Clamp YUV videos to their visible size in the shader

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 "base/bind.h"
 #include "base/logging.h"
 #include "cc/layers/video_frame_provider_client_impl.h"
 #include "cc/quads/io_surface_draw_quad.h"
@@ skipping 170 matching lines @@
   // Pixels for macroblocked formats.
   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();
   const float tex_x_offset =
       static_cast<float>(visible_rect.x()) / coded_size.width();
   const float tex_y_offset =
       static_cast<float>(visible_rect.y()) / coded_size.height();
 
+  // Vertex shader should clamp to the visible rect, and then minus
+  // half a pixel (of the coded size) to account for bilinear filtering.
+  // This prevents sampling outside of the visible rect.
+  gfx::SizeF half_pixel(0.5f / coded_size.width(), 0.5f / coded_size.height());
+  gfx::SizeF clamp_size(tex_width_scale + tex_x_offset - half_pixel.width(),
+                        tex_height_scale + tex_y_offset - half_pixel.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);
       if (software_resources_.size() < 1u)
         break;
       bool premultiplied_alpha = true;
       gfx::PointF uv_top_left(0.f, 0.f);
       gfx::PointF uv_bottom_right(tex_width_scale, tex_height_scale);
@@ skipping 22 matching lines @@
         break;
       YUVVideoDrawQuad::ColorSpace color_space =
           frame_->format() == media::VideoFrame::YV12J
               ? YUVVideoDrawQuad::REC_601_JPEG
               : YUVVideoDrawQuad::REC_601;
       gfx::RectF tex_coord_rect(
           tex_x_offset, tex_y_offset, tex_width_scale, tex_height_scale);
       YUVVideoDrawQuad* yuv_video_quad =
           render_pass->CreateAndAppendDrawQuad<YUVVideoDrawQuad>();
       yuv_video_quad->SetNew(
-          shared_quad_state,
-          quad_rect,
-          opaque_rect,
-          visible_quad_rect,
-          tex_coord_rect,
-          frame_resources_[0],
-          frame_resources_[1],
+          shared_quad_state, quad_rect, opaque_rect, visible_quad_rect,
+          tex_coord_rect, clamp_size, frame_resources_[0], frame_resources_[1],
           frame_resources_[2],
-          frame_resources_.size() > 3 ? frame_resources_[3] : 0,
-          color_space);
+          frame_resources_.size() > 3 ? frame_resources_[3] : 0, color_space);
       break;
     }
     case VideoFrameExternalResources::RGB_RESOURCE: {
       DCHECK_EQ(frame_resources_.size(), 1u);
       if (frame_resources_.size() < 1u)
         break;
       bool premultiplied_alpha = true;
       gfx::PointF uv_top_left(0.f, 0.f);
       gfx::PointF uv_bottom_right(tex_width_scale, tex_height_scale);
       float opacity[] = {1.0f, 1.0f, 1.0f, 1.0f};
@@ skipping 116 matching lines @@
 void VideoLayerImpl::SetProviderClientImpl(
     scoped_refptr<VideoFrameProviderClientImpl> provider_client_impl) {
   provider_client_impl_ = provider_client_impl;
 }
 
 const char* VideoLayerImpl::LayerTypeAsString() const {
   return "cc::VideoLayerImpl";
 }
 
 }  // namespace cc