libchimara/pager.c

   1 #include <gdk/gdkkeysyms.h>
   2
   3 #include "pager.h"
   4
   5 /* Helper function: move the pager to the last visible position in the buffer,
   6  and return the distance between the pager and the end of the buffer in buffer
   7  coordinates */
   8 static void
   9 move_pager_and_get_scroll_distance(GtkTextView *textview, gint *view_height, gint *scroll_distance)
  10 {
  11         GdkRectangle pagerpos, endpos, visiblerect;
  12         GtkTextIter oldpager, newpager, end;
  13         GtkTextBuffer *buffer = gtk_text_view_get_buffer(textview);
  14         GtkTextMark *pager = gtk_text_buffer_get_mark(buffer, "pager_position");
  15
  16         /* Get an iter at the lower right corner of the visible part of the buffer */
  17         gtk_text_view_get_visible_rect(textview, &visiblerect);
  18         gtk_text_view_get_iter_at_location(
  19                 textview,
  20                 &newpager,
  21                 visiblerect.x + visiblerect.width,
  22                 visiblerect.y + visiblerect.height
  23         );
  24         gtk_text_buffer_get_iter_at_mark(buffer, &oldpager, pager);
  25
  26         gtk_text_buffer_move_mark(buffer, pager, &newpager);
  27
  28         /* Get the buffer coordinates of the pager and the end iter */
  29         gtk_text_buffer_get_end_iter(buffer, &end);
  30         gtk_text_buffer_get_iter_at_mark(buffer, &newpager, pager);
  31         gtk_text_view_get_iter_location(textview, &newpager, &pagerpos);
  32         gtk_text_view_get_iter_location(textview, &end, &endpos);
  33
  34         g_printerr("View height = %d\n", visiblerect.height);
  35         g_printerr("End - Pager = %d\n", endpos.y - pagerpos.y);
  36
  37         *view_height = visiblerect.height;
  38         *scroll_distance = endpos.y - pagerpos.y;
  39 }
  40
  41 /* Helper function: turn on paging for this textview */
  42 static void
  43 start_paging(winid_t win)
  44 {
  45         win->currently_paging = TRUE;
  46         g_signal_handler_unblock(win->widget, win->pager_expose_handler);
  47         g_signal_handler_unblock(win->widget, win->pager_keypress_handler);
  48 }
  49
  50 /* Helper function: turn off paging for this textview */
  51 static void
  52 stop_paging(winid_t win)
  53 {
  54         win->currently_paging = FALSE;
  55         g_signal_handler_block(win->widget, win->pager_expose_handler);
  56         g_signal_handler_block(win->widget, win->pager_keypress_handler);
  57 }
  58
  59 /* Check whether paging should be done. This function is called inside the
  60  * idle handler, after the textview has finished updating. */
  61 gboolean
  62 pager_check(gpointer data)
  63 {
  64
  65         printf("pager check...\n");
  66         winid_t win = (winid_t) data;
  67
  68
  69         /* Move the pager to the last visible character in the buffer */
  70         gint view_height, scroll_distance;
  71         move_pager_and_get_scroll_distance( GTK_TEXT_VIEW(win->widget), &view_height, &scroll_distance );
  72
  73         if(view_height <= 1)
  74                 /* Paging is unusable when window is too small */
  75                 return FALSE;
  76
  77         if(!win->currently_paging) {
  78                 if(scroll_distance > view_height) {
  79                         start_paging(win);
  80                         /* Seriously... */
  81                         /* COMPAT: */
  82 #if GTK_CHECK_VERSION(2,14,0)
  83                         gdk_window_invalidate_rect(gtk_widget_get_window(win->widget), NULL, TRUE);
  84 #else
  85                         gdk_window_invalidate_rect(win->widget->window, NULL, TRUE);
  86 #endif
  87                 }
  88                 else if(scroll_distance > 0) {
  89                         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(win->widget));
  90                         GtkTextMark *end = gtk_text_buffer_get_mark(buffer, "end_position");
  91
  92                         gdk_threads_enter();
  93                         gtk_text_view_scroll_mark_onscreen(GTK_TEXT_VIEW(win->widget), end);
  94                         gdk_threads_leave();
  95                 }
  96         }
  97
  98         /* Returning FALSE to prevent this function from being called multiple times */
  99         return FALSE;
 100 }
 101
 102 /* When the user scrolls up in a textbuffer, start paging. */
 103 void
 104 pager_after_adjustment_changed(GtkAdjustment *adj, winid_t win)
 105 {
 106         /* Move the pager, etc. */
 107         gint scroll_distance, view_height;
 108         move_pager_and_get_scroll_distance( GTK_TEXT_VIEW(win->widget), &view_height, &scroll_distance );
 109
 110         if(scroll_distance > 0 && !win->currently_paging)
 111                 start_paging(win);
 112         else if(scroll_distance == 0 && win->currently_paging)
 113                 stop_paging(win);
 114
 115         /* Refresh the widget so that any extra "more" prompts disappear */
 116         gtk_widget_queue_draw(win->widget);
 117 }
 118
 119 /* Handle key press events in the textview while paging is active */
 120 gboolean
 121 pager_on_key_press_event(GtkTextView *textview, GdkEventKey *event, winid_t win)
 122 {
 123         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment( GTK_SCROLLED_WINDOW(win->frame) );
 124         gdouble step_increment, page_size, upper, lower, value;
 125         g_object_get(adj,
 126                 "page-size", &page_size,
 127                 "step-increment", &step_increment,
 128                 "upper", &upper,
 129                 "lower", &lower,
 130                 "value", &value,
 131                 NULL);
 132
 133         switch (event->keyval) {
 134                 case GDK_space: case GDK_KP_Space: case GDK_Page_Down: case GDK_KP_Page_Down:
 135                         gtk_adjustment_set_value(adj, CLAMP(value + page_size, lower, upper - page_size));
 136                         return TRUE;
 137                 case GDK_Page_Up: case GDK_KP_Page_Up:
 138                         gtk_adjustment_set_value(adj, CLAMP(value - page_size, lower, upper - page_size));
 139                         return TRUE;
 140                 case GDK_Return: case GDK_KP_Enter:
 141                         gtk_adjustment_set_value(adj, CLAMP(value + step_increment, lower, upper - page_size));
 142                         return TRUE;
 143                         /* don't handle "up" and "down", they're used for input history */
 144         }
 145
 146         return FALSE; /* if the key wasn't handled here, pass it to other handlers */
 147 }
 148
 149 /* Draw the "more" prompt on top of the buffer, after the regular expose event has run */
 150 gboolean
 151 pager_on_expose(GtkTextView *textview, GdkEventExpose *event, winid_t win)
 152 {
 153         /* Calculate the position of the 'more' tag */
 154         gint promptwidth, promptheight;
 155         pango_layout_get_pixel_size(win->pager_layout, &promptwidth, &promptheight);
 156
 157         gint winx, winy, winwidth, winheight;
 158         gdk_window_get_position(event->window, &winx, &winy);
 159         gdk_drawable_get_size(GDK_DRAWABLE(event->window), &winwidth, &winheight);
 160
 161         /* Draw the 'more' tag */
 162         GdkGC *context = gdk_gc_new(GDK_DRAWABLE(event->window));
 163         gdk_draw_layout(event->window, context,
 164                 winx + winwidth - promptwidth,
 165                 winy + winheight - promptheight,
 166                 win->pager_layout);
 167
 168         return FALSE; /* Propagate event further */
 169 }
 170