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 gboolean
  17 quit()
  18 {
  19         gtk_main_quit();
  20         return TRUE;
  21 }
  22
  23 /* Vomit a load of text onto the screen */
  24 static void
  25 barf(GtkButton *button, GtkTextView *textview)
  26 {
  27         GtkTextIter end;
  28         GtkTextBuffer *buffer = gtk_text_view_get_buffer(textview);
  29         gtk_text_buffer_get_end_iter(buffer, &end);
  30
  31         gchar *loremipsum;
  32         g_file_get_contents("loremipsum.txt", &loremipsum, NULL, NULL);
  33         gtk_text_buffer_insert(buffer, &end, loremipsum, -1);
  34         g_free(loremipsum);
  35
  36         gtk_widget_grab_focus(GTK_WIDGET(textview));
  37 }
  38
  39 /* Helper function: move the pager to the last visible position in the buffer,
  40  and return the distance between the pager and the end of the buffer in buffer
  41  coordinates */
  42 static gint
  43 move_pager_and_get_scroll_distance(GtkTextView *textview)
  44 {
  45         GdkRectangle pagerpos, endpos, visiblerect;
  46         GtkTextIter oldpager, newpager, end;
  47         GtkTextBuffer *buffer = gtk_text_view_get_buffer(textview);
  48         GtkTextMark *pager = gtk_text_buffer_get_mark(buffer, "pager_position");
  49
  50         /* Get an iter at the lower right corner of the visible part of the buffer */
  51         gtk_text_view_get_visible_rect(textview, &visiblerect);
  52         gtk_text_view_get_iter_at_location(textview, &newpager, visiblerect.x + visiblerect.width, visiblerect.y + visiblerect.height);
  53         gtk_text_buffer_get_iter_at_mark(buffer, &oldpager, pager);
  54
  55 #ifdef PAGE_ONLY_UNSEEN
  56         if(gtk_text_iter_compare(&oldpager, &newpager) < 0)
  57                 gtk_text_buffer_move_mark(buffer, pager, &newpager);
  58 #else
  59         gtk_text_buffer_move_mark(buffer, pager, &newpager);
  60 #endif
  61
  62         /* Get the buffer coordinates of the pager and the end iter */
  63         gtk_text_buffer_get_end_iter(buffer, &end);
  64         gtk_text_buffer_get_iter_at_mark(buffer, &newpager, pager);
  65         gtk_text_view_get_iter_location(textview, &newpager, &pagerpos);
  66         gtk_text_view_get_iter_location(textview, &end, &endpos);
  67
  68         g_printerr("View height = %d\n", visiblerect.height);
  69         g_printerr("End - Pager = %d\n", endpos.y - pagerpos.y);
  70
  71         return endpos.y - pagerpos.y;
  72 }
  73
  74 /* Helper function: turn on paging for this textview */
  75 static void
  76 start_paging(GtkTextView *textview)
  77 {
  78         currently_paging = TRUE;
  79         g_signal_handler_unblock(textview, expose_handler);
  80         g_signal_handler_unblock(textview, pager_handler);
  81 }
  82
  83 /* Helper function: turn off paging for this textview */
  84 static void
  85 stop_paging(GtkTextView *textview)
  86 {
  87         currently_paging = FALSE;
  88         g_signal_handler_block(textview, expose_handler);
  89         g_signal_handler_block(textview, pager_handler);
  90 }
  91
  92 /* Update the pager position after new text is inserted in the buffer */
  93 static void
  94 after_insert(GtkTextBuffer *buffer, GtkTextIter *location, gchar *text, gint len, GtkTextView *textview)
  95 {
  96         while(gtk_events_pending())
  97                 gtk_main_iteration();
  98
  99         /* Move the pager to the last visible character in the buffer */
 100         gint scroll_distance = move_pager_and_get_scroll_distance(textview);
 101
 102         if(scroll_distance > 0 && !currently_paging)
 103                 start_paging(textview);
 104 }
 105
 106 static void
 107 adjustment_changed(GtkAdjustment *adjustment, GtkTextView *textview)
 108 {
 109         while(gtk_events_pending())
 110                 gtk_main_iteration();
 111
 112         /* Move the pager, etc. */
 113         gint scroll_distance = move_pager_and_get_scroll_distance(textview);
 114
 115         if(scroll_distance > 0 && !currently_paging)
 116                 start_paging(textview);
 117         else if(scroll_distance == 0 && currently_paging)
 118                 stop_paging(textview);
