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         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         win->currently_paging = FALSE;
  57         g_signal_handler_block(win->widget, win->pager_expose_handler);
  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 /* When the user scrolls up in a textbuffer, start paging. */
  76 void
  77 pager_after_adjustment_changed(GtkAdjustment *adj, winid_t win)
  78 {
  79         /* Move the pager, etc. */
  80         gint scroll_distance, view_height;
  81         move_pager_and_get_scroll_distance( GTK_TEXT_VIEW(win->widget), &view_height, &scroll_distance, TRUE );
  82
  83         if(scroll_distance > 0 && !win->currently_paging)
  84         {
  85                 start_paging(win);
  86                 return;
  87         }
  88         else if(scroll_distance == 0 && win->currently_paging)
  89         {
  90                 stop_paging(win);
  91                 gtk_widget_queue_draw(win->widget);
  92                 return;
  93         }
  94
  95         /* Refresh the widget so that any extra "more" prompts disappear */
  96         gtk_widget_queue_draw(win->widget);
  97
  98         check_paging(adj, win);
  99 }
 100
 101 /* Handle key press events in the textview while paging is active */
 102 gboolean
 103 pager_on_key_press_event(GtkTextView *textview, GdkEventKey *event, winid_t win)
 104 {
 105         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment( GTK_SCROLLED_WINDOW(win->frame) );
 106         gdouble page_size, upper, lower, value;
 107         g_object_get(adj,
 108                 "page-size", &page_size,
 109                 "upper", &upper,
 110                 "lower", &lower,
 111                 "value", &value,
 112                 NULL);
 113
 114         switch (event->keyval) {
 115                 case GDK_KEY_space: case GDK_KEY_KP_Space:
 116                 case GDK_KEY_Page_Down: case GDK_KEY_KP_Page_Down:
 117                 case GDK_KEY_Return: case GDK_KEY_KP_Enter:
 118                         gtk_adjustment_set_value(adj, CLAMP(value + page_size, lower, upper - page_size));
 119                         check_paging(adj, win);
 120                         return TRUE;
 121                 case GDK_KEY_Page_Up: case GDK_KEY_KP_Page_Up:
 122                         gtk_adjustment_set_value(adj, CLAMP(value - page_size, lower, upper - page_size));
 123                         check_paging(adj, win);
 124                         return TRUE;
 125                         /* don't handle "up" and "down", they're used for input history */
 126         }
 127
 128         return FALSE; /* if the key wasn't handled here, pass it to other handlers */
 129 }
 130
 131 /* Draw the "more" prompt on top of the buffer, after the regular expose event has run */
 132 gboolean
 133 pager_on_expose(GtkTextView *textview, GdkEventExpose *event, winid_t win)
 134 {
 135         /* Calculate the position of the 'more' tag */
 136         gint promptwidth, promptheight;
 137         pango_layout_get_pixel_size(win->pager_layout, &promptwidth, &promptheight);
 138
 139         int winx, winy;
 140         gdk_window_get_position(event->window, &winx, &winy);
 141         int winwidth = gdk_window_get_width(event->window);
 142         int winheight = gdk_window_get_height(event->window);
 143
 144         /* Draw the 'more' tag */
 145         cairo_t *cr = gdk_cairo_create(event->window);
 146         cairo_move_to(cr,
 147                 winx + winwidth - promptwidth,
 148                 winy + winheight - promptheight);
 149         pango_cairo_show_layout(cr, win->pager_layout);
 150
 151         return FALSE; /* Propagate event further */
 152 }
 153
 154 /* Check whether paging should be done. This function is called after the
 155  * textview has finished validating text positions. */
 156 void
 157 pager_after_size_request(GtkTextView *textview, GtkRequisition *requisition, winid_t win)
 158 {
 159         /* Move the pager to the last visible character in the buffer */
 160         gint view_height, scroll_distance;
 161         move_pager_and_get_scroll_distance(GTK_TEXT_VIEW(win->widget), &view_height, &scroll_distance, FALSE);
 162
 163         if(view_height <= 1)
 164                 /* Paging is unusable when window is too small */
 165                 return;
 166
 167         /* If not in interactive mode, then just scroll to the bottom. */
 168         ChimaraGlk *glk = CHIMARA_GLK(gtk_widget_get_ancestor(GTK_WIDGET(textview), CHIMARA_TYPE_GLK));
 169         g_assert(glk);
 170         if(!chimara_glk_get_interactive(glk)) {
 171                 GtkTextIter end;
 172                 gtk_text_buffer_get_end_iter(gtk_text_view_get_buffer(textview), &end);
 173                 gtk_text_view_scroll_to_iter(textview, &end, 0.0, TRUE, 0.0, 0.0);
 174                 return;
 175         }
 176
 177         /* Scroll past text already read by user. This is automatic scrolling, so disable the pager_ajustment_handler
 178          * first, that acts on the belief the scolling is performed by the user. */
 179         GtkAdjustment *adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(win->frame));
 180         g_signal_handler_block(adj, win->pager_adjustment_handler);
 181         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(win->widget));
 182         GtkTextMark *pager_position = gtk_text_buffer_get_mark(buffer, "pager_position");
 183         gtk_text_view_scroll_to_mark(GTK_TEXT_VIEW(win->widget), pager_position, 0.0, TRUE, 0.0, 0.0);
 184         g_signal_handler_unblock(adj, win->pager_adjustment_handler);
 185
 186         if(!win->currently_paging) {
 187                 if(scroll_distance > view_height) {
 188                         start_paging(win);
 189                         gdk_window_invalidate_rect(gtk_widget_get_window(win->widget), NULL, TRUE);
 190                 }
 191         }
 192 }
 193
 194 void
 195 pager_update(winid_t win)
 196 {
 197         GtkTextIter input_iter;
 198         GtkTextBuffer *buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(win->widget));
 199         GtkTextMark *input_position = gtk_text_buffer_get_mark(buffer, "input_position");
 200         GtkTextMark *pager_position = gtk_text_buffer_get_mark(buffer, "pager_position");
 201         gtk_text_buffer_get_iter_at_mark(buffer, &input_iter, input_position);
 202         gtk_text_buffer_move_mark(buffer, pager_position, &input_iter);
 203 }