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, gboolean move )
  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         if(move)
  27                 gtk_text_buffer_move_mark(buffer, pager, &newpager);
  28
  29         /* Get the buffer coordinates of the pager and the end iter */
  30         gtk_text_buffer_get_end_iter(buffer, &end);
  31         gtk_text_buffer_get_iter_at_mark(buffer, &newpager, pager);
  32         gtk_text_view_get_iter_location(textview, &newpager, &pagerpos);
  33         gtk_text_view_get_iter_location(textview, &end, &endpos);
  34
  35         /*
  36         g_printerr("View height = %d\n", visiblerect.height);
  37         g_printerr("End - Pager = %d\n", endpos.y - pagerpos.y);
  38         */
  39
  40         *view_height = visiblerect.height;
  41         *scroll_distance = endpos.y - pagerpos.y;
  42 }
  43
  44 /* Helper function: turn on paging for this textview */
  45 static void
  46 start_paging(winid_t win)
  47 {
  48         win->currently_paging = TRUE;
  49         g_signal_handler_unblock(win->widget, win->pager_expose_handler);
  50         g_signal_handler_unblock(win->widget, win->pager_keypress_handler);
  51 }
  52
  53 /* Helper function: turn off paging for this textview */
  54 static void
  55 stop_paging(winid_t win)
  56 {
  57         win->currently_paging = FALSE;
  58         g_signal_handler_block(win->widget, win->pager_expose_handler);
  59         g_signal_handler_block(win->widget, win->pager_keypress_handler);
  60 }
  61
  62 /* Check whether paging should be done. This function is called inside the
  63  * idle handler, after the textview has finished updating. */
  64 gboolean
  65 pager_check(gpointer data)
  66 {
  67
  68         winid_t win = (winid_t) data;
  69
  70         /* Move the pager to the last visible character in the buffer */
  71         gint view_height, scroll_distance;
  72         move_pager_and_get_scroll_distance( GTK_TEXT_VIEW(win->widget), &view_height, &scroll_distance, FALSE );
  73
  74         gdk_threads_enter();
  75
  76         if(view_height <= 1)
  77                 /* Paging is unusable when window is too small */
  78                 return FALSE;
  79
  80         /* Scroll past text already read by user. This is automatic scrolling, so disable the pager_ajustment_handler
  81          * first, that acts on the belief the scolling is performed by the user. */
  82         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(win->frame));
  83         g_signal_handler_block(adj, win->pager_adjustment_handler);
  84         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(win->widget));
  85         GtkTextMark *pager_position = gtk_text_buffer_get_mark(buffer, "pager_position");
  86         gtk_text_view_scroll_to_mark(GTK_TEXT_VIEW(win->widget), pager_position, 0.0, TRUE, 0.0, 0.0);
  87         g_signal_handler_unblock(adj, win->pager_adjustment_handler);
  88
  89         if(!win->currently_paging) {
  90                 if(scroll_distance > view_height) {
  91                         start_paging(win);
  92                         /* Seriously... */
  93                         /* COMPAT: */
  94 #if GTK_CHECK_VERSION(2,14,0)
  95                         gdk_window_invalidate_rect(gtk_widget_get_window(win->widget), NULL, TRUE);
  96 #else
  97                         gdk_window_invalidate_rect(win->widget->window, NULL, TRUE);
  98 #endif
  99                 }
 100         }
 101         gdk_threads_leave();
 102
 103         /* Returning FALSE to prevent this function from being called multiple times */
 104         return FALSE;
 105 }
 106
 107 /* When the user scrolls up in a textbuffer, start paging. */
 108 void
 109 pager_after_adjustment_changed(GtkAdjustment *adj, winid_t win)
 110 {
 111         /* Move the pager, etc. */
 112         gint scroll_distance, view_height;
 113         move_pager_and_get_scroll_distance( GTK_TEXT_VIEW(win->widget), &view_height, &scroll_distance, TRUE );
 114
 115         if(scroll_distance > 0 && !win->currently_paging)
 116                 start_paging(win);
 117         else if(scroll_distance == 0 && win->currently_paging)
 118                 stop_paging(win);
 119
 120         /* Refresh the widget so that any extra "more" prompts disappear */
 121         gtk_widget_queue_draw(win->widget);
 122 }
 123
 124 /* Handle key press events in the textview while paging is active */
 125 gboolean
 126 pager_on_key_press_event(GtkTextView *textview, GdkEventKey *event, winid_t win)
 127 {
 128         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment( GTK_SCROLLED_WINDOW(win->frame) );
 129         gdouble step_increment, page_size, upper, lower, value;
 130         g_object_get(adj,
 131                 "page-size", &page_size,
 132                 "step-increment", &step_increment,
 133                 "upper", &upper,
 134                 "lower", &lower,
 135                 "value", &value,
 136                 NULL);
 137
 138         switch (event->keyval) {
 139                 case GDK_space: case GDK_KP_Space: case GDK_Page_Down: case GDK_KP_Page_Down:
 140                         gtk_adjustment_set_value(adj, CLAMP(value + page_size, lower, upper - page_size));
 141                         return TRUE;
 142                 case GDK_Page_Up: case GDK_KP_Page_Up:
 143                         gtk_adjustment_set_value(adj, CLAMP(value - page_size, lower, upper - page_size));
 144                         return TRUE;
 145                 case GDK_Return: case GDK_KP_Enter:
 146                         gtk_adjustment_set_value(adj, CLAMP(value + step_increment, lower, upper - page_size));
 147                         return TRUE;
 148                         /* don't handle "up" and "down", they're used for input history */
 149         }
 150
 151         return FALSE; /* if the key wasn't handled here, pass it to other handlers */
 152 }
 153
 154 /* Draw the "more" prompt on top of the buffer, after the regular expose event has run */
 155 gboolean
 156 pager_on_expose(GtkTextView *textview, GdkEventExpose *event, winid_t win)
 157 {
 158         /* Calculate the position of the 'more' tag */
 159         gint promptwidth, promptheight;
 160         pango_layout_get_pixel_size(win->pager_layout, &promptwidth, &promptheight);
 161
 162         gint winx, winy, winwidth, winheight;
 163         gdk_window_get_position(event->window, &winx, &winy);
 164         gdk_drawable_get_size(GDK_DRAWABLE(event->window), &winwidth, &winheight);
 165
 166         /* Draw the 'more' tag */
 167         GdkGC *context = gdk_gc_new(GDK_DRAWABLE(event->window));
 168         gdk_draw_layout(event->window, context,
 169                 winx + winwidth - promptwidth,
 170                 winy + winheight - promptheight,
 171                 win->pager_layout);
 172
 173         return FALSE; /* Propagate event further */
 174 }
 175
 176 gboolean
 177 pager_after_expose_event(GtkTextView *textview, GdkEventExpose *event, winid_t win)
 178 {
 179         g_idle_add(pager_check, win);
 180         return FALSE;
 181 }
 182
 183 void
 184 pager_after_size_request(GtkTextView *textview, GtkRequisition *requisition, winid_t win)
 185 {
 186         g_idle_add(pager_check, win);
 187 }
 188
 189 void
 190 pager_update(winid_t win)
 191 {
 192         GtkTextIter input_iter;
 193         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(win->widget));
 194         GtkTextMark *input_position = gtk_text_buffer_get_mark(buffer, "input_position");
 195         GtkTextMark *pager_position = gtk_text_buffer_get_mark(buffer, "pager_position");
 196         gtk_text_buffer_get_iter_at_mark(buffer, &input_iter, input_position);
 197         gtk_text_buffer_move_mark(buffer, pager_position, &input_iter);
 198 }