From ef60401d92fa2300a419544dae47375d72217ae8 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Tue, 16 Apr 2013 14:20:04 -0400
Subject: (hopefully) fix double-buffering design of ArdourCanvas::Image

---
 libs/canvas/image.cc | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

(limited to 'libs/canvas/image.cc')

diff --git a/libs/canvas/image.cc b/libs/canvas/image.cc
index 26bc35eb37..71a5df64dd 100644
--- a/libs/canvas/image.cc
+++ b/libs/canvas/image.cc
@@ -35,19 +35,20 @@ Image::Image (Group* group, Cairo::Format fmt, int width, int height)
 void 
 Image::render (Rect const& area, Cairo::RefPtr<Cairo::Context> context) const
 {
-	if (_current) {
-		_surface = Cairo::ImageSurface::create (_current->data.get(),
-							_current->format,
-							_current->width,
-							_current->height,
-							_current->stride);
+	if (_need_render && _pending) {
+		_surface = Cairo::ImageSurface::create (_pending->data.get(),
+							_pending->format,
+							_pending->width,
+							_pending->height,
+							_pending->stride);
+		_current = _pending;
 	}
 
-	_current.reset ();
-
-	context->set_source (_surface, 0, 0);
-	context->rectangle (area.x0, area.y0, area.width(), area.height());
-	context->fill ();
+	if (_surface) {
+		context->set_source (_surface, 0, 0);
+		context->rectangle (area.x0, area.y0, area.width(), area.height());
+		context->fill ();
+	}
 }
 
 void
@@ -83,11 +84,7 @@ Image::accept_data ()
 	/* must be executed in gui thread */
 
 	begin_change ();
-
-	_current = _pending;
-	_pending.reset ();
 	_need_render = true;
-
 	end_change (); // notify canvas that we need redrawing
 }	     
 
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