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// Copyright (c) 2012 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 MEDIA_VIDEO_CAPTURE_SCREEN_SCREEN_CAPTURER_H_
#define MEDIA_VIDEO_CAPTURE_SCREEN_SCREEN_CAPTURER_H_
#include "base/basictypes.h"
#include "base/callback.h"
#include "base/memory/ref_counted.h"
#include "base/shared_memory.h"
#include "media/base/media_export.h"
#include "media/video/capture/screen/shared_buffer.h"
#include "third_party/skia/include/core/SkRegion.h"
namespace media {
class ScreenCaptureData;
struct MouseCursorShape;
class SharedBuffer;
// Class used to capture video frames asynchronously.
//
// The full capture sequence is as follows:
//
// (1) Start
// This is when pre-capture steps are executed, such as flagging the
// display to prevent it from sleeping during a session.
//
// (2) InvalidateRegion
// This is an optional step where regions of the screen are marked as
// invalid. Some platforms (Windows, for now) won't use this and will
// instead calculate the diff-regions later (in step (2). Other
// platforms (Mac) will use this to mark all the changed regions of the
// screen. Some limited rect-merging (e.g., to eliminate exact
// duplicates) may be done here.
//
// (3) CaptureFrame
// This is where the bits for the invalid rects are packaged up and sent
// to the encoder.
// A screen capture is performed if needed. For example, Windows requires
// a capture to calculate the diff from the previous screen, whereas the
// Mac version does not.
//
// (4) Stop
// This is when post-capture steps are executed, such as releasing the
// assertion that prevents the display from sleeping.
//
// Implementation has to ensure the following guarantees:
// 1. Double buffering
// Since data can be read while another capture action is happening.
class MEDIA_EXPORT ScreenCapturer {
public:
// Provides callbacks used by the capturer to pass captured video frames and
// mouse cursor shapes to the processing pipeline.
class MEDIA_EXPORT Delegate {
public:
// Creates a shared memory buffer of the given size. Returns NULL if shared
// buffers are not supported.
virtual scoped_refptr<SharedBuffer> CreateSharedBuffer(uint32 size);
// Notifies the delegate that the buffer is no longer used and can be
// released.
virtual void ReleaseSharedBuffer(scoped_refptr<SharedBuffer> buffer);
// Called when a video frame has been captured. |capture_data| describes
// a captured frame.
virtual void OnCaptureCompleted(
scoped_refptr<ScreenCaptureData> capture_data) = 0;
// Called when the cursor shape has changed.
// TODO(sergeyu): Move cursor shape capturing to a separate class.
virtual void OnCursorShapeChanged(
scoped_ptr<MouseCursorShape> cursor_shape) = 0;
protected:
virtual ~Delegate() {}
};
virtual ~ScreenCapturer() {}
// Creates platform-specific capturer.
static scoped_ptr<ScreenCapturer> Create();
#if defined(OS_LINUX)
// Creates platform-specific capturer and instructs it whether it should use
// X DAMAGE support.
static scoped_ptr<ScreenCapturer> CreateWithXDamage(bool use_x_damage);
#elif defined(OS_WIN)
// Creates Windows-specific capturer and instructs it whether or not to
// disable desktop compositing.
static scoped_ptr<ScreenCapturer> CreateWithDisableAero(bool disable_aero);
#endif
// Called at the beginning of a capturing session. |delegate| must remain
// valid until Stop() is called.
virtual void Start(Delegate* delegate) = 0;
// Called at the end of a capturing session.
virtual void Stop() = 0;
// Invalidates the specified region.
virtual void InvalidateRegion(const SkRegion& invalid_region) = 0;
// Captures the screen data associated with each of the accumulated
// dirty region. When the capture is complete, the delegate is notified even
// if the dirty region is empty.
//
// It is OK to call this method while another thread is reading
// data of the previous capture. There can be at most one concurrent read
// going on when this method is called.
virtual void CaptureFrame() = 0;
};
} // namespace media
#endif // MEDIA_VIDEO_CAPTURE_SCREEN_SCREEN_CAPTURER_H_
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