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
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * 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/layout/HitTestCanvasResult.h"
#include "core/offscreencanvas/OffscreenCanvas.h"
#include "platform/graphics/ColorBehavior.h"
#include "public/platform/WebThread.h"
#include "third_party/skia/include/core/SkColorSpace.h"
#include "third_party/skia/include/core/SkImageInfo.h"
#include "wtf/HashSet.h"
#include "wtf/Noncopyable.h"
#include "wtf/text/StringHash.h"

namespace blink {

class CanvasImageSource;
class HTMLCanvasElement;
class ImageData;
class ImageBitmap;
class WebLayer;

enum CanvasColorSpace {
  kLegacyCanvasColorSpace,
  kSRGBCanvasColorSpace,
  kLinearRGBCanvasColorSpace,
  kRec2020CanvasColorSpace,
  kP3CanvasColorSpace,
};

class CORE_EXPORT CanvasRenderingContext
    : public GarbageCollectedFinalized<CanvasRenderingContext>,
      public ScriptWrappable,
      public WebThread::TaskObserver {
  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;
  // The color space in which the the content should be interpreted by the
  // compositor. This is always defined.
  gfx::ColorSpace gfxColorSpace() const;
  // The color space that should be used for SkSurface creation. This may
  // be nullptr.
  sk_sp<SkColorSpace> skSurfaceColorSpace() const;
  SkColorType colorType() const;
  ColorBehavior colorBehaviorForMediaDrawnToCanvas() const;
  bool skSurfacesUseColorSpace() const;

  virtual PassRefPtr<Image> getImage(AccelerationHint,
                                     SnapshotReason) const = 0;
  virtual ImageData* toImageData(SnapshotReason reason) { return nullptr; }
  virtual ContextType getContextType() const = 0;
  virtual bool isAccelerated() const { return false; }
  virtual bool shouldAntialias() const { return false; }
  virtual void setIsHidden(bool) = 0;
  virtual bool isContextLost() const { return true; }
  virtual void setCanvasGetContextResult(RenderingContext&) { NOTREACHED(); };
  virtual void setOffscreenCanvasGetContextResult(OffscreenRenderingContext&) {
    NOTREACHED();
  }
  virtual bool isPaintable() const = 0;
  virtual void didDraw(const SkIRect& dirtyRect);

  // Return true if the content is updated.
  virtual bool paintRenderingResultsToCanvas(SourceDrawingBuffer) {
    return false;
  }

  virtual WebLayer* platformLayer() const { return nullptr; }

  enum LostContextMode {
    NotLostContext,

    // Lost context occurred at the graphics system level.
    RealLostContext,

    // Lost context provoked by WEBGL_lose_context.
    WebGLLoseContextLostContext,

    // Lost context occurred due to internal implementation reasons.
    SyntheticLostContext,
  };
  virtual void loseContext(LostContextMode) {}

  // WebThread::TaskObserver implementation
  void didProcessTask() override;
  void willProcessTask() final {}

  // Canvas2D-specific interface
  virtual bool is2d() const { return false; }
  virtual void restoreCanvasMatrixClipStack(PaintCanvas*) const {}
  virtual void reset() {}
  virtual void clearRect(double x, double y, double width, double height) {}
  virtual void didSetSurfaceSize() {}
  virtual void setShouldAntialias(bool) {}
  virtual unsigned hitRegionsCount() const { return 0; }
  virtual void setFont(const String&) {}
  virtual void styleDidChange(const ComputedStyle* oldStyle,
                              const ComputedStyle& newStyle) {}
  virtual HitTestCanvasResult* getControlAndIdIfHitRegionExists(
      const LayoutPoint& location) {
    NOTREACHED();
    return HitTestCanvasResult::create(String(), nullptr);
  }
  virtual String getIdFromControl(const Element* element) { return String(); }
  virtual bool isAccelerationOptimalForCanvasContent() const { return true; }
  virtual void resetUsageTracking(){};
  virtual void incrementFrameCount(){};

  // WebGL-specific interface
  virtual bool is3d() const { return false; }
  virtual void setFilterQuality(SkFilterQuality) { NOTREACHED(); }
  virtual void reshape(int width, int height) { NOTREACHED(); }
  virtual void markLayerComposited() { NOTREACHED(); }
  virtual ImageData* paintRenderingResultsToImageData(SourceDrawingBuffer) {
    NOTREACHED();
    return nullptr;
  }
  virtual int externallyAllocatedBytesPerPixel() {
    NOTREACHED();
    return 0;
  }

  // ImageBitmap-specific interface
  virtual bool paint(GraphicsContext&, const IntRect&) { return false; }

  // OffscreenCanvas-specific methods
  OffscreenCanvas* offscreenCanvas() const { return m_offscreenCanvas; }
  virtual ImageBitmap* transferToImageBitmap(ScriptState*) { return nullptr; }

  bool wouldTaintOrigin(CanvasImageSource*, SecurityOrigin* = nullptr);
  void didMoveToNewDocument(Document*);

  void detachCanvas() { m_canvas = nullptr; }
  void detachOffscreenCanvas() { m_offscreenCanvas = nullptr; }

  const CanvasContextCreationAttributes& creationAttributes() const {
    return m_creationAttributes;
  }

 protected:
  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;
  bool m_finalizeFrameScheduled = false;
};

}  // namespace blink

#endif