Implement a paint offset cache for slimming paint v2

Source/core/paint/FieldsetPainter.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/FieldsetPainter.h"
 
 #include "core/layout/LayoutFieldset.h"
 #include "core/paint/BoxDecorationData.h"
 #include "core/paint/BoxPainter.h"
 #include "core/paint/LayoutObjectDrawingRecorder.h"
 #include "core/paint/PaintInfo.h"
 #include "platform/graphics/GraphicsContextStateSaver.h"
 
 namespace blink {
 
 void FieldsetPainter::paintBoxDecorationBackground(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     if (!paintInfo.shouldPaintWithinRoot(&m_layoutFieldset))
         return;
 
     LayoutRect paintRect(paintOffset, m_layoutFieldset.size());
     LayoutBox* legend = m_layoutFieldset.findInFlowLegend();
     if (!legend)
         return BoxPainter(m_layoutFieldset).paintBoxDecorationBackground(paintInfo, paintOffset);
 
-    if (LayoutObjectDrawingRecorder::useCachedDrawingIfPossible(*paintInfo.context, m_layoutFieldset, paintInfo.phase))
+    if (LayoutObjectDrawingRecorder::useCachedDrawingIfPossible(*paintInfo.context, m_layoutFieldset, paintInfo.phase, paintOffset))
         return;
 
     // FIXME: We need to work with "rl" and "bt" block flow directions.  In those
     // cases the legend is embedded in the right and bottom borders respectively.
     // https://bugs.webkit.org/show_bug.cgi?id=47236
     if (m_layoutFieldset.style()->isHorizontalWritingMode()) {
         LayoutUnit yOff = (legend->location().y() > 0) ? LayoutUnit() : (legend->size().height() - m_layoutFieldset.borderTop()) / 2;
         paintRect.setHeight(paintRect.height() - yOff);
         paintRect.setY(paintRect.y() + yOff);
     } else {
         LayoutUnit xOff = (legend->location().x() > 0) ? LayoutUnit() : (legend->size().width() - m_layoutFieldset.borderLeft()) / 2;
         paintRect.setWidth(paintRect.width() - xOff);
         paintRect.setX(paintRect.x() + xOff);
     }
 
     // TODO(chrishtr): pixel-snapping here is likely wrong.
-    LayoutObjectDrawingRecorder recorder(*paintInfo.context, m_layoutFieldset, paintInfo.phase, paintRect);
+    LayoutObjectDrawingRecorder recorder(*paintInfo.context, m_layoutFieldset, paintInfo.phase, paintRect, paintOffset);
     BoxDecorationData boxDecorationData(m_layoutFieldset);
 
     if (boxDecorationData.bleedAvoidance == BackgroundBleedNone)
         BoxPainter::paintBoxShadow(paintInfo, paintRect, m_layoutFieldset.styleRef(), Normal);
     BoxPainter(m_layoutFieldset).paintFillLayers(paintInfo, boxDecorationData.backgroundColor, m_layoutFieldset.style()->backgroundLayers(), paintRect);
     BoxPainter::paintBoxShadow(paintInfo, paintRect, m_layoutFieldset.styleRef(), Inset);
 
     if (!boxDecorationData.hasBorderDecoration)
         return;
 
@@ skipping 20 matching lines @@
 void FieldsetPainter::paintMask(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     if (m_layoutFieldset.style()->visibility() != VISIBLE || paintInfo.phase != PaintPhaseMask)
         return;
 
     LayoutRect paintRect = LayoutRect(paintOffset, m_layoutFieldset.size());
     LayoutBox* legend = m_layoutFieldset.findInFlowLegend();
     if (!legend)
         return BoxPainter(m_layoutFieldset).paintMask(paintInfo, paintOffset);
 
-    if (LayoutObjectDrawingRecorder::useCachedDrawingIfPossible(*paintInfo.context, m_layoutFieldset, paintInfo.phase))
+    if (LayoutObjectDrawingRecorder::useCachedDrawingIfPossible(*paintInfo.context, m_layoutFieldset, paintInfo.phase, paintOffset))
         return;
 
     // FIXME: We need to work with "rl" and "bt" block flow directions.  In those
     // cases the legend is embedded in the right and bottom borders respectively.
     // https://bugs.webkit.org/show_bug.cgi?id=47236
     if (m_layoutFieldset.style()->isHorizontalWritingMode()) {
         LayoutUnit yOff = (legend->location().y() > 0) ? LayoutUnit() : (legend->size().height() - m_layoutFieldset.borderTop()) / 2;
         paintRect.expand(0, -yOff);
         paintRect.move(0, yOff);
     } else {
         LayoutUnit xOff = (legend->location().x() > 0) ? LayoutUnit() : (legend->size().width() - m_layoutFieldset.borderLeft()) / 2;
         paintRect.expand(-xOff, 0);
         paintRect.move(xOff, 0);
     }
 
-    LayoutObjectDrawingRecorder recorder(*paintInfo.context, m_layoutFieldset, paintInfo.phase, paintRect);
+    LayoutObjectDrawingRecorder recorder(*paintInfo.context, m_layoutFieldset, paintInfo.phase, paintRect, paintOffset);
     BoxPainter(m_layoutFieldset).paintMaskImages(paintInfo, paintRect);
 }
 
 } // namespace blink