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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef UI_GL_GL_CONTEXT_H_
6 #define UI_GL_GL_CONTEXT_H_
7 
8 #include <string>
9 
10 #include "base/basictypes.h"
11 #include "base/memory/ref_counted.h"
12 #include "base/memory/scoped_ptr.h"
13 #include "ui/gl/gl_share_group.h"
14 #include "ui/gl/gl_state_restorer.h"
15 #include "ui/gl/gpu_preference.h"
16 
17 namespace gfx {
18 
19 class GLSurface;
20 class VirtualGLApi;
21 
22 // Encapsulates an OpenGL context, hiding platform specific management.
23 class GL_EXPORT GLContext : public base::RefCounted<GLContext> {
24  public:
25   explicit GLContext(GLShareGroup* share_group);
26 
27   // Initializes the GL context to be compatible with the given surface. The GL
28   // context can be made with other surface's of the same type. The compatible
29   // surface is only needed for certain platforms like WGL, OSMesa and GLX. It
30   // should be specific for all platforms though.
31   virtual bool Initialize(
32       GLSurface* compatible_surface, GpuPreference gpu_preference) = 0;
33 
34   // Destroys the GL context.
35   virtual void Destroy() = 0;
36 
37   // Makes the GL context and a surface current on the current thread.
38   virtual bool MakeCurrent(GLSurface* surface) = 0;
39 
40   // Releases this GL context and surface as current on the current thread.
41   virtual void ReleaseCurrent(GLSurface* surface) = 0;
42 
43   // Returns true if this context and surface is current. Pass a null surface
44   // if the current surface is not important.
45   virtual bool IsCurrent(GLSurface* surface) = 0;
46 
47   // Get the underlying platform specific GL context "handle".
48   virtual void* GetHandle() = 0;
49 
50   // Gets the GLStateRestorer for the context.
51   GLStateRestorer* GetGLStateRestorer();
52 
53   // Sets the GLStateRestorer for the context (takes ownership).
54   void SetGLStateRestorer(GLStateRestorer* state_restorer);
55 
56   // Set swap interval. This context must be current.
57   virtual void SetSwapInterval(int interval) = 0;
58 
59   // Returns space separated list of extensions. The context must be current.
60   virtual std::string GetExtensions();
61 
62   // Returns in bytes the total amount of GPU memory for the GPU which this
63   // context is currently rendering on. Returns false if no extension exists
64   // to get the exact amount of GPU memory.
65   virtual bool GetTotalGpuMemory(size_t* bytes);
66 
67   // Indicate that it is safe to force this context to switch GPUs, since
68   // transitioning can cause corruption and hangs (OS X only).
69   virtual void SetSafeToForceGpuSwitch();
70 
71   // Indicate that the real context switches should unbind the FBO first
72   // (For an Android work-around only).
73   virtual void SetUnbindFboOnMakeCurrent();
74 
75   // Returns whether the current context supports the named extension. The
76   // context must be current.
77   bool HasExtension(const char* name);
78 
79   GLShareGroup* share_group();
80 
81   // Create a GL context that is compatible with the given surface.
82   // |share_group|, if non-NULL, is a group of contexts which the
83   // internally created OpenGL context shares textures and other resources.
84   static scoped_refptr<GLContext> CreateGLContext(
85       GLShareGroup* share_group,
86       GLSurface* compatible_surface,
87       GpuPreference gpu_preference);
88 
89   static bool LosesAllContextsOnContextLost();
90 
91   // Returns the last GLContext made current, virtual or real.
92   static GLContext* GetCurrent();
93 
94   virtual bool WasAllocatedUsingRobustnessExtension();
95 
96   // Use this context for virtualization.
97   void SetupForVirtualization();
98 
99   // Make this context current when used for context virtualization.
100   bool MakeVirtuallyCurrent(GLContext* virtual_context, GLSurface* surface);
101 
102   // Notify this context that |virtual_context|, that was using us, is
103   // being released or destroyed.
104   void OnReleaseVirtuallyCurrent(GLContext* virtual_context);
105 
106  protected:
107   virtual ~GLContext();
108 
109   // Sets the GL api to the real hardware API (vs the VirtualAPI)
110   static void SetRealGLApi();
111   virtual void SetCurrent(GLSurface* surface);
112 
113   // Initialize function pointers to extension functions in the GL
114   // implementation. Should be called immediately after this context is made
115   // current.
116   bool InitializeExtensionBindings();
117 
118   // Returns the last real (non-virtual) GLContext made current.
119   static GLContext* GetRealCurrent();
120 
121  private:
122   friend class base::RefCounted<GLContext>;
123 
124   // For GetRealCurrent.
125   friend class VirtualGLApi;
126 
127   scoped_refptr<GLShareGroup> share_group_;
128   scoped_ptr<VirtualGLApi> virtual_gl_api_;
129   scoped_ptr<GLStateRestorer> state_restorer_;
130 
131   DISALLOW_COPY_AND_ASSIGN(GLContext);
132 };
133 
134 class GL_EXPORT GLContextReal : public GLContext {
135  public:
136   explicit GLContextReal(GLShareGroup* share_group);
137 
138  protected:
139   virtual ~GLContextReal();
140 
141   virtual void SetCurrent(GLSurface* surface) OVERRIDE;
142 
143  private:
144   DISALLOW_COPY_AND_ASSIGN(GLContextReal);
145 };
146 
147 }  // namespace gfx
148 
149 #endif  // UI_GL_GL_CONTEXT_H_
150