Implement clip and scroll DisplayItems for PartPainter

Source/core/paint/ContentBoxRadiusClipper.cpp

Index: Source/core/paint/ContentBoxRadiusClipper.cpp
diff --git a/Source/core/paint/ContentBoxRadiusClipper.cpp b/Source/core/paint/ContentBoxRadiusClipper.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..15a836232750cd10fa1af6ffe9f86e117037f7fb
--- /dev/null
+++ b/Source/core/paint/ContentBoxRadiusClipper.cpp
@@ -0,0 +1,96 @@
+// Copyright 2015 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/ContentBoxRadiusClipper.h"
+
+#include "core/rendering/PaintInfo.h"
+#include "core/rendering/RenderBox.h"
+#include "platform/graphics/paint/ClipDisplayItem.h"
+#include "platform/graphics/paint/DisplayItemList.h"
+
+namespace blink {
+
+ContentBoxRadiusClipper::ContentBoxRadiusClipper(RenderBox& box, const PaintInfo& paintInfo, const LayoutPoint& accumulatedOffset)
+    : m_box(box)
+    , m_paintInfo(paintInfo)
+    , m_pushedClip(false)
+    , m_completelyClipped(false)
+{
+    if (!box.style()->hasBorderRadius())
+        return;
+
+    LayoutRect borderRect = LayoutRect(accumulatedOffset, m_box.size());
+
+    FloatRoundedRect roundedContentBox = box.style()->getRoundedInnerBorderFor(borderRect,
+        box.paddingTop() + box.borderTop(),
+        box.paddingBottom() + box.borderBottom(),
+        box.paddingLeft() + box.borderLeft(),
+        box.paddingRight() + box.borderRight(), true, true);
+
+    if (roundedContentBox.isEmpty()) {
+        m_completelyClipped = true;
+        return;
+    }
+
+    DisplayItem::Type clipType = DisplayItem::ClipBoxForeground;
+    if (RuntimeEnabledFeatures::slimmingPaintEnabled())
+        clipType = m_paintInfo.displayItemTypeForClipping();
+
+    OwnPtr<ClipDisplayItem> clipDisplayItem = ClipDisplayItem::create(box.displayItemClient(), clipType, pixelSnappedIntRect(borderRect));
+
+    if (roundedContentBox.isRenderable()) {

[chrishtr, 2015/01/23 05:07:12]

I don't get it. Where is all the logic in this class in the old code? If it is
present, why duplicate code?

+        clipDisplayItem->roundedRectClips().append(roundedContentBox);
+    } else {
+        // We create a rounded rect for each of the corners and clip it, while making sure we clip opposing corners together.
+        if (!roundedContentBox.radii().topLeft().isEmpty() || !roundedContentBox.radii().bottomRight().isEmpty()) {
+            FloatRect topCorner(roundedContentBox.rect().x(), roundedContentBox.rect().y(), borderRect.maxX() - roundedContentBox.rect().x(), borderRect.maxY() - roundedContentBox.rect().y());
+            FloatRoundedRect::Radii topCornerRadii;
+            topCornerRadii.setTopLeft(roundedContentBox.radii().topLeft());
+            clipDisplayItem->roundedRectClips().append(FloatRoundedRect(topCorner, topCornerRadii));
+
+            FloatRect bottomCorner(borderRect.x().toFloat(), borderRect.y().toFloat(), roundedContentBox.rect().maxX() - borderRect.x().toFloat(), roundedContentBox.rect().maxY() - borderRect.y().toFloat());
+            FloatRoundedRect::Radii bottomCornerRadii;
+            bottomCornerRadii.setBottomRight(roundedContentBox.radii().bottomRight());
+            clipDisplayItem->roundedRectClips().append(FloatRoundedRect(bottomCorner, bottomCornerRadii));
+        }
+
+        if (!roundedContentBox.radii().topRight().isEmpty() || !roundedContentBox.radii().bottomLeft().isEmpty()) {
+            FloatRect topCorner(borderRect.x().toFloat(), roundedContentBox.rect().y(), roundedContentBox.rect().maxX() - borderRect.x().toFloat(), borderRect.maxY() - roundedContentBox.rect().y());
+            FloatRoundedRect::Radii topCornerRadii;
+            topCornerRadii.setTopRight(roundedContentBox.radii().topRight());
+            clipDisplayItem->roundedRectClips().append(FloatRoundedRect(topCorner, topCornerRadii));
+
+            FloatRect bottomCorner(roundedContentBox.rect().x(), borderRect.y().toFloat(), borderRect.maxX() - roundedContentBox.rect().x(), roundedContentBox.rect().maxY() - borderRect.y().toFloat());
+            FloatRoundedRect::Radii bottomCornerRadii;
+            bottomCornerRadii.setBottomLeft(roundedContentBox.radii().bottomLeft());
+            clipDisplayItem->roundedRectClips().append(FloatRoundedRect(bottomCorner, bottomCornerRadii));
+        }
+    }
+
+    if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
+        ASSERT(m_paintInfo.context->displayItemList());
+        m_paintInfo.context->displayItemList()->add(clipDisplayItem.release());
+    } else {
+        clipDisplayItem->replay(paintInfo.context);
+    }
+    m_pushedClip = true;
+}
+
+ContentBoxRadiusClipper::~ContentBoxRadiusClipper()
+{
+    if (!m_pushedClip)
+        return;
+
+    OwnPtr<EndClipDisplayItem> endClipDisplayItem = EndClipDisplayItem::create(m_box.displayItemClient());
+
+    if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
+        ASSERT(m_paintInfo.context->displayItemList());
+        m_paintInfo.context->displayItemList()->add(endClipDisplayItem.release());
+    } else {
+        endClipDisplayItem->replay(m_paintInfo.context);
+    }
+}
+
+} // namespace blink