cc: The RenderSurface contentRect can have negative position.

cc/render_surface_impl.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/render_surface_impl.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/stringprintf.h"
@@ skipping 191 matching lines @@
 
     gfx::RectF maskUVRect(0.0f, 0.0f, 1.0f, 1.0f);
     if (maskLayer) {
         gfx::Vector2dF owningLayerDrawScale = MathUtil::computeTransform2dScaleComponents(m_owningLayer->drawTransform(), 1.f);
         gfx::SizeF unclippedSurfaceSize = gfx::ScaleSize(
             m_owningLayer->contentBounds(),
             owningLayerDrawScale.x(),
             owningLayerDrawScale.y());
         // This assumes that the owning layer clips its subtree when a mask is
         // present.
-        DCHECK(gfx::RectF(unclippedSurfaceSize).Contains(contentRect()));
+        DCHECK(gfx::RectF(unclippedSurfaceSize).Contains(
+            gfx::Rect(contentRect().size())));

[shawnsingh, 2013/02/04 21:51:08]

Thanks for catching this.  I think it might be a stricter (better) check to
include positions in this DCHECK too.  Is there some reason we shouldnt?

i.e.   DCHECK(gfx::RectF(unclippedSurfacePos,
unclippedSurfaceSize).Contains(contentRect())));

[danakj, 2013/02/04 21:52:15]

I just didn't think we have the position of the unclipped surface here. Do we?

[shawnsingh, 2013/02/04 21:59:24]

Oh, I see, you're right.

Also, thinking a second time - your change looks fine, but isn't it true that we
pin the origin of the surface to the owning layer, ** in the case where the
layer does have a mask / masksToBounds ?

So what is the case where a contentRect on a surface with mask would have
actually triggered the original DCHECK incorrectly?

 
         float uvScaleX = contentRect().width() / unclippedSurfaceSize.width();
         float uvScaleY = contentRect().height() / unclippedSurfaceSize.height();
 
         maskUVRect = gfx::RectF(
             static_cast<float>(contentRect().x()) / contentRect().width() * uvScaleX,
             static_cast<float>(contentRect().y()) / contentRect().height() * uvScaleY,
             uvScaleX,
             uvScaleY);
     }
 
     ResourceProvider::ResourceId maskResourceId = maskLayer ? maskLayer->contentsResourceId() : 0;
     gfx::Rect contentsChangedSinceLastFrame = contentsChanged() ? m_contentRect : gfx::Rect();
 
     scoped_ptr<RenderPassDrawQuad> quad = RenderPassDrawQuad::Create();
     quad->SetNew(sharedQuadState, contentRect(), renderPassId, forReplica, maskResourceId, contentsChangedSinceLastFrame, maskUVRect, m_owningLayer->filters(), m_owningLayer->filter(), m_owningLayer->backgroundFilters());
     quadSink.append(quad.PassAs<DrawQuad>(), appendQuadsData);
 }
 
 }  // namespace cc