Remove the SVG paint culling optimization

Source/core/paint/SVGForeignObjectPainter.cpp

 // Copyright 2014 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 "config.h"
 #include "core/paint/SVGForeignObjectPainter.h"
 
 #include "core/paint/BlockPainter.h"
 #include "core/rendering/PaintInfo.h"
 #include "core/rendering/svg/RenderSVGForeignObject.h"
 #include "core/rendering/svg/SVGRenderSupport.h"
 #include "core/rendering/svg/SVGRenderingContext.h"
 #include "platform/graphics/GraphicsContextStateSaver.h"
 
 namespace blink {
 
 void SVGForeignObjectPainter::paint(const PaintInfo& paintInfo)
 {
     if (paintInfo.phase != PaintPhaseForeground && paintInfo.phase != PaintPhaseSelection)
         return;
 
     PaintInfo childPaintInfo(paintInfo);
     GraphicsContextStateSaver stateSaver(*childPaintInfo.context);
     childPaintInfo.applyTransform(m_renderSVGForeignObject.localTransform());
 
+    // When transitioning from SVG to HTML painters we need to keep the PaintInfo rect up-to-date
+    // because it can be used for clipping.
+    // FIXME: We need to find an approach that's not O(n^2).
+    const AffineTransform& transform = SVGRenderSupport::transformToRootBorderBox(m_renderSVGForeignObject, m_renderSVGForeignObject.localTransform());

[pdr., 2014/12/15 05:02:21]

How can we cache this from paint invalidation? (similarly for SVGTextPainter)

[fs, 2014/12/15 10:28:16]

Add:

m_cachedRootTransform = paintInvalidationState->svgTransform() *
localTransform();

(w/ checks and fallbacks)

in RenderSVGBlock::invalidateTreeIfNeeded (invalidatePaintIfNeeded might be
better in theory, but the result should be the same none the less...)

May also just say: 48 additional bytes in RenderSVGBlock - ouch!

[pdr., 2014/12/16 06:29:56]

Thank you! This worked a charm.

I'm not /too/ worried about the extra memory since it's only on RenderSVGText
and RenderSVGForeignObject. The hardest case I know of is iWork which, IIRC,
does one text element per word. WDYT?

[fs, 2014/12/16 09:43:55]

I'm not too worried either - let's just hope that we can offset this increase in
size somehow. (Just get used to me complaining every time you add a few bytes to
some datastructure ;-))

+    childPaintInfo.rect = enclosingIntRect(transform.inverse().mapRect(FloatRect(childPaintInfo.rect)));

[fs, 2014/12/15 10:28:16]

One inverse() too many (since transformToRootBorderBox currently returns the
inverse.) I suppose this is the reason for the try-bot failures?

+

[chrishtr, 2014/12/15 16:36:24]

Maybe just use an infinite rect here to turn off culling for HTML subtrees of
SVG?

     if (SVGRenderSupport::isOverflowHidden(&m_renderSVGForeignObject))
         childPaintInfo.context->clip(m_renderSVGForeignObject.viewportRect());
 
     SVGRenderingContext renderingContext;
     bool continueRendering = true;
     if (paintInfo.phase == PaintPhaseForeground) {
         renderingContext.prepareToRenderSVGContent(&m_renderSVGForeignObject, childPaintInfo);
         continueRendering = renderingContext.isRenderingPrepared();
     }
 
@@ skipping 10 matching lines @@
             BlockPainter(m_renderSVGForeignObject).paint(childPaintInfo, childPoint);
             childPaintInfo.phase = PaintPhaseForeground;
             BlockPainter(m_renderSVGForeignObject).paint(childPaintInfo, childPoint);
             childPaintInfo.phase = PaintPhaseOutline;
             BlockPainter(m_renderSVGForeignObject).paint(childPaintInfo, childPoint);
         }
     }
 }
 
 } // namespace blink