Introduce SVGPaintServer

Source/core/rendering/svg/RenderSVGResourcePattern.cpp

 /*
  * Copyright (C) 2006 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "config.h"
-
 #include "core/rendering/svg/RenderSVGResourcePattern.h"
 
 #include "core/dom/ElementTraversal.h"
-#include "core/rendering/svg/SVGRenderSupport.h"
+#include "core/paint/SVGPaintServer.h"
 #include "core/rendering/svg/SVGRenderingContext.h"
 #include "core/svg/SVGFitToViewBox.h"
 #include "platform/graphics/GraphicsContext.h"
 
 namespace blink {
 
 const RenderSVGResourceType RenderSVGResourcePattern::s_resourceType = PatternResourceType;
 
 RenderSVGResourcePattern::RenderSVGResourcePattern(SVGPatternElement* node)
     : RenderSVGResourceContainer(node)
@@ skipping 68 matching lines @@
     AffineTransform patternTransform = m_attributes.patternTransform();
     if (!patternTransform.isIdentity())
         patternData->transform = patternTransform * patternData->transform;
 
     // Various calls above may trigger invalidations in some fringe cases (ImageBuffer allocation
     // failures in the SVG image cache for example). To avoid having our PatternData deleted by
     // removeAllClientsFromCache(), we only make it visible in the cache at the very end.
     return m_patternMap.set(object, patternData.release()).storedValue->value.get();
 }
 
-bool RenderSVGResourcePattern::applyResource(RenderObject* object, RenderStyle* style, GraphicsContext* context, RenderSVGResourceModeFlags resourceMode)
+SVGPaintServer RenderSVGResourcePattern::preparePaintServer(RenderObject* object, RenderStyle* style, RenderSVGResourceModeFlags resourceMode)
 {
     ASSERT(object);
     ASSERT(style);
-    ASSERT(context);
 
     clearInvalidationMask();
 
     SVGPatternElement* patternElement = toSVGPatternElement(element());
     if (!patternElement)
-        return false;
+        return SVGPaintServer::invalid();
 
     if (m_shouldCollectPatternAttributes) {
         patternElement->synchronizeAnimatedSVGAttribute(anyQName());
 
         m_attributes = PatternAttributes();
         patternElement->collectPatternAttributes(m_attributes);
         m_shouldCollectPatternAttributes = false;
     }
 
     // Spec: When the geometry of the applicable element has no width or height and objectBoundingBox is specified,
     // then the given effect (e.g. a gradient or a filter) will be ignored.
     FloatRect objectBoundingBox = object->objectBoundingBox();
     if (m_attributes.patternUnits() == SVGUnitTypes::SVG_UNIT_TYPE_OBJECTBOUNDINGBOX && objectBoundingBox.isEmpty())
-        return false;
+        return SVGPaintServer::invalid();
 
     PatternData* patternData = buildPattern(object, patternElement);
     if (!patternData)
-        return false;
+        return SVGPaintServer::invalid();
 
     const SVGRenderStyle& svgStyle = style->svgStyle();
 
     AffineTransform computedPatternSpaceTransform = computeResourceSpaceTransform(object, patternData->transform, svgStyle, resourceMode);
     patternData->pattern->setPatternSpaceTransform(computedPatternSpaceTransform);
 
-    // Draw pattern
-    context->save();
-
-    if (resourceMode & ApplyToFillMode)
-        context->setFillPattern(patternData->pattern);
-    else if (resourceMode & ApplyToStrokeMode)
-        context->setStrokePattern(patternData->pattern);
-
-    updateGraphicsContext(context, style, *object, resourceMode);
-    return true;
-}
-
-void RenderSVGResourcePattern::postApplyResource(GraphicsContext* context)
-{
-    ASSERT(context);
-    context->restore();
+    return SVGPaintServer(patternData->pattern);

[chrishtr, 2014/10/10 16:59:20]

Why not just have a method that exposes the data needed to construct the
SVGPaintServer, and have the constructor call entirely in the paint/ directory?
That would seem to be a cleaner separation of style and details of painting
algorithms, and avoid the need to link against something in the paint/ directory
here.

[fs, 2014/10/11 12:05:50]

Then I'd have to think, that it'd be better to just move SVGPaintServer to
rendering/ and move the updateGraphicsContext helper to SVGRenderSupport (for
now - it should be possible to move to paint/ in due time). Otherwise, since
there exists no one type this method can return, we'd need to build another
parameter blob - either exactly the same (structurally) as SVGPaintServer or a
conglomerate of *GradientAttributes and similar for Pattern [1] ( essentially
PatternData/GradientData but w/ a common base-class and different contents).
With the per-renderer caching moved out the latter seems more tractable [2], but
I'm 1-2 CLs away from being in a decent position for doing that.

So does the suggestion in the first sentence sound good enough for now? I'd be
happy to try and work towards the "larger param-blob" thingy and the caching
separation (which I was planning to do anyway, since there some stuff that would
benefit from that already). What side should do the caching could probably be
discussed further.

I must say though, that it's pretty darn hard to adapt to a design that you're
fed piece-meal on a need-to-know basis - feels a bit like being back in the army
;-). (Requested access to the doc, but no luck accessing it yet.)

Anyway, thanks for looking. I'll try to get something uploaded monday
(discussions are unfortunately not very practical w/ a ~1h window and 20h
latency).

[1] transform + display list/imagebuffer (or maybe root/list of content
elements/renderers or something)
[2] I.e. then you'd have a context blob in, and a parameter blob out.

 }
 
 static inline FloatRect calculatePatternBoundaries(const PatternAttributes& attributes,
                                                    const FloatRect& objectBoundingBox,
                                                    const SVGPatternElement* patternElement)
 {
     ASSERT(patternElement);
     return SVGLengthContext::resolveRectangle(patternElement, attributes.patternUnits(), objectBoundingBox, attributes.x(), attributes.y(), attributes.width(), attributes.height());
 }
 
@@ skipping 60 matching lines @@
             continue;
         if (element->renderer()->needsLayout())
             return nullptr;
         SVGRenderingContext::renderSubtree(tileImage->context(), element->renderer(), contentTransformation);
     }
 
     return tileImage.release();
 }
 
 }