Fixed partially out of screen window capture in unix

webrtc/modules/desktop_capture/x11/x_server_pixel_buffer.cc

 /*
  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 42 matching lines @@
       image->red_mask == 0xff0000 &&
       image->green_mask == 0xff00 &&
       image->blue_mask == 0xff;
 }
 
 }  // namespace
 
 namespace webrtc {
 
 XServerPixelBuffer::XServerPixelBuffer()
-    : display_(NULL), window_(0),
+    : display_(NULL),
+      window_(0),
       x_image_(NULL),
-      shm_segment_info_(NULL), shm_pixmap_(0), shm_gc_(NULL) {
-}
+      shm_segment_info_(NULL),
+      shm_pixmap_(0),
+      shm_gc_(NULL),
+      is_xshmgetimage_success_(false) {}

[Sergey Ulanov, 2016/06/09 22:04:21]

Move all initializers to the class definition in the .h please.

[GeorgeZ, 2016/06/10 20:10:37]

Done.

 
 XServerPixelBuffer::~XServerPixelBuffer() {
   Release();
 }
 
 void XServerPixelBuffer::Release() {
   if (x_image_) {
     XDestroyImage(x_image_);
     x_image_ = NULL;
   }
@@ skipping 145 matching lines @@
       return false;
     }
   }
   return true;
 }
 
 void XServerPixelBuffer::Synchronize() {
   if (shm_segment_info_ && !shm_pixmap_) {
     // XShmGetImage can fail if the display is being reconfigured.
     XErrorTrap error_trap(display_);
-    XShmGetImage(display_, window_, x_image_, 0, 0, AllPlanes);
+    if (XShmGetImage(display_, window_, x_image_, 0, 0, AllPlanes))

[Sergey Ulanov, 2016/06/09 22:04:21]

 is_xshmgetimage_success_  = XShmGetImage(...);

[Sergey Ulanov, 2016/06/09 22:04:21]

Add a comment that the call may also fail if the window is partially visible.

[GeorgeZ, 2016/06/10 20:10:37]

Done.

[GeorgeZ, 2016/06/10 20:10:37]

Done.

+      is_xshmgetimage_success_ = true;
+    else
+      is_xshmgetimage_success_ = false;
   }
 }
 
 void XServerPixelBuffer::CaptureRect(const DesktopRect& rect,
                                      DesktopFrame* frame) {
   assert(rect.right() <= window_size_.width());
   assert(rect.bottom() <= window_size_.height());
 
   uint8_t* data;
 
-  if (shm_segment_info_) {
+  if (shm_segment_info_ && is_xshmgetimage_success_) {

[Sergey Ulanov, 2016/06/09 22:04:21]

This code won't work correctly when using shm_pixmap_ because when shm_pixmap_
is set then Synchronize won't set is_xshmgetimage_success_.
So I think you want to change this to 
 (shm_segment_info_ && (shm_pixmal || is_xshmgetimage_success_))

[GeorgeZ, 2016/06/10 20:10:37]

Done. Good to know.

     if (shm_pixmap_) {
       XCopyArea(display_, window_, shm_pixmap_, shm_gc_,
                 rect.left(), rect.top(), rect.width(), rect.height(),
                 rect.left(), rect.top());
       XSync(display_, False);
     }
     data = reinterpret_cast<uint8_t*>(x_image_->data) +
         rect.top() * x_image_->bytes_per_line +
         rect.left() * x_image_->bits_per_pixel / 8;
   } else {
@@ skipping 74 matching lines @@
       // Write as 32-bit RGB.
       dst_pos_32[x] = ((r >> 8) & 0xff0000) | ((g >> 16) & 0xff00) |
           ((b >> 24) & 0xff);
     }
     dst_pos += frame->stride();
     src_pos += src_stride;
   }
 }
 
 }  // namespace webrtc