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      1 /*
      2  * Copyright (c) 2010, Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef DrawingBuffer_h
     32 #define DrawingBuffer_h
     33 
     34 #include "platform/PlatformExport.h"
     35 #include "platform/geometry/IntSize.h"
     36 #include "platform/graphics/GraphicsTypes3D.h"
     37 #include "platform/graphics/gpu/WebGLImageConversion.h"
     38 #include "public/platform/WebExternalTextureLayerClient.h"
     39 #include "public/platform/WebExternalTextureMailbox.h"
     40 #include "public/platform/WebGraphicsContext3D.h"
     41 #include "third_party/khronos/GLES2/gl2.h"
     42 #include "third_party/khronos/GLES2/gl2ext.h"
     43 #include "third_party/skia/include/core/SkBitmap.h"
     44 #include "wtf/Deque.h"
     45 #include "wtf/Noncopyable.h"
     46 #include "wtf/OwnPtr.h"
     47 #include "wtf/PassOwnPtr.h"
     48 
     49 namespace blink {
     50 
     51 class Extensions3DUtil;
     52 class ImageBuffer;
     53 class WebExternalBitmap;
     54 class WebExternalTextureLayer;
     55 class WebGraphicsContext3D;
     56 class WebLayer;
     57 
     58 // Abstract interface to allow basic context eviction management
     59 class PLATFORM_EXPORT ContextEvictionManager : public RefCounted<ContextEvictionManager> {
     60 public:
     61     virtual ~ContextEvictionManager() {};
     62 
     63     virtual void forciblyLoseOldestContext(const String& reason) = 0;
     64     virtual IntSize oldestContextSize() = 0;
     65 };
     66 
     67 // Manages a rendering target (framebuffer + attachment) for a canvas.  Can publish its rendering
     68 // results to a WebLayer for compositing.
     69 class PLATFORM_EXPORT DrawingBuffer : public RefCounted<DrawingBuffer>, public WebExternalTextureLayerClient  {
     70     // If we used CHROMIUM_image as the backing storage for our buffers,
     71     // we need to know the mapping from texture id to image.
     72     struct TextureInfo {
     73         Platform3DObject textureId;
     74         WGC3Duint imageId;
     75 
     76         TextureInfo()
     77             : textureId(0)
     78             , imageId(0)
     79         {
     80         }
     81     };
     82 
     83     struct MailboxInfo : public RefCounted<MailboxInfo> {
     84         WebExternalTextureMailbox mailbox;
     85         TextureInfo textureInfo;
     86         IntSize size;
     87         // This keeps the parent drawing buffer alive as long as the compositor is
     88         // referring to one of the mailboxes DrawingBuffer produced. The parent drawing buffer is
     89         // cleared when the compositor returns the mailbox. See mailboxReleased().
     90         RefPtr<DrawingBuffer> m_parentDrawingBuffer;
     91     };
     92 public:
     93     enum PreserveDrawingBuffer {
     94         Preserve,
     95         Discard
     96     };
     97 
     98     static PassRefPtr<DrawingBuffer> create(PassOwnPtr<WebGraphicsContext3D>, const IntSize&, PreserveDrawingBuffer, WebGraphicsContext3D::Attributes requestedAttributes, PassRefPtr<ContextEvictionManager>);
     99 
    100     virtual ~DrawingBuffer();
    101 
    102     // Destruction will be completed after all mailboxes are released.
    103     void beginDestruction();
    104 
    105     // Issues a glClear() on all framebuffers associated with this DrawingBuffer. The caller is responsible for
    106     // making the context current and setting the clear values and masks. Modifies the framebuffer binding.
    107     void clearFramebuffers(GLbitfield clearMask);
    108 
    109     // Given the desired buffer size, provides the largest dimensions that will fit in the pixel budget.
    110     static IntSize adjustSize(const IntSize& desiredSize, const IntSize& curSize, int maxTextureSize);
    111     bool reset(const IntSize&);
    112     void bind();
    113     IntSize size() const { return m_size; }
    114 
    115     // Copies the multisample color buffer to the normal color buffer and leaves m_fbo bound.
    116     void commit(long x = 0, long y = 0, long width = -1, long height = -1);
    117 
    118     // commit should copy the full multisample buffer, and not respect the
    119     // current scissor bounds. Track the state of the scissor test so that it
    120     // can be disabled during calls to commit.
