tests/barf.c

   1 /*
   2  * Compile me with:
   3  * gcc -g -O0 -Wall -pthread -o barf barf.c `pkg-config --cflags --libs gtk+-2.0`
   4  */
   5
   6 #include <gtk/gtk.h>
   7 #include <gdk/gdkkeysyms.h>
   8
   9 /* Uncomment to try the other paging method */
  10 /* #define PAGE_ONLY_UNSEEN 1 */
  11
  12 static gulong pager_handler = 0;
  13 static gulong expose_handler = 0;
  14 static gboolean currently_paging = FALSE;
  15
  16 static gint promptwidth, promptheight;
  17 static PangoLayout *prompt;
  18 static GdkColor red, white;
  19
  20 static gboolean
  21 quit()
  22 {
  23         gtk_main_quit();
  24         return TRUE;
  25 }
  26
  27 /* Vomit a load of text onto the screen */
  28 static void
  29 barf(GtkButton *button, GtkTextView *textview)
  30 {
  31         GtkTextIter end;
  32         GtkTextBuffer *buffer = gtk_text_view_get_buffer(textview);
  33         gtk_text_buffer_get_end_iter(buffer, &end);
  34
  35         gchar *loremipsum;
  36         g_file_get_contents("loremipsum.txt", &loremipsum, NULL, NULL);
  37         gtk_text_buffer_insert(buffer, &end, loremipsum, -1);
  38         g_free(loremipsum);
  39
  40         gtk_widget_grab_focus(GTK_WIDGET(textview));
  41 }
  42
  43 /* Helper function: move the pager to the last visible position in the buffer,
  44  and return the distance between the pager and the end of the buffer in buffer
  45  coordinates */
  46 static gint
  47 move_pager_and_get_scroll_distance(GtkTextView *textview)
  48 {
  49         GdkRectangle pagerpos, endpos, visiblerect;
  50         GtkTextIter oldpager, newpager, end;
  51         GtkTextBuffer *buffer = gtk_text_view_get_buffer(textview);
  52         GtkTextMark *pager = gtk_text_buffer_get_mark(buffer, "pager_position");
  53
  54         /* Get an iter at the lower right corner of the visible part of the buffer */
  55         gtk_text_view_get_visible_rect(textview, &visiblerect);
  56         gtk_text_view_get_iter_at_location(textview, &newpager, visiblerect.x + visiblerect.width, visiblerect.y + visiblerect.height);
  57         gtk_text_buffer_get_iter_at_mark(buffer, &oldpager, pager);
  58
  59 #ifdef PAGE_ONLY_UNSEEN
  60         if(gtk_text_iter_compare(&oldpager, &newpager) < 0)
  61                 gtk_text_buffer_move_mark(buffer, pager, &newpager);
  62 #else
  63         gtk_text_buffer_move_mark(buffer, pager, &newpager);
  64 #endif
  65
  66         /* Get the buffer coordinates of the pager and the end iter */
  67         gtk_text_buffer_get_end_iter(buffer, &end);
  68         gtk_text_buffer_get_iter_at_mark(buffer, &newpager, pager);
  69         gtk_text_view_get_iter_location(textview, &newpager, &pagerpos);
  70         gtk_text_view_get_iter_location(textview, &end, &endpos);
  71
  72         //g_printerr("View height = %d\n", visiblerect.height);
  73         //g_printerr("End - Pager = %d\n", endpos.y - pagerpos.y);
  74
  75         return endpos.y - pagerpos.y;
  76 }
  77
  78 /* Helper function: turn on paging for this textview */
  79 static void
  80 start_paging(GtkTextView *textview)
  81 {
  82         currently_paging = TRUE;
  83         g_signal_handler_unblock(textview, expose_handler);
  84         g_signal_handler_unblock(textview, pager_handler);
  85 }
  86
  87 /* Helper function: turn off paging for this textview */
  88 static void
  89 stop_paging(GtkTextView *textview)
  90 {
  91         currently_paging = FALSE;
  92         g_signal_handler_block(textview, expose_handler);
  93         g_signal_handler_block(textview, pager_handler);
  94 }
  95
  96 /* Update the pager position after new text is inserted in the buffer */
  97 static void
  98 after_insert(GtkTextBuffer *buffer, GtkTextIter *location, gchar *text, gint len, GtkTextView *textview)
  99 {
 100         while(gtk_events_pending())
 101                 gtk_main_iteration();
 102
 103         /* Move the pager to the last visible character in the buffer */
 104         gint scroll_distance = move_pager_and_get_scroll_distance(textview);
 105
 106         if(scroll_distance > 0 && !currently_paging)
 107                 start_paging(textview);
 108 }
 109
 110 static void
 111 adjustment_changed(GtkAdjustment *adjustment, GtkTextView *textview)
 112 {
 113         while(gtk_events_pending())
 114                 gtk_main_iteration();
 115
 116         /* Move the pager, etc. */
 117         gint scroll_distance = move_pager_and_get_scroll_distance(textview);
 118
 119         if(scroll_distance > 0 && !currently_paging)
 120                 start_paging(textview);
 121         else if(scroll_distance == 0 && currently_paging)
 122                 stop_paging(textview);
 123
 124         /* Refresh the widget so that any extra "more" prompts disappear */
 125         gtk_widget_queue_draw(GTK_WIDGET(textview));
 126 }
 127
 128 /* Handle key press events in the textview while paging is active */
 129 static gboolean
 130 pager_wait(GtkTextView *textview, GdkEventKey *event, GtkTextBuffer *buffer)
 131 {
 132         /*** ALTERNATIVE, POSSIBLY INFERIOR, METHOD OF SCROLLING ***
 133         GtkTextMark *pagermark = gtk_text_buffer_get_mark(buffer, "pager_position");
 134         gtk_text_view_scroll_to_mark(textview, pagermark, 0.0, TRUE, 0.0, 0.0);
 135         */
 136
 137         GtkWidget *scrolledwindow = gtk_widget_get_parent(GTK_WIDGET(textview));
