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         /* Give the focus back to the text view */
  83         gtk_widget_grab_focus(win->widget);
  84 }
  85
  86 /* When the user scrolls up in a textbuffer, start paging. */
  87 void
  88 pager_after_adjustment_changed(GtkAdjustment *adj, winid_t win)
  89 {
  90         /* Move the pager, etc. */
  91         gint scroll_distance, view_height;
  92         move_pager_and_get_scroll_distance( GTK_TEXT_VIEW(win->widget), &view_height, &scroll_distance, TRUE );
  93
  94         if(scroll_distance > 0 && !win->currently_paging)
  95         {
  96                 start_paging(win);
  97                 return;
  98         }
  99         else if(scroll_distance == 0 && win->currently_paging)
 100         {
 101                 stop_paging(win);
 102                 return;
 103         }
 104
 105         check_paging(adj, win);
 106 }
 107
 108 /* Handle key press events in the textview while paging is active */
 109 gboolean
 110 pager_on_key_press_event(GtkTextView *textview, GdkEventKey *event, winid_t win)
 111 {
 112         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment( GTK_SCROLLED_WINDOW(win->scrolledwindow) );
 113         gdouble page_size, upper, lower, value;
 114         g_object_get(adj,
 115                 "page-size", &page_size,
 116                 "upper", &upper,
 117                 "lower", &lower,
 118                 "value", &value,
 119                 NULL);
 120
 121         switch (event->keyval) {
 122                 case GDK_KEY_space: case GDK_KEY_KP_Space:
 123                 case GDK_KEY_Page_Down: case GDK_KEY_KP_Page_Down:
 124                 case GDK_KEY_Return: case GDK_KEY_KP_Enter:
 125                         gtk_adjustment_set_value(adj, CLAMP(value + page_size, lower, upper - page_size));
 126                         check_paging(adj, win);
 127                         return TRUE;
 128                 case GDK_KEY_Page_Up: case GDK_KEY_KP_Page_Up:
 129                         gtk_adjustment_set_value(adj, CLAMP(value - page_size, lower, upper - page_size));
 130                         check_paging(adj, win);
 131                         return TRUE;
 132                 case GDK_KEY_End: case GDK_KEY_KP_End:
 133                         gtk_adjustment_set_value(adj, upper - page_size);
 134                         check_paging(adj, win);
 135                         return TRUE;
 136                         /* don't handle "up" and "down", they're used for input history */
 137         }
 138
 139         return FALSE; /* if the key wasn't handled here, pass it to other handlers */
 140 }
 141
 142 /* Check whether paging should be done. This function is called after the
 143  * textview has finished validating text positions. */
 144 void
 145 pager_after_size_allocate(GtkTextView *textview, GdkRectangle *allocation, winid_t win)
 146 {
 147         /* Move the pager to the last visible character in the buffer */
 148         gint view_height, scroll_distance;
 149         move_pager_and_get_scroll_distance(GTK_TEXT_VIEW(win->widget), &view_height, &scroll_distance, FALSE);
 150
 151         if(view_height <= 1)
 152                 /* Paging is unusable when window is too small */
 153                 return;
 154
 155         /* If not in interactive mode, then just scroll to the bottom. */
 156         ChimaraGlk *glk = CHIMARA_GLK(gtk_widget_get_ancestor(GTK_WIDGET(textview), CHIMARA_TYPE_GLK));
 157         g_assert(glk);
 158         if(!chimara_glk_get_interactive(glk)) {
 159                 GtkTextIter end;
 160                 gtk_text_buffer_get_end_iter(gtk_text_view_get_buffer(textview), &end);
 161                 gtk_text_view_scroll_to_iter(textview, &end, 0.0, TRUE, 0.0, 0.0);
 162                 return;
 163         }
 164
 165         /* Scroll past text already read by user. This is automatic scrolling, so disable the pager_ajustment_handler
 166          * first, that acts on the belief the scolling is performed by the user. */
 167         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(win->scrolledwindow));
 168         g_signal_handler_block(adj, win->pager_adjustment_handler);
 169         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(win->widget));
 170         GtkTextMark *pager_position = gtk_text_buffer_get_mark(buffer, "pager_position");
 171         gtk_text_view_scroll_to_mark(GTK_TEXT_VIEW(win->widget), pager_position, 0.0, TRUE, 0.0, 0.0);
 172         g_signal_handler_unblock(adj, win->pager_adjustment_handler);
 173
 174         if(!win->currently_paging) {
 175                 if(scroll_distance > view_height) {
 176                         start_paging(win);
 177                         gdk_window_invalidate_rect(gtk_widget_get_window(win->widget), NULL, TRUE);
 178                 }
 179         }
 180 }
 181
 182 void
 183 pager_update(winid_t win)
 184 {
 185         GtkTextIter input_iter;
 186         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(win->widget));
 187         GtkTextMark *input_position = gtk_text_buffer_get_mark(buffer, "input_position");
 188         GtkTextMark *pager_position = gtk_text_buffer_get_mark(buffer, "pager_position");
 189         gtk_text_buffer_get_iter_at_mark(buffer, &input_iter, input_position);
 190         gtk_text_buffer_move_mark(buffer, pager_position, &input_iter);
 191 }