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         g_printerr("View height = %d\n", visiblerect.height);
  36         g_printerr("End - Pager = %d\n", endpos.y - pagerpos.y);
  37
  38         *view_height = visiblerect.height;
  39         *scroll_distance = endpos.y - pagerpos.y;
  40 }
  41
  42 /* Helper function: turn on paging for this textview */
  43 static void
  44 start_paging(winid_t win)
  45 {
  46         printf("Start paging\n");
  47         win->currently_paging = TRUE;
  48         g_signal_handler_unblock(win->widget, win->pager_expose_handler);
  49         g_signal_handler_unblock(win->widget, win->pager_keypress_handler);
  50 }
  51
  52 /* Helper function: turn off paging for this textview */
  53 static void
  54 stop_paging(winid_t win)
  55 {
  56         printf("Stop paging\n");
  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         printf("pager check (idle)...\n");
  69         winid_t win = (winid_t) data;
  70
  71         /* Move the pager to the last visible character in the buffer */
  72         gint view_height, scroll_distance;
  73         move_pager_and_get_scroll_distance( GTK_TEXT_VIEW(win->widget), &view_height, &scroll_distance, FALSE );
  74
  75         gdk_threads_enter();
  76
  77         if(view_height <= 1)
  78                 /* Paging is unusable when window is too small */
  79                 return FALSE;
  80
  81         /* Scroll past text already read by user. This is automatic scrolling, so disable the pager_ajustment_handler
  82          * first, that acts on the belief the scolling is performed by the user. */
  83         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(win->frame));
  84         g_signal_handler_block(adj, win->pager_adjustment_handler);
  85         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(win->widget));
  86         GtkTextMark *pager_position = gtk_text_buffer_get_mark(buffer, "pager_position");
  87         gtk_text_view_scroll_to_mark(GTK_TEXT_VIEW(win->widget), pager_position, 0.0, TRUE, 0.0, 0.0);
  88         g_signal_handler_unblock(adj, win->pager_adjustment_handler);
  89
  90         if(!win->currently_paging) {
  91                 if(scroll_distance > view_height) {
  92                         start_paging(win);
  93                         /* Seriously... */
  94                         /* COMPAT: */
  95 #if GTK_CHECK_VERSION(2,14,0)
  96                         gdk_window_invalidate_rect(gtk_widget_get_window(win->widget), NULL, TRUE);
  97 #else
  98                         gdk_window_invalidate_rect(win->widget->window, NULL, TRUE);
  99 #endif
 100                 }
 101         }
 102         gdk_threads_leave();
 103
 104         /* Returning FALSE to prevent this function from being called multiple times */
 105         return FALSE;
 106 }
 107
 108 /* When the user scrolls up in a textbuffer, start paging. */
 109 void
 110 pager_after_adjustment_changed(GtkAdjustment *adj, winid_t win)
 111 {
 112         /* Move the pager, etc. */
 113         gint scroll_distance, view_height;
 114         move_pager_and_get_scroll_distance( GTK_TEXT_VIEW(win->widget), &view_height, &scroll_distance, TRUE );
 115
 116         if(scroll_distance > 0 && !win->currently_paging)
 117                 start_paging(win);
 118         else if(scroll_distance == 0 && win->currently_paging)
 119                 stop_paging(win);
 120
 121         /* Refresh the widget so that any extra "more" prompts disappear */
 122         gtk_widget_queue_draw(win->widget);
 123 }
 124
 125 /* Handle key press events in the textview while paging is active */
 126 gboolean
 127 pager_on_key_press_event(GtkTextView *textview, GdkEventKey *event, winid_t win)
 128 {
 129         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment( GTK_SCROLLED_WINDOW(win->frame) );
 130         gdouble step_increment, page_size, upper, lower, value;
 131         g_object_get(adj,
 132                 "page-size", &page_size,
 133                 "step-increment", &step_increment,
 134                 "upper", &upper,
 135                 "lower", &lower,
 136                 "value", &value,
 137                 NULL);
 138
 139         switch (event->keyval) {
 140                 case GDK_space: case GDK_KP_Space: case GDK_Page_Down: case GDK_KP_Page_Down:
 141                         gtk_adjustment_set_value(adj, CLAMP(value + page_size, lower, upper - page_size));
 142                         return TRUE;
 143                 case GDK_Page_Up: case GDK_KP_Page_Up:
 144                         gtk_adjustment_set_value(adj, CLAMP(value - page_size, lower, upper - page_size));
 145                         return TRUE;
 146                 case GDK_Return: case GDK_KP_Enter:
 147                         gtk_adjustment_set_value(adj, CLAMP(value + step_increment, lower, upper - page_size));
 148                         return TRUE;
 149                         /* don't handle "up" and "down", they're used for input history */
 150         }
 151
 152         return FALSE; /* if the key wasn't handled here, pass it to other handlers */
 153 }
 154
 155 /* Draw the "more" prompt on top of the buffer, after the regular expose event has run */
 156 gboolean
 157 pager_on_expose(GtkTextView *textview, GdkEventExpose *event, winid_t win)
 158 {
 159         /* Calculate the position of the 'more' tag */
 160         gint promptwidth, promptheight;
 161         pango_layout_get_pixel_size(win->pager_layout, &promptwidth, &promptheight);
 162
 163         gint winx, winy, winwidth, winheight;
 164         gdk_window_get_position(event->window, &winx, &winy);
 165         gdk_drawable_get_size(GDK_DRAWABLE(event->window), &winwidth, &winheight);
 166
 167         /* Draw the 'more' tag */
 168         GdkGC *context = gdk_gc_new(GDK_DRAWABLE(event->window));
 169         gdk_draw_layout(event->window, context,
 170                 winx + winwidth - promptwidth,
 171                 winy + winheight - promptheight,
 172                 win->pager_layout);
 173
 174         return FALSE; /* Propagate event further */
 175 }
 176
 177 gboolean
 178 pager_after_expose_event(GtkTextView *textview, GdkEventExpose *event, winid_t win)
 179 {
 180         printf("pager check (expose)...\n");
 181         g_idle_add(pager_check, win);
 182         return FALSE;
 183 }
 184
 185 void
 186 pager_after_size_request(GtkTextView *textview, GtkRequisition *requisition, winid_t win)
 187 {
 188         printf("pager check (size request)...\n");
 189         g_idle_add(pager_check, win);
 190 }
 191
 192 void
 193 pager_update(winid_t win)
 194 {
 195         GtkTextIter input_iter;
 196         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(win->widget));
 197         GtkTextMark *input_position = gtk_text_buffer_get_mark(buffer, "input_position");
 198         GtkTextMark *pager_position = gtk_text_buffer_get_mark(buffer, "pager_position");
 199         gtk_text_buffer_get_iter_at_mark(buffer, &input_iter, input_position);
 200         gtk_text_buffer_move_mark(buffer, pager_position, &input_iter);
 201 }