Merge ScreenCapturerWinDirectx::frames_ and contexts_

webrtc/modules/desktop_capture/win/dxgi_frame.h

+/*
+ *  Copyright (c) 2017 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_FRAME_H_
+#define WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_DXGI_FRAME_H_
+
+#include <memory>
+#include <vector>
+
+#include "webrtc/modules/desktop_capture/desktop_capturer.h"
+#include "webrtc/modules/desktop_capture/desktop_capture_types.h"
+#include "webrtc/modules/desktop_capture/desktop_geometry.h"
+#include "webrtc/modules/desktop_capture/resolution_change_detector.h"
+#include "webrtc/modules/desktop_capture/shared_desktop_frame.h"
+#include "webrtc/modules/desktop_capture/shared_memory.h"
+#include "webrtc/modules/desktop_capture/win/dxgi_adapter_duplicator.h"
+
+namespace webrtc {
+
+class DxgiDuplicatorController;
+
+// A pair of a SharedDesktopFrame and a DxgiDuplicatorController::Context for
+// the client of DxgiDuplicatorController.
+class DxgiFrame final {
+ public:
+  // DxgiFrame does not take ownership of |factory|, consumers should ensure it
+  // outlives this instance. nullptr is acceptable.
+  explicit DxgiFrame(SharedMemoryFactory* factory);
+  ~DxgiFrame();
+
+  // Should not be called if Prepare() is not executed or returns false.
+  SharedDesktopFrame* frame() const;
+
+ private:
+  // A Context to store the status of a single DxgiFrame of
+  // DxgiDuplicatorController.
+  struct Context final {

[Sergey Ulanov, 2017/04/18 23:39:09]

Looking at the there Context classes we have I think the logic can be simplified
here. This class stores vector of vectors of DesktopRegion objects. This vector
can be replaced with a single DesktopRegion that accumulates changes for all
displays. Then each output capture would split the parts that it cares about
when capturing. The Setup() and Unregister() calls would get DxgiFrame pointer
instead of a context. Or alternatively this class could store a set (in
std::vector) of DesktopRegion objects for each output. 
WDYT?

In either I think moving all Context structs to this file would make it clearer
how it's used.

[Hzj_jie, 2017/04/19 04:35:54]

Merging the DesktopRegion into one will cause the DxigOutputDuplicator to do the
translation back and forth, as what we have before: IDXGIOutputDuplicator always
returns untranslated updated region.
But storing a vector of DesktopRegion object for each output breaks the
hierarchy of Duplicator objects, i.e. DxgiOutputDuplicator needs to know the its
exact position in all the outputs, which is unavailable now.
Both changes will impact the existing logic seriously, and enlarge this change.
I think I can move all contexts into a single file to help to make the hierarchy
clear. And we may consider other improvements in a different change.

+   public:
+    Context();
+    // Unregister this Context instance from DxgiDuplicatorController during
+    // destructing.
+    ~Context();
+
+    // Reset current Context, so it will be reinitialized next time.
+    void Reset();
+
+    // A Context will have an exactly same |identity_| as
+    // DxgiDuplicatorController, to ensure it has been correctly setted up after
+    // each DxgiDuplicatorController::Initialize().
+    int identity = 0;

[Sergey Ulanov, 2017/04/18 23:39:09]

maybe call it controller_id?

[Hzj_jie, 2017/04/19 04:35:54]

Done.

+
+    // Child DxgiAdapterDuplicator::Context belongs to this Context.
+    std::vector<DxgiAdapterDuplicator::Context> contexts;
+  };
+
+  // Allows DxgiDuplicatorController to access Prepare() and context() function
+  // as well as Context class.
+  friend class DxgiDuplicatorController;
+
+  // Prepares current instance with desktop size and source id.
+  bool Prepare(DesktopSize size, DesktopCapturer::SourceId source_id);
+
+  // Should not be called if Prepare() is not executed or returns false.
+  Context* context();
+
+  SharedMemoryFactory* const factory_;
+  ResolutionChangeDetector resolution_change_detector_;
+  DesktopCapturer::SourceId source_id_ = kFullDesktopScreenId;
+  std::unique_ptr<SharedDesktopFrame> frame_;
+  Context context_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_WIN_DXGI_FRAME_H_