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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 class WebExternalBitmap;
     51 class WebExternalTextureLayer;
     52 class WebGraphicsContext3D;
     53 class WebLayer;
     54 }
     55 
     56 namespace WebCore {
     57 class Extensions3DUtil;
     58 class ImageData;
     59 class ImageBuffer;
     60 
     61 // Abstract interface to allow basic context eviction management
     62 class PLATFORM_EXPORT ContextEvictionManager : public RefCounted<ContextEvictionManager> {
     63 public:
     64     virtual ~ContextEvictionManager() {};
     65 
     66     virtual void forciblyLoseOldestContext(const String& reason) = 0;
     67     virtual IntSize oldestContextSize() = 0;
     68 };
     69 
     70 // Manages a rendering target (framebuffer + attachment) for a canvas.  Can publish its rendering
     71 // results to a blink::WebLayer for compositing.
     72 class PLATFORM_EXPORT DrawingBuffer : public RefCounted<DrawingBuffer>, public blink::WebExternalTextureLayerClient  {
     73     // If we used CHROMIUM_image as the backing storage for our buffers,
     74     // we need to know the mapping from texture id to image.
     75     struct TextureInfo {
     76         Platform3DObject textureId;
     77         blink::WGC3Duint imageId;
     78 
     79         TextureInfo()
     80             : textureId(0)
     81             , imageId(0)
     82         {
     83         }
     84     };
     85 
     86     struct MailboxInfo : public RefCounted<MailboxInfo> {
     87         blink::WebExternalTextureMailbox mailbox;
     88         TextureInfo textureInfo;
     89         IntSize size;
     90         // This keeps the parent drawing buffer alive as long as the compositor is
     91         // referring to one of the mailboxes DrawingBuffer produced. The parent drawing buffer is
     92         // cleared when the compositor returns the mailbox. See mailboxReleased().
     93         RefPtr<DrawingBuffer> m_parentDrawingBuffer;
     94     };
     95 public:
     96     enum PreserveDrawingBuffer {
     97         Preserve,
     98         Discard
     99     };
    100 
    101     static PassRefPtr<DrawingBuffer> create(PassOwnPtr<blink::WebGraphicsContext3D>, const IntSize&, PreserveDrawingBuffer, blink::WebGraphicsContext3D::Attributes requestedAttributes, PassRefPtr<ContextEvictionManager>);
    102 
    103     virtual ~DrawingBuffer();
    104 
    105     // Destruction will be completed after all mailboxes are released.
    106     void beginDestruction();
    107 
    108     // Issues a glClear() on all framebuffers associated with this DrawingBuffer. The caller is responsible for
    109     // making the context current and setting the clear values and masks. Modifies the framebuffer binding.
    110     void clearFramebuffers(GLbitfield clearMask);
    111 
    112     // Given the desired buffer size, provides the largest dimensions that will fit in the pixel budget.
    113     static IntSize adjustSize(const IntSize& desiredSize, const IntSize& curSize, int maxTextureSize);
    114     bool reset(const IntSize&);
    115     void bind();
    116     IntSize size() const { return m_size; }
    117 
    118     // Copies the multisample color buffer to the normal color buffer and leaves m_fbo bound.
    119     void commit(long x = 0, long y = 0, long width = -1, long height = -1);
    120 
    121     // commit should copy the full multisample buffer, and not respect the
    122     // current scissor bounds. Track the state of the scissor test so that it
    123     // can be disabled during calls to commit.
    124     void setScissorEnabled(bool scissorEnabled) { m_scissorEnabled = scissorEnabled; }
    125 
    126     // The DrawingBuffer needs to track the texture bound to texture unit 0.
    127     // The bound texture is tracked to avoid costly queries during rendering.
    128     void setTexture2DBinding(Platform3DObject texture) { m_texture2DBinding = texture; }
    129 
    130     // The DrawingBuffer needs to track the currently bound framebuffer so it
    131     // restore the binding when needed.
    132     void setFramebufferBinding(Platform3DObject fbo) { m_framebufferBinding = fbo; }
    133 
    134     // Track the currently active texture unit. Texture unit 0 is used as host for a scratch
    135     // texture.
    136     void setActiveTextureUnit(GLint textureUnit) { m_activeTextureUnit = textureUnit; }
    137 
    138     bool multisample() const;
    139 
    140     Platform3DObject framebuffer() const;
    141 
    142     void markContentsChanged();
    143     void markLayerComposited();
    144     bool layerComposited() const;
    145 
    146     blink::WebLayer* platformLayer();
    147     void paintCompositedResultsToCanvas(ImageBuffer*);
    148 
    149     blink::WebGraphicsContext3D* context();
    150 
    151     // Returns the actual context attributes for this drawing buffer which may differ from the
    152     // requested context attributes due to implementation limits.
    153     blink::WebGraphicsContext3D::Attributes getActualAttributes() const { return m_actualAttributes; }
    154 
    155     // WebExternalTextureLayerClient implementation.
