michael@0: 
michael@0: /*
michael@0:  * Copyright 2008 The Android Open Source Project
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: 
michael@0: #ifndef SkWriter32_DEFINED
michael@0: #define SkWriter32_DEFINED
michael@0: 
michael@0: #include "SkData.h"
michael@0: #include "SkMatrix.h"
michael@0: #include "SkPath.h"
michael@0: #include "SkPoint.h"
michael@0: #include "SkRRect.h"
michael@0: #include "SkRect.h"
michael@0: #include "SkRegion.h"
michael@0: #include "SkScalar.h"
michael@0: #include "SkStream.h"
michael@0: #include "SkTemplates.h"
michael@0: #include "SkTypes.h"
michael@0: 
michael@0: class SkWriter32 : SkNoncopyable {
michael@0: public:
michael@0:     /**
michael@0:      *  The caller can specify an initial block of storage, which the caller manages.
michael@0:      *
michael@0:      *  SkWriter32 will try to back reserve and write calls with this external storage until the
michael@0:      *  first time an allocation doesn't fit.  From then it will use dynamically allocated storage.
michael@0:      *  This used to be optional behavior, but pipe now relies on it.
michael@0:      */
michael@0:     SkWriter32(void* external = NULL, size_t externalBytes = 0) {
michael@0:         this->reset(external, externalBytes);
michael@0:     }
michael@0: 
michael@0:     // return the current offset (will always be a multiple of 4)
michael@0:     size_t bytesWritten() const { return fUsed; }
michael@0: 
michael@0:     SK_ATTR_DEPRECATED("use bytesWritten")
michael@0:     size_t size() const { return this->bytesWritten(); }
michael@0: 
michael@0:     void reset(void* external = NULL, size_t externalBytes = 0) {
michael@0:         SkASSERT(SkIsAlign4((uintptr_t)external));
michael@0:         SkASSERT(SkIsAlign4(externalBytes));
michael@0: 
michael@0:         fSnapshot.reset(NULL);
michael@0:         fData = (uint8_t*)external;
michael@0:         fCapacity = externalBytes;
michael@0:         fUsed = 0;
michael@0:         fExternal = external;
michael@0:     }
michael@0: 
michael@0:     // Returns the current buffer.
michael@0:     // The pointer may be invalidated by any future write calls.
michael@0:     const uint32_t* contiguousArray() const {
michael@0:         return (uint32_t*)fData;
michael@0:     }
michael@0: 
michael@0:     // size MUST be multiple of 4
michael@0:     uint32_t* reserve(size_t size) {
michael@0:         SkASSERT(SkAlign4(size) == size);
michael@0:         size_t offset = fUsed;
michael@0:         size_t totalRequired = fUsed + size;
michael@0:         if (totalRequired > fCapacity) {
michael@0:             this->growToAtLeast(totalRequired);
michael@0:         }
michael@0:         fUsed = totalRequired;
michael@0:         return (uint32_t*)(fData + offset);
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      *  Read a T record at offset, which must be a multiple of 4. Only legal if the record
michael@0:      *  was written atomically using the write methods below.
michael@0:      */
michael@0:     template<typename T>
michael@0:     const T& readTAt(size_t offset) const {
michael@0:         SkASSERT(SkAlign4(offset) == offset);
michael@0:         SkASSERT(offset < fUsed);
michael@0:         return *(T*)(fData + offset);
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      *  Overwrite a T record at offset, which must be a multiple of 4. Only legal if the record
michael@0:      *  was written atomically using the write methods below.
