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      1 /*
      2  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 // Don't include this file in any .h files because it pulls in some X headers.
     12 
     13 #ifndef WEBRTC_MODULES_DESKTOP_CAPTURE_X11_X_SERVER_PIXEL_BUFFER_H_
     14 #define WEBRTC_MODULES_DESKTOP_CAPTURE_X11_X_SERVER_PIXEL_BUFFER_H_
     15 
     16 #include "webrtc/modules/desktop_capture/desktop_geometry.h"
     17 
     18 #include <X11/Xutil.h>
     19 #include <X11/extensions/XShm.h>
     20 
     21 namespace webrtc {
     22 
     23 class DesktopFrame;
     24 
     25 // A class to allow the X server's pixel buffer to be accessed as efficiently
     26 // as possible.
     27 class XServerPixelBuffer {
     28  public:
     29   XServerPixelBuffer();
     30   ~XServerPixelBuffer();
     31 
     32   void Release();
     33 
     34   // Allocate (or reallocate) the pixel buffer for |window|. Returns false in
     35   // case of an error (e.g. window doesn't exist).
     36   bool Init(Display* display, Window window);
     37 
     38   bool is_initialized() { return window_ != 0; }
     39 
     40   // Returns the size of the window the buffer was initialized for.
     41   const DesktopSize& window_size() { return window_size_; }
     42 
     43   // Returns true if the window can be found.
     44   bool IsWindowValid() const;
     45 
     46   // If shared memory is being used without pixmaps, synchronize this pixel
     47   // buffer with the root window contents (otherwise, this is a no-op).
     48   // This is to avoid doing a full-screen capture for each individual
     49   // rectangle in the capture list, when it only needs to be done once at the
     50   // beginning.
     51   void Synchronize();
     52 
     53   // Capture the specified rectangle and stores it in the |frame|. In the case
     54   // where the full-screen data is captured by Synchronize(), this simply
     55   // returns the pointer without doing any more work. The caller must ensure
     56   // that |rect| is not larger than window_size().
     57   void CaptureRect(const DesktopRect& rect, DesktopFrame* frame);
     58 
     59  private:
     60   void InitShm(const XWindowAttributes& attributes);
     61   bool InitPixmaps(int depth);
     62 
     63   // We expose two forms of blitting to handle variations in the pixel format.
     64   // In FastBlit(), the operation is effectively a memcpy.
     65   void FastBlit(uint8_t* image,
     66                 const DesktopRect& rect,
     67                 DesktopFrame* frame);
     68   void SlowBlit(uint8_t* image,
     69                 const DesktopRect& rect,
     70                 DesktopFrame* frame);
     71 
     72   Display* display_;
     73   Window window_;
     74   DesktopSize window_size_;
     75   XImage* x_image_;
     76   XShmSegmentInfo* shm_segment_info_;
     77   Pixmap shm_pixmap_;
     78   GC shm_gc_;
     79 
     80   DISALLOW_COPY_AND_ASSIGN(XServerPixelBuffer);
     81 };
     82 
     83 }  // namespace webrtc
     84 
     85 #endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_X11_X_SERVER_PIXEL_BUFFER_H_
     86