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 /*

  * 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 "SkPath.h"

 #include "SkPoint.h"

 #include "SkRRect.h"

 #include "SkRect.h"

 #include "SkRegion.h"

 #include "SkScalar.h"

 #include "SkStream.h"

 #include "SkTemplates.h"

 #include "SkTypes.h"

 class 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 = NULL, 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; }

     SK_ATTR_DEPRECATED("use bytesWritten")

     size_t size() const { return this->bytesWritten(); }

     void reset(void* external = NULL, size_t externalBytes = 0) {

         SkASSERT(SkIsAlign4((uintptr_t)external));

         SkASSERT(SkIsAlign4(externalBytes));

         fSnapshot.reset(NULL);

         fData = (uint8_t*)external;

         fCapacity = externalBytes;

         fUsed = 0;

         fExternal = external;

     }

     // Returns the current buffer.

     // The pointer may be invalidated by any future write calls.

     const uint32_t* contiguousArray() const {

         return (uint32_t*)fData;

     }

     // 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);

         SkASSERT(fSnapshot.get() == NULL);

         *(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) {

         *(void**)this->reserve(sizeof(value)) = value;

     }

     void writeScalar(SkScalar value) {

         *(SkScalar*)this->reserve(sizeof(value)) = value;

     }

     void writePoint(const SkPoint& pt) {

         *(SkPoint*)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(NULL);

         SkASSERT(SkAlign4(size) == size);

         path.writeToMemory(this->reserve(size));

     }

     void writeMatrix(const SkMatrix& matrix) {

         size_t size = matrix.writeToMemory(NULL);

         SkASSERT(SkAlign4(size) == size);

         matrix.writeToMemory(this->reserve(size));

     }

     void writeRegion(const SkRegion& rgn) {

         size_t size = rgn.writeToMemory(NULL);

         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);

         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) {

         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);

     /**

      *  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.

      *  Multiple calls without intervening writes may return the same SkData,

      *  but this is not guaranteed.

      *  Future appends will not affect the returned buffer.

      *  It is illegal to call overwriteTAt after this without an intervening

      *  append. It may cause the snapshot buffer to be corrupted.

      *  Callers must unref the returned SkData.

      *  This is not thread safe, it should only be called on the writing thread,

      *  the result however can be shared across threads.

      */

     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.

     SkAutoTUnref<SkData> fSnapshot;    // Holds the result of last asData.

 };

 /**

  *  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