michael@0:      */
michael@0:     template<typename T>
michael@0:     void overwriteTAt(size_t offset, const T& value) {
michael@0:         SkASSERT(SkAlign4(offset) == offset);
michael@0:         SkASSERT(offset < fUsed);
michael@0:         SkASSERT(fSnapshot.get() == NULL);
michael@0:         *(T*)(fData + offset) = value;
michael@0:     }
michael@0: 
michael@0:     bool writeBool(bool value) {
michael@0:         this->write32(value);
michael@0:         return value;
michael@0:     }
michael@0: 
michael@0:     void writeInt(int32_t value) {
michael@0:         this->write32(value);
michael@0:     }
michael@0: 
michael@0:     void write8(int32_t value) {
michael@0:         *(int32_t*)this->reserve(sizeof(value)) = value & 0xFF;
michael@0:     }
michael@0: 
michael@0:     void write16(int32_t value) {
michael@0:         *(int32_t*)this->reserve(sizeof(value)) = value & 0xFFFF;
michael@0:     }
michael@0: 
michael@0:     void write32(int32_t value) {
michael@0:         *(int32_t*)this->reserve(sizeof(value)) = value;
michael@0:     }
michael@0: 
michael@0:     void writePtr(void* value) {
michael@0:         *(void**)this->reserve(sizeof(value)) = value;
michael@0:     }
michael@0: 
michael@0:     void writeScalar(SkScalar value) {
michael@0:         *(SkScalar*)this->reserve(sizeof(value)) = value;
michael@0:     }
michael@0: 
michael@0:     void writePoint(const SkPoint& pt) {
michael@0:         *(SkPoint*)this->reserve(sizeof(pt)) = pt;
michael@0:     }
michael@0: 
michael@0:     void writeRect(const SkRect& rect) {
michael@0:         *(SkRect*)this->reserve(sizeof(rect)) = rect;
michael@0:     }
michael@0: 
michael@0:     void writeIRect(const SkIRect& rect) {
michael@0:         *(SkIRect*)this->reserve(sizeof(rect)) = rect;
michael@0:     }
michael@0: 
michael@0:     void writeRRect(const SkRRect& rrect) {
michael@0:         rrect.writeToMemory(this->reserve(SkRRect::kSizeInMemory));
michael@0:     }
michael@0: 
michael@0:     void writePath(const SkPath& path) {
michael@0:         size_t size = path.writeToMemory(NULL);
michael@0:         SkASSERT(SkAlign4(size) == size);
michael@0:         path.writeToMemory(this->reserve(size));
michael@0:     }
michael@0: 
michael@0:     void writeMatrix(const SkMatrix& matrix) {
michael@0:         size_t size = matrix.writeToMemory(NULL);
michael@0:         SkASSERT(SkAlign4(size) == size);
michael@0:         matrix.writeToMemory(this->reserve(size));
michael@0:     }
michael@0: 
michael@0:     void writeRegion(const SkRegion& rgn) {
michael@0:         size_t size = rgn.writeToMemory(NULL);
michael@0:         SkASSERT(SkAlign4(size) == size);
michael@0:         rgn.writeToMemory(this->reserve(size));
michael@0:     }
michael@0: 
michael@0:     // write count bytes (must be a multiple of 4)
michael@0:     void writeMul4(const void* values, size_t size) {
michael@0:         this->write(values, size);
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      *  Write size bytes from values. size must be a multiple of 4, though
michael@0:      *  values need not be 4-byte aligned.
michael@0:      */
michael@0:     void write(const void* values, size_t size) {
michael@0:         SkASSERT(SkAlign4(size) == size);
michael@0:         memcpy(this->reserve(size), values, size);
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      *  Reserve size bytes. Does not need to be 4 byte aligned. The remaining space (if any) will be
michael@0:      *  filled in with zeroes.
michael@0:      */
michael@0:     uint32_t* reservePad(size_t size) {
michael@0:         size_t alignedSize = SkAlign4(size);
michael@0:         uint32_t* p = this->reserve(alignedSize);
michael@0:         if (alignedSize != size) {
michael@0:             SkASSERT(alignedSize >= 4);
michael@0:             p[alignedSize / 4 - 1] = 0;
michael@0:         }
michael@0:         return p;
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      *  Write size bytes from src, and pad to 4 byte alignment with zeroes.
michael@0:      */
michael@0:     void writePad(const void* src, size_t size) {
michael@0:         memcpy(this->reservePad(size), src, size);
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      *  Writes a string to the writer, which can be retrieved with
michael@0:      *  SkReader32::readString().
