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