Factor SVG root painter code into SVGRootPainter

Source/core/paint/SVGRootPainter.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/SVGRootPainter.h"
+
+#include "core/paint/BoxPainter.h"
+#include "core/rendering/PaintInfo.h"
+#include "core/rendering/svg/RenderSVGRoot.h"
+#include "core/rendering/svg/SVGRenderingContext.h"
+#include "core/rendering/svg/SVGResources.h"
+#include "core/rendering/svg/SVGResourcesCache.h"
+#include "core/svg/SVGSVGElement.h"
+
+namespace blink {
+
+void SVGRootPainter::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
+{
+    // An empty viewport disables rendering.
+    if (m_renderSVGRoot.pixelSnappedBorderBoxRect().isEmpty())
+        return;
+
+    // SVG outlines are painted during PaintPhaseForeground.
+    if (paintInfo.phase == PaintPhaseOutline || paintInfo.phase == PaintPhaseSelfOutline)
+        return;
+
+    // An empty viewBox also disables rendering.
+    // (http://www.w3.org/TR/SVG/coords.html#ViewBoxAttribute)
+    SVGSVGElement* svg = toSVGSVGElement(m_renderSVGRoot.node());
+    ASSERT(svg);
+    if (svg->hasEmptyViewBox())
+        return;
+
+    // Don't paint if we don't have kids, except if we have filters we should paint those.
+    if (!m_renderSVGRoot.firstChild()) {
+        SVGResources* resources = SVGResourcesCache::cachedResourcesForRenderObject(&m_renderSVGRoot);
+        if (!resources || !resources->filter())
+            return;
+    }
+
+    // Make a copy of the PaintInfo because applyTransform will modify the damage rect.
+    PaintInfo childPaintInfo(paintInfo);
+    GraphicsContextStateSaver stateSaver(*childPaintInfo.context);
+
+    // Apply initial viewport clip.
+    if (m_renderSVGRoot.shouldApplyViewportClip())
+        childPaintInfo.context->clip(pixelSnappedIntRect(m_renderSVGRoot.overflowClipRect(paintOffset)));
+
+    // Convert from container offsets (html renderers) to a relative transform (svg renderers).
+    // Transform from our paint container's coordinate system to our local coords.
+    IntPoint adjustedPaintOffset = roundedIntPoint(paintOffset);
+    childPaintInfo.applyTransform(AffineTransform::translation(adjustedPaintOffset.x(), adjustedPaintOffset.y()) * m_renderSVGRoot.localToBorderBoxTransform());
+
+    SVGRenderingContext renderingContext;
+    if (childPaintInfo.phase == PaintPhaseForeground) {
+        renderingContext.prepareToRenderSVGContent(&m_renderSVGRoot, childPaintInfo);
+        if (!renderingContext.isRenderingPrepared())
+            return;
+    }
+
+    BoxPainter(m_renderSVGRoot).paint(childPaintInfo, LayoutPoint());
+}
+
+} // namespace blink