 138         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(scrolledwindow));
 139         gdouble step_increment, page_size, upper, lower, value;
 140         g_object_get(adj,
 141                 "page-size", &page_size,
 142                 "step-increment", &step_increment,
 143                 "upper", &upper,
 144                 "lower", &lower,
 145                 "value", &value,
 146                 NULL);
 147
 148         switch (event->keyval) {
 149                 case GDK_space: case GDK_KP_Space: case GDK_Page_Down: case GDK_KP_Page_Down:
 150                         gtk_adjustment_set_value(adj, CLAMP(value + page_size, lower, upper - page_size));
 151                         break;
 152                 case GDK_Page_Up: case GDK_KP_Page_Up:
 153                         gtk_adjustment_set_value(adj, CLAMP(value - page_size, lower, upper - page_size));
 154                         break;
 155                 case GDK_Return: case GDK_KP_Enter:
 156                         gtk_adjustment_set_value(adj, CLAMP(value + step_increment, lower, upper - page_size));
 157                         break;
 158                         /* don't handle "up" and "down", they're used for input history */
 159                 default:
 160                         return FALSE; /* if the key wasn't handled here, pass it to other handlers */
 161         }
 162
 163         gdk_window_process_updates(gtk_widget_get_window(GTK_WIDGET(textview)), TRUE);
 164         return TRUE; /* handled it, stop this event now */
 165 }
 166
 167 /* Draw the "more" prompt on top of the buffer, after the regular expose event has run */
 168 static gboolean
 169 expose_prompt(GtkTextView *textview, GdkEventExpose *event)
 170 {
 171         GdkGC *context = gdk_gc_new(GDK_DRAWABLE(event->window));
 172
 173         gint winx, winy, winwidth, winheight;
 174         gdk_window_get_position(event->window, &winx, &winy);
 175         gdk_drawable_get_size(GDK_DRAWABLE(event->window), &winwidth, &winheight);
 176
 177         gdk_draw_layout_with_colors(event->window, context,
 178                 winx + winwidth - promptwidth,
 179                 winy + winheight - promptheight,
 180                 prompt, &white, &red);
 181
 182         return FALSE; /* Propagate event further */
 183 }
 184
 185 int
 186 main(int argc, char **argv)
 187 {
 188         gtk_init(&argc, &argv);
 189
 190         /* Construct the widgets */
 191         GtkWidget *window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
 192         gtk_widget_set_size_request(window, 400, 400);
 193         GtkWidget *button = gtk_button_new_with_label("Barf");
 194         GtkWidget *scrolledwindow = gtk_scrolled_window_new(NULL, NULL);
 195         GtkWidget *textview = gtk_text_view_new();
 196         gtk_text_view_set_wrap_mode(GTK_TEXT_VIEW(textview), GTK_WRAP_WORD_CHAR);
 197         gtk_text_view_set_editable(GTK_TEXT_VIEW(textview), FALSE);
 198         GtkWidget *vbox = gtk_vbox_new(FALSE, 6);
 199
 200         /* Pack all the widgets into their containers */
 201         gtk_container_add(GTK_CONTAINER(scrolledwindow), textview);
 202         gtk_box_pack_start(GTK_BOX(vbox), button, FALSE, FALSE, 0);
 203         gtk_box_pack_start(GTK_BOX(vbox), scrolledwindow, TRUE, TRUE, 0);
 204         gtk_container_add(GTK_CONTAINER(window), vbox);
 205         gtk_widget_show_all(window);
 206
 207         /* Set up the textview widget to receive exposure events, must be done after widget has been shown */
 208         gdk_window_set_events(gtk_widget_get_window(textview), GDK_EXPOSURE_MASK);
 209
 210         /* Create the 'more' prompt */
 211         prompt = gtk_widget_create_pango_layout(GTK_WIDGET(textview), "More");
 212         pango_layout_get_pixel_size(prompt, &promptwidth, &promptheight);
 213         gdk_color_parse("red", &red);
 214         gdk_color_parse("white", &white);
 215
 216         /* Connect paging signals */
 217         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(textview));
 218         g_signal_connect_after(buffer, "insert-text", G_CALLBACK(after_insert), textview);
 219         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(scrolledwindow));
 220         g_signal_connect_after(adj, "value-changed", G_CALLBACK(adjustment_changed), textview);
 221         pager_handler = g_signal_connect(textview, "key-press-event", G_CALLBACK(pager_wait), buffer);
 222         g_signal_handler_block(textview, pager_handler);
 223         expose_handler = g_signal_connect_after(textview, "expose-event", G_CALLBACK(expose_prompt), NULL);
 224         g_signal_handler_block(textview, expose_handler);
 225
 226         /* Create the pager position mark; it stands for the last character in the buffer
 227          that has been on-screen */
 228         GtkTextIter end;
 229         gtk_text_buffer_get_end_iter(buffer, &end);
 230         GtkTextMark *pagermark = gtk_text_buffer_create_mark(buffer, "pager_position", &end, TRUE);
 231         gtk_text_mark_set_visible(pagermark, TRUE);
 232
 233         /* Connect "regular program" signals */
 234         g_signal_connect(window, "delete-event", G_CALLBACK(quit), NULL);
 235         g_signal_connect(button, "clicked", G_CALLBACK(barf), textview);
 236
 237         gtk_main();
 238
 239         g_object_unref(prompt);
 240         return 0;
 241 }