>
3279 * call uses anywhere from four to six #gluniversal_t objects, as demonstrated
3282 * The basic type codes:
3285 * <term><code>Iu, Is</code></term>
3286 * <listitem><para>Unsigned and signed 32-bit integer.</para></listitem>
3289 * <term><code>Cn, Cu, Cs</code></term>
3290 * <listitem><para>Character, #unsigned #char, and #signed #char.</para>
3291 * <note><para>Of course <code>Cn</code> will be the same as either
3292 * <code>Cu</code> or <code>Cs</code>, depending on the platform. For this
3293 * reason, Glk avoids using it, but it is included here for completeness.
3298 * <term><code>S</code></term>
3299 * <listitem><para>A C-style string (null-terminated array of #char). In Glk,
3300 * strings are always treated as read-only and used immediately; the library
3301 * does not retain a reference to a string between Glk calls. A Glk call that
3302 * wants to use writable char arrays will use an array type
3303 * (<code>"#C"</code>), not string (<code>"S"</code>).</para></listitem>
3306 * <term><code>U</code></term>
3307 * <listitem><para>A zero-terminated array of 32-bit integers. This is
3308 * primarily intended as a Unicode equivalent of <code>"S"</code>. Like
3309 * <code>"S"</code> strings, <code>"U"</code> strings are read-only and used
3310 * immediately. A Glk call that wants to use writable Unicode arrays will use
3311 * an array type (<code>"#Iu"</code>) instead of <code>"U"</code>.</para>
3315 * <term><code>F</code></term>
3316 * <listitem><para>A floating-point value. Glk does not currently use
3317 * floating-point values, but we might as well define a code for them.</para>
3321 * <term><code>Qa, Qb, Qc...</code></term>
3322 * <listitem><para>A reference to an opaque object. The second letter
3323 * determines which class is involved. (The number of classes can be gleaned
3324 * from gidispatch_count_classes(); see <link
3325 * linkend="chimara-Interrogating-the-Interface">Interrogating the
3326 * Interface</link>).</para>
3328 * If Glk expands to have more than 26 classes, we'll think of something.
3329 * </para></note></listitem>
3332 * Any type code can be prefixed with one or more of the following characters:
3335 * <term><code>&</code></term>
3336 * <listitem><para>A reference to the type; or, if you like, a variable passed
3337 * by reference. The reference is passed both in and out, so you must copy the
3338 * value in before calling gidispatch_call() and copy it out afterward.</para>
3342 * <term><code><</code></term>
3343 * <listitem><para>A reference which is pass-out only. The initial value is
3344 * ignored, so you only need copy out the value after the call.</para>
3348 * <term><code>></code></term>
3349 * <listitem><para>A reference which is pass-in only.</para>
3351 * This is not generally used for simple types, but is useful for structures
3353 * </para></note></listitem>
3356 * <term><code>+</code></term>
3357 * <listitem><para>Combined with <code>"&"</code>, <code>"<"</code>, or
3358 * <code>">"</code>, indicates that a valid reference is mandatory; %NULL
3359 * cannot be passed.</para>
3361 * Note that even though the @ptrflag #gluniversal_t for a <code>"+"</code>
3362 * reference is always %TRUE, it cannot be omitted.
3363 * </para></note></listitem>
3366 * <term><code>:</code></term>
3367 * <listitem><para>The colon separates the arguments from the return value, or
3368 * terminates the string if there is no return value. Since return values are
3369 * always non-%NULL pass-out references, you may treat <code>":"</code> as
3370 * equivalent to <code>"<+"</code>. The colon is never combined with any
3371 * other prefix character.</para></listitem>
3374 * <term><code>[...]</code></term>
3375 * <listitem><para>Combined with <code>"&"</code>, <code>"<"</code>, or
3376 * <code>">"</code>, indicates a structure reference. Between the brackets
3377 * is a complete argument list encoding string, including the number of
3380 * For example, the prototype string for glk_select() is
3381 * <code>"1<+[4IuQaIuIu]:"</code> — one argument, which is a
3382 * pass-out non-%NULL reference to a structure, which contains four
3385 * <para>Currently, structures in Glk contain only basic types.</para>
3389 * <term><code>#</code></term>
3390 * <listitem><para>Combined with <code>"&"</code>, <code>"<"</code>, or
3391 * <code>">"</code>, indicates an array reference. As described above, this
3392 * encompasses up to three #gluniversal_t objects — @ptrflag, pointer,
3393 * and integer length.</para>
3395 * Depending on the design of your program, you may wish to pass a pointer
3396 * directly to your program's memory, or allocate an array and copy the
3397 * contents in and out. See <link linkend="chimara-Arrays">Arrays</link>.
