Add some plumbing for the color management of canvases

third_party/WebKit/Source/core/html/canvas/CanvasRenderingContext.h

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 10 matching lines @@
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef CanvasRenderingContext_h
 #define CanvasRenderingContext_h
 
 #include "core/CoreExport.h"
 #include "core/html/HTMLCanvasElement.h"
+#include "core/html/canvas/CanvasContextCreationAttributes.h"
 #include "core/offscreencanvas/OffscreenCanvas.h"
+#include "third_party/skia/include/core/SkColorSpace.h"
 #include "wtf/HashSet.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/text/StringHash.h"
 
 class SkCanvas;
 
-namespace blink { class WebLayer; }
-
 namespace blink {
 
 class CanvasImageSource;
 class HTMLCanvasElement;
 class ImageData;
 class ImageBitmap;
+class WebLayer;
+
+enum CanvasColorSpace {
+    kLegacyCanvasColorSpace,
+    kSRGBCanvasColorSpace,
+    kLinearRGBCanvasColorSpace,
+};
 
 class CORE_EXPORT CanvasRenderingContext : public GarbageCollectedFinalized<CanvasRenderingContext>, public ScriptWrappable {
     WTF_MAKE_NONCOPYABLE(CanvasRenderingContext);
     USING_PRE_FINALIZER(CanvasRenderingContext, dispose);
 public:
     virtual ~CanvasRenderingContext() { }
 
     // A Canvas can either be "2D" or "webgl" but never both. If you request a 2D canvas and the existing
     // context is already 2D, just return that. If the existing context is WebGL, then destroy it
     // before creating a new 2D context. Vice versa when requesting a WebGL canvas. Requesting a
     // context with any other type string will destroy any existing context.
     enum ContextType {
         // Do not change assigned numbers of existing items: add new features to the end of the list.
         Context2d = 0,
         ContextExperimentalWebgl = 2,
         ContextWebgl = 3,
         ContextWebgl2 = 4,
         ContextImageBitmap = 5,
         ContextTypeCount,
     };
 
     static ContextType contextTypeFromId(const String& id);
     static ContextType resolveContextTypeAliases(ContextType);
 
     HTMLCanvasElement* canvas() const { return m_canvas; }
 
+    CanvasColorSpace colorSpace() const { return m_colorSpace; };
+    WTF::String colorSpaceAsString() const;
+    sk_sp<SkColorSpace> skColorSpace() const;
+
+    virtual bool hasAlpha() const { return creationAttributes().alpha(); }

[Stephen White, 2016/08/12 19:48:31]

As discussed, let's see if we can get rid of this double-virtual hasAlpha().

(And long-term, let's see if there's a way to get rid of the spaghetti
inheritance!)

[Justin Novosad, 2016/08/12 20:08:49]

Done.

     virtual ContextType getContextType() const = 0;
     virtual bool isAccelerated() const { return false; }
     virtual bool shouldAntialias() const { return false; }
-    virtual bool hasAlpha() const { return true; }
     virtual void setIsHidden(bool) = 0;
     virtual bool isContextLost() const { return true; }
     virtual void setCanvasGetContextResult(RenderingContext&) { NOTREACHED(); };
     virtual void setOffscreenCanvasGetContextResult(OffscreenRenderingContext&) { NOTREACHED(); }
 
     // Return true if the content is updated.
     virtual bool paintRenderingResultsToCanvas(SourceDrawingBuffer) { return false; }
 
     virtual WebLayer* platformLayer() const { return nullptr; }
 
@@ skipping 40 matching lines @@
 
     bool wouldTaintOrigin(CanvasImageSource*, SecurityOrigin* = nullptr);
     void didMoveToNewDocument(Document*);
 
     // OffscreenCanvas-specific methods
     OffscreenCanvas* getOffscreenCanvas() const { return m_offscreenCanvas; }
     virtual ImageBitmap* transferToImageBitmap(ExceptionState&) { return nullptr; }
 
     void detachCanvas() { m_canvas = nullptr; }
 
+    const CanvasContextCreationAttributes& creationAttributes() const { return m_creationAttributes; }
+
 protected:
-    CanvasRenderingContext(HTMLCanvasElement* = nullptr, OffscreenCanvas* = nullptr);
+    CanvasRenderingContext(HTMLCanvasElement*, OffscreenCanvas*, const CanvasContextCreationAttributes&);
     DECLARE_VIRTUAL_TRACE();
     virtual void stop() = 0;
 
 private:
     void dispose();
 
     Member<HTMLCanvasElement> m_canvas;
     Member<OffscreenCanvas> m_offscreenCanvas;
     HashSet<String> m_cleanURLs;
     HashSet<String> m_dirtyURLs;
+    CanvasColorSpace m_colorSpace;
+    CanvasContextCreationAttributes m_creationAttributes;
 };
 
 } // namespace blink
 
 #endif