content/public/browser/android/synchronous_compositor.h

// Copyright 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 CONTENT_PUBLIC_BROWSER_ANDROID_SYNCHRONOUS_COMPOSITOR_H_
#define CONTENT_PUBLIC_BROWSER_ANDROID_SYNCHRONOUS_COMPOSITOR_H_

#include "base/memory/ref_counted.h"
#include "content/common/content_export.h"
#include "gpu/command_buffer/service/in_process_command_buffer.h"
#include "ui/gfx/rect.h"
#include "ui/gfx/size.h"

class SkCanvas;

namespace gfx {
class GLSurface;
class Transform;
};

namespace content {

class WebContents;

class SynchronousCompositorClient;

struct CONTENT_EXPORT SynchronousCompositorMemoryPolicy {
  // Memory limit for rendering and pre-rendering.
  size_t bytes_limit;

  // Limit of number of GL resources used for rendering and pre-rendering.
  size_t num_resources_limit;

  SynchronousCompositorMemoryPolicy();

  bool operator==(const SynchronousCompositorMemoryPolicy& other) const;
  bool operator!=(const SynchronousCompositorMemoryPolicy& other) const;
};

// Interface for embedders that wish to direct compositing operations
// synchronously under their own control. Only meaningful when the
// kEnableSyncrhonousRendererCompositor flag is specified.
class CONTENT_EXPORT SynchronousCompositor {
 public:
  // Must be called once per WebContents instance. Will create the compositor
  // instance as needed, but only if |client| is non-NULL.
  static void SetClientForWebContents(WebContents* contents,
                                      SynchronousCompositorClient* client);

  // Allows changing or resetting the client to NULL (this must be used if
  // the client is being deleted prior to the DidDestroyCompositor() call
  // being received by the client). Ownership of |client| remains with
  // the caller.
  virtual void SetClient(SynchronousCompositorClient* client) = 0;

  static void SetGpuService(
      scoped_refptr<gpu::InProcessCommandBuffer::Service> service);

  // Synchronously initialize compositor for hardware draw. Can only be called
  // while compositor is in software only mode, either after compositor is
  // first created or after ReleaseHwDraw is called. It is invalid to
  // DemandDrawHw before this returns true. |surface| is the GLSurface that
  // should be used to create the underlying hardware context.
  virtual bool InitializeHwDraw(scoped_refptr<gfx::GLSurface> surface) = 0;

  // Reverse of InitializeHwDraw above. Can only be called while hardware draw
  // is already initialized. Brings compositor back to software only mode and
  // releases all hardware resources.
  virtual void ReleaseHwDraw() = 0;

  // "On demand" hardware draw. The content is first clipped to |damage_area|,
  // then transformed through |transform|, and finally clipped to |view_size|
  // and by the existing stencil buffer if any.
  virtual bool DemandDrawHw(
      gfx::Size surface_size,
      const gfx::Transform& transform,
      gfx::Rect viewport,
      gfx::Rect clip,
      bool stencil_enabled) = 0;

  // "On demand" SW draw, into the supplied canvas (observing the transform
  // and clip set there-in).
  virtual bool DemandDrawSw(SkCanvas* canvas) = 0;

  // Set the memory limit policy of this compositor.
  virtual void SetMemoryPolicy(
      const SynchronousCompositorMemoryPolicy& policy) = 0;

  // Should be called by the embedder after the embedder had modified the
  // scroll offset of the root layer (as returned by
  // SynchronousCompositorClient::GetTotalRootLayerScrollOffset).
  virtual void DidChangeRootLayerScrollOffset() = 0;

 protected:
  virtual ~SynchronousCompositor() {}
};

}  // namespace content

#endif  // CONTENT_PUBLIC_BROWSER_ANDROID_SYNCHRONOUS_COMPOSITOR_H_