cc/output/context_provider.h

// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CC_OUTPUT_CONTEXT_PROVIDER_H_
#define CC_OUTPUT_CONTEXT_PROVIDER_H_

#include <stddef.h>
#include <stdint.h>

#include "base/callback.h"
#include "base/memory/ref_counted.h"
#include "base/synchronization/lock.h"
#include "cc/base/cc_export.h"
#include "gpu/command_buffer/common/capabilities.h"

class GrContext;

namespace base {
class Lock;
}

namespace gpu {
class ContextSupport;
namespace gles2 { class GLES2Interface; }
}

namespace cc {
struct ManagedMemoryPolicy;

class ContextProvider : public base::RefCountedThreadSafe<ContextProvider> {
 public:
  class ScopedContextLock {
   public:
    explicit ScopedContextLock(ContextProvider* context_provider)
        : context_provider_(context_provider),
          context_lock_(*context_provider_->GetLock()) {
      // Allow current thread to use |context_provider_|.
      context_provider_->DetachFromThread();
    }
    ~ScopedContextLock() {
      // Allow usage by thread for which |context_provider_| is bound to.
      context_provider_->DetachFromThread();
    }

    gpu::gles2::GLES2Interface* ContextGL() {
      return context_provider_->ContextGL();
    }

   private:
    ContextProvider* const context_provider_;
    base::AutoLock context_lock_;
  };
  // Bind the 3d context to the current thread. This should be called before
  // accessing the contexts. Calling it more than once should have no effect.
  // Once this function has been called, the class should only be accessed
  // from the same thread unless the function has some explicitly specified
  // rules for access on a different thread. See SetupLockOnMainThread(), which
  // can be used to provide access from multiple threads.
  virtual bool BindToCurrentThread() = 0;
  virtual void DetachFromThread() {}

  virtual gpu::gles2::GLES2Interface* ContextGL() = 0;
  virtual gpu::ContextSupport* ContextSupport() = 0;
  virtual class GrContext* GrContext() = 0;

  struct Capabilities {
    gpu::Capabilities gpu;
    size_t max_transfer_buffer_usage_bytes;

    CC_EXPORT Capabilities();
  };

  // Invalidates the cached OpenGL state in GrContext.
  // See skia GrContext::resetContext for details.
  virtual void InvalidateGrContext(uint32_t state) = 0;

  // Sets up a lock so this context can be used from multiple threads. After
  // calling this, all functions without explicit thread usage constraints can
  // be used on any thread while the lock returned by GetLock() is acquired.
  virtual void SetupLock() = 0;

  // Returns the lock that should be held if using this context from multiple
  // threads. This can be called on any thread.
  virtual base::Lock* GetLock() = 0;

  // Returns the capabilities of the currently bound 3d context.
  virtual Capabilities ContextCapabilities() = 0;

  // Delete all cached gpu resources.
  virtual void DeleteCachedResources() = 0;

  // Sets a callback to be called when the context is lost. This should be
  // called from the same thread that the context is bound to. To avoid races,
  // it should be called before BindToCurrentThread().
  typedef base::Closure LostContextCallback;
  virtual void SetLostContextCallback(
      const LostContextCallback& lost_context_callback) = 0;

 protected:
  friend class base::RefCountedThreadSafe<ContextProvider>;
  virtual ~ContextProvider() {}
};

}  // namespace cc

#endif  // CC_OUTPUT_CONTEXT_PROVIDER_H_