3398 * </para></note></listitem>
3401 * <term><code>!</code></term>
3402 * <listitem><para>Combined with <code>"#"</code>, indicates that the
3403 * array is retained by the library. The library will keep a reference to the
3404 * array; the contents are undefined until further notice. You should not use
3405 * or copy the contents of the array out after the call, even for
3406 * <code>"&#!"</code> or <code>"<#!"</code> arrays. Instead, do
3407 * it when the library releases the array.</para>
3409 * For example, glk_stream_open_memory() retains the array that you pass it,
3410 * and releases it when the stream is closed. The library can notify you
3411 * automatically when arrays are retained and released; see <link
3412 * linkend="gidispatch-set-retained-registry">Retained Array
3414 * </para></note></listitem>
3418 * The order of these characters and prefixes is not completely arbitrary. Here
3419 * is a formal grammar for the prototype strings.
3421 * <note><para>Thanks to Neil Cerutti for working this out.</para></note>
3424 * <production id="prototype">
3425 * <lhs>prototype</lhs>
3426 * <rhs>ArgCount [ <nonterminal def="#arg_list">arg_list</nonterminal> ]
3427 * ':' [ <nonterminal def="#arg">arg</nonterminal> ] EOL</rhs>
3429 * <production id="arg_list">
3430 * <lhs>arg_list</lhs>
3431 * <rhs><nonterminal def="#arg">arg</nonterminal> { <nonterminal
3432 * def="#arg">arg</nonterminal> }</rhs>
3434 * <production id="arg">
3436 * <rhs>TypeName | <nonterminal def="#ref_type">ref_type</nonterminal>
3439 * <production id="ref_type">
3440 * <lhs>ref_type</lhs>
3441 * <rhs>RefType [ '+' ] <nonterminal
3442 * def="#target_type">target_type</nonterminal></rhs>
3444 * <production id="target_type">
3445 * <lhs>target_type</lhs>
3446 * <rhs>TypeName | <nonterminal def="#array">array</nonterminal> |
3447 * <nonterminal def="#struct">struct</nonterminal></rhs>
3449 * <production id="array">
3451 * <rhs>'#' [ '!' ] TypeName</rhs>
3453 * <production id="struct">
3455 * <rhs>'[' ArgCount [ <nonterminal def="#arg_list">arg_list</nonterminal>
3459 * <constraintdef id="TypeName">
3460 * <para>TypeName is <code>I[us]<!---->|C[nus]<!---->|S|U|F|Q[a-z]</code>
3463 * <constraintdef id="ArgCount">
3464 * <para>ArgCount is <code>\d+</code></para>
3466 * <constraintdef id="RefType">
3467 * <para>RefType is <code>&|<|></code></para>
3469 * <constraintdef id="EOL">
3470 * <para>EOL is end of input</para>
3473 * Returns: A string which encodes the prototype of the specified Glk function.
3477 * gidisp_Class_Window:
3479 * Represents a #winid_t opaque object.
3483 * gidisp_Class_Stream:
3485 * Represents a #strid_t opaque object.
3489 * gidisp_Class_Fileref:
3491 * Represents a #frefid_t opaque object.
3495 * gidisp_Class_Schannel:
3497 * Represents a #schanid_t opaque object.
3501 * gidispatch_rock_t:
3502 * @num: Space for storing an integer.
3503 * @ptr: Space for storing a pointer.
3505 * You can store any value you want in this object; return it from your object
3506 * registry and retained array registry callbacks, and the library will stash it
3507 * away. You can retrieve it with gidispatch_get_objrock().
