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/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkRWBuffer_DEFINED
#define SkRWBuffer_DEFINED
#include "SkRefCnt.h"
struct SkBufferBlock;
struct SkBufferHead;
class SkRWBuffer;
class SkStreamAsset;
/**
* Contains a read-only, thread-sharable block of memory. To access the memory, the caller must
* instantiate a local iterator, as the memory is stored in 1 or more contiguous blocks.
*/
class SK_API SkROBuffer : public SkRefCnt {
public:
/**
* Return the logical length of the data owned/shared by this buffer. It may be stored in
* multiple contiguous blocks, accessible via the iterator.
*/
size_t size() const { return fAvailable; }
class SK_API Iter {
public:
Iter(const SkROBuffer*);
Iter(const sk_sp<SkROBuffer>&);
void reset(const SkROBuffer*);
/**
* Return the current continuous block of memory, or nullptr if the iterator is exhausted
*/
const void* data() const;
/**
* Returns the number of bytes in the current continguous block of memory, or 0 if the
* iterator is exhausted.
*/
size_t size() const;
/**
* Advance to the next contiguous block of memory, returning true if there is another
* block, or false if the iterator is exhausted.
*/
bool next();
private:
const SkBufferBlock* fBlock;
size_t fRemaining;
const SkROBuffer* fBuffer;
};
private:
SkROBuffer(const SkBufferHead* head, size_t available, const SkBufferBlock* fTail);
virtual ~SkROBuffer();
const SkBufferHead* fHead;
const size_t fAvailable;
const SkBufferBlock* fTail;
friend class SkRWBuffer;
};
/**
* Accumulates bytes of memory that are "appended" to it, growing internal storage as needed.
* The growth is done such that at any time in the writer's thread, an RBuffer or StreamAsset
* can be snapped off (and safely passed to another thread). The RBuffer/StreamAsset snapshot
* can see the previously stored bytes, but will be unaware of any future writes.
*/
class SK_API SkRWBuffer {
public:
SkRWBuffer(size_t initialCapacity = 0);
~SkRWBuffer();
size_t size() const { return fTotalUsed; }
/**
* Append |length| bytes from |buffer|.
*
* If the caller knows in advance how much more data they are going to append, they can
* pass a |reserve| hint (representing the number of upcoming bytes *in addition* to the
* current append), to minimize the number of internal allocations.
*/
void append(const void* buffer, size_t length, size_t reserve = 0);
sk_sp<SkROBuffer> makeROBufferSnapshot() const {
return sk_sp<SkROBuffer>(new SkROBuffer(fHead, fTotalUsed, fTail));
}
std::unique_ptr<SkStreamAsset> makeStreamSnapshot() const;
#ifdef SK_DEBUG
void validate() const;
#else
void validate() const {}
#endif
private:
SkBufferHead* fHead;
SkBufferBlock* fTail;
size_t fTotalUsed;
};
#endif
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