remoting/codec/video_decoder.h

   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_