libchimara/pager.c

   1 #include <gdk/gdkkeysyms.h>
   2
   3 #include "pager.h"
   4
   5 /* Not sure if necessary, but this is the margin within which the pager will
   6 stop paging if it's close to the end of the text buffer */
   7 #define PAGER_FUZZINESS 1.0
   8
   9 /* Helper function: move the pager to the last visible position in the buffer,
  10  and return the distance between the pager and the end of the buffer in buffer
  11  coordinates */
  12 static void
  13 move_pager_and_get_scroll_distance(GtkTextView *textview, gint *view_height, gint *scroll_distance, gboolean move )
  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(
  23                 textview,
  24                 &newpager,
  25                 visiblerect.x + visiblerect.width,
  26                 visiblerect.y + visiblerect.height
  27         );
  28         gtk_text_buffer_get_iter_at_mark(buffer, &oldpager, pager);
  29
  30         if(move)
  31                 gtk_text_buffer_move_mark(buffer, pager, &newpager);
  32
  33         /* Get the buffer coordinates of the pager and the end iter */
  34         gtk_text_buffer_get_end_iter(buffer, &end);
  35         gtk_text_buffer_get_iter_at_mark(buffer, &newpager, pager);
  36         gtk_text_view_get_iter_location(textview, &newpager, &pagerpos);
  37         gtk_text_view_get_iter_location(textview, &end, &endpos);
  38
  39         *view_height = visiblerect.height;
  40         *scroll_distance = endpos.y - pagerpos.y;
  41 }
  42
  43 /* Helper function: turn on paging for this textview */
  44 static void
  45 start_paging(winid_t win)
  46 {
  47         win->currently_paging = TRUE;
  48         gtk_widget_show(win->pager);
  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         win->currently_paging = FALSE;
  57         gtk_widget_hide(win->pager);
  58         g_signal_handler_block(win->widget, win->pager_keypress_handler);
  59 }
  60
  61 /* Helper function: If the adjustment is at its maximum value, stop paging */
  62 static void
  63 check_paging(GtkAdjustment *adj, winid_t win)
  64 {
  65         double page_size, upper, value;
  66         g_object_get(adj,
  67                 "page-size", &page_size,
  68                 "upper", &upper,
  69                 "value", &value,
  70                 NULL);
  71         if(value + PAGER_FUZZINESS >= upper - page_size && win->currently_paging)
  72                 stop_paging(win);
  73 }
  74
  75 void
  76 pager_on_clicked(GtkButton *pager, winid_t win)
  77 {
  78         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment( GTK_SCROLLED_WINDOW(win->scrolledwindow) );
  79         double upper = gtk_adjustment_get_upper(adj);
  80         gtk_adjustment_set_value(adj, upper);
  81         check_paging(adj, win);
  82 }
  83
  84 /* When the user scrolls up in a textbuffer, start paging. */
  85 void
  86 pager_after_adjustment_changed(GtkAdjustment *adj, winid_t win)
  87 {
  88         /* Move the pager, etc. */
  89         gint scroll_distance, view_height;
  90         move_pager_and_get_scroll_distance( GTK_TEXT_VIEW(win->widget), &view_height, &scroll_distance, TRUE );
  91
  92         if(scroll_distance > 0 && !win->currently_paging)
  93         {
  94                 start_paging(win);
  95                 return;
  96         }
  97         else if(scroll_distance == 0 && win->currently_paging)
  98         {
  99                 stop_paging(win);
 100                 return;
 101         }
 102
 103         check_paging(adj, win);
 104 }
 105
 106 /* Handle key press events in the textview while paging is active */
 107 gboolean
 108 pager_on_key_press_event(GtkTextView *textview, GdkEventKey *event, winid_t win)
 109 {
 110         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment( GTK_SCROLLED_WINDOW(win->scrolledwindow) );
 111         gdouble page_size, upper, lower, value;
 112         g_object_get(adj,
 113                 "page-size", &page_size,
 114                 "upper", &upper,
