Optimize to copy from rotated video to canvas.

media/filters/skcanvas_video_renderer.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 "media/filters/skcanvas_video_renderer.h"
 
 #include "base/logging.h"
 #include "media/base/video_frame.h"
 #include "media/base/yuv_convert.h"
 #include "third_party/libyuv/include/libyuv.h"
@@ skipping 310 matching lines @@
   // Check if we should convert and update |last_frame_|.
   if (last_frame_.isNull() ||
       video_frame->timestamp() != last_frame_timestamp_) {
     generator_ = new VideoImageGenerator(video_frame);
 
     // Note: This takes ownership of |generator_|.
     if (!SkInstallDiscardablePixelRef(generator_, &last_frame_)) {
       NOTREACHED();
     }
 
-    // TODO(rileya): Perform this rotation on the canvas, rather than allocating
-    // a new bitmap and copying.
-    switch (video_rotation) {
-      case VIDEO_ROTATION_0:
-        break;
-      case VIDEO_ROTATION_90:
-        last_frame_ = SkBitmapOperations::Rotate(
-            last_frame_, SkBitmapOperations::ROTATION_90_CW);
-        break;
-      case VIDEO_ROTATION_180:
-        last_frame_ = SkBitmapOperations::Rotate(
-            last_frame_, SkBitmapOperations::ROTATION_180_CW);
-        break;
-      case VIDEO_ROTATION_270:
-        last_frame_ = SkBitmapOperations::Rotate(
-            last_frame_, SkBitmapOperations::ROTATION_270_CW);
-        break;
-    }
-
-    // We copied the frame into a new bitmap and threw out the old one, so we
-    // no longer have a |generator_| around. This should be removed when the
-    // above TODO is addressed.
-    if (video_rotation != VIDEO_ROTATION_0)
-      generator_ = NULL;
-
     last_frame_timestamp_ = video_frame->timestamp();
   } else if (generator_) {
     generator_->set_frame(video_frame);
   }
 
   paint.setXfermodeMode(mode);
+  paint.setFilterLevel(SkPaint::kLow_FilterLevel);
 
-  // Paint using |last_frame_|.
-  paint.setFilterLevel(SkPaint::kLow_FilterLevel);
-  canvas->drawBitmapRect(last_frame_, NULL, dest, &paint);
+  SkScalar angle = SkFloatToScalar(0.0f);
+  switch (video_rotation) {
+    case VIDEO_ROTATION_0:
+      break;
+    case VIDEO_ROTATION_90:
+      angle = SkFloatToScalar(90.0f);
+      break;
+    case VIDEO_ROTATION_180:
+      angle = SkFloatToScalar(180.0f);
+      break;
+    case VIDEO_ROTATION_270:
+      angle = SkFloatToScalar(270.0f);
+      break;
+  }
+  if (video_rotation != VIDEO_ROTATION_0) {
+    canvas->save();
+    canvas->translate(SkFloatToScalar(dest_rect.width() * 0.5f),
+                     SkFloatToScalar(dest_rect.height() * 0.5f));
+    canvas->rotate(angle);
+    canvas->translate(-SkFloatToScalar(dest_rect.width() * 0.5f),
+                     -SkFloatToScalar(dest_rect.height() * 0.5f));
+  }
+  canvas->drawBitmap(last_frame_, 0, 0, &paint);
+  if (video_rotation != VIDEO_ROTATION_0)
+    canvas->restore();

[dshwang, 2014/10/02 19:17:30]

This code is almost copy&paste from
https://code.google.com/p/chromium/codesearch#chromium/src/ui/gfx/skbitmap_op...

   canvas->flush();
 }
 
 void SkCanvasVideoRenderer::Copy(const scoped_refptr<VideoFrame>& video_frame,
                                  SkCanvas* canvas) {
   Paint(video_frame,
         canvas,
         video_frame->visible_rect(),
         0xff,
         SkXfermode::kSrc_Mode,
         media::VIDEO_ROTATION_0);
 }
 
 }  // namespace media