VideoLayerImpl: subtract 1 from visible size when calculating tex stretch.

cc/layers/video_layer_impl.cc

 // Copyright 2011 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 "cc/layers/video_layer_impl.h"
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 166 matching lines @@
 
   Occlusion occlusion_in_video_space =
       draw_properties()
           .occlusion_in_content_space.GetOcclusionWithGivenDrawTransform(
               transform);
   gfx::Rect visible_quad_rect =
       occlusion_in_video_space.GetUnoccludedContentRect(quad_rect);
   if (visible_quad_rect.IsEmpty())
     return;
 
-  // Pixels for macroblocked formats.
+  // Pixels for macroblocked formats. To prevent sampling outside the visible
+  // rect, stretch the video if needed.
+  if (visible_rect.width() < coded_size.width() && visible_rect.width() > 1)
+    visible_rect.set_width(visible_rect.width() - 1);
+  if (visible_rect.height() < coded_size.height() && visible_rect.height() > 1)
+    visible_rect.set_height(visible_rect.height() - 1);
   const float tex_width_scale =
       static_cast<float>(visible_rect.width()) / coded_size.width();
   const float tex_height_scale =
       static_cast<float>(visible_rect.height()) / coded_size.height();
 
   switch (frame_resource_type_) {
     // TODO(danakj): Remove this, hide it in the hardware path.
     case VideoFrameExternalResources::SOFTWARE_RESOURCE: {
       DCHECK_EQ(frame_resources_.size(), 0u);
       DCHECK_EQ(software_resources_.size(), 1u);
@@ skipping 117 matching lines @@
       ValidateQuadResources(stream_video_quad);
       break;
     }
     case VideoFrameExternalResources::IO_SURFACE: {
       DCHECK_EQ(frame_resources_.size(), 1u);
       if (frame_resources_.size() < 1u)
         break;
       IOSurfaceDrawQuad* io_surface_quad =
           render_pass->CreateAndAppendDrawQuad<IOSurfaceDrawQuad>();
       io_surface_quad->SetNew(shared_quad_state, quad_rect, opaque_rect,
                               visible_quad_rect, visible_rect.size(),

[wuchengli, 2016/02/02 08:54:50]

|visible_rect| is also used here. Is it correct?

                               frame_resources_[0].id,
                               IOSurfaceDrawQuad::UNFLIPPED);
       ValidateQuadResources(io_surface_quad);
       break;
     }
 #if defined(VIDEO_HOLE)
     // This block and other blocks wrapped around #if defined(VIDEO_HOLE) is not
     // maintained by the general compositor team. Please contact the following
     // people instead:
     //
@@ skipping 65 matching lines @@
 void VideoLayerImpl::SetNeedsRedraw() {
   SetUpdateRect(gfx::UnionRects(update_rect(), gfx::Rect(bounds())));
   layer_tree_impl()->SetNeedsRedraw();
 }
 
 const char* VideoLayerImpl::LayerTypeAsString() const {
   return "cc::VideoLayerImpl";
 }
 
 }  // namespace cc