WebRtc Win Desktop capture: ignore Win8+ Modern Apps' windows.

webrtc/modules/desktop_capture/window_capturer_win.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.
  */
 
 #include "webrtc/modules/desktop_capture/window_capturer.h"
 
 #include <assert.h>
 
 #include "webrtc/base/scoped_ptr.h"
+#include "webrtc/base/checks.h"
 #include "webrtc/base/win32.h"
 #include "webrtc/modules/desktop_capture/desktop_frame_win.h"
 #include "webrtc/modules/desktop_capture/win/window_capture_utils.h"
 #include "webrtc/system_wrappers/interface/logging.h"
 
 namespace webrtc {
 
 namespace {
 
+const int kMaxNameLength = 1024;
+
 BOOL CALLBACK WindowsEnumerationHandler(HWND hwnd, LPARAM param) {
   WindowCapturer::WindowList* list =
       reinterpret_cast<WindowCapturer::WindowList*>(param);
 
   // Skip windows that are invisible, minimized, have no title, or are owned,
   // unless they have the app window style set.
   int len = GetWindowTextLength(hwnd);
   HWND owner = GetWindow(hwnd, GW_OWNER);
   LONG exstyle = GetWindowLong(hwnd, GWL_EXSTYLE);
   if (len == 0 || IsIconic(hwnd) || !IsWindowVisible(hwnd) ||
@@ skipping 17 matching lines @@
   const size_t kTitleLength = 500;
   WCHAR window_title[kTitleLength];
   // Truncate the title if it's longer than kTitleLength.
   GetWindowText(hwnd, window_title, kTitleLength);
   window.title = rtc::ToUtf8(window_title);
 
   // Skip windows when we failed to convert the title or it is empty.
   if (window.title.empty())
     return TRUE;
 
+  // Filter out windows modern apps' windows that cannot be captured.
+  // Issue 526883
+  // Microsoft introduced modern app which can be used cross the Microsoft's
+  // platforms (Desktop, mobile phone and etc.) from Win8.
+  // Microsoft confirmed that those windows cannot be captured.
+  // Modern app's window class name will be ApplicationFrameWindow
+  // and/or windows.UI.Core.coreWindow.

[mcasas, 2015/10/01 21:59:17]

Suggestion of rephrase:
  // Windows 8 introduced a "Modern App" identified by their class name being
  // either ApplicationFrameWindow or windows.UI.Core.coreWindow. The associated
  // windows cannot be captured, so we skip them, http://crbug.com/526883.

[gyzhou, 2015/10/02 18:30:34]

Done.

+  if (rtc::IsWindows8OrLater()) {
+    char class_name[kMaxNameLength];

[mcasas, 2015/10/01 21:59:17]

Why not reuse |kClassLength|? (l.43)

[gyzhou, 2015/10/02 18:30:34]

Done.

Since GetClassName() called in lin45. It makes sensor to move this part of code
up to remove some redundancy.

+    int class_name_length = GetClassNameA(hwnd, class_name, kMaxNameLength);

[mcasas, 2015/10/01 21:59:17]

const

[mcasas, 2015/10/01 21:59:17]

|class_name_length| or |classNameLength| ?

[gyzhou, 2015/10/02 18:30:35]

Done.

[gyzhou, 2015/10/02 18:30:35]

Done.

[gyzhou, 2015/10/02 18:30:35]

class_name_length is consistent with other part of the code.

+    RTC_DCHECK(class_name_length) <<
+        "Error retrieving the application's class name";
+    if (strcmp(class_name, "ApplicationFrameWindow") == 0 ||
+        strcmp(class_name, "Windows.UI.Core.CoreWindow") == 0)
+      return TRUE;
+  }
+
   list->push_back(window);
 
   return TRUE;
 }
 
 class WindowCapturerWin : public WindowCapturer {
  public:
   WindowCapturerWin();
   virtual ~WindowCapturerWin();
 
@@ skipping 162 matching lines @@
 }
 
 }  // namespace
 
 // static
 WindowCapturer* WindowCapturer::Create(const DesktopCaptureOptions& options) {
   return new WindowCapturerWin();
 }
 
 }  // namespace webrtc