Prevent a "bad_alloc" error caused by the bounding boxes changing when the user chang...

git-svn-id: http://svn.voria.com/code@1580 1f10aa63-cdf2-0310-b900-c93c546f37ac

diff --git a/synfig-core/trunk/src/synfig/layer_pastecanvas.cpp b/synfig-core/trunk/src/synfig/layer_pastecanvas.cpp
index e632f26..d7d5b39 100644 (file)
--- a/synfig-core/trunk/src/synfig/layer_pastecanvas.cpp
+++ b/synfig-core/trunk/src/synfig/layer_pastecanvas.cpp
@@ -341,8 +341,27 @@ 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())
        {