michael@0:      *  The length can be specified, or if -1 is passed, it will be computed by
michael@0:      *  calling strlen(). The length must be < max size_t.
michael@0:      *
michael@0:      *  If you write NULL, it will be read as "".
michael@0:      */
michael@0:     void writeString(const char* str, size_t len = (size_t)-1);
michael@0: 
michael@0:     /**
michael@0:      *  Computes the size (aligned to multiple of 4) need to write the string
michael@0:      *  in a call to writeString(). If the length is not specified, it will be
michael@0:      *  computed by calling strlen().
michael@0:      */
michael@0:     static size_t WriteStringSize(const char* str, size_t len = (size_t)-1);
michael@0: 
michael@0:     /**
michael@0:      *  Move the cursor back to offset bytes from the beginning.
michael@0:      *  offset must be a multiple of 4 no greater than size().
michael@0:      */
michael@0:     void rewindToOffset(size_t offset) {
michael@0:         SkASSERT(SkAlign4(offset) == offset);
michael@0:         SkASSERT(offset <= bytesWritten());
michael@0:         fUsed = offset;
michael@0:     }
michael@0: 
michael@0:     // copy into a single buffer (allocated by caller). Must be at least size()
michael@0:     void flatten(void* dst) const {
michael@0:         memcpy(dst, fData, fUsed);
michael@0:     }
michael@0: 
michael@0:     bool writeToStream(SkWStream* stream) const {
michael@0:         return stream->write(fData, fUsed);
michael@0:     }
michael@0: 
michael@0:     // read from the stream, and write up to length bytes. Return the actual
michael@0:     // number of bytes written.
michael@0:     size_t readFromStream(SkStream* stream, size_t length) {
michael@0:         return stream->read(this->reservePad(length), length);
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      *  Captures a snapshot of the data as it is right now, and return it.
michael@0:      *  Multiple calls without intervening writes may return the same SkData,
michael@0:      *  but this is not guaranteed.
michael@0:      *  Future appends will not affect the returned buffer.
michael@0:      *  It is illegal to call overwriteTAt after this without an intervening
michael@0:      *  append. It may cause the snapshot buffer to be corrupted.
michael@0:      *  Callers must unref the returned SkData.
michael@0:      *  This is not thread safe, it should only be called on the writing thread,
michael@0:      *  the result however can be shared across threads.
michael@0:      */
michael@0:     SkData* snapshotAsData() const;
michael@0: private:
michael@0:     void growToAtLeast(size_t size);
michael@0: 
michael@0:     uint8_t* fData;                    // Points to either fInternal or fExternal.
michael@0:     size_t fCapacity;                  // Number of bytes we can write to fData.
michael@0:     size_t fUsed;                      // Number of bytes written.
michael@0:     void* fExternal;                   // Unmanaged memory block.
michael@0:     SkAutoTMalloc<uint8_t> fInternal;  // Managed memory block.
michael@0:     SkAutoTUnref<SkData> fSnapshot;    // Holds the result of last asData.
michael@0: };
michael@0: 
michael@0: /**
michael@0:  *  Helper class to allocated SIZE bytes as part of the writer, and to provide
michael@0:  *  that storage to the constructor as its initial storage buffer.
michael@0:  *
michael@0:  *  This wrapper ensures proper alignment rules are met for the storage.
michael@0:  */
michael@0: template <size_t SIZE> class SkSWriter32 : public SkWriter32 {
michael@0: public:
michael@0:     SkSWriter32() { this->reset(); }
michael@0: 
michael@0:     void reset() {this->INHERITED::reset(fData.fStorage, SIZE); }
michael@0: 
michael@0: private:
michael@0:     union {
michael@0:         void*   fPtrAlignment;
michael@0:         double  fDoubleAlignment;
michael@0:         char    fStorage[SIZE];
michael@0:     } fData;
michael@0: 
michael@0:     typedef SkWriter32 INHERITED;
michael@0: };
michael@0: 
michael@0: #endif