0038c12f33
BUG= R=reed@google.com Review URL: https://codereview.chromium.org/22862002 git-svn-id: http://skia.googlecode.com/svn/trunk@10754 2bbb7eff-a529-9590-31e7-b0007b416f81
302 lines
9.0 KiB
C++
302 lines
9.0 KiB
C++
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/*
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* Copyright 2008 The Android Open Source Project
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkWriter32_DEFINED
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#define SkWriter32_DEFINED
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#include "SkTypes.h"
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#include "SkScalar.h"
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#include "SkPath.h"
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#include "SkPoint.h"
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#include "SkRect.h"
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#include "SkRRect.h"
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#include "SkMatrix.h"
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#include "SkRegion.h"
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class SkStream;
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class SkWStream;
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class SkWriter32 : SkNoncopyable {
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struct BlockHeader;
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public:
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/**
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* The caller can specify an initial block of storage, which the caller manages.
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* SkWriter32 will not attempt to free this in its destructor. It is up to the
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* implementation to decide if, and how much, of the storage to utilize, and it
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* is possible that it may be ignored entirely.
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*/
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SkWriter32(size_t minSize, void* initialStorage, size_t storageSize);
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SkWriter32(size_t minSize)
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: fHead(NULL)
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, fTail(NULL)
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, fMinSize(minSize)
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, fSize(0)
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, fWrittenBeforeLastBlock(0)
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{}
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~SkWriter32();
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// return the current offset (will always be a multiple of 4)
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uint32_t bytesWritten() const { return fSize; }
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// DEPRECATED: use bytesWritten instead TODO(mtklein): clean up
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uint32_t size() const { return this->bytesWritten(); }
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// Returns true if we've written only into the storage passed into constructor or reset.
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// (You may be able to use this to avoid a call to flatten.)
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bool wroteOnlyToStorage() const {
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return fHead == &fExternalBlock && this->bytesWritten() <= fExternalBlock.fSizeOfBlock;
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}
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void reset();
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void reset(void* storage, size_t size);
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// size MUST be multiple of 4
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uint32_t* reserve(size_t size) {
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SkASSERT(SkAlign4(size) == size);
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Block* block = fTail;
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if (NULL == block || block->available() < size) {
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block = this->doReserve(size);
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}
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fSize += size;
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return block->alloc(size);
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}
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bool writeBool(bool value) {
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this->writeInt(value);
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return value;
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}
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void writeInt(int32_t value) {
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*(int32_t*)this->reserve(sizeof(value)) = value;
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}
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void write8(int32_t value) {
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*(int32_t*)this->reserve(sizeof(value)) = value & 0xFF;
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}
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void write16(int32_t value) {
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*(int32_t*)this->reserve(sizeof(value)) = value & 0xFFFF;
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}
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void write32(int32_t value) {
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*(int32_t*)this->reserve(sizeof(value)) = value;
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}
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void writePtr(void* ptr) {
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// Since we "know" that we're always 4-byte aligned, we can tell the
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// compiler that here, by assigning to an int32 ptr.
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int32_t* addr = (int32_t*)this->reserve(sizeof(void*));
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if (4 == sizeof(void*)) {
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*(void**)addr = ptr;
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} else {
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memcpy(addr, &ptr, sizeof(void*));
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}
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}
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void writeScalar(SkScalar value) {
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*(SkScalar*)this->reserve(sizeof(value)) = value;
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}
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void writePoint(const SkPoint& pt) {
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*(SkPoint*)this->reserve(sizeof(pt)) = pt;
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}
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void writeRect(const SkRect& rect) {
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*(SkRect*)this->reserve(sizeof(rect)) = rect;
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}
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void writeRRect(const SkRRect& rrect) {
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rrect.writeToMemory(this->reserve(SkRRect::kSizeInMemory));
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}
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void writePath(const SkPath& path) {
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size_t size = path.writeToMemory(NULL);
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SkASSERT(SkAlign4(size) == size);
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path.writeToMemory(this->reserve(size));
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}
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void writeMatrix(const SkMatrix& matrix) {
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size_t size = matrix.writeToMemory(NULL);
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SkASSERT(SkAlign4(size) == size);
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matrix.writeToMemory(this->reserve(size));
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}
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void writeRegion(const SkRegion& rgn) {
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size_t size = rgn.writeToMemory(NULL);
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SkASSERT(SkAlign4(size) == size);
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rgn.writeToMemory(this->reserve(size));
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}
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// write count bytes (must be a multiple of 4)
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void writeMul4(const void* values, size_t size) {
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this->write(values, size);
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}
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/**
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* Write size bytes from values. size must be a multiple of 4, though
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* values need not be 4-byte aligned.
