From b02ebd72a56c180073d93c332263550543b85eeb Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Thu, 27 Oct 2011 20:24:29 +0000
Subject: [PATCH] remove offscreen pixmap rendering design from CairoWidget:
 this helps only when widgets are partially re-exposed due to WM-level
 operations, which is relatively rare compared to the update frequency for
 various things that this widget will be used for. Plus, in GTK3, the need for
 this widget will mostly go away, and we'd like to be as close to the GTK3
 model as possible

git-svn-id: svn://localhost/ardour2/branches/3.0@10317 d708f5d6-7413-0410-9779-e7cbd77b26cf
---
 gtk2_ardour/cairo_widget.cc | 53 +++++--------------------------------
 gtk2_ardour/cairo_widget.h  |  4 +--
 2 files changed, 7 insertions(+), 50 deletions(-)

diff --git a/gtk2_ardour/cairo_widget.cc b/gtk2_ardour/cairo_widget.cc
index d5dc846ee4..86c431cc60 100644
--- a/gtk2_ardour/cairo_widget.cc
+++ b/gtk2_ardour/cairo_widget.cc
@@ -25,7 +25,6 @@ CairoWidget::CairoWidget ()
 	, _height (1)
 	, _active_state (CairoWidget::ActiveState (0))
 	, _visual_state (CairoWidget::VisualState (0))
-	, _pixmap (0)
 	, _dirty (true)
 {
 
@@ -33,54 +32,16 @@ CairoWidget::CairoWidget ()
 
 CairoWidget::~CairoWidget ()
 {
-	if (_pixmap) {
-		g_object_unref (_pixmap);
-	}
 }
 
 bool
-CairoWidget::on_expose_event (GdkEventExpose *event)
+CairoWidget::on_expose_event (GdkEventExpose *ev)
 {
-	Gdk::Rectangle const exposure (
-		event->area.x, event->area.y, event->area.width, event->area.height
-		);
-
-	Gdk::Rectangle r = exposure;
-	Gdk::Rectangle content (0, 0, _width, _height);
-	bool intersects;
-	r.intersect (content, intersects);
-
-	if (intersects) {
-
-		GdkDrawable* drawable = get_window()->gobj ();
-
-		if (_dirty) {
-
-			if (_pixmap) {
-				g_object_unref (_pixmap);
-			}
-
-			_pixmap = gdk_pixmap_new (drawable, _width, _height, -1);
-
-			cairo_t* cr = gdk_cairo_create (_pixmap);
-			render (cr);
-			cairo_destroy (cr);
-
-			_dirty = false;
-		}
-
-		gdk_draw_drawable (
-			drawable,
-			get_style()->get_fg_gc (Gtk::STATE_NORMAL)->gobj(),
-			_pixmap,
- 			r.get_x(),
- 			r.get_y(),
- 			r.get_x(),
- 			r.get_y(),
- 			r.get_width(),
- 			r.get_height()
-			);
-	}
+	cairo_t* cr = gdk_cairo_create (get_window ()->gobj());
+	cairo_rectangle (cr, ev->area.x, ev->area.y, ev->area.width, ev->area.height);
+	cairo_clip (cr);
+	render (cr);
+	cairo_destroy (cr);
 
 	return true;
 }
@@ -93,8 +54,6 @@ void
 CairoWidget::set_dirty ()
 {
 	ENSURE_GUI_THREAD (*this, &CairoWidget::set_dirty)
-
-	_dirty = true;
 	queue_draw ();
 }
 
diff --git a/gtk2_ardour/cairo_widget.h b/gtk2_ardour/cairo_widget.h
index ff0533643b..65de9b5e31 100644
--- a/gtk2_ardour/cairo_widget.h
+++ b/gtk2_ardour/cairo_widget.h
@@ -22,9 +22,7 @@
 
 #include <gtkmm/eventbox.h>
 
-/** A parent class for widgets that are made up of a pixmap rendered using Cairo.
- *  The pixmap is painted to screen on GTK expose events, but the rendering
- *  is only done after set_dirty() has been called.
+/** A parent class for widgets that are rendered using Cairo.
  */
 
 class CairoWidget : public Gtk::EventBox