- A prototype which allows to expose CanvasPixelArray functionality...

src/objects.h

 // Copyright 2006-2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 34 matching lines @@
 //         - JSArray
 //         - JSRegExp
 //         - JSFunction
 //         - GlobalObject
 //           - JSGlobalObject
 //           - JSBuiltinsObject
 //         - JSGlobalProxy
 //         - JSValue
 //       - Array
 //         - ByteArray
+//         - PixelArray
 //         - FixedArray
 //           - DescriptorArray
 //           - HashTable
 //             - Dictionary
 //             - SymbolTable
 //             - CompilationCacheTable
 //             - MapCache
 //           - Context
 //           - GlobalContext
 //       - String
@@ skipping 23 matching lines @@
 //         - SignatureInfo
 //         - TypeSwitchInfo
 //         - DebugInfo
 //         - BreakPointInfo
 //
 // Formats of Object*:
 //  Smi:        [31 bit signed int] 0
 //  HeapObject: [32 bit direct pointer] (4 byte aligned) | 01
 //  Failure:    [30 bit signed int] 11
 
-
 // Ecma-262 3rd 8.6.1
 enum PropertyAttributes {
   NONE              = v8::None,
   READ_ONLY         = v8::ReadOnly,
   DONT_ENUM         = v8::DontEnum,
   DONT_DELETE       = v8::DontDelete,
   ABSENT            = 16  // Used in runtime to indicate a property is absent.
   // ABSENT can never be stored in or returned from a descriptor's attributes
   // bitfield.  It is only used as a return value meaning the attributes of
   // a non-existent property.
@@ skipping 154 matching lines @@
   V(LONG_PRIVATE_EXTERNAL_ASCII_STRING_TYPE)    \
                                                 \
   V(MAP_TYPE)                                   \
   V(HEAP_NUMBER_TYPE)                           \
   V(FIXED_ARRAY_TYPE)                           \
   V(CODE_TYPE)                                  \
   V(JS_GLOBAL_PROPERTY_CELL_TYPE)               \
   V(ODDBALL_TYPE)                               \
   V(PROXY_TYPE)                                 \
   V(BYTE_ARRAY_TYPE)                            \
+  V(PIXEL_ARRAY_TYPE)                           \
   V(FILLER_TYPE)                                \
                                                 \
   V(ACCESSOR_INFO_TYPE)                         \
   V(ACCESS_CHECK_INFO_TYPE)                     \
   V(INTERCEPTOR_INFO_TYPE)                      \
   V(SHARED_FUNCTION_INFO_TYPE)                  \
   V(CALL_HANDLER_INFO_TYPE)                     \
   V(FUNCTION_TEMPLATE_INFO_TYPE)                \
   V(OBJECT_TEMPLATE_INFO_TYPE)                  \
   V(SIGNATURE_INFO_TYPE)                        \
@@ skipping 369 matching lines @@
   LONG_PRIVATE_EXTERNAL_ASCII_STRING_TYPE = LONG_EXTERNAL_ASCII_STRING_TYPE,
 
   MAP_TYPE = kNotStringTag,
   HEAP_NUMBER_TYPE,
   FIXED_ARRAY_TYPE,
   CODE_TYPE,
   ODDBALL_TYPE,
   JS_GLOBAL_PROPERTY_CELL_TYPE,
   PROXY_TYPE,
   BYTE_ARRAY_TYPE,
+  PIXEL_ARRAY_TYPE,
   FILLER_TYPE,
   SMI_TYPE,
 
   ACCESSOR_INFO_TYPE,
   ACCESS_CHECK_INFO_TYPE,
   INTERCEPTOR_INFO_TYPE,
   SHARED_FUNCTION_INFO_TYPE,
   CALL_HANDLER_INFO_TYPE,
   FUNCTION_TEMPLATE_INFO_TYPE,
   OBJECT_TEMPLATE_INFO_TYPE,
@@ skipping 81 matching lines @@
   inline bool IsSlicedString();
   inline bool IsExternalString();
   inline bool IsConsString();
   inline bool IsExternalTwoByteString();
   inline bool IsExternalAsciiString();
   inline bool IsSeqTwoByteString();
   inline bool IsSeqAsciiString();
 
   inline bool IsNumber();
   inline bool IsByteArray();
+  inline bool IsPixelArray();
   inline bool IsFailure();
   inline bool IsRetryAfterGC();
   inline bool IsOutOfMemoryFailure();
   inline bool IsException();
   inline bool IsJSObject();
   inline bool IsJSContextExtensionObject();
   inline bool IsMap();
   inline bool IsFixedArray();
   inline bool IsDescriptorArray();
   inline bool IsContext();
@@ skipping 522 matching lines @@
 };
 
