/*
* Copyright 2008 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkWriter32_DEFINED
#define SkWriter32_DEFINED
#include "SkData.h"
#include "SkMatrix.h"
#include "SkNoncopyable.h"
#include "SkPath.h"
#include "SkPoint.h"
#include "SkPoint3.h"
#include "SkRRect.h"
#include "SkRect.h"
#include "SkRegion.h"
#include "SkScalar.h"
#include "SkStream.h"
#include "SkTemplates.h"
#include "SkTo.h"
#include "SkTypes.h"
class SK_API SkWriter32 : SkNoncopyable {
public:
/**
* The caller can specify an initial block of storage, which the caller manages.
*
* SkWriter32 will try to back reserve and write calls with this external storage until the
* first time an allocation doesn't fit. From then it will use dynamically allocated storage.
* This used to be optional behavior, but pipe now relies on it.
*/
SkWriter32(void* external = nullptr, size_t externalBytes = 0) {
this->reset(external, externalBytes);
}
// return the current offset (will always be a multiple of 4)
size_t bytesWritten() const { return fUsed; }
// Returns true iff all of the bytes written so far are stored in the initial storage
// buffer provided in the constructor or the most recent call to reset.
bool usingInitialStorage() const { return fData == fExternal; }
void reset(void* external = nullptr, size_t externalBytes = 0) {
// we cast this pointer to int* and float* at times, so assert that it is aligned.
SkASSERT(SkIsAlign4((uintptr_t)external));
// we always write multiples of 4-bytes, so truncate down the size to match that
externalBytes &= ~3;
fData = (uint8_t*)external;
fCapacity = externalBytes;
fUsed = 0;
fExternal = external;
}
// size MUST be multiple of 4
uint32_t* reserve(size_t size) {
SkASSERT(SkAlign4(size) == size);
size_t offset = fUsed;
size_t totalRequired = fUsed + size;
if (totalRequired > fCapacity) {
this->growToAtLeast(totalRequired);
}
fUsed = totalRequired;
return (uint32_t*)(fData + offset);
}
/**
* Read a T record at offset, which must be a multiple of 4. Only legal if the record
* was written atomically using the write methods below.
*/
template<typename T>
const T& readTAt(size_t offset) const {
SkASSERT(SkAlign4(offset) == offset);
SkASSERT(offset < fUsed);
return *(T*)(fData + offset);
}
/**
* Overwrite a T record at offset, which must be a multiple of 4. Only legal if the record
* was written atomically using the write methods below.
*/
template<typename T>
void overwriteTAt(size_t offset, const T& value) {
SkASSERT(SkAlign4(offset) == offset);
SkASSERT(offset < fUsed);
*(T*)(fData + offset) = value;
}
bool writeBool(bool value) {
this->write32(value);
return value;
}
void writeInt(int32_t value) {
this->write32(value);
}
void write8(int32_t value) {
*(int32_t*)this->reserve(sizeof(value)) = value & 0xFF;
}
void write16(int32_t value) {
*(int32_t*)this->reserve(sizeof(value)) = value & 0xFFFF;
}
void write32(int32_t value) {
*(int32_t*)this->reserve(sizeof(value)) = value;
}
void writePtr(void* value) {
// this->reserve() only returns 4-byte aligned pointers,
// so this may be an under-aligned write if we were to do this like the others.
memcpy(this->reserve(sizeof(value)), &value, sizeof(value));
}
void writeScalar(SkScalar value) {
*(SkScalar*)this->reserve(sizeof(value)) = value;
}
void writePoint(const SkPoint& pt) {
*(SkPoint*)this->reserve(sizeof(pt)) = pt;
}
void writePoint3(const SkPoint3& pt) {
*(SkPoint3*)this->reserve(sizeof(pt)) = pt;
}
void writeRect(const SkRect& rect) {
*(SkRect*)this->reserve(sizeof(rect)) = rect;
}
void writeIRect(const SkIRect& rect) {
*(SkIRect*)this->reserve(sizeof(rect)) = rect;
}
void writeRRect(const SkRRect& rrect) {
rrect.writeToMemory(this->reserve(SkRRect::kSizeInMemory));
}
void writePath(const SkPath& path) {
size_t size = path.writeToMemory(nullptr);
SkASSERT(SkAlign4(size) == size);
path.writeToMemory(this->reserve(size));
}
void writeMatrix(const SkMatrix& matrix);
void writeRegion(const SkRegion& rgn) {
size_t size = rgn.writeToMemory(nullptr);
SkASSERT(SkAlign4(size) == size);
rgn.writeToMemory(this->reserve(size));
}
// write count bytes (must be a multiple of 4)
void writeMul4(const void* values, size_t size) {
this->write(values, size);
}
/**
* Write size bytes from values. size must be a multiple of 4, though
* values need not be 4-byte aligned.
