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// Copyright (c) 2010 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 "base/lock.h"
#include "base/task.h"
#include "remoting/base/capture_data.h"
#include "remoting/base/types.h"
class MessageLoop;
namespace remoting {
// 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) 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.
//
// (2) 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.
//
// 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 Callback1<scoped_refptr<CaptureData> >::Type CaptureCompletedCallback;
virtual ~Capturer();
// Create platform-specific cpaturer.
static Capturer* Create(MessageLoop* message_loop);
// Called when the screen configuration is changed.
virtual void ScreenConfigurationChanged() = 0;
// Return the width of the screen.
virtual int width() const;
// Return the height of the screen.
virtual int height() const;
// Return the pixel format of the screen.
virtual media::VideoFrame::Format pixel_format() const;
// Clear out the list of invalid rects.
void ClearInvalidRects();
// Invalidate the specified screen rects.
void InvalidateRects(const InvalidRects& inval_rects);
// Invalidate the entire screen.
virtual void InvalidateFullScreen();
// Capture the screen data associated with each of the accumulated
// rects in |inval_rects|.
// This routine will first call CalculateInvalidRects to update the
// list of |inval_rects|.
// When the capture is complete, |callback| is called.
//
// If |inval_rects_| is empty, then this does nothing except
// call the |callback| routine.
//
// It is OK to call this method while another thread is reading
// data of the last capture.
// There can be at most one concurrent read going on when this
// method is called.
virtual void CaptureInvalidRects(CaptureCompletedCallback* callback);
protected:
explicit Capturer(MessageLoop* message_loop);
// Update the list of |invalid_rects| to prepare for capturing the
// screen data.
// Depending on the platform implementation, this routine might:
// (a) Analyze screen and calculate the list of rects that have changed
// since the last capture.
// (b) Merge already-acculumated rects into a more optimal list (for
// example, by combining or removing rects).
virtual void CalculateInvalidRects() = 0;
// Capture the specified screen rects and call |callback| when complete.
// Dirty or invalid regions are ignored and only the given |rects| areas are
// captured.
// This routine is used internally by CaptureInvalidRects().
virtual void CaptureRects(const InvalidRects& rects,
CaptureCompletedCallback* callback) = 0;
// Finish/cleanup capture task.
// This should be called by CaptureRects() when it finishes.
// This routine should (at least):
// (1) Call the |callback| routine.
// (2) Select the next screen buffer.
// Note that capturers are required to be double-buffered so that we can
// read from one which capturing into another.
void FinishCapture(scoped_refptr<CaptureData> data,
CaptureCompletedCallback* callback);
// Number of screen buffers.
static const int kNumBuffers = 2;
// Capture screen dimensions.
int width_;
int height_;
// Format of pixels returned in buffer.
media::VideoFrame::Format pixel_format_;
int bytes_per_row_;
// The current buffer with valid data for reading.
int current_buffer_;
// Message loop that operations should run on.
MessageLoop* message_loop_;
private:
// Rects that have been manually invalidated (through InvalidateRect).
// These will be returned as dirty_rects in the capture data during the next
// capture.
InvalidRects inval_rects_;
// A lock protecting |inval_rects_| across threads.
Lock inval_rects_lock_;
};
} // namespace remoting
#endif // REMOTING_HOST_CAPTURER_H_
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