X-Git-Url: https://git.pterodactylus.net/?a=blobdiff_plain;f=synfig-core%2Ftrunk%2Fsrc%2Fsynfig%2Flayer_pastecanvas.cpp;h=b161412a5c796ee718917ed30b42bf1e7523bee3;hb=756c0d29ac1742f231e6615f9a577e574e35a4af;hp=edc3d0b6b6fbada291cd657ca250fe6ffc0e06a0;hpb=9fa49a5c11359714a62afc430499897538b59cc4;p=synfig.git

diff --git a/synfig-core/trunk/src/synfig/layer_pastecanvas.cpp b/synfig-core/trunk/src/synfig/layer_pastecanvas.cpp
index edc3d0b..b161412 100644
--- a/synfig-core/trunk/src/synfig/layer_pastecanvas.cpp
+++ b/synfig-core/trunk/src/synfig/layer_pastecanvas.cpp
@@ -6,7 +6,7 @@
 **
 **	\legal
 **	Copyright (c) 2002-2005 Robert B. Quattlebaum Jr., Adrian Bentley
-**	Copyright (c) 2007 Chris Moore
+**	Copyright (c) 2007, 2008 Chris Moore
 **
 **	This package is free software; you can redistribute it and/or
 **	modify it under the terms of the GNU General Public License as
@@ -341,16 +341,42 @@ Layer_PasteCanvas::accelerated_render(Context context,Surface *surface,int quali
 
 	Color::BlendMethod blend_method(get_blend_method());
 	const Rect full_bounding_rect(canvas->get_context().get_full_bounding_rect());
+
 	bool blend_using_straight = false; // use 'straight' just for the central blit
 
+	// sometimes the user changes the parameters while we're
+	// rendering, causing our pasted canvas' bounding box to shrink
+	// and no longer overlap with our tile.  if that has happened,
+	// let's just stop now - we'll be refreshing soon anyway
+	//! \todo shouldn't a mutex ensure this isn't needed?
+	// http://synfig.org/images/d/d2/Bbox-change.sifz is an example
+	// that shows this happening - open the encapsulation, select the
+	// 'shade', and toggle the 'invert' parameter quickly.
+	// Occasionally you'll see:
+	//   error: Context::accelerated_render(): Layer "shade" threw a bad_alloc exception!
+	// where the shade layer tries to allocate itself a canvas of
+	// negative proportions, due to changing bounding boxes.
+	if (!etl::intersect(desc.get_rect(), full_bounding_rect))
+	{
+		warning("%s:%d bounding box shrank while rendering?", __FILE__, __LINE__);
+		return true;
+	}
+
+	// we have rendered what's under us, if necessary
 	if(context->empty())
 	{
+		// if there's nothing under us, and we're blending 'onto', then we've finished
 		if (Color::is_onto(blend_method)) return true;
-		if (blend_method==Color::BLEND_COMPOSITE) blend_method=Color::BLEND_STRAIGHT;
+
+		// there's nothing under us, so using straight blending is
+		// faster than and equivalent to using composite, but we don't
+		// want to blank the surrounding areas
+		if (blend_method==Color::BLEND_COMPOSITE) blend_using_straight = true;
 	}
 
 	if (!etl::intersect(context.get_full_bounding_rect(),full_bounding_rect+origin))
 	{
+		// if there's no intersection between the context and our surface, and we're rendering 'onto', then we're done
 		if (Color::is_onto(blend_method)) return true;
 
 		/* 'straight' is faster than 'composite' and has the same