 115                 "lower", &lower,
 116                 "value", &value,
 117                 NULL);
 118
 119         switch (event->keyval) {
 120                 case GDK_KEY_space: case GDK_KEY_KP_Space:
 121                 case GDK_KEY_Page_Down: case GDK_KEY_KP_Page_Down:
 122                 case GDK_KEY_Return: case GDK_KEY_KP_Enter:
 123                         gtk_adjustment_set_value(adj, CLAMP(value + page_size, lower, upper - page_size));
 124                         check_paging(adj, win);
 125                         return TRUE;
 126                 case GDK_KEY_Page_Up: case GDK_KEY_KP_Page_Up:
 127                         gtk_adjustment_set_value(adj, CLAMP(value - page_size, lower, upper - page_size));
 128                         check_paging(adj, win);
 129                         return TRUE;
 130                 case GDK_KEY_End: case GDK_KEY_KP_End:
 131                         gtk_adjustment_set_value(adj, upper - page_size);
 132                         check_paging(adj, win);
 133                         return TRUE;
 134                         /* don't handle "up" and "down", they're used for input history */
 135         }
 136
 137         return FALSE; /* if the key wasn't handled here, pass it to other handlers */
 138 }
 139
 140 /* Check whether paging should be done. This function is called after the
 141  * textview has finished validating text positions. */
 142 void
 143 pager_after_size_allocate(GtkTextView *textview, GdkRectangle *allocation, winid_t win)
 144 {
 145         /* Move the pager to the last visible character in the buffer */
 146         gint view_height, scroll_distance;
 147         move_pager_and_get_scroll_distance(GTK_TEXT_VIEW(win->widget), &view_height, &scroll_distance, FALSE);
 148
 149         if(view_height <= 1)
 150                 /* Paging is unusable when window is too small */
 151                 return;
 152
 153         /* If not in interactive mode, then just scroll to the bottom. */
 154         ChimaraGlk *glk = CHIMARA_GLK(gtk_widget_get_ancestor(GTK_WIDGET(textview), CHIMARA_TYPE_GLK));
 155         g_assert(glk);
 156         if(!chimara_glk_get_interactive(glk)) {
 157                 GtkTextIter end;
 158                 gtk_text_buffer_get_end_iter(gtk_text_view_get_buffer(textview), &end);
 159                 gtk_text_view_scroll_to_iter(textview, &end, 0.0, TRUE, 0.0, 0.0);
 160                 return;
 161         }
 162
 163         /* Scroll past text already read by user. This is automatic scrolling, so disable the pager_ajustment_handler
 164          * first, that acts on the belief the scolling is performed by the user. */
 165         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(win->scrolledwindow));
 166         g_signal_handler_block(adj, win->pager_adjustment_handler);
 167         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(win->widget));
 168         GtkTextMark *pager_position = gtk_text_buffer_get_mark(buffer, "pager_position");
 169         gtk_text_view_scroll_to_mark(GTK_TEXT_VIEW(win->widget), pager_position, 0.0, TRUE, 0.0, 0.0);
 170         g_signal_handler_unblock(adj, win->pager_adjustment_handler);
 171
 172         if(!win->currently_paging) {
 173                 if(scroll_distance > view_height) {
 174                         start_paging(win);
 175                         gdk_window_invalidate_rect(gtk_widget_get_window(win->widget), NULL, TRUE);
 176                 }
 177         }
 178 }
 179
 180 void
 181 pager_update(winid_t win)
 182 {
 183         GtkTextIter input_iter;
 184         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(win->widget));
 185         GtkTextMark *input_position = gtk_text_buffer_get_mark(buffer, "input_position");
 186         GtkTextMark *pager_position = gtk_text_buffer_get_mark(buffer, "pager_position");
 187         gtk_text_buffer_get_iter_at_mark(buffer, &input_iter, input_position);
 188         gtk_text_buffer_move_mark(buffer, pager_position, &input_iter);
 189 }