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 "GraphicsContext3D.h"
35#include "GraphicsTypes3D.h"
36#include "IntSize.h"
37#include "PlatformLayer.h"
38
39#include <wtf/Noncopyable.h>
40#include <wtf/OwnPtr.h>
41#include <wtf/PassOwnPtr.h>
42#if PLATFORM(MAC)
43#include <wtf/RetainPtr.h>
44#endif
45
46namespace WebCore {
47class GraphicsContext3D;
48class ImageData;
49
50// Manages a rendering target (framebuffer + attachment) for a canvas.  Can publish its rendering
51// results to a PlatformLayer for compositing.
52class DrawingBuffer : public RefCounted<DrawingBuffer> {
53public:
54    enum PreserveDrawingBuffer {
55        Preserve,
56        Discard
57    };
58
59    enum AlphaRequirement {
60        Alpha,
61        Opaque
62    };
63
64    static PassRefPtr<DrawingBuffer> create(GraphicsContext3D*, const IntSize&, PreserveDrawingBuffer, AlphaRequirement);
65    friend class GraphicsContext3D;
66
67    ~DrawingBuffer();
68
69    // Issues a glClear() on all framebuffers associated with this DrawingBuffer. The caller is responsible for
70    // making the context current and setting the clear values and masks. Modifies the framebuffer binding.
71    void clearFramebuffers(GC3Dbitfield clearMask);
72
73    // Returns true if the buffer was successfully resized.
74    bool reset(const IntSize&);
75    void bind();
76    IntSize size() const { return m_size; }
77    Platform3DObject colorBuffer() const { return m_colorBuffer; }
78
79    // Clear all resources from this object, as well as context. Called when context is destroyed
80    // to prevent invalid accesses to the resources.
81    void clear();
82
83    // Create the depth/stencil and multisample buffers, if needed.
84    void createSecondaryBuffers();
85
86    void resizeDepthStencil(int sampleCount);
87
88    // Copies the multisample color buffer to the normal color buffer and leaves m_fbo bound
89    void commit(long x = 0, long y = 0, long width = -1, long height = -1);
90
91    // commit should copy the full multisample buffer, and not respect the
92    // current scissor bounds. Track the state of the scissor test so that it
93    // can be disabled during calls to commit.
94    void setScissorEnabled(bool scissorEnabled) { m_scissorEnabled = scissorEnabled; }
95
96    // The DrawingBuffer needs to track the texture bound to texture unit 0.
97    // The bound texture is tracked to avoid costly queries during rendering.
98    void setTexture2DBinding(Platform3DObject texture) { m_texture2DBinding = texture; }
99
100    // The DrawingBuffer needs to track the currently bound framebuffer so it
101    // restore the binding when needed.
102    void setFramebufferBinding(Platform3DObject fbo) { m_framebufferBinding = fbo; }
103
104    // Bind to the m_framebufferBinding if it's not 0.
105    void restoreFramebufferBinding();
106
107    // Track the currently active texture unit. Texture unit 0 is used as host for a scratch
108    // texture.
109    void setActiveTextureUnit(GC3Dint textureUnit) { m_activeTextureUnit = textureUnit; }
110
111    bool multisample() const;
112
113    Platform3DObject framebuffer() const;
114
115    PassRefPtr<ImageData> paintRenderingResultsToImageData();
116
117    // Immediately releases ownership of all resources. Call upon loss of the
118    // graphics context to prevent freeing invalid resources.
119    void discardResources();
120
121    void markContentsChanged() { m_contentsChanged = true; }
122
123#if USE(ACCELERATED_COMPOSITING)
124    PlatformLayer* platformLayer();
125    void prepareBackBuffer();
126    bool requiresCopyFromBackToFrontBuffer() const;
127    unsigned frontColorBuffer() const;
128    void paintCompositedResultsToCanvas(ImageBuffer*);
129    void clearPlatformLayer();
130#endif
131
132    GraphicsContext3D* graphicsContext3D() const { return m_context.get(); }
133
134private:
135    DrawingBuffer(GraphicsContext3D*, const IntSize&, bool multisampleExtensionSupported,
136                  bool packedDepthStencilExtensionSupported, PreserveDrawingBuffer, AlphaRequirement);
137
138    void initialize(const IntSize&);
139
140    bool checkBufferIntegrity();
141
142    PreserveDrawingBuffer m_preserveDrawingBuffer;
143    AlphaRequirement m_alpha;
144    bool m_scissorEnabled;
145    Platform3DObject m_texture2DBinding;
146    Platform3DObject m_framebufferBinding;
147    GC3Denum m_activeTextureUnit;
148
149    RefPtr<GraphicsContext3D> m_context;
150    IntSize m_size;
151    bool m_multisampleExtensionSupported;
152    bool m_packedDepthStencilExtensionSupported;
153    Platform3DObject m_fbo;
154    Platform3DObject m_colorBuffer;
155    Platform3DObject m_frontColorBuffer;
156    bool m_separateFrontTexture;
157
158    // This is used when we have OES_packed_depth_stencil.
159    Platform3DObject m_depthStencilBuffer;
160
161    // These are used when we don't.
162    Platform3DObject m_depthBuffer;
163    Platform3DObject m_stencilBuffer;
164
165    // For multisampling
166    Platform3DObject m_multisampleFBO;
167    Platform3DObject m_multisampleColorBuffer;
168
169    // True if our contents have been modified since the last presentation of this buffer.
170    bool m_contentsChanged;
171
172#if PLATFORM(MAC)
173    RetainPtr<WebGLLayer> m_platformLayer;
174#endif
175};
176
177} // namespace WebCore
178
179#endif // DrawingBuffer_h
180