Separate display item clients for negative and normal/positive z-order children

third_party/WebKit/Source/platform/graphics/paint/DisplayItem.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 DisplayItem_h
 #define DisplayItem_h
 
 #include "platform/PlatformExport.h"
 #include "platform/graphics/ContiguousContainer.h"
 #include "platform/graphics/paint/DisplayItemClient.h"
@@ skipping 150 matching lines @@
         EndCompositing,
         BeginTransform,
         EndTransform,
         BeginClipPath,
         EndClipPath,
         BeginFixedPosition,
         EndFixedPosition,
         BeginFixedPositionContainer,
         EndFixedPositionContainer,
 
-        SubsequenceFirst,
-        SubsequenceNegativeZOrder = SubsequenceFirst,
-        SubsequenceNormalFlowAndPositiveZOrder,
-        SubsequenceLast = SubsequenceNormalFlowAndPositiveZOrder,
-        EndSubsequenceFirst,
-        EndSubsequenceLast = EndSubsequenceFirst + SubsequenceLast - SubsequenceFirst,
-        CachedSubsequenceFirst,
-        CachedSubsequenceLast = CachedSubsequenceFirst + SubsequenceLast - SubsequenceFirst,
+        Subsequence,
+        EndSubsequence,
+        CachedSubsequence,
 
         CachedDisplayItemList,
 
         UninitializedType,
         TypeLast = UninitializedType
     };
 
     static_assert(TableCollapsedBorderBase >= TableCollapsedBorderUnalignedBase, "TableCollapsedBorder types overlap with other types");
     static_assert((TableCollapsedBorderBase & 0xf) == 0, "The lowest 4 bits of TableCollapsedBorderBase should be zero");
     // Bits or'ed onto TableCollapsedBorderBase to generate a real table collapsed border type.
     enum TableCollapsedBorderSides {
         TableCollapsedBorderTop = 1 << 0,
         TableCollapsedBorderRight = 1 << 1,
         TableCollapsedBorderBottom = 1 << 2,
         TableCollapsedBorderLeft = 1 << 3,
     };
 
     DisplayItem(const DisplayItemClientWrapper& client, Type type, size_t derivedSize)
-        : m_client(client.displayItemClient())
+        : m_clientObject(client.displayItemClient().object)
         , m_scope(0)
+        , m_subClientId(client.displayItemClient().subClientId)
         , m_type(type)
         , m_derivedSize(derivedSize)
         , m_skippedCache(false)
 #ifndef NDEBUG
         , m_clientDebugString(client.debugName())
 #endif
     {
         // derivedSize must fit in m_derivedSize.
         // If it doesn't, enlarge m_derivedSize and fix this assert.
         ASSERT_WITH_SECURITY_IMPLICATION(derivedSize < (1 << 8));
         ASSERT_WITH_SECURITY_IMPLICATION(derivedSize >= sizeof(*this));
     }
 
     virtual ~DisplayItem() { }
 
     // Ids are for matching new DisplayItems with existing DisplayItems.
     struct Id {
         Id(const DisplayItemClient client, const Type type, const unsigned scope)
             : client(client)
             , type(type)
             , scope(scope) { }
 
         bool matches(const DisplayItem& item) const
         {
             // We should always convert to non-cached types before matching.
             ASSERT(!isCachedType(item.m_type));
             ASSERT(!isCachedType(type));
-            return client == item.m_client
+            return client == item.client()
                 && type == item.m_type
                 && scope == item.m_scope;
         }
 
         const DisplayItemClient client;
         const Type type;
         const unsigned scope;
     };
 
     // Convert cached type to non-cached type (e.g., Type::CachedSVGImage -> Type::SVGImage).
     static Type nonCachedType(Type type)
     {
         if (isCachedDrawingType(type))
             return cachedDrawingTypeToDrawingType(type);
-        if (isCachedSubsequenceType(type))
-            return cachedSubsequenceTypeToSubsequenceType(type);
+        if (type == CachedSubsequence)
+            return Subsequence;
         return type;
     }
 
     // Return the Id with cached type converted to non-cached type.
     Id nonCachedId() const
     {
-        return Id(m_client, nonCachedType(m_type), m_scope);
+        return Id(client(), nonCachedType(m_type), m_scope);
     }
 
     virtual void replay(GraphicsContext&) const { }
 
-    DisplayItemClient client() const { return m_client; }
+    DisplayItemClient client() const { return DisplayItemClient(m_clientObject, m_subClientId); }
     Type type() const { return m_type; }
 
     void setScope(unsigned scope) { m_scope = scope; }
     unsigned scope() { return m_scope; }
 
