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Add an optional ArdourCanvas::Item::prepare_for_render interface

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Called when an item has requested a redraw and intersects with visible
canvas area.

Also add Canvas::prepare_for_render that will call Item::prepare_for_render for
items visible on the canvas.
This commit is contained in:
Tim Mayberry 2017-04-01 23:02:49 +10:00
parent 265f52535a
commit c4e31fc322
6 changed files with 93 additions and 1 deletions
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33
libs/canvas/canvas.cc
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@ -144,6 +144,22 @@ Canvas::render (Rect const & area, Cairo::RefPtr<Cairo::Context> const & context
}
void
Canvas::prepare_for_render (Rect const & area) const
{
Rect root_bbox = _root.bounding_box();
if (!root_bbox) {
/* the root has no bounding box, so there's nothing to render */
return;
}
Rect draw = root_bbox.intersection (area);
if (draw) {
_root.prepare_for_render (draw);
}
}
ostream&
operator<< (ostream& o, Canvas& c)
{
@ -231,9 +247,17 @@ Canvas::item_changed (Item* item, Rect pre_change_bounding_box)
Rect post_change_bounding_box = item->bounding_box ();
if (post_change_bounding_box) {
if (item->item_to_window (post_change_bounding_box).intersection (window_bbox)) {
Rect const window_intersection =
item->item_to_window (post_change_bounding_box).intersection (window_bbox);
if (window_intersection) {
/* request a redraw of the item's new bounding box */
queue_draw_item_area (item, post_change_bounding_box);
// Allow item to do any work necessary to prepare for being rendered.
item->prepare_for_render (window_intersection);
} else {
// No intersection with visible window area
}
}
}
@ -937,6 +961,13 @@ GtkCanvas::on_expose_event (GdkEventExpose* ev)
return true;
}
void
GtkCanvas::prepare_for_render () const
{
Rect window_bbox = visible_area ();
Canvas::prepare_for_render (window_bbox);
}
/** Handler for GDK scroll events.
* @param ev Event.
* @return true if the event was handled.