    121     void setScissorEnabled(bool scissorEnabled) { m_scissorEnabled = scissorEnabled; }
    122 
    123     // The DrawingBuffer needs to track the texture bound to texture unit 0.
    124     // The bound texture is tracked to avoid costly queries during rendering.
    125     void setTexture2DBinding(Platform3DObject texture) { m_texture2DBinding = texture; }
    126 
    127     // The DrawingBuffer needs to track the currently bound framebuffer so it
    128     // restore the binding when needed.
    129     void setFramebufferBinding(Platform3DObject fbo) { m_framebufferBinding = fbo; }
    130 
    131     // Track the currently active texture unit. Texture unit 0 is used as host for a scratch
    132     // texture.
    133     void setActiveTextureUnit(GLint textureUnit) { m_activeTextureUnit = textureUnit; }
    134 
    135     bool multisample() const;
    136 
    137     Platform3DObject framebuffer() const;
    138 
    139     void markContentsChanged();
    140     void markLayerComposited();
    141     bool layerComposited() const;
    142     void setIsHidden(bool);
    143 
    144     WebLayer* platformLayer();
    145     void paintCompositedResultsToCanvas(ImageBuffer*);
    146 
    147     WebGraphicsContext3D* context();
    148 
    149     // Returns the actual context attributes for this drawing buffer which may differ from the
    150     // requested context attributes due to implementation limits.
    151     WebGraphicsContext3D::Attributes getActualAttributes() const { return m_actualAttributes; }
    152 
    153     // WebExternalTextureLayerClient implementation.
    154     virtual bool prepareMailbox(WebExternalTextureMailbox*, WebExternalBitmap*) OVERRIDE;
    155     virtual void mailboxReleased(const WebExternalTextureMailbox&, bool lostResource = false) OVERRIDE;
    156 
    157     // Destroys the TEXTURE_2D binding for the owned context
    158     bool copyToPlatformTexture(WebGraphicsContext3D*, Platform3DObject texture, GLenum internalFormat,
    159         GLenum destType, GLint level, bool premultiplyAlpha, bool flipY, bool fromFrontBuffer = false);
    160 
    161     void setPackAlignment(GLint param);
    162 
    163     void paintRenderingResultsToCanvas(ImageBuffer*);
    164     PassRefPtr<Uint8ClampedArray> paintRenderingResultsToImageData(int&, int&);
    165 
    166 protected: // For unittests
    167     DrawingBuffer(
    168         PassOwnPtr<WebGraphicsContext3D>,
    169         PassOwnPtr<Extensions3DUtil>,
    170         bool multisampleExtensionSupported,
    171         bool packedDepthStencilExtensionSupported,
    172         PreserveDrawingBuffer,
    173         WebGraphicsContext3D::Attributes requestedAttributes,
    174         PassRefPtr<ContextEvictionManager>);
    175 
    176     bool initialize(const IntSize&);
    177 
    178 private:
    179     void mailboxReleasedWithoutRecycling(const WebExternalTextureMailbox&);
    180 
    181     unsigned createColorTexture();
    182     // Create the depth/stencil and multisample buffers, if needed.
    183     void createSecondaryBuffers();
    184     bool resizeFramebuffer(const IntSize&);
    185     bool resizeMultisampleFramebuffer(const IntSize&);
    186     void resizeDepthStencil(const IntSize&);
    187 
    188     // Bind to the m_framebufferBinding if it's not 0.
    189     void restoreFramebufferBinding();
    190 
    191     void clearPlatformLayer();
    192 
    193     PassRefPtr<MailboxInfo> recycledMailbox();
    194     PassRefPtr<MailboxInfo> createNewMailbox(const TextureInfo&);
    195     void deleteMailbox(const WebExternalTextureMailbox&);
    196     void freeRecycledMailboxes();
    197 
    198     // Updates the current size of the buffer, ensuring that s_currentResourceUsePixels is updated.
    199     void setSize(const IntSize& size);
    200 
    201     // Calculates the difference in pixels between the current buffer size and the proposed size.
    202     static int pixelDelta(const IntSize& newSize, const IntSize& curSize);
    203 
    204     // Given the desired buffer size, provides the largest dimensions that will fit in the pixel budget
    205     // Returns true if the buffer will only fit if the oldest WebGL context is forcibly lost
    206     IntSize adjustSizeWithContextEviction(const IntSize&, bool& evictContext);
    207 
    208     void paintFramebufferToCanvas(int framebuffer, int width, int height, bool premultiplyAlpha, ImageBuffer*);
    209 
    210     // This is the order of bytes to use when doing a readback.