    156     virtual bool prepareMailbox(blink::WebExternalTextureMailbox*, blink::WebExternalBitmap*) OVERRIDE;
    157     virtual void mailboxReleased(const blink::WebExternalTextureMailbox&) OVERRIDE;
    158 
    159     // Destroys the TEXTURE_2D binding for the owned context
    160     bool copyToPlatformTexture(blink::WebGraphicsContext3D*, Platform3DObject texture, GLenum internalFormat,
    161         GLenum destType, GLint level, bool premultiplyAlpha, bool flipY, bool fromFrontBuffer = false);
    162 
    163     void setPackAlignment(GLint param);
    164 
    165     void paintRenderingResultsToCanvas(ImageBuffer*);
    166     PassRefPtr<Uint8ClampedArray> paintRenderingResultsToImageData(int&, int&);
    167 
    168 protected: // For unittests
    169     DrawingBuffer(
    170         PassOwnPtr<blink::WebGraphicsContext3D>,
    171         PassOwnPtr<Extensions3DUtil>,
    172         bool multisampleExtensionSupported,
    173         bool packedDepthStencilExtensionSupported,
    174         PreserveDrawingBuffer,
    175         blink::WebGraphicsContext3D::Attributes requestedAttributes,
    176         PassRefPtr<ContextEvictionManager>);
    177 
    178     bool initialize(const IntSize&);
    179 
    180 private:
    181     void mailboxReleasedWhileDestructionInProgress(const blink::WebExternalTextureMailbox&);
    182 
    183     unsigned createColorTexture();
    184     // Create the depth/stencil and multisample buffers, if needed.
    185     void createSecondaryBuffers();
    186     bool resizeFramebuffer(const IntSize&);
    187     bool resizeMultisampleFramebuffer(const IntSize&);
    188     void resizeDepthStencil(const IntSize&);
    189 
    190     // Bind to the m_framebufferBinding if it's not 0.
    191     void restoreFramebufferBinding();
    192 
    193     void clearPlatformLayer();
    194 
    195     PassRefPtr<MailboxInfo> recycledMailbox();
    196     PassRefPtr<MailboxInfo> createNewMailbox(const TextureInfo&);
    197     void deleteMailbox(const blink::WebExternalTextureMailbox&);
    198 
    199     // Updates the current size of the buffer, ensuring that s_currentResourceUsePixels is updated.
    200     void setSize(const IntSize& size);
    201 
    202     // Calculates the difference in pixels between the current buffer size and the proposed size.
    203     static int pixelDelta(const IntSize& newSize, const IntSize& curSize);
    204 
    205     // Given the desired buffer size, provides the largest dimensions that will fit in the pixel budget
    206     // Returns true if the buffer will only fit if the oldest WebGL context is forcibly lost
    207     IntSize adjustSizeWithContextEviction(const IntSize&, bool& evictContext);
    208 
    209     void paintFramebufferToCanvas(int framebuffer, int width, int height, bool premultiplyAlpha, ImageBuffer*);
    210 
    211     // This is the order of bytes to use when doing a readback.
    212     enum ReadbackOrder {
    213         ReadbackRGBA,
    214         ReadbackSkia
    215     };
    216 
    217     // Helper function which does a readback from the currently-bound
    218     // framebuffer into a buffer of a certain size with 4-byte pixels.
    219     void readBackFramebuffer(unsigned char* pixels, int width, int height, ReadbackOrder, WebGLImageConversion::AlphaOp);
    220 
    221     // Helper function to flip a bitmap vertically.
    222     void flipVertically(uint8_t* data, int width, int height);
    223 
    224     // Helper to texImage2D with pixel==0 case: pixels are initialized to 0.
    225     // By default, alignment is 4, the OpenGL default setting.
    226     void texImage2DResourceSafe(GLenum target, GLint level, GLenum internalformat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, GLint alignment = 4);
    227     // Allocate buffer storage to be sent to compositor using either texImage2D or CHROMIUM_image based on available support.
    228     void allocateTextureMemory(TextureInfo*, const IntSize&);
    229     void deleteChromiumImageForTexture(TextureInfo*);
    230 
    231     PreserveDrawingBuffer m_preserveDrawingBuffer;
    232     bool m_scissorEnabled;
    233     Platform3DObject m_texture2DBinding;
    234     Platform3DObject m_framebufferBinding;
    235     GLenum m_activeTextureUnit;
    236 
    237     OwnPtr<blink::WebGraphicsContext3D> m_context;
    238     OwnPtr<Extensions3DUtil> m_extensionsUtil;
    239     IntSize m_size;
    240     blink::WebGraphicsContext3D::Attributes m_requestedAttributes;
    241     bool m_multisampleExtensionSupported;
    242     bool m_packedDepthStencilExtensionSupported;
    243     Platform3DObject m_fbo;
    244     // DrawingBuffer's output is double-buffered. m_colorBuffer is the back buffer.
    245     TextureInfo m_colorBuffer;
    246     TextureInfo m_frontColorBuffer;
    247 
    248     // This is used when we have OES_packed_depth_stencil.
    249     Platform3DObject m_depthStencilBuffer;
    250 
    251     // These are used when we don't.
    252     Platform3DObject m_depthBuffer;
    253     Platform3DObject m_stencilBuffer;
    254 
    255     // For multisampling.
    256     Platform3DObject m_multisampleFBO;
    257     Platform3DObject m_multisampleColorBuffer;
    258 
    259     // True if our contents have been modified since the last presentation of this buffer.
    260     bool m_contentsChanged;
    261 
    262     // True if commit() has been called since the last time markContentsChanged() had been called.
    263     bool m_contentsChangeCommitted;
    264     bool m_layerComposited;
    265 
    266     enum MultisampleMode {
    267         None,
    268         ImplicitResolve,
    269         ExplicitResolve,
    270     };
    271 
    272     MultisampleMode m_multisampleMode;
    273 
    274     blink::WebGraphicsContext3D::Attributes m_actualAttributes;
    275     unsigned m_internalColorFormat;
    276     unsigned m_colorFormat;
    277     unsigned m_internalRenderbufferFormat;
    278     int m_maxTextureSize;
    279     int m_sampleCount;
    280     int m_packAlignment;
    281     bool m_destructionInProgress;
    282 
    283     OwnPtr<blink::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<blink::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 WebCore
    304 
    305 #endif // DrawingBuffer_h
    306