**
** \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
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