Improving the decoder pipeline.

remoting/base/util.cc

 // Copyright (c) 2012 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/base/util.h"
 
 #include <math.h>
 
 #include "base/logging.h"
 #include "base/stringprintf.h"
@@ skipping 201 matching lines @@
   int x = RoundToTwosMultiple(rect.left());
   int y = RoundToTwosMultiple(rect.top());
   int right = RoundToTwosMultiple(rect.right() + 1);
   int bottom = RoundToTwosMultiple(rect.bottom() + 1);
   return SkIRect::MakeLTRB(x, y, right, bottom);
 }
 
 SkIRect ScaleRect(const SkIRect& rect,
                   const SkISize& in_size,
                   const SkISize& out_size) {
-  int left = (rect.left() * out_size.width()) / in_size.width();
-  int top = (rect.top() * out_size.height()) / in_size.height();
-  int right = (rect.right() * out_size.width() + out_size.width() - 1) /
-      in_size.width();
-  int bottom = (rect.bottom() * out_size.height() + out_size.height() - 1) /
-      in_size.height();
+  // Use floating point to up/down scale more accurately.
+  float scale_x = static_cast<float>(out_size.width()) / in_size.width();
+  float scale_y = static_cast<float>(out_size.height()) / in_size.height();
+
+  int left = static_cast<int>(floor(scale_x * rect.left()));
+  int top = static_cast<int>(floor(scale_y * rect.top()));
+  int right = static_cast<int>(ceil(scale_x * rect.right()));
+  int bottom = static_cast<int>(ceil(scale_y * rect.bottom()));
   return SkIRect::MakeLTRB(left, top, right, bottom);
 }
 
 void CopyRect(const uint8* src_plane,
               int src_plane_stride,
               uint8* dest_plane,
               int dest_plane_stride,
               int bytes_per_pixel,
               const SkIRect& rect) {
   // Get the address of the starting point.
@@ skipping 34 matching lines @@
   // Copy bits.
   CopyRect(source_buffer + source_offset,
            source_stride,
            dest_buffer + dest_offset,
            dest_stride,
            GetBytesPerPixel(media::VideoFrame::RGB32),
            SkIRect::MakeWH(dest_rect.width(), dest_rect.height()));
 }
 
 }  // namespace remoting