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 "../private/SkTemplates.h" 14 #include "SkData.h" 15 #include "SkMatrix.h" 16 #include "SkPath.h" 17 #include "SkPoint.h" 18 #include "SkRRect.h" 19 #include "SkRect.h" 20 #include "SkRegion.h" 21 #include "SkScalar.h" 22 #include "SkStream.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 // size MUST be multiple of 4 55 uint32_t* reserve(size_t size) { 56 SkASSERT(SkAlign4(size) == size); 57 size_t offset = fUsed; 58 size_t totalRequired = fUsed + size; 59 if (totalRequired > fCapacity) { 60 this->growToAtLeast(totalRequired); 61 } 62 fUsed = totalRequired; 63 return (uint32_t*)(fData + offset); 64 } 65 66 /** 67 * Read a T record at offset, which must be a multiple of 4. Only legal if the record 68 * was written atomically using the write methods below. 69 */ 70 template<typename T> 71 const T& readTAt(size_t offset) const { 72 SkASSERT(SkAlign4(offset) == offset); 73 SkASSERT(offset < fUsed); 74 return *(T*)(fData + offset); 75 } 76 77 /** 78 * Overwrite a T record at offset, which must be a multiple of 4. Only legal if the record 79 * was written atomically using the write methods below. 80 */ 81 template<typename T> 82 void overwriteTAt(size_t offset, const T& value) { 83 SkASSERT(SkAlign4(offset) == offset); 84 SkASSERT(offset < fUsed); 85 *(T*)(fData + offset) = value; 86 } 87 88 bool writeBool(bool value) { 89 this->write32(value); 90 return value; 91 } 92 93 void writeInt(int32_t value) { 94 this->write32(value); 95 } 96 97 void write8(int32_t value) { 98 *(int32_t*)this->reserve(sizeof(value)) = value & 0xFF; 99 } 100 101 void write16(int32_t value) { 102 *(int32_t*)this->reserve(sizeof(value)) = value & 0xFFFF; 103 } 104 105 void write32(int32_t value) { 106 *(int32_t*)this->reserve(sizeof(value)) = value; 107 } 108 109 void writePtr(void* value) { 110 *(void**)this->reserve(sizeof(value)) = value; 111 } 112 113 void writeScalar(SkScalar value) { 114 *(SkScalar*)this->reserve(sizeof(value)) = value; 115 } 116 117 void writePoint(const SkPoint& pt) { 118 *(SkPoint*)this->reserve(sizeof(pt)) = pt; 119 } 120 121 void writeRect(const SkRect& rect) { 122 *(SkRect*)this->reserve(sizeof(rect)) = rect; 123 } 124 125 void writeIRect(const SkIRect& rect) { 126 *(SkIRect*)this->reserve(sizeof(rect)) = rect; 127 } 128 129 void writeRRect(const SkRRect& rrect) { 130 rrect.writeToMemory(this->reserve(SkRRect::kSizeInMemory)); 131 } 132 133 void writePath(const SkPath& path) { 134 size_t size = path.writeToMemory(NULL); 135 SkASSERT(SkAlign4(size) == size); 136 path.writeToMemory(this->reserve(size)); 137 } 138 139 void writeMatrix(const SkMatrix& matrix) { 140 size_t size = matrix.writeToMemory(NULL); 141 SkASSERT(SkAlign4(size) == size); 142 matrix.writeToMemory(this->reserve(size)); 143 } 144 145 void writeRegion(const SkRegion& rgn) { 146 size_t size = rgn.writeToMemory(NULL); 147 SkASSERT(SkAlign4(size) == size); 148 rgn.writeToMemory(this->reserve(size)); 149 } 150 151 // write count bytes (must be a multiple of 4) 152 void writeMul4(const void* values, size_t size) { 153 this->write(values, size); 154 } 155 156 /** 157 * Write size bytes from values. size must be a multiple of 4, though 158 * values need not be 4-byte aligned. 159 */ 160 void write(const void* values, size_t size) { 161 SkASSERT(SkAlign4(size) == size); 162 sk_careful_memcpy(this->reserve(size), values, size); 163 } 164 165 /** 166 * Reserve size bytes. Does not need to be 4 byte aligned. The remaining space (if any) will be 167 * filled in with zeroes. 