[Chromoting] Implement DualBufferFrameConsumer

remoting/client/gl_desktop.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "remoting/client/gl_desktop.h"
 
 #include "base/logging.h"
 #include "remoting/client/gl_canvas.h"
 #include "remoting/client/gl_render_layer.h"
 #include "third_party/webrtc/modules/desktop_capture/desktop_frame.h"
 
 namespace {
 
 const int kTextureId = 0;
 
 }  // namespace
 
 namespace remoting {
 
 GlDesktop::GlDesktop() {}
 
 GlDesktop::~GlDesktop() {}
 
 void GlDesktop::SetCanvas(GlCanvas* canvas) {
   if (!canvas) {
     layer_.reset();
     return;
   }
   layer_.reset(new GlRenderLayer(kTextureId, canvas));
-  if (last_frame_) {
-    layer_->SetTexture(last_frame_->data(), last_frame_->size().width(),
-                       last_frame_->size().height());
+  last_desktop_size_.set(0, 0);
+}
+
+void GlDesktop::SetVideoFrame(std::unique_ptr<webrtc::DesktopFrame> frame) {
+  if (!layer_) {
+    return;
+  }
+  if (!frame->size().equals(last_desktop_size_)) {
+    layer_->SetTexture(frame->data(), frame->size().width(),
+                       frame->size().height());
+    last_desktop_size_.set(frame->size().width(), frame->size().height());
+  } else {
+    for (webrtc::DesktopRegion::Iterator i(frame->updated_region());
+        !i.IsAtEnd(); i.Advance()) {
+      const uint8_t* rect_start =
+          frame->GetFrameDataAtPos(i.rect().top_left());
+      layer_->UpdateTexture(
+          rect_start, i.rect().left(), i.rect().top(), i.rect().width(),
+          i.rect().height(), frame->stride());
+    }
   }
 }
 
-void GlDesktop::SetVideoFrame(std::unique_ptr<webrtc::DesktopFrame> frame) {
-  if (layer_) {
-    if (!last_frame_ || !frame->size().equals(last_frame_->size())) {
-      layer_->SetTexture(frame->data(), frame->size().width(),
-                         frame->size().height());
-    } else {
-      for (webrtc::DesktopRegion::Iterator i(frame->updated_region());
-          !i.IsAtEnd(); i.Advance()) {
-        const uint8_t* rect_start =
-            frame->GetFrameDataAtPos(i.rect().top_left());
-        layer_->UpdateTexture(
-            rect_start, i.rect().left(), i.rect().top(), i.rect().width(),
-            i.rect().height(), frame->stride());
-      }
-    }
-  }
-  last_frame_ = std::move(frame);
-}
-
 void GlDesktop::Draw() {
-  if (layer_ && last_frame_) {
+  if (layer_ && !last_desktop_size_.is_empty()) {
     layer_->Draw(1.f);
   }
 }
 
 }  // namespace remoting