3510 /*---------- TYPES, FUNCTIONS AND CONSTANTS FROM GI_BLORB.H ------------------*/
3515 * An integer type that can hold the Blorb error codes.
3525 * giblorb_err_CompileTime:
3527 * Something is compiled wrong in the Blorb layer.
3531 * giblorb_err_Alloc:
3533 * Memory could not be allocated.
3534 * <note><title>Chimara</title>
3536 * The Blorb layer in the Chimara library should not return this error code;
3537 * instead, the program aborts if memory allocation fails, in keeping with
3545 * Data could not be read from the file.
3549 * giblorb_err_NotAMap:
3551 * The map parameter is invalid.
3555 * giblorb_err_Format:
3557 * The Blorb file is corrupted or invalid.
3561 * giblorb_err_NotFound:
3563 * The requested data could not be found.
3567 * giblorb_method_DontLoad:
3569 * Pass this to giblorb_load_chunk_by_type(), giblorb_load_chunk_by_number(), or
3570 * giblorb_load_resource() to obtain information about a chunk without actually
3575 * giblorb_method_Memory:
3577 * Pass this to giblorb_load_chunk_by_type(), giblorb_load_chunk_by_number(), or
3578 * giblorb_load_resource() to load a chunk into memory.
3582 * giblorb_method_FilePos:
3584 * Pass this to giblorb_load_chunk_by_type(), giblorb_load_chunk_by_number(), or
3585 * giblorb_load_resource() to get the position in the Blorb file at which the
3586 * chunk data starts.
3592 * Resource usage constant representing a sound file.
3598 * Resource usage constant representing an executable program.
3604 * Resource usage constant representing an image file.
3608 * giblorb_ID_Copyright:
3610 * Resource usage constant representing the copyright message (date and holder,
3611 * without the actual copyright symbol). There should only be one such chunk per
3618 * Resource usage constant representing the name of the author or creator of the
3619 * file. This could be a login name on multi-user systems, for example. There
3620 * should only be one such chunk per file.
3626 * Resource usage constant representing any textual annotation that the user or
3627 * writing program sees fit to include.
3633 * Holds the complete description of an open Blorb file. This type is opaque for
3634 * normal interpreter use.
3639 * @chunknum: The chunk number (for use in giblorb_unload_chunk(), etc.)
3640 * @length: The length of the data
3641 * @chunktype: The type of the chunk.
3643 * Holds information about a chunk loaded from a Blorb file, and the method of
3644 * accessing the chunk data. @data is a union of @ptr, a pointer to the data (if
3645 * you used %giblorb_method_Memory) and @startpos, the position in the file (if
3646 * you used %giblorb_method_FilePos). See giblorb_load_chunk_by_type() and
3647 * giblorb_load_chunk_by_number().
3651 * giblorb_create_map:
3652 * @file: An input stream pointing to a Blorb file.
3653 * @newmap: Return location for a Blorb resource map.
3655 * Reads Blorb data out of a Glk stream. It does not load every resource at
3656 * once; instead, it creates a map in memory which makes it easy to find
3657 * resources. A pointer to the map is stored in @newmap. This is an opaque
3658 * object; you pass it to the other Blorb-layer functions.
3660 * Returns: a Blorb error code.
3664 * giblorb_destroy_map:
3665 * @map: A Blorb resource map to deallocate.
3667 * Deallocates @map and all associated memory. This does
3668 * <emphasis>not</emphasis> close the original stream.
3670 * Returns: a Blorb error code.
3674 * giblorb_load_chunk_by_type:
3675 * @map: The Blorb resource map to load a chunk from.
3676 * @method: The loading method to use, one of %giblorb_method_DontLoad,
3677 * %giblorb_method_Memory, or %giblorb_method_FilePos.
3678 * @res: Return location for the result.
3679 * @chunktype: The type of chunk to load.
3680 * @count: The chunk number of type @chunktype to load.
3682 * Loads a chunk of a given type. The @count parameter distinguishes between
3683 * chunks of the same type. If @count is zero, the first chunk of that type is
3684 * loaded, and so on.
3686 * To load a chunk of an IFF FORM type (such as AIFF), you should pass in the
3687 * form type, rather than FORM.
