1 2 /* 3 * Copyright 2008 The Android Open Source Project 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10 #ifndef SkWriter32_DEFINED 11 #define SkWriter32_DEFINED 12 13 #include "SkData.h" 14 #include "SkMatrix.h" 15 #include "SkPath.h" 16 #include "SkPoint.h" 17 #include "SkRRect.h" 18 #include "SkRect.h" 19 #include "SkRegion.h" 20 #include "SkScalar.h" 21 #include "SkStream.h" 22 #include "SkTemplates.h" 23 #include "SkTypes.h" 24 25 class SK_API SkWriter32 : SkNoncopyable { 26 public: 27 /** 28 * The caller can specify an initial block of storage, which the caller manages. 29 * 30 * SkWriter32 will try to back reserve and write calls with this external storage until the 31 * first time an allocation doesn't fit. From then it will use dynamically allocated storage. 32 * This used to be optional behavior, but pipe now relies on it. 33 */ 34 SkWriter32(void* external = NULL, size_t externalBytes = 0) { 35 this->reset(external, externalBytes); 36 } 37 38 // return the current offset (will always be a multiple of 4) 39 size_t bytesWritten() const { return fUsed; } 40 41 SK_ATTR_DEPRECATED("use bytesWritten") 42 size_t size() const { return this->bytesWritten(); } 43 44 void reset(void* external = NULL, size_t externalBytes = 0) { 45 SkASSERT(SkIsAlign4((uintptr_t)external)); 46 SkASSERT(SkIsAlign4(externalBytes)); 47 48 fData = (uint8_t*)external; 49 fCapacity = externalBytes; 50 fUsed = 0; 51 fExternal = external; 52 } 53 54 // Returns the current buffer. 55 // The pointer may be invalidated by any future write calls. 56 const uint32_t* contiguousArray() const { 57 return (uint32_t*)fData; 58 } 59 60 // size MUST be multiple of 4 61 uint32_t* reserve(size_t size) { 62 SkASSERT(SkAlign4(size) == size); 63 size_t offset = fUsed; 64 size_t totalRequired = fUsed + size; 65 if (totalRequired > fCapacity) { 66 this->growToAtLeast(totalRequired); 67 } 68 fUsed = totalRequired; 69 return (uint32_t*)(fData + offset); 70 } 71 72 /** 73 * Read a T record at offset, which must be a multiple of 4. Only legal if the record 74 * was written atomically using the write methods below. 75 */ 76 template<typename T> 77 const T& readTAt(size_t offset) const { 78 SkASSERT(SkAlign4(offset) == offset); 79 SkASSERT(offset < fUsed); 80 return *(T*)(fData + offset); 81 } 82 83 /** 84 * Overwrite a T record at offset, which must be a multiple of 4. Only legal if the record 85 * was written atomically using the write methods below. 86 */ 87 template<typename T> 88 void overwriteTAt(size_t offset, const T& value) { 89 SkASSERT(SkAlign4(offset) == offset); 90 SkASSERT(offset < fUsed); 91 *(T*)(fData + offset) = value; 92 } 93 94 bool writeBool(bool value) { 95 this->write32(value); 96 return value; 97 } 98 99 void writeInt(int32_t value) { 100 this->write32(value); 101 } 102 103 void write8(int32_t value) { 104 *(int32_t*)this->reserve(sizeof(value)) = value & 0xFF; 105 } 106 107 void write16(int32_t value) { 108 *(int32_t*)this->reserve(sizeof(value)) = value & 0xFFFF; 109 } 110 111 void write32(int32_t value) { 112 *(int32_t*)this->reserve(sizeof(value)) = value; 113 } 114 115 void writePtr(void* value) { 116 *(void**)this->reserve(sizeof(value)) = value; 117 } 118 119 void writeScalar(SkScalar value) { 120 *(SkScalar*)this->reserve(sizeof(value)) = value; 121 } 122 123 void writePoint(const SkPoint& pt) { 124 *(SkPoint*)this->reserve(sizeof(pt)) = pt; 125 } 126 127 void writeRect(const SkRect& rect) { 128 *(SkRect*)this->reserve(sizeof(rect)) = rect; 129 } 130 131 void writeIRect(const SkIRect& rect) { 132 *(SkIRect*)this->reserve(sizeof(rect)) = rect; 133 } 134 135 void writeRRect(const SkRRect& rrect) { 136 rrect.writeToMemory(this->reserve(SkRRect::kSizeInMemory)); 137 } 138 139 void writePath(const SkPath& path) { 140 size_t size = path.writeToMemory(NULL); 141 SkASSERT(SkAlign4(size) == size); 142 path.writeToMemory(this->reserve(size)); 143 } 144 145 