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      1 /*
      2  * Copyright 2013 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #include "SkTypes.h"
      9 
     10 class SkStream;
     11 class SkStreamRewindable;
     12 
     13 /**
     14  *  Specialized stream that buffers the first X bytes of a stream,
     15  *  where X is passed in by the user. Note that unlike some buffered
     16  *  stream APIs, once more bytes than can fit in the buffer are read,
     17  *  no more buffering is done. This stream is designed for a use case
     18  *  where the caller knows that rewind will only be called from within
     19  *  X bytes (inclusive), and the wrapped stream is not necessarily
     20  *  able to rewind at all.
     21  */
     22 class SkFrontBufferedStream {
     23 public:
     24     /**
     25      *  Creates a new stream that wraps and buffers an SkStream.
     26      *  @param stream SkStream to buffer. If stream is NULL, NULL is
     27      *      returned. When this call succeeds (i.e. returns non NULL),
     28      *      SkFrontBufferedStream is expected to be the only owner of
     29      *      stream, so it should no be longer used directly.
     30      *      SkFrontBufferedStream will delete stream upon deletion.
     31      *  @param minBufferSize Minimum size of buffer required.
     32      *  @return An SkStream that can buffer at least minBufferSize, or
     33      *      NULL on failure. The caller is required to delete when finished with
     34      *      this object.
     35      */
     36     static SkStreamRewindable* Create(SkStream* stream, size_t minBufferSize);
     37 };
     38