    211     enum ReadbackOrder {
    212         ReadbackRGBA,
    213         ReadbackSkia
    214     };
    215 
    216     // Helper function which does a readback from the currently-bound
    217     // framebuffer into a buffer of a certain size with 4-byte pixels.
    218     void readBackFramebuffer(unsigned char* pixels, int width, int height, ReadbackOrder, WebGLImageConversion::AlphaOp);
    219 
    220     // Helper function to flip a bitmap vertically.
    221     void flipVertically(uint8_t* data, int width, int height);
    222 
    223     // Helper to texImage2D with pixel==0 case: pixels are initialized to 0.
    224     // By default, alignment is 4, the OpenGL default setting.
    225     void texImage2DResourceSafe(GLenum target, GLint level, GLenum internalformat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, GLint alignment = 4);
    226     // Allocate buffer storage to be sent to compositor using either texImage2D or CHROMIUM_image based on available support.
    227     void allocateTextureMemory(TextureInfo*, const IntSize&);
    228     void deleteChromiumImageForTexture(TextureInfo*);
    229 
    230     PreserveDrawingBuffer m_preserveDrawingBuffer;
    231     bool m_scissorEnabled;
    232     Platform3DObject m_texture2DBinding;
    233     Platform3DObject m_framebufferBinding;
    234     GLenum m_activeTextureUnit;
    235 
    236     OwnPtr<WebGraphicsContext3D> m_context;
    237     OwnPtr<Extensions3DUtil> m_extensionsUtil;
    238     IntSize m_size;
    239     WebGraphicsContext3D::Attributes m_requestedAttributes;
    240     bool m_multisampleExtensionSupported;
    241     bool m_packedDepthStencilExtensionSupported;
    242     Platform3DObject m_fbo;
    243     // DrawingBuffer's output is double-buffered. m_colorBuffer is the back buffer.
    244     TextureInfo m_colorBuffer;
    245     TextureInfo m_frontColorBuffer;
    246 
    247     // This is used when we have OES_packed_depth_stencil.
    248     Platform3DObject m_depthStencilBuffer;
    249 
    250     // These are used when we don't.
    251     Platform3DObject m_depthBuffer;
    252     Platform3DObject m_stencilBuffer;
    253 
    254     // For multisampling.
    255     Platform3DObject m_multisampleFBO;
    256     Platform3DObject m_multisampleColorBuffer;
    257 
    258     // True if our contents have been modified since the last presentation of this buffer.
    259     bool m_contentsChanged;
    260 
    261     // True if commit() has been called since the last time markContentsChanged() had been called.
    262     bool m_contentsChangeCommitted;
    263     bool m_layerComposited;
    264 
    265     enum MultisampleMode {
    266         None,
    267         ImplicitResolve,
    268         ExplicitResolve,
    269     };
    270 
    271     MultisampleMode m_multisampleMode;
    272 
    273     WebGraphicsContext3D::Attributes m_actualAttributes;
    274     unsigned m_internalColorFormat;
    275     unsigned m_colorFormat;
    276     unsigned m_internalRenderbufferFormat;
    277     int m_maxTextureSize;
    278     int m_sampleCount;
    279     int m_packAlignment;
    280     bool m_destructionInProgress;
    281     bool m_isHidden;
    282 
    283     OwnPtr<WebExternalTextureLayer> m_layer;
    284 
    285     // All of the mailboxes that this DrawingBuffer has ever created.
    286     Vector<RefPtr<MailboxInfo> > m_textureMailboxes;
    287     // Mailboxes that were released by the compositor can be used again by this DrawingBuffer.
    288     Deque<WebExternalTextureMailbox> m_recycledMailboxQueue;
    289 
    290     RefPtr<ContextEvictionManager> m_contextEvictionManager;
    291 
    292     // If the width and height of the Canvas's backing store don't
    293     // match those that we were given in the most recent call to
    294     // reshape(), then we need an intermediate bitmap to read back the
    295     // frame buffer into. This seems to happen when CSS styles are
    296     // used to resize the Canvas.
    297     SkBitmap m_resizingBitmap;
    298 
    299     // Used to flip a bitmap vertically.
    300     Vector<uint8_t> m_scanline;
    301 };
    302 
    303 } // namespace blink
    304 
    305 #endif // DrawingBuffer_h
    306