void writeMatrix(const SkMatrix& matrix) { 146 size_t size = matrix.writeToMemory(NULL); 147 SkASSERT(SkAlign4(size) == size); 148 matrix.writeToMemory(this->reserve(size)); 149 } 150 151 void writeRegion(const SkRegion& rgn) { 152 size_t size = rgn.writeToMemory(NULL); 153 SkASSERT(SkAlign4(size) == size); 154 rgn.writeToMemory(this->reserve(size)); 155 } 156 157 // write count bytes (must be a multiple of 4) 158 void writeMul4(const void* values, size_t size) { 159 this->write(values, size); 160 } 161 162 /** 163 * Write size bytes from values. size must be a multiple of 4, though 164 * values need not be 4-byte aligned. 165 */ 166 void write(const void* values, size_t size) { 167 SkASSERT(SkAlign4(size) == size); 168 memcpy(this->reserve(size), values, size); 169 } 170 171 /** 172 * Reserve size bytes. Does not need to be 4 byte aligned. The remaining space (if any) will be 173 * filled in with zeroes. 174 */ 175 uint32_t* reservePad(size_t size) { 176 size_t alignedSize = SkAlign4(size); 177 uint32_t* p = this->reserve(alignedSize); 178 if (alignedSize != size) { 179 SkASSERT(alignedSize >= 4); 180 p[alignedSize / 4 - 1] = 0; 181 } 182 return p; 183 } 184 185 /** 186 * Write size bytes from src, and pad to 4 byte alignment with zeroes. 187 */ 188 void writePad(const void* src, size_t size) { 189 memcpy(this->reservePad(size), src, size); 190 } 191 192 /** 193 * Writes a string to the writer, which can be retrieved with 194 * SkReader32::readString(). 195 * The length can be specified, or if -1 is passed, it will be computed by 196 * calling strlen(). The length must be < max size_t. 197 * 198 * If you write NULL, it will be read as "". 199 */ 200 void writeString(const char* str, size_t len = (size_t)-1); 201 202 /** 203 * Computes the size (aligned to multiple of 4) need to write the string 204 * in a call to writeString(). If the length is not specified, it will be 205 * computed by calling strlen(). 206 */ 207 static size_t WriteStringSize(const char* str, size_t len = (size_t)-1); 208 209 /** 210 * Move the cursor back to offset bytes from the beginning. 211 * offset must be a multiple of 4 no greater than size(). 212 */ 213 void rewindToOffset(size_t offset) { 214 SkASSERT(SkAlign4(offset) == offset); 215 SkASSERT(offset <= bytesWritten()); 216 fUsed = offset; 217 } 218 219 // copy into a single buffer (allocated by caller). Must be at least size() 220 void flatten(void* dst) const { 221 memcpy(dst, fData, fUsed); 222 } 223 224 bool writeToStream(SkWStream* stream) const { 225 return stream->write(fData, fUsed); 226 } 227 228 // read from the stream, and write up to length bytes. Return the actual 229 // number of bytes written. 230 size_t readFromStream(SkStream* stream, size_t length) { 231 return stream->read(this->reservePad(length), length); 232 } 233 234 /** 235 * Captures a snapshot of the data as it is right now, and return it. 236 */ 237 SkData* snapshotAsData() const; 238 private: 239 void growToAtLeast(size_t size); 240 241 uint8_t* fData; // Points to either fInternal or fExternal. 242 size_t fCapacity; // Number of bytes we can write to fData. 243 size_t fUsed; // Number of bytes written. 244 void* fExternal; // Unmanaged memory block. 245 SkAutoTMalloc<uint8_t> fInternal; // Managed memory block. 246 }; 247 248 /** 249 * Helper class to allocated SIZE bytes as part of the writer, and to provide 250 * that storage to the constructor as its initial storage buffer. 251 * 252 * This wrapper ensures proper alignment rules are met for the storage. 253 */ 254 template <size_t SIZE> class SkSWriter32 : public SkWriter32 { 255 public: 256 SkSWriter32() { this->reset(); } 257 258 void reset() {this->INHERITED::reset(fData.fStorage, SIZE); } 259 260 private: 261 union { 262 void* fPtrAlignment; 263 double fDoubleAlignment; 264 char fStorage[SIZE]; 265 } fData; 266 267 typedef SkWriter32 INHERITED; 268 }; 269 270 #endif 271
