Move paint code from RenderHTMLCanvas to HTMLCanvasPainter.

Source/core/paint/HTMLCanvasPainter.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/HTMLCanvasPainter.h"
+
+#include "core/html/HTMLCanvasElement.h"
+#include "core/rendering/PaintInfo.h"
+#include "core/rendering/RenderHTMLCanvas.h"
+#include "platform/geometry/LayoutPoint.h"
+
+namespace blink {
+
+void HTMLCanvasPainter::paintReplaced(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
+{
+    GraphicsContext* context = paintInfo.context;
+
+    LayoutRect contentRect = m_renderHTMLCanvas.contentBoxRect();
+    contentRect.moveBy(paintOffset);
+    LayoutRect paintRect = m_renderHTMLCanvas.replacedContentRect();
+    paintRect.moveBy(paintOffset);
+
+    bool clip = !contentRect.contains(paintRect);
+    if (clip) {
+        // Not allowed to overflow the content box.
+        paintInfo.context->save();
+        paintInfo.context->clip(pixelSnappedIntRect(contentRect));
+    }
+
+    // FIXME: InterpolationNone should be used if ImageRenderingOptimizeContrast is set.
+    // See bug for more details: crbug.com/353716.
+    InterpolationQuality interpolationQuality = m_renderHTMLCanvas.style()->imageRendering() == ImageRenderingOptimizeContrast ? InterpolationLow : CanvasDefaultInterpolationQuality;
+
+    HTMLCanvasElement* canvas = toHTMLCanvasElement(m_renderHTMLCanvas.node());
+    LayoutSize layoutSize = contentRect.size();
+    if (m_renderHTMLCanvas.style()->imageRendering() == ImageRenderingPixelated
+        && (layoutSize.width() > canvas->width() || layoutSize.height() > canvas->height() || layoutSize == canvas->size())) {
+        interpolationQuality = InterpolationNone;
+    }
+
+    InterpolationQuality previousInterpolationQuality = context->imageInterpolationQuality();
+    context->setImageInterpolationQuality(interpolationQuality);
+    canvas->paint(context, paintRect);
+    context->setImageInterpolationQuality(previousInterpolationQuality);
+
+    if (clip)
+        context->restore();
+}
+
+} // namespace blink