3689 * This introduces a slight ambiguity — you cannot distiguish between a
3690 * FORM AIFF chunk and a non-FORM chunk of type AIFF. However, the latter is
3691 * almost certainly a mistake.
3694 * The returned data is written into @res, according to @method.
3696 * The <structfield>chunknum</structfield> field is filled in with the number of
3697 * the chunk. (This value can then be passed to giblorb_load_chunk_by_number()
3698 * or giblorb_unload_chunk().) The <structfield>length</structfield> field is
3699 * filled in with the length of the chunk in bytes. The
3700 * <structfield>chunktype</structfield> field is the chunk's type, which of
3701 * course will be the type you asked for.
3703 * If you specify %giblorb_method_DontLoad, no data is actually loaded in. You
3704 * can use this if you are only interested in whether a chunk exists, or in the
3705 * <structfield>chunknum</structfield> and <structfield>length</structfield>
3708 * If you specify %giblorb_method_FilePos,
3709 * <structfield>data.startpos</structfield> is filled in with the file position
3710 * of the chunk data. You can use glk_stream_set_position() to read the data
3713 * If you specify %giblorb_method_Memory, <structfield>data.ptr</structfield> is
3714 * filled with a pointer to allocated memory containing the chunk data. This
3715 * memory is owned by the map, not you. If you load the chunk more than once
3716 * with %giblorb_method_Memory, the Blorb layer is smart enough to keep just one
3717 * copy in memory. You should not deallocate this memory yourself; call
3718 * giblorb_unload_chunk() instead.
3720 * Returns: a Blorb error code.
3724 * giblorb_load_chunk_by_number:
3725 * @map: The Blorb resource map to load a chunk from.
3726 * @method: The loading method to use, one of %giblorb_method_DontLoad,
3727 * %giblorb_method_Memory, or %giblorb_method_FilePos.
3728 * @res: Return location for the result.
3729 * @chunknum: The chunk number to load.
3731 * This is similar to giblorb_load_chunk_by_type(), but it loads a chunk with a
3732 * given chunk number. The type of the chunk can be found in the
3733 * <structfield>chunktype</structfield> field of #giblorb_result_t. You can get
3734 * the chunk number from the <structfield>chunknum</structfield> field, after
3735 * calling one of the other load functions.
3737 * Returns: a Blorb error code.
3741 * giblorb_unload_chunk:
3742 * @map: The Blorb resource map to unload a chunk from.
3743 * @chunknum: The chunk number to unload.
3745 * Frees the chunk data allocated by %giblorb_method_Memory. If the given chunk
3746 * has never been loaded into memory, this has no effect.
3748 * Returns: a Blorb error code.
3752 * giblorb_load_resource:
3753 * @map: The Blorb resource map to load a resource from.
3754 * @method: The loading method to use, one of %giblorb_method_DontLoad,
3755 * %giblorb_method_Memory, or %giblorb_method_FilePos.
3756 * @res: Return location for the result.
3757 * @usage: The type of data resource to load.
3758 * @resnum: The resource number to load.
3760 * Loads a resource, given its usage and resource number. Currently, the three
3761 * usage values are %giblorb_ID_Pict (images), %giblorb_ID_Snd (sounds), and
3762 * %giblorb_ID_Exec (executable program). See the Blorb specification for more
3763 * information about the types of data that can be stored for these usages.
3765 * Note that a resource number is not the same as a chunk number. The resource
3766 * number is the sound or image number specified by a Glk program. Chunk number
3767 * is arbitrary, since chunks in a Blorb file can be in any order. To find the
3768 * chunk number of a given resource, call giblorb_load_resource() and look in
3769 * <structfield>res.chunknum</structfield>.
3771 * Returns: a Blorb error code.
3775 * giblorb_count_resources:
3776 * @map: The Blorb resource map in which to count the resources.
3777 * @usage: The type of data resource to count.
3778 * @num: Return location for the number of chunks of @usage.
3779 * @min: Return location for the lowest resource number of @usage.
3780 * @max: Return location for the highest resource number of @usage.
3782 * Counts the number of chunks with a given usage (image, sound, or executable.)
