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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef REMOTING_CODEC_VIDEO_DECODER_H_
      6 #define REMOTING_CODEC_VIDEO_DECODER_H_
      7 
      8 #include "base/basictypes.h"
      9 #include "remoting/proto/video.pb.h"
     10 #include "third_party/skia/include/core/SkRect.h"
     11 #include "third_party/skia/include/core/SkRegion.h"
     12 #include "third_party/skia/include/core/SkSize.h"
     13 
     14 namespace remoting {
     15 
     16 // Interface for a decoder that takes a stream of bytes from the network and
     17 // outputs frames of data.
     18 //
     19 // TODO(ajwong): Beef up this documentation once the API stablizes.
     20 class VideoDecoder {
     21  public:
     22   // DecodeResult is returned from DecodePacket() and indicates current state
     23   // of the decoder. DECODE_DONE means that last packet for the frame was
     24   // processed, and the frame can be displayed now. DECODE_IN_PROGRESS
     25   // indicates that the decoder must receive more data before the frame can be
     26   // displayed. DECODE_ERROR is returned if there was an error in the stream.
     27   enum DecodeResult {
     28     DECODE_ERROR = -1,
     29     DECODE_IN_PROGRESS,
     30     DECODE_DONE,
     31   };
     32 
     33   VideoDecoder() {}
     34   virtual ~VideoDecoder() {}
     35 
     36   // Initializes the decoder and sets the output dimensions.
     37   // |screen size| must not be empty.
     38   virtual void Initialize(const SkISize& screen_size) = 0;
     39 
     40   // Feeds more data into the decoder.
     41   virtual DecodeResult DecodePacket(const VideoPacket* packet) = 0;
     42 
     43   // Returns true if decoder is ready to accept data via DecodePacket.
     44   virtual bool IsReadyForData() = 0;
     45 
     46   virtual VideoPacketFormat::Encoding Encoding() = 0;
     47 
     48   // Marks the specified |region| of the view for update the next time
     49   // RenderFrame() is called.  |region| is expressed in |view_size| coordinates.
     50   // |view_size| must not be empty.
     51   virtual void Invalidate(const SkISize& view_size,
     52                           const SkRegion& region) = 0;
     53 
     54   // Copies invalidated pixels within |clip_area| to |image_buffer|. Pixels are
     55   // invalidated either by new data received in DecodePacket(), or by explicit
     56   // calls to Invalidate(). |clip_area| is specified in |view_size| coordinates.
     57   // If |view_size| differs from the source size then the copied pixels will be
     58   // scaled accordingly. |view_size| cannot be empty.
     59   //
     60   // |image_buffer|'s origin must correspond to the top-left of |clip_area|,
     61   // and the buffer must be large enough to hold |clip_area| RGBA32 pixels.
     62   // |image_stride| gives the output buffer's stride in pixels.
     63   //
     64   // On return, |output_region| contains the updated area, in |view_size|
     65   // coordinates.
     66   virtual void RenderFrame(const SkISize& view_size,
     67                            const SkIRect& clip_area,
     68                            uint8* image_buffer,
     69                            int image_stride,
     70                            SkRegion* output_region) = 0;
     71 
     72   // Returns the "shape", if any, of the most recently rendered frame.
     73   // The shape is returned in source dimensions.
     74   virtual const SkRegion* GetImageShape() = 0;
     75 };
     76 
     77 }  // namespace remoting
     78 
     79 #endif  // REMOTING_CODEC_VIDEO_DECODER_H_
     80