168 */ 169 uint32_t* reservePad(size_t size) { 170 size_t alignedSize = SkAlign4(size); 171 uint32_t* p = this->reserve(alignedSize); 172 if (alignedSize != size) { 173 SkASSERT(alignedSize >= 4); 174 p[alignedSize / 4 - 1] = 0; 175 } 176 return p; 177 } 178 179 /** 180 * Write size bytes from src, and pad to 4 byte alignment with zeroes. 181 */ 182 void writePad(const void* src, size_t size) { 183 sk_careful_memcpy(this->reservePad(size), src, size); 184 } 185 186 /** 187 * Writes a string to the writer, which can be retrieved with 188 * SkReader32::readString(). 189 * The length can be specified, or if -1 is passed, it will be computed by 190 * calling strlen(). The length must be < max size_t. 191 * 192 * If you write NULL, it will be read as "". 193 */ 194 void writeString(const char* str, size_t len = (size_t)-1); 195 196 /** 197 * Computes the size (aligned to multiple of 4) need to write the string 198 * in a call to writeString(). If the length is not specified, it will be 199 * computed by calling strlen(). 200 */ 201 static size_t WriteStringSize(const char* str, size_t len = (size_t)-1); 202 203 void writeData(const SkData* data) { 204 uint32_t len = data ? SkToU32(data->size()) : 0; 205 this->write32(len); 206 if (data) { 207 this->writePad(data->data(), len); 208 } 209 } 210 211 static size_t WriteDataSize(const SkData* data) { 212 return 4 + SkAlign4(data ? data->size() : 0); 213 } 214 215 /** 216 * Move the cursor back to offset bytes from the beginning. 217 * offset must be a multiple of 4 no greater than size(). 218 */ 219 void rewindToOffset(size_t offset) { 220 SkASSERT(SkAlign4(offset) == offset); 221 SkASSERT(offset <= bytesWritten()); 222 fUsed = offset; 223 } 224 225 // copy into a single buffer (allocated by caller). Must be at least size() 226 void flatten(void* dst) const { 227 memcpy(dst, fData, fUsed); 228 } 229 230 bool writeToStream(SkWStream* stream) const { 231 return stream->write(fData, fUsed); 232 } 233 234 // read from the stream, and write up to length bytes. Return the actual 235 // number of bytes written. 236 size_t readFromStream(SkStream* stream, size_t length) { 237 return stream->read(this->reservePad(length), length); 238 } 239 240 /** 241 * Captures a snapshot of the data as it is right now, and return it. 242 */ 243 sk_sp<SkData> snapshotAsData() const; 244 private: 245 void growToAtLeast(size_t size); 246 247 uint8_t* fData; // Points to either fInternal or fExternal. 248 size_t fCapacity; // Number of bytes we can write to fData. 249 size_t fUsed; // Number of bytes written. 250 void* fExternal; // Unmanaged memory block. 251 SkAutoTMalloc<uint8_t> fInternal; // Managed memory block. 252 }; 253 254 /** 255 * Helper class to allocated SIZE bytes as part of the writer, and to provide 256 * that storage to the constructor as its initial storage buffer. 257 * 258 * This wrapper ensures proper alignment rules are met for the storage. 259 */ 260 template <size_t SIZE> class SkSWriter32 : public SkWriter32 { 261 public: 262 SkSWriter32() { this->reset(); } 263 264 void reset() {this->INHERITED::reset(fData.fStorage, SIZE); } 265 266 private: 267 union { 268 void* fPtrAlignment; 269 double fDoubleAlignment; 270 char fStorage[SIZE]; 271 } fData; 272 273 typedef SkWriter32 INHERITED; 274 }; 275 276 #endif 277
