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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 REMOTING_HOST_CAPTURER_H_
#define REMOTING_HOST_CAPTURER_H_
#include "base/basictypes.h"
#include "base/callback.h"
#include "media/base/video_frame.h"
#include "third_party/skia/include/core/SkRegion.h"
namespace remoting {
namespace protocol {
class CursorShapeInfo;
}
class CaptureData;
// A class to perform the task of capturing the image of a window.
// The capture action is asynchronous to allow maximum throughput.
//
// The full capture process 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) InvalidateRects
// 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) CaptureInvalidRects
// 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 Capturer {
public:
// CaptureCompletedCallback is called when the capturer has completed.
typedef base::Callback<void(scoped_refptr<CaptureData>)>
CaptureCompletedCallback;
// CursorShapeChangedCallback is called when the cursor shape has changed.
typedef base::Callback<void(scoped_ptr<protocol::CursorShapeInfo>)>
CursorShapeChangedCallback;
virtual ~Capturer() {}
// Create platform-specific capturer.
static Capturer* Create();
#if defined(OS_LINUX)
// Set whether the Capturer should try to use X DAMAGE support if it is
// available. This needs to be called before the Capturer is created.
// This is used by the Virtual Me2Me host, since the XDamage extension is
// known to work reliably in this case.
// TODO(lambroslambrou): This currently sets a global flag, referenced during
// Capturer::Create(). This is a temporary solution, until the
// DesktopEnvironment class is refactored to allow applications to control
// the creation of various stubs (including the Capturer) - see
// http://crbug.com/104544
static void EnableXDamage(bool enable);
#endif // defined(OS_LINUX)
// Called at the beginning of a capturing session.
virtual void Start(
const CursorShapeChangedCallback& callback) = 0;
// Called at the end of a capturing session.
virtual void Stop() = 0;
// Called when the screen configuration is changed.
virtual void ScreenConfigurationChanged() = 0;
// Return the pixel format of the screen.
virtual media::VideoFrame::Format pixel_format() const = 0;
// Clear out the invalid region.
virtual void ClearInvalidRegion() = 0;
// Invalidate the specified region.
virtual void InvalidateRegion(const SkRegion& invalid_region) = 0;
// Invalidate the entire screen, of a given size.
virtual void InvalidateScreen(const SkISize& size) = 0;
// Invalidate the entire screen, using the size of the most recently
// captured screen.
virtual void InvalidateFullScreen() = 0;
// Capture the screen data associated with each of the accumulated
// dirty region.
// When the capture is complete, |callback| is called 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 CaptureInvalidRegion(
const CaptureCompletedCallback& callback) = 0;
// Get the size of the most recently captured screen.
virtual const SkISize& size_most_recent() const = 0;
};
} // namespace remoting
#endif // REMOTING_HOST_CAPTURER_H_
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