skia2/include/core/SkData.h
2012-06-21 20:25:03 +00:00

142 lines
3.8 KiB
C++

/*
* Copyright 2011 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkData_DEFINED
#define SkData_DEFINED
#include "SkRefCnt.h"
/**
* SkData holds an immutable data buffer. Not only is the data immutable,
* but the actual ptr that is returned (by data() or bytes()) is guaranteed
* to always be the same for the life of this instance.
*/
class SkData : public SkRefCnt {
public:
SK_DECLARE_INST_COUNT(SkData)
/**
* Returns the number of bytes stored.
*/
size_t size() const { return fSize; }
/**
* Returns the ptr to the data.
*/
const void* data() const { return fPtr; }
/**
* Like data(), returns a read-only ptr into the data, but in this case
* it is cast to uint8_t*, to make it easy to add an offset to it.
*/
const uint8_t* bytes() const {
return reinterpret_cast<const uint8_t*>(fPtr);
}
/**
* Helper to copy a range of the data into a caller-provided buffer.
* Returns the actual number of bytes copied, after clamping offset and
* length to the size of the data. If buffer is NULL, it is ignored, and
* only the computed number of bytes is returned.
*/
size_t copyRange(size_t offset, size_t length, void* buffer) const;
/**
* Function that, if provided, will be called when the SkData goes out
* of scope, allowing for custom allocation/freeing of the data.
*/
typedef void (*ReleaseProc)(const void* ptr, size_t length, void* context);
/**
* Create a new dataref by copying the specified data
*/
static SkData* NewWithCopy(const void* data, size_t length);
/**
* Create a new dataref, taking the data ptr as is, and using the
* releaseproc to free it. The proc may be NULL.
*/
static SkData* NewWithProc(const void* data, size_t length,
ReleaseProc proc, void* context);
/**
* Create a new dataref from a pointer allocated by malloc. The Data object
* takes ownership of that allocation, and will handling calling sk_free.
*/
static SkData* NewFromMalloc(const void* data, size_t length);
/**
* Create a new dataref using a subset of the data in the specified
* src dataref.
*/
static SkData* NewSubset(const SkData* src, size_t offset, size_t length);
/**
* Returns a new empty dataref (or a reference to a shared empty dataref).
* New or shared, the caller must see that unref() is eventually called.
*/
static SkData* NewEmpty();
private:
ReleaseProc fReleaseProc;
void* fReleaseProcContext;
const void* fPtr;
size_t fSize;
SkData(const void* ptr, size_t size, ReleaseProc, void* context);
~SkData();
typedef SkRefCnt INHERITED;
};
/**
* Specialized version of SkAutoTUnref<SkData> for automatically unref-ing a
* SkData. If the SkData is null, data(), bytes() and size() will return 0.
*/
class SkAutoDataUnref : SkNoncopyable {
public:
SkAutoDataUnref(SkData* data) : fRef(data) {
if (data) {
fData = data->data();
fSize = data->size();
} else {
fData = NULL;
fSize = 0;
}
}
~SkAutoDataUnref() {
SkSafeUnref(fRef);
}
const void* data() const { return fData; }
const uint8_t* bytes() const {
return reinterpret_cast<const uint8_t*> (fData);
}
size_t size() const { return fSize; }
SkData* get() const { return fRef; }
void release() {
if (fRef) {
fRef->unref();
fRef = NULL;
fData = NULL;
fSize = 0;
}
}
private:
SkData* fRef;
const void* fData;
size_t fSize;
};
#endif