3783 * The total number of chunks of that usage is stored in @num. The lowest and
3784 * highest resource number of that usage are stored in @min and @max. You can
3785 * leave any of the three pointers %NULL if you don't care about that
3788 * Returns: a Blorb error code.
3791 /*--------------------TYPES AND CONSTANTS FROM GLKSTART.H---------------------*/
3794 * glkunix_argumentlist_t:
3795 * @name: the option as it would appear on the command line (including the
3796 * leading dash, if any.)
3797 * @desc: a description of the argument; this is used when the library is
3798 * printing a list of options.
3799 * @argtype: one of the <code>glkunix_arg_</code> constants.
3803 * <term>%glkunix_arg_NoValue</term>
3804 * <listitem><para>The argument appears by itself.</para></listitem>
3807 * <term>%glkunix_arg_ValueFollows</term>
3808 * <listitem><para>The argument must be followed by another argument (the
3809 * value).</para></listitem>
3812 * <term>%glkunix_arg_ValueCanFollow</term>
3813 * <listitem><para>The argument may be followed by a value, optionally. (If the
3814 * next argument starts with a dash, it is taken to be a new argument, not the
3815 * value of this one.)</para></listitem>
3818 * <term>%glkunix_arg_NumberValue</term>
3819 * <listitem><para>The argument must be followed by a number, which may be the
3820 * next argument or part of this one. (That is, either <quote><code>-width
3821 * 20</code></quote> or <quote><code>-width20</code></quote> will be accepted.)
3822 * </para></listitem>
3825 * <term>%glkunix_arg_End</term>
3826 * <listitem><para>The <code>glkunix_arguments[]</code> array must be
3827 * terminated with an entry containing this value.</para></listitem>
3831 * To accept arbitrary arguments which lack dashes, specify a name of
3832 * <code>""</code> and an argtype of %glkunix_arg_ValueFollows.
3834 * If you don't care about command-line arguments, you must still define an
3835 * empty arguments list, as follows:
3837 * glkunix_argumentlist_t glkunix_arguments[] = {
3838 * { NULL, glkunix_arg_End, NULL }
3842 * Here is a more complete sample list:
3844 * glkunix_argumentlist_t glkunix_arguments[] = {
3845 * { "", glkunix_arg_ValueFollows, "filename: The game file to load." },
3846 * { "-hum", glkunix_arg_ValueFollows, "-hum NUM: Hum some NUM." },
3847 * { "-bom", glkunix_arg_ValueCanFollow, "-bom [ NUM ]: Do a bom (on
3848 * the NUM, if given)." },
3849 * { "-goo", glkunix_arg_NoValue, "-goo: Find goo." },
3850 * { "-wob", glkunix_arg_NumberValue, "-wob NUM: Wob NUM times." },
3851 * { NULL, glkunix_arg_End, NULL }
3854 * This would match the arguments <quote><code>thingfile -goo -wob8 -bom -hum
3855 * song</code></quote>.
3857 * After the library parses the command line, it does various occult rituals of
3858 * initialization, and then calls glkunix_startup_code().
3860 * |[ int glkunix_startup_code(glkunix_startup_t *data); ]|
3862 * This should return %TRUE if everything initializes properly. If it returns
3863 * %FALSE, the library will shut down without ever calling your glk_main()
3868 * glkunix_startup_t:
3869 * @argc: The number of arguments in @argv.
3870 * @argv: Strings representing command line arguments.
3872 * The fields are a standard Unix <code>(argc, argv)</code> list, which contain
3873 * the arguments you requested from the command line. In deference to custom,
3874 * <code>argv[0]</code> is always the program name.
3880 * Terminates a list of #glkunix_argumentlist_t.
3884 * glkunix_arg_ValueFollows:
3886 * Indicates an argument which must be followed by a value, as the next
3891 * glkunix_arg_NoValue:
3893 * Indicates an argument which occurs by itself, without a value.
3897 * glkunix_arg_ValueCanFollow:
3899 * Indicates an argument which may be followed by a value, or may occur by
3904 * glkunix_arg_NumberValue:
3906 * Indicates an argument which must be followed by a numerical value, either as
3907 * the next argument or tacked onto the end of this argument.