tests/barf.c.eventbox

   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(GtkWidget *eventbox)
  81 {
  82         currently_paging = TRUE;
  83         g_signal_handler_unblock(eventbox, expose_handler);
  84         g_signal_handler_unblock(eventbox, pager_handler);
  85 }
  86
  87 /* Helper function: turn off paging for this textview */
  88 static void
  89 stop_paging(GtkWidget *eventbox)
  90 {
  91         currently_paging = FALSE;
  92         g_signal_handler_block(eventbox, expose_handler);
  93         g_signal_handler_block(eventbox, 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                 GtkWidget *eventbox = gtk_widget_get_parent( gtk_widget_get_parent(GTK_WIDGET(textview)) );
 108                 start_paging(eventbox);
 109         }
 110 }
 111
 112 static void
 113 adjustment_changed(GtkAdjustment *adjustment, GtkTextView *textview)
 114 {
 115         while(gtk_events_pending())
 116                 gtk_main_iteration();
 117
 118         /* Move the pager, etc. */
 119         gint scroll_distance = move_pager_and_get_scroll_distance(textview);
 120
 121         GtkWidget *eventbox = gtk_widget_get_parent( gtk_widget_get_parent(GTK_WIDGET(textview)) );
 122         if(scroll_distance > 0 && !currently_paging)
 123                 start_paging(eventbox);
 124         else if(scroll_distance == 0 && currently_paging)
 125                 stop_paging(eventbox);
 126
 127         /* Refresh the widget so that any extra "more" prompts disappear */
 128         gtk_widget_queue_draw(GTK_WIDGET(eventbox));
 129 }
 130
 131 /* Handle key press events in the textview while paging is active */
 132 static gboolean
 133 pager_wait(GtkTextView *eventbox, GdkEventKey *event, GtkTextBuffer *buffer)
 134 {
 135         /*** ALTERNATIVE, POSSIBLY INFERIOR, METHOD OF SCROLLING ***
 136         GtkTextMark *pagermark = gtk_text_buffer_get_mark(buffer, "pager_position");
 137         gtk_text_view_scroll_to_mark(textview, pagermark, 0.0, TRUE, 0.0, 0.0);
 138         */
 139
 140         GtkWidget *scrolledwindow = gtk_bin_get_child(GTK_BIN(eventbox));
 141         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(scrolledwindow));
 142         gdouble step_increment, page_size, upper, lower, value;
 143         g_object_get(adj,
 144                 "page-size", &page_size,
 145                 "step-increment", &step_increment,
 146                 "upper", &upper,
 147                 "lower", &lower,
 148                 "value", &value,
 149                 NULL);
 150
 151         switch (event->keyval) {
 152                 case GDK_space: case GDK_KP_Space: case GDK_Page_Down: case GDK_KP_Page_Down:
 153                         gtk_adjustment_set_value(adj, CLAMP(value + page_size, lower, upper - page_size));
 154                         return TRUE;
 155                 case GDK_Page_Up: case GDK_KP_Page_Up:
 156                         gtk_adjustment_set_value(adj, CLAMP(value - page_size, lower, upper - page_size));
 157                         return TRUE;
 158                 case GDK_Return: case GDK_KP_Enter:
 159                         gtk_adjustment_set_value(adj, CLAMP(value + step_increment, lower, upper - page_size));
 160                         return TRUE;
 161                         /* don't handle "up" and "down", they're used for input history */
 162         }
 163
 164         return FALSE; /* if the key wasn't handled here, pass it to other handlers */
 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(GtkEventBox *eventbox, 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                 winy - 5,
 181                 prompt, &white, &red);
 182
 183         return FALSE; /* Propagate event further */
 184 }
 185
 186 int
 187 main(int argc, char **argv)
 188 {
 189         gtk_init(&argc, &argv);
 190
 191         /* Construct the widgets */
 192         GtkWidget *window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
 193         gtk_widget_set_size_request(window, 400, 400);
 194         GtkWidget *button = gtk_button_new_with_label("Barf");
 195         GtkWidget *eventbox = gtk_event_box_new();
 196 //      gtk_event_box_set_above_child( GTK_EVENT_BOX(eventbox), TRUE );
 197         GTK_WIDGET_SET_FLAGS(eventbox, GTK_APP_PAINTABLE);
 198         GtkWidget *scrolledwindow = gtk_scrolled_window_new(NULL, NULL);
 199         GtkWidget *textview = gtk_text_view_new();
 200         gtk_text_view_set_wrap_mode(GTK_TEXT_VIEW(textview), GTK_WRAP_WORD_CHAR);
 201         gtk_text_view_set_editable(GTK_TEXT_VIEW(textview), FALSE);
 202         GtkWidget *vbox = gtk_vbox_new(FALSE, 6);
 203
 204         /* Pack all the widgets into their containers */
 205         gtk_container_add(GTK_CONTAINER(scrolledwindow), textview);
 206         gtk_container_add(GTK_CONTAINER(eventbox), scrolledwindow);
 207         gtk_box_pack_start(GTK_BOX(vbox), button, FALSE, FALSE, 0);
 208         gtk_box_pack_start(GTK_BOX(vbox), eventbox, TRUE, TRUE, 0);
 209         gtk_container_add(GTK_CONTAINER(window), vbox);
 210         gtk_widget_show_all(window);
 211
 212         /* Set up the textview widget to receive exposure events, must be done after widget has been shown */
 213         gdk_window_set_events(gtk_widget_get_window(eventbox), GDK_EXPOSURE_MASK);
 214
 215         /* Create the 'more' prompt */
 216         prompt = gtk_widget_create_pango_layout(GTK_WIDGET(textview), "More");
 217         pango_layout_get_pixel_size(prompt, &promptwidth, &promptheight);
 218         gdk_color_parse("red", &red);
 219         gdk_color_parse("white", &white);
 220
 221         /* Connect paging signals */
 222         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(textview));
 223         g_signal_connect_after(buffer, "insert-text", G_CALLBACK(after_insert), textview);
 224         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(scrolledwindow));
 225         g_signal_connect_after(adj, "value-changed", G_CALLBACK(adjustment_changed), textview);
 226         pager_handler = g_signal_connect(eventbox, "key-press-event", G_CALLBACK(pager_wait), buffer);
 227         g_signal_handler_block(eventbox, pager_handler);
 228         expose_handler = g_signal_connect(eventbox, "expose-event", G_CALLBACK(expose_prompt), NULL);
 229         g_signal_handler_block(eventbox, expose_handler);
 230
 231         /* Create the pager position mark; it stands for the last character in the buffer
 232          that has been on-screen */
 233         GtkTextIter end;
 234         gtk_text_buffer_get_end_iter(buffer, &end);
 235         GtkTextMark *pagermark = gtk_text_buffer_create_mark(buffer, "pager_position", &end, TRUE);
 236         gtk_text_mark_set_visible(pagermark, TRUE);
 237
 238         /* Connect "regular program" signals */
 239         g_signal_connect(window, "delete-event", G_CALLBACK(quit), NULL);
 240         g_signal_connect(button, "clicked", G_CALLBACK(barf), textview);
 241
 242         gtk_main();
 243
 244         g_object_unref(prompt);
 245         return 0;
 246 }