[DesktopCapture] Detect screen resolution changes in DirectX capturer

webrtc/modules/desktop_capture/win/dxgi_texture.h

 /*
  *  Copyright (c) 2016 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.
  */
 
 #ifndef WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_DXGI_TEXTURE_H_
 #define WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_DXGI_TEXTURE_H_
 
+#include <D3D11.h>
 #include <DXGI1_2.h>
 
 #include <memory>
 
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
 #include "webrtc/modules/desktop_capture/desktop_geometry.h"
+#include "webrtc/modules/desktop_capture/resolution_change_detector.h"
 
 namespace webrtc {
 
 class DesktopRegion;
 
 // A texture copied or mapped from a DXGI_OUTDUPL_FRAME_INFO and IDXGIResource.
 class DxgiTexture {
  public:
   // Creates a DxgiTexture instance, which represents the |desktop_size| area of
   // entire screen -- usually a monitor on the system.
-  explicit DxgiTexture(const DesktopSize& desktop_size);
+  DxgiTexture();
 
   virtual ~DxgiTexture();
 
   // Copies selected regions of a frame represented by frame_info and resource.
   // Returns false if anything wrong.
-  virtual bool CopyFrom(const DXGI_OUTDUPL_FRAME_INFO& frame_info,
-                        IDXGIResource* resource) = 0;
+  bool CopyFrom(const DXGI_OUTDUPL_FRAME_INFO& frame_info,
+                IDXGIResource* resource);
 
   const DesktopSize& desktop_size() const { return desktop_size_; }
 
   uint8_t* bits() const { return static_cast<uint8_t*>(rect_.pBits); }
 
   int pitch() const { return static_cast<int>(rect_.Pitch); }
 
   // Releases the resource currently holds by this instance. Returns false if
   // anything wrong, and this instance should be deprecated in this state. bits,
   // pitch and AsDesktopFrame are only valid after a success CopyFrom() call,
   // but before Release() call.
   bool Release();
 
   // Returns a DesktopFrame snapshot of a DxgiTexture instance. This
   // DesktopFrame is used to copy a DxgiTexture content to another DesktopFrame
   // only. And it should not outlive its DxgiTexture instance.
   const DesktopFrame& AsDesktopFrame();
 
  protected:
   DXGI_MAPPED_RECT rect_ = {0};

[Sergey Ulanov, 2017/02/15 01:38:52]

BTW, style guide doesn't allow protected data fields, only methods.

 
  private:
+  virtual bool CopyFromTexture(const DXGI_OUTDUPL_FRAME_INFO& frame_info,
+                               ID3D11Texture2D* texture) = 0;
+
   virtual bool DoRelease() = 0;

[Sergey Ulanov, 2017/02/10 19:58:25]

These two methods are intended to be overwritten by children. It's better to
make the protected to make this clear.

[Hzj_jie, 2017/02/11 01:51:22]

In C++, private functions are also overrideable, though not accessible. Do we
always prefer to use protected here? These two functions should not be called
directly by derived classes, though technically derived classes can still access
these functionalities.

[Sergey Ulanov, 2017/02/15 01:38:51]

Right, private methods can still be overridden, but putting them in the
protected makes it clear that child classes need to override these methods .
Children can still call these methods directly because they will override them,
so you don't gain anything by declaring them in the private section here.

[Hzj_jie, 2017/02/15 03:53:16]

I have no opinion on this. Indeed, some modern languages do no t support private
overridable functions, which resolves this issue permanently.
I have updated the code here.

 
-  const DesktopSize desktop_size_;
+  DesktopSize desktop_size_;
   std::unique_ptr<DesktopFrame> frame_;
+  ResolutionChangeDetector resolution_change_detector_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_DXGI_TEXTURE_H_