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* Copyright 2013 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#include "SkStream.h"
#include "SkTemplates.h"
* Specialized stream that only buffers the first X bytes of a stream,
* where X is passed in by the user. Note that unlike some buffered
* stream APIs, once more than those bytes are read, no more buffering
* is done. This stream is designed for a use case where the caller
* knows that rewind will only be called from within X bytes (inclusive),
* and the wrapped stream is not necessarily able to rewind at all.
class SkFrontBufferedStream : public SkStreamRewindable {
* Creates a new stream that wraps and buffers SkStream.
* @param stream SkStream to buffer. If NULL, NULL is returned. After
* this call, unref stream and do not refer to it.
* SkFrontBufferedStream is expected to be its only owner.
* @param bufferSize Exact size of the buffer to be used.
* @return An SkStream that can buffer up to bufferSize.
static SkStreamRewindable* Create(SkStream* stream, size_t bufferSize);
virtual size_t read(void* buffer, size_t size) SK_OVERRIDE;
virtual bool isAtEnd() const SK_OVERRIDE;
virtual bool rewind() SK_OVERRIDE;
virtual bool hasPosition() const SK_OVERRIDE { return true; }
virtual size_t getPosition() const SK_OVERRIDE { return fOffset; }
virtual bool hasLength() const SK_OVERRIDE;
virtual size_t getLength() const SK_OVERRIDE;
virtual SkStreamRewindable* duplicate() const SK_OVERRIDE { return NULL; }
SkAutoTUnref<SkStream> fStream;
// Current offset into the stream. Always >= 0.
size_t fOffset;
// Amount that has been buffered by calls to read. Will always be less than
// fBufferSize.
size_t fBufferedSoFar;
// Total size of the buffer.
const size_t fBufferSize;
SkAutoTMalloc<char> fBuffer;
// Private. Use Create.
SkFrontBufferedStream(SkStream*, size_t bufferSize);
// Read up to size bytes from already buffered data, and copy to
// dst, if non-NULL. Updates fOffset. Assumes that fOffset is less
// than fBufferedSoFar.
size_t readFromBuffer(char* dst, size_t size);
// Buffer up to size bytes from the stream, and copy to dst if non-
// NULL. Updates fOffset and fBufferedSoFar. Assumes that fOffset is
// less than fBufferedSoFar, and size is greater than 0.
size_t bufferAndWriteTo(char* dst, size_t size);
// Read up to size bytes directly from the stream and into dst if non-
// NULL. Updates fOffset. Assumes fOffset is at or beyond the buffered
// data, and size is greater than 0.
size_t readDirectlyFromStream(char* dst, size_t size);
typedef SkStream INHERITED;