 
 // The JSObject describes real heap allocated JavaScript objects with
 // properties.
 // Note that the map of JSObject changes during execution to enable inline
 // caching.
 class JSObject: public HeapObject {
  public:
   enum DeleteMode { NORMAL_DELETION, FORCE_DELETION };
+  enum ElementsKind {
+    FAST_ELEMENTS,
+    DICTIONARY_ELEMENTS,
+    PIXEL_ELEMENTS
+  };
 
   // [properties]: Backing storage for properties.
   // properties is a FixedArray in the fast case, and a Dictionary in the
   // slow case.
   DECL_ACCESSORS(properties, FixedArray)  // Get and set fast properties.
   inline void initialize_properties();
   inline bool HasFastProperties();
   inline StringDictionary* property_dictionary();  // Gets slow properties.
 
   // [elements]: The elements (properties with names that are integers).
   // elements is a FixedArray in the fast case, and a Dictionary in the slow
-  // case.
-  DECL_ACCESSORS(elements, FixedArray)  // Get and set fast elements.
+  // case or a PixelArray in a special case.
+  DECL_ACCESSORS(elements, Array)  // Get and set fast elements.
   inline void initialize_elements();
+  inline ElementsKind GetElementsKind();
   inline bool HasFastElements();
+  inline bool HasDictionaryElements();
+  inline bool HasPixelElements();
   inline NumberDictionary* element_dictionary();  // Gets slow elements.
 
   // Collects elements starting at index 0.
   // Undefined values are placed after non-undefined values.
   // Returns the number of non-undefined values.
   Object* PrepareElementsForSort(uint32_t limit);
   // As PrepareElementsForSort, but only on objects where elements is
   // a dictionary, and it will stay a dictionary.
   Object* PrepareSlowElementsForSort(uint32_t limit);
 
@@ skipping 1103 matching lines @@
 
   // ByteArray headers are not quadword aligned.
   static const int kHeaderSize = Array::kHeaderSize;
   static const int kAlignedSize = Array::kAlignedSize;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ByteArray);
 };
 
 
+// PixelArray represents a fixed size byte array with special sematics used for
+// implementing the CanvasPixelArray object. Please see the specification at:
+// http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#canvaspixelarray
+// In particular write access clamps the values to 0 or 255 if the value
+// used is outside this range.
+class PixelArray: public Array {
+ public:
+  // [external_pointer]: The pointer to the external memory area backing this
+  // pixel array.
+  DECL_ACCESSORS(external_pointer, uint8_t)  // Pointer to the data store.
+  
+  // Setter and getter.
+  inline uint8_t get(int index);
+  inline void set(int index, uint8_t value);
+
+  // This accessor applies the correct conversion from Smi, HeapNumber and
+  // undefined and clamps the converted value between 0 and 255.
+  Object* SetValue(uint32_t index, Object* value);
+
+  // Casting.
+  static inline PixelArray* cast(Object* obj);
+
+#ifdef DEBUG
+  void PixelArrayPrint();
+  void PixelArrayVerify();
+#endif  // DEBUG
+
+  // PixelArray headers are not quadword aligned.
+  static const int kExternalPointerOffset = Array::kAlignedSize;
+  static const int kHeaderSize = kExternalPointerOffset + kPointerSize;
+  static const int kAlignedSize = OBJECT_SIZE_ALIGN(kHeaderSize);
+  
+private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(PixelArray);
+};
+
+
 // Code describes objects with on-the-fly generated machine code.
 class Code: public HeapObject {
  public:
   // Opaque data type for encapsulating code flags like kind, inline
   // cache state, and arguments count.
   enum Flags { };
 
   enum Kind {
     FUNCTION,
     STUB,
@@ skipping 2294 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_