Introduce SVGPaintServer

Source/core/paint/SVGPaintServer.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/SVGPaintServer.h"
+
+#include "core/rendering/style/RenderStyle.h"
+#include "core/rendering/style/SVGRenderStyle.h"
+#include "core/rendering/svg/RenderSVGResourceSolidColor.h"
+#include "core/rendering/svg/SVGRenderSupport.h"
+#include "platform/graphics/GraphicsContext.h"
+#include "platform/graphics/GraphicsContextStateSaver.h"
+
+namespace blink {
+
+SVGPaintServer::SVGPaintServer()
+    : m_color(Color::black)
+{
+}
+
+void SVGPaintServer::setColor(Color color)
+{
+    m_gradient.clear();
+    m_pattern.clear();
+    m_color = color;
+}
+
+void SVGPaintServer::setGradient(const PassRefPtr<Gradient> gradient)
+{
+    m_gradient = gradient;
+    m_pattern.clear();
+    m_color = Color::black;
+}
+
+void SVGPaintServer::setPattern(const PassRefPtr<Pattern> pattern)
+{
+    m_gradient.clear();
+    m_pattern = pattern;
+    m_color = Color::black;
+}
+
+void SVGPaintServer::apply(GraphicsContext& context, RenderSVGResourceMode resourceMode, GraphicsContextStateSaver* stateSaver)
+{
+    ASSERT(resourceMode == ApplyToFillMode || resourceMode == ApplyToStrokeMode);
+    if (stateSaver && (m_gradient || m_pattern))
+        stateSaver->saveIfNeeded();
+
+    if (resourceMode == ApplyToFillMode) {
+        if (m_pattern)
+            context.setFillPattern(m_pattern);
+        else if (m_gradient)
+            context.setFillGradient(m_gradient);
+        else
+            context.setFillColor(m_color);
+    } else {
+        if (m_pattern)
+            context.setStrokePattern(m_pattern);
+        else if (m_gradient)
+            context.setStrokeGradient(m_gradient);
+        else
+            context.setStrokeColor(m_color);
+    }
+}
+
+bool SVGPaintServer::requestForRenderer(RenderObject& renderer, RenderStyle* style, RenderSVGResourceModeFlags resourceModeFlags, SVGPaintServer& paintServer)

[pdr., 2014/10/09 01:00:50]

Can we create and return the paintserver from this function instead of passing
it in? Using an OwnPtr<SVGPaintServer>, returning 0 can signify the failure
mode.

An alternative is to create the paint server in preparePaintServer which would
let you set the gradient/color/pattern in the constructor so only a
setFallbackColor function would be needed on SVGPaintServer.

[fs, 2014/10/09 07:23:08]

Definitely possible.
I like the idea of reducing/removing the setters. I'll have to try it though.

[fs, 2014/10/10 13:08:58]

Made SVGPaintServer more RAII (per ~above), and started passing it via the
return-value instead of an out-parameter (definitely looks a bit nicer).

+{
+    ASSERT(style);
+    RenderSVGResourceMode resourceMode = static_cast<RenderSVGResourceMode>(resourceModeFlags & (ApplyToFillMode | ApplyToStrokeMode));
+    ASSERT(resourceMode == ApplyToFillMode || resourceMode == ApplyToStrokeMode);
+
+    bool hasFallback = false;
+    RenderSVGResource* paintingResource = RenderSVGResource::requestPaintingResource(resourceMode, &renderer, style, hasFallback);
+    if (!paintingResource)
+        return false;
+
+    if (!paintingResource->preparePaintServer(&renderer, style, resourceModeFlags, paintServer)) {
+        if (!hasFallback)
+            return false;
+
+        paintServer.setColor(RenderSVGResource::sharedSolidPaintingResource()->color());
+    }
+    return true;
+}
+
+bool SVGPaintServer::existsForRenderer(RenderObject& renderer, const RenderStyle* style, RenderSVGResourceMode resourceMode)
+{
+    bool hasFallback;
+    return RenderSVGResource::requestPaintingResource(resourceMode, &renderer, style, hasFallback);
+}
+
+bool SVGPaintServer::updateGraphicsContext(GraphicsContext* context, RenderStyle* style, RenderObject& renderer, RenderSVGResourceModeFlags resourceModeFlags, GraphicsContextStateSaver& stateSaver)
+{
+    ASSERT(context);
+    ASSERT(style);
+
+    RenderSVGResourceMode resourceMode = static_cast<RenderSVGResourceMode>(resourceModeFlags & (ApplyToFillMode | ApplyToStrokeMode));
+    ASSERT(resourceMode == ApplyToFillMode || resourceMode == ApplyToStrokeMode);
+
+    if (SVGRenderSupport::isRenderingClipPathAsMaskImage(renderer)) {
+        if (resourceMode == ApplyToStrokeMode)
+            return false;
+        context->setAlphaAsFloat(1);
+        context->setFillColor(SVGRenderStyle::initialFillPaintColor());
+        return true;
+    }
+
+    SVGPaintServer paintServer;
+    if (!requestForRenderer(renderer, style, resourceModeFlags, paintServer))
+        return false;
+    paintServer.apply(*context, resourceMode, &stateSaver);
+
+    const SVGRenderStyle& svgStyle = style->svgStyle();
+
+    if (resourceMode == ApplyToFillMode) {
+        context->setAlphaAsFloat(svgStyle.fillOpacity());
+        context->setFillRule(svgStyle.fillRule());
+    } else {
+        context->setAlphaAsFloat(svgStyle.strokeOpacity());
+        SVGRenderSupport::applyStrokeStyleToContext(context, style, &renderer);
+    }
+    return true;
+}
+
+} // namespace blink