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*/
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void write(const void* values, size_t size) {
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SkASSERT(SkAlign4(size) == size);
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// if we could query how much is avail in the current block, we might
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// copy that much, and then alloc the rest. That would reduce the waste
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// in the current block
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memcpy(this->reserve(size), values, size);
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}
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/**
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* Reserve size bytes. Does not need to be 4 byte aligned. The remaining space (if any) will be
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* filled in with zeroes.
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*/
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uint32_t* reservePad(size_t size);
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/**
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* Write size bytes from src, and pad to 4 byte alignment with zeroes.
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*/
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void writePad(const void* src, size_t size);
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/**
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* Writes a string to the writer, which can be retrieved with
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* SkReader32::readString().
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* The length can be specified, or if -1 is passed, it will be computed by
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* calling strlen(). The length must be < max size_t.
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*
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* If you write NULL, it will be read as "".
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*/
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void writeString(const char* str, size_t len = (size_t)-1);
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/**
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* Computes the size (aligned to multiple of 4) need to write the string
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* in a call to writeString(). If the length is not specified, it will be
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* computed by calling strlen().
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*/
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static size_t WriteStringSize(const char* str, size_t len = (size_t)-1);
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// return the address of the 4byte int at the specified offset (which must
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// be a multiple of 4. This does not allocate any new space, so the returned
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// address is only valid for 1 int.
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uint32_t* peek32(size_t offset);
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/**
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* Move the cursor back to offset bytes from the beginning.
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* This has the same restrictions as peek32: offset must be <= size() and
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* offset must be a multiple of 4.
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*/
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void rewindToOffset(size_t offset);
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// copy into a single buffer (allocated by caller). Must be at least size()
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void flatten(void* dst) const;
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// read from the stream, and write up to length bytes. Return the actual
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// number of bytes written.
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size_t readFromStream(SkStream*, size_t length);
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bool writeToStream(SkWStream*);
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private:
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struct Block {
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Block* fNext;
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char* fBasePtr;
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size_t fSizeOfBlock; // total space allocated (after this)
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size_t fAllocatedSoFar; // space used so far
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size_t available() const { return fSizeOfBlock - fAllocatedSoFar; }
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char* base() { return fBasePtr; }
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const char* base() const { return fBasePtr; }
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uint32_t* alloc(size_t size) {
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SkASSERT(SkAlign4(size) == size);
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SkASSERT(this->available() >= size);
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void* ptr = this->base() + fAllocatedSoFar;
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fAllocatedSoFar += size;
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SkASSERT(fAllocatedSoFar <= fSizeOfBlock);
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return (uint32_t*)ptr;
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}
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uint32_t* peek32(size_t offset) {
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SkASSERT(offset <= fAllocatedSoFar + 4);
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void* ptr = this->base() + offset;
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return (uint32_t*)ptr;
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}
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void rewind() {
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fNext = NULL;
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fAllocatedSoFar = 0;
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// keep fSizeOfBlock as is
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}
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static Block* Create(size_t size) {
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SkASSERT(SkIsAlign4(size));
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Block* block = (Block*)sk_malloc_throw(sizeof(Block) + size);
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block->fNext = NULL;
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block->fBasePtr = (char*)(block + 1);
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block->fSizeOfBlock = size;
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block->fAllocatedSoFar = 0;
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return block;
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}
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Block* initFromStorage(void* storage, size_t size) {
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SkASSERT(SkIsAlign4((intptr_t)storage));
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SkASSERT(SkIsAlign4(size));
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Block* block = this;
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block->fNext = NULL;
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block->fBasePtr = (char*)storage;
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block->fSizeOfBlock = size;
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block->fAllocatedSoFar = 0;
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return block;
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}
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};
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enum {
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MIN_BLOCKSIZE = sizeof(SkWriter32::Block) + sizeof(intptr_t)
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};
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Block fExternalBlock;
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Block* fHead;
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Block* fTail;
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size_t fMinSize;
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uint32_t fSize;
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// sum of bytes written in all blocks *before* fTail
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uint32_t fWrittenBeforeLastBlock;
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bool isHeadExternallyAllocated() const {
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return fHead == &fExternalBlock;
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}
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Block* newBlock(size_t bytes);
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// only call from reserve()
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Block* doReserve(size_t bytes);
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SkDEBUGCODE(void validate() const;)
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};
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/**
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* Helper class to allocated SIZE bytes as part of the writer, and to provide
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* that storage to the constructor as its initial storage buffer.
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*
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* This wrapper ensures proper alignment rules are met for the storage.
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*/
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template <size_t SIZE> class SkSWriter32 : public SkWriter32 {
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public:
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SkSWriter32(size_t minSize) : SkWriter32(minSize, fData.fStorage, SIZE) {}
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private:
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union {
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void* fPtrAlignment;
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double fDoubleAlignment;
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char fStorage[SIZE];
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} fData;
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};
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#endif
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