*/
void write(const void* values, size_t size) {
SkASSERT(SkAlign4(size) == size);
sk_careful_memcpy(this->reserve(size), values, size);
}
/**
* Reserve size bytes. Does not need to be 4 byte aligned. The remaining space (if any) will be
* filled in with zeroes.
*/
uint32_t* reservePad(size_t size) {
size_t alignedSize = SkAlign4(size);
uint32_t* p = this->reserve(alignedSize);
if (alignedSize != size) {
SkASSERT(alignedSize >= 4);
p[alignedSize / 4 - 1] = 0;
}
return p;
}
/**
* Write size bytes from src, and pad to 4 byte alignment with zeroes.
*/
void writePad(const void* src, size_t size) {
sk_careful_memcpy(this->reservePad(size), src, size);
}
/**
* Writes a string to the writer, which can be retrieved with
* SkReader32::readString().
* The length can be specified, or if -1 is passed, it will be computed by
* calling strlen(). The length must be < max size_t.
*
* If you write NULL, it will be read as "".
*/
void writeString(const char* str, size_t len = (size_t)-1);
/**
* Computes the size (aligned to multiple of 4) need to write the string
* in a call to writeString(). If the length is not specified, it will be
* computed by calling strlen().
*/
static size_t WriteStringSize(const char* str, size_t len = (size_t)-1);
void writeData(const SkData* data) {
uint32_t len = data ? SkToU32(data->size()) : 0;
this->write32(len);
if (data) {
this->writePad(data->data(), len);
}
}
static size_t WriteDataSize(const SkData* data) {
return 4 + SkAlign4(data ? data->size() : 0);
}
/**
* Move the cursor back to offset bytes from the beginning.
* offset must be a multiple of 4 no greater than size().
*/
void rewindToOffset(size_t offset) {
SkASSERT(SkAlign4(offset) == offset);
SkASSERT(offset <= bytesWritten());
fUsed = offset;
}
// copy into a single buffer (allocated by caller). Must be at least size()
void flatten(void* dst) const {
memcpy(dst, fData, fUsed);
}
bool writeToStream(SkWStream* stream) const {
return stream->write(fData, fUsed);
}
// read from the stream, and write up to length bytes. Return the actual
// number of bytes written.
size_t readFromStream(SkStream* stream, size_t length) {
return stream->read(this->reservePad(length), length);
}
/**
* Captures a snapshot of the data as it is right now, and return it.
*/
sk_sp<SkData> snapshotAsData() const;
private:
void growToAtLeast(size_t size);
uint8_t* fData; // Points to either fInternal or fExternal.
size_t fCapacity; // Number of bytes we can write to fData.
size_t fUsed; // Number of bytes written.
void* fExternal; // Unmanaged memory block.
SkAutoTMalloc<uint8_t> fInternal; // Managed memory block.
};
/**
* Helper class to allocated SIZE bytes as part of the writer, and to provide
* that storage to the constructor as its initial storage buffer.
*
* This wrapper ensures proper alignment rules are met for the storage.
*/
template <size_t SIZE> class SkSWriter32 : public SkWriter32 {
public:
SkSWriter32() { this->reset(); }
void reset() {this->INHERITED::reset(fData.fStorage, SIZE); }
private:
union {
void* fPtrAlignment;
double fDoubleAlignment;
char fStorage[SIZE];
} fData;
typedef SkWriter32 INHERITED;
};
#endif