Update I420Buffer to new VideoFrameBuffer interface

webrtc/api/video/video_frame_buffer.cc

 /*
  *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/api/video/video_frame_buffer.h"
 
 #include "libyuv/convert.h"
 #include "webrtc/api/video/i420_buffer.h"
 #include "webrtc/base/checks.h"
 
 namespace webrtc {
 
 namespace {
 
 // TODO(magjed): Remove this class. It is only used for providing a default
 // implementation of ToI420() until external clients are updated. ToI420() will
 // then be made pure virtual. This adapter adapts a VideoFrameBuffer (which is
 // expected to be in I420 format) to I420BufferInterface. The reason this is
 // needed is because of the return type mismatch in NativeToI420Buffer (returns
 // VideoFrameBuffer) vs ToI420 (returns I420BufferInterface).
 class I420InterfaceAdapter : public I420BufferInterface {
  public:
-  explicit I420InterfaceAdapter(rtc::scoped_refptr<VideoFrameBuffer> buffer)
+  explicit I420InterfaceAdapter(const VideoFrameBuffer* buffer)
       : buffer_(buffer) {}
 
   int width() const override { return buffer_->width(); }
   int height() const override { return buffer_->height(); }
 
   const uint8_t* DataY() const override { return buffer_->DataY(); }
   const uint8_t* DataU() const override { return buffer_->DataU(); }
   const uint8_t* DataV() const override { return buffer_->DataV(); }
 
   int StrideY() const override { return buffer_->StrideY(); }
   int StrideU() const override { return buffer_->StrideU(); }
   int StrideV() const override { return buffer_->StrideV(); }
 
  private:
-  rtc::scoped_refptr<VideoFrameBuffer> buffer_;
+  rtc::scoped_refptr<const VideoFrameBuffer> buffer_;
 };
 
 }  // namespace
 
 // TODO(magjed): The default implementations in VideoFrameBuffer are provided in
 // order to support the deprecated interface until external clients are updated.
 // Remove once done.
 VideoFrameBuffer::Type VideoFrameBuffer::type() const {
   return native_handle() ? Type::kNative : Type::kI420;
 }
 
 const uint8_t* VideoFrameBuffer::DataY() const {
-  return const_cast<VideoFrameBuffer*>(this)->GetI420()->DataY();
+  return GetI420()->DataY();
 }
 
 const uint8_t* VideoFrameBuffer::DataU() const {
-  return const_cast<VideoFrameBuffer*>(this)->GetI420()->DataU();
+  return GetI420()->DataU();
 }
 
 const uint8_t* VideoFrameBuffer::DataV() const {
-  return const_cast<VideoFrameBuffer*>(this)->GetI420()->DataV();
+  return GetI420()->DataV();
 }
 
 // Returns the number of bytes between successive rows for a given plane.
 int VideoFrameBuffer::StrideY() const {
-  return const_cast<VideoFrameBuffer*>(this)->GetI420()->StrideY();
+  return GetI420()->StrideY();
 }
 
 int VideoFrameBuffer::StrideU() const {
-  return const_cast<VideoFrameBuffer*>(this)->GetI420()->StrideU();
+  return GetI420()->StrideU();
 }
 
 int VideoFrameBuffer::StrideV() const {
-  return const_cast<VideoFrameBuffer*>(this)->GetI420()->StrideV();
+  return GetI420()->StrideV();
 }
 
 void* VideoFrameBuffer::native_handle() const {
   RTC_DCHECK(type() != Type::kNative);
   return nullptr;
 }
 
 rtc::scoped_refptr<VideoFrameBuffer> VideoFrameBuffer::NativeToI420Buffer() {
   return ToI420();
 }
 
 rtc::scoped_refptr<I420BufferInterface> VideoFrameBuffer::ToI420() {
   return new rtc::RefCountedObject<I420InterfaceAdapter>(NativeToI420Buffer());
 }
 
 rtc::scoped_refptr<I420BufferInterface> VideoFrameBuffer::GetI420() {
   RTC_CHECK(type() == Type::kI420);
   // TODO(magjed): static_cast to I420BufferInterface instead once external
   // clients are updated.
   return new rtc::RefCountedObject<I420InterfaceAdapter>(this);
 }
 
-rtc::scoped_refptr<I444BufferInterface> VideoFrameBuffer::GetI444() {
+rtc::scoped_refptr<const I420BufferInterface> VideoFrameBuffer::GetI420()
+    const {
+  RTC_CHECK(type() == Type::kI420);
+  // TODO(magjed): static_cast to I420BufferInterface instead once external
+  // clients are updated.
+  return new rtc::RefCountedObject<I420InterfaceAdapter>(this);
+}
+
+I444BufferInterface* VideoFrameBuffer::GetI444() {
   RTC_CHECK(type() == Type::kI444);
   return static_cast<I444BufferInterface*>(this);
 }
 
+const I444BufferInterface* VideoFrameBuffer::GetI444() const {
+  RTC_CHECK(type() == Type::kI444);
+  return static_cast<const I444BufferInterface*>(this);
+}
+
 VideoFrameBuffer::Type I420BufferInterface::type() const {
   return Type::kI420;
 }
 
 int I420BufferInterface::ChromaWidth() const {
   return (width() + 1) / 2;
 }
 
 int I420BufferInterface::ChromaHeight() const {
   return (height() + 1) / 2;
@@ skipping 20 matching lines @@
       I420Buffer::Create(width(), height());
   libyuv::I444ToI420(DataY(), StrideY(), DataU(), StrideU(), DataV(), StrideV(),
                      i420_buffer->MutableDataY(), i420_buffer->StrideY(),
                      i420_buffer->MutableDataU(), i420_buffer->StrideU(),
                      i420_buffer->MutableDataV(), i420_buffer->StrideV(),
                      width(), height());
   return i420_buffer;
 }
 
 }  // namespace webrtc