     // Size of this object in memory, used to move it with memcpy.
     // This is not sizeof(*this), because it needs to account for the size of
     // the derived class (i.e. runtime type). Derived classes are expected to
     // supply this to the DisplayItem constructor.
     size_t derivedSize() const { return m_derivedSize; }
@@ skipping 47 matching lines @@
     DEFINE_PAINT_PHASE_CONVERSION_METHOD(ClipColumnBounds)
 
     DEFINE_PAIRED_CATEGORY_METHODS(FloatClip, floatClip)
     DEFINE_PAINT_PHASE_CONVERSION_METHOD(FloatClip)
 
     DEFINE_PAIRED_CATEGORY_METHODS(Scroll, scroll)
     DEFINE_PAINT_PHASE_CONVERSION_METHOD(Scroll)
 
     DEFINE_PAIRED_CATEGORY_METHODS(Transform3D, transform3D)
 
-    DEFINE_PAIRED_CATEGORY_METHODS(Subsequence, subsequence)
-    DEFINE_CATEGORY_METHODS(CachedSubsequence)
-    DEFINE_CONVERSION_METHODS(Subsequence, subsequence, CachedSubsequence, cachedSubsequence)
-
-    static bool isCachedType(Type type) { return isCachedDrawingType(type) || isCachedSubsequenceType(type) || type == CachedDisplayItemList; }
+    static bool isCachedType(Type type) { return isCachedDrawingType(type) || type == CachedSubsequence || type == CachedDisplayItemList; }
     bool isCached() const { return isCachedType(m_type); }
-    static bool isCacheableType(Type type) { return isDrawingType(type) || isSubsequenceType(type); }
+    static bool isCacheableType(Type type) { return isDrawingType(type) || type == Subsequence; }
     bool isCacheable() const { return !skippedCache() && isCacheableType(m_type); }
 
     virtual bool isBegin() const { return false; }
     virtual bool isEnd() const { return false; }
 
 #if ENABLE(ASSERT)
     virtual bool isEndAndPairedWith(DisplayItem::Type otherType) const { return false; }
     virtual bool equals(const DisplayItem& other) const
     {
-        return m_client == other.m_client
+        return client() == other.client()
             && m_scope == other.m_scope
             && m_type == other.m_type
             && m_derivedSize == other.m_derivedSize
             && m_skippedCache == other.m_skippedCache;
     }
 #endif
 
     virtual bool drawsContent() const { return false; }
 
-    bool isValid() const { return m_client; }
+    bool isValid() const { return m_clientObject; }
 
 #ifndef NDEBUG
     static WTF::String typeAsDebugString(DisplayItem::Type);
     const WTF::String& clientDebugString() const { return m_clientDebugString; }
     void setClientDebugString(const WTF::String& s) { m_clientDebugString = s; }
     WTF::String asDebugString() const;
     virtual void dumpPropertiesAsDebugString(WTF::StringBuilder&) const;
 #endif
 
 private:
     // The default DisplayItem constructor is only used by
     // ContiguousContainer::appendByMoving where an invalid DisplaItem is
     // constructed at the source location.
     template <typename T, unsigned alignment> friend class ContiguousContainer;
 
     DisplayItem()
-        : m_client(nullptr)
+        : m_clientObject(nullptr)
         , m_scope(0)
+        , m_subClientId(0)
         , m_type(UninitializedType)
         , m_derivedSize(sizeof(*this))
         , m_skippedCache(false)
     { }
 
-    const DisplayItemClient m_client;
+    const DisplayItemClientObject m_clientObject;
     unsigned m_scope;
+
+    static_assert(kMaxSubDisplayItemClientId == (1 << 6) - 1, "subClientId should fit in 6 bits");
+    const unsigned m_subClientId : 6;
+
     static_assert(TypeLast < (1 << 16), "DisplayItem::Type should fit in 16 bits");
     const Type m_type : 16;
+
     const unsigned m_derivedSize : 8; // size of the actual derived class
     unsigned m_skippedCache : 1;
 
 #ifndef NDEBUG
     WTF::String m_clientDebugString;
 #endif
 };
 
 class PLATFORM_EXPORT PairedBeginDisplayItem : public DisplayItem {
 protected:
@@ skipping 11 matching lines @@
     bool isEndAndPairedWith(DisplayItem::Type otherType) const override = 0;
 #endif
 
 private:
     bool isEnd() const final { return true; }
 };
 
 } // namespace blink
 
 #endif // DisplayItem_h