 119
 120         /* Refresh the widget so that any extra "more" prompts disappear */
 121         gtk_widget_queue_draw(GTK_WIDGET(textview));
 122 }
 123
 124 /* Handle key press events in the textview while paging is active */
 125 static gboolean
 126 pager_wait(GtkTextView *textview, GdkEventKey *event, GtkTextBuffer *buffer)
 127 {
 128         /*** ALTERNATIVE, POSSIBLY INFERIOR, METHOD OF SCROLLING ***
 129         GtkTextMark *pagermark = gtk_text_buffer_get_mark(buffer, "pager_position");
 130         gtk_text_view_scroll_to_mark(textview, pagermark, 0.0, TRUE, 0.0, 0.0);
 131         */
 132
 133         GtkWidget *scrolledwindow = gtk_widget_get_parent(GTK_WIDGET(textview));
 134         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(scrolledwindow));
 135         gdouble step_increment, page_size, upper, lower, value;
 136         g_object_get(adj,
 137                 "page-size", &page_size,
 138                 "step-increment", &step_increment,
 139                 "upper", &upper,
 140                 "lower", &lower,
 141                 "value", &value,
 142                 NULL);
 143
 144         switch (event->keyval) {
 145                 case GDK_space: case GDK_KP_Space: case GDK_Page_Down: case GDK_KP_Page_Down:
 146                         gtk_adjustment_set_value(adj, CLAMP(value + page_size, lower, upper - page_size));
 147                         return TRUE;
 148                 case GDK_Page_Up: case GDK_KP_Page_Up:
 149                         gtk_adjustment_set_value(adj, CLAMP(value - page_size, lower, upper - page_size));
 150                         return TRUE;
 151                 case GDK_Return: case GDK_KP_Enter:
 152                         gtk_adjustment_set_value(adj, CLAMP(value + step_increment, lower, upper - page_size));
 153                         return TRUE;
 154                         /* don't handle "up" and "down", they're used for input history */
 155         }
 156
 157         return FALSE; /* if the key wasn't handled here, pass it to other handlers */
 158 }
 159
 160 /* Draw the "more" prompt on top of the buffer, after the regular expose event has run */
 161 static gboolean
 162 expose_prompt(GtkTextView *textview, GdkEventExpose *event)
 163 {
 164         PangoLayout *prompt = gtk_widget_create_pango_layout(GTK_WIDGET(textview), "More");
 165         gint promptwidth, promptheight;
 166         pango_layout_get_pixel_size(prompt, &promptwidth, &promptheight);
 167
 168         GdkGC *context = gdk_gc_new(GDK_DRAWABLE(event->window));
 169         GdkColor red, white;
 170         gdk_color_parse("red", &red);
 171         gdk_color_parse("white", &white);
 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         /* Connect paging signals */
 211         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(textview));
 212         g_signal_connect_after(buffer, "insert-text", G_CALLBACK(after_insert), textview);
 213         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(scrolledwindow));
 214         g_signal_connect_after(adj, "value-changed", G_CALLBACK(adjustment_changed), textview);
 215         pager_handler = g_signal_connect(textview, "key-press-event", G_CALLBACK(pager_wait), buffer);
 216         g_signal_handler_block(textview, pager_handler);
 217         expose_handler = g_signal_connect_after(textview, "expose-event", G_CALLBACK(expose_prompt), NULL);
 218         g_signal_handler_block(textview, expose_handler);
 219
 220         /* Create the pager position mark; it stands for the last character in the buffer
 221          that has been on-screen */
 222         GtkTextIter end;
 223         gtk_text_buffer_get_end_iter(buffer, &end);
 224         GtkTextMark *pagermark = gtk_text_buffer_create_mark(buffer, "pager_position", &end, TRUE);
 225         gtk_text_mark_set_visible(pagermark, TRUE);
 226
 227         /* Connect "regular program" signals */
 228         g_signal_connect(window, "delete-event", G_CALLBACK(quit), NULL);
 229         g_signal_connect(button, "clicked", G_CALLBACK(barf), textview);
 230
 231         gtk_main();
 232         return 0;
 233 }