Calculate and track display item opaqueness

third_party/WebKit/Source/platform/graphics/paint/DrawingDisplayItem.h

 // 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.
 
 #ifndef DrawingDisplayItem_h
 #define DrawingDisplayItem_h
 
 #include "platform/PlatformExport.h"
+#include "platform/RuntimeEnabledFeatures.h"
 #include "platform/geometry/FloatPoint.h"
 #include "platform/graphics/paint/DisplayItem.h"
 #include "third_party/skia/include/core/SkPicture.h"
 #include "wtf/PassOwnPtr.h"
 
 namespace blink {
 
 class PLATFORM_EXPORT DrawingDisplayItem final : public DisplayItem {
 public:
 #if ENABLE(ASSERT)
     enum UnderInvalidationCheckingMode {
         CheckPicture, // Check if the new picture and the old picture are the same
         CheckBitmap, // Check if the new picture and the old picture produce the same bitmap
     };
 #endif
 
     DrawingDisplayItem(const DisplayItemClient& client
         , Type type
         , PassRefPtr<const SkPicture> picture
+        , bool knownToBeOpaque = false
 #if ENABLE(ASSERT)
         , UnderInvalidationCheckingMode underInvalidationCheckingMode = CheckPicture
 #endif
         )
         : DisplayItem(client, type, sizeof(*this))
         , m_picture(picture && picture->approximateOpCount() ? picture : nullptr)
+        , m_knownToBeOpaque(knownToBeOpaque)
 #if ENABLE(ASSERT)
         , m_underInvalidationCheckingMode(underInvalidationCheckingMode)
 #endif
     {
         ASSERT(isDrawingType(type));
     }
 
     void replay(GraphicsContext&) const override;
     void appendToWebDisplayItemList(const IntRect&, WebDisplayItemList*) const override;
     bool drawsContent() const override;
 
     const SkPicture* picture() const { return m_picture.get(); }
 
+    bool knownToBeOpaque() const { ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled()); return m_knownToBeOpaque; }
+
 #if ENABLE(ASSERT)
     UnderInvalidationCheckingMode underInvalidationCheckingMode() const { return m_underInvalidationCheckingMode; }
     bool equals(const DisplayItem& other) const final;
 #endif
 
 private:
 #ifndef NDEBUG
     void dumpPropertiesAsDebugString(WTF::StringBuilder&) const override;
 #endif
 
     RefPtr<const SkPicture> m_picture;
 
+    // True if there are no transparent areas. Only used for SlimmingPaintV2.
+    // TODO(pdr): It's messy, but we may want to move this to DisplayItem which has free bits.
+    const bool m_knownToBeOpaque;
+
 #if ENABLE(ASSERT)
     UnderInvalidationCheckingMode m_underInvalidationCheckingMode;
 #endif
 };
 
 } // namespace blink
 
 #endif // DrawingDisplayItem_h