SkStream.h revision 09d9435835f48b06954904f16d14c1c2eeaaad2e
1/* 2 * Copyright 2006 The Android Open Source Project 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8#ifndef SkStream_DEFINED 9#define SkStream_DEFINED 10 11#include "SkData.h" 12#include "SkRefCnt.h" 13#include "SkScalar.h" 14 15class SkStream; 16class SkStreamRewindable; 17class SkStreamSeekable; 18class SkStreamAsset; 19class SkStreamMemory; 20 21/** 22 * SkStream -- abstraction for a source of bytes. Subclasses can be backed by 23 * memory, or a file, or something else. 24 * 25 * NOTE: 26 * 27 * Classic "streams" APIs are sort of async, in that on a request for N 28 * bytes, they may return fewer than N bytes on a given call, in which case 29 * the caller can "try again" to get more bytes, eventually (modulo an error) 30 * receiving their total N bytes. 31 * 32 * Skia streams behave differently. They are effectively synchronous, and will 33 * always return all N bytes of the request if possible. If they return fewer 34 * (the read() call returns the number of bytes read) then that means there is 35 * no more data (at EOF or hit an error). The caller should *not* call again 36 * in hopes of fulfilling more of the request. 37 */ 38class SK_API SkStream : public SkNoncopyable { 39public: 40 virtual ~SkStream() {} 41 42 /** 43 * Attempts to open the specified file as a stream, returns nullptr on failure. 44 */ 45 static std::unique_ptr<SkStreamAsset> MakeFromFile(const char path[]); 46 47 /** Reads or skips size number of bytes. 48 * If buffer == NULL, skip size bytes, return how many were skipped. 49 * If buffer != NULL, copy size bytes into buffer, return how many were copied. 50 * @param buffer when NULL skip size bytes, otherwise copy size bytes into buffer 51 * @param size the number of bytes to skip or copy 52 * @return the number of bytes actually read. 53 */ 54 virtual size_t read(void* buffer, size_t size) = 0; 55 56 /** Skip size number of bytes. 57 * @return the actual number bytes that could be skipped. 58 */ 59 size_t skip(size_t size) { 60 return this->read(NULL, size); 61 } 62 63 /** 64 * Attempt to peek at size bytes. 65 * If this stream supports peeking, copy min(size, peekable bytes) into 66 * buffer, and return the number of bytes copied. 67 * If the stream does not support peeking, or cannot peek any bytes, 68 * return 0 and leave buffer unchanged. 69 * The stream is guaranteed to be in the same visible state after this 70 * call, regardless of success or failure. 71 * @param buffer Must not be NULL, and must be at least size bytes. Destination 72 * to copy bytes. 73 * @param size Number of bytes to copy. 74 * @return The number of bytes peeked/copied. 75 */ 76 virtual size_t peek(void* /*buffer*/, size_t /*size*/) const { return 0; } 77 78 /** Returns true when all the bytes in the stream have been read. 79 * This may return true early (when there are no more bytes to be read) 80 * or late (after the first unsuccessful read). 81 */ 82 virtual bool isAtEnd() const = 0; 83 84 int8_t readS8(); 85 int16_t readS16(); 86 int32_t readS32(); 87 88 uint8_t readU8() { return (uint8_t)this->readS8(); } 89 uint16_t readU16() { return (uint16_t)this->readS16(); } 90 uint32_t readU32() { return (uint32_t)this->readS32(); } 91 92 bool readBool() { return this->readU8() != 0; } 93 SkScalar readScalar(); 94 size_t readPackedUInt(); 95 96//SkStreamRewindable 97 /** Rewinds to the beginning of the stream. Returns true if the stream is known 98 * to be at the beginning after this call returns. 99 */ 100 virtual bool rewind() { return false; } 101 102 /** Duplicates this stream. If this cannot be done, returns NULL. 103 * The returned stream will be positioned at the beginning of its data. 104 */ 105 virtual SkStreamRewindable* duplicate() const { return NULL; } 106 107//SkStreamSeekable 108 /** Returns true if this stream can report it's current position. */ 109 virtual bool hasPosition() const { return false; } 110 /** Returns the current position in the stream. If this cannot be done, returns 0. */ 111 virtual size_t getPosition() const { return 0; } 112 113 /** Seeks to an absolute position in the stream. If this cannot be done, returns false. 114 * If an attempt is made to seek past the end of the stream, the position will be set 115 * to the end of the stream. 116 */ 117 virtual bool seek(size_t /*position*/) { return false; } 118 119 /** Seeks to an relative offset in the stream. If this cannot be done, returns false. 120 * If an attempt is made to move to a position outside the stream, the position will be set 121 * to the closest point within the stream (beginning or end). 122 */ 123 virtual bool move(long /*offset*/) { return false; } 124 125 /** Duplicates this stream. If this cannot be done, returns NULL. 126 * The returned stream will be positioned the same as this stream. 127 */ 128 virtual SkStreamSeekable* fork() const { return NULL; } 129 130//SkStreamAsset 131 /** Returns true if this stream can report it's total length. */ 132 virtual bool hasLength() const { return false; } 133 /** Returns the total length of the stream. If this cannot be done, returns 0. */ 134 virtual size_t getLength() const { return 0; } 135 136//SkStreamMemory 137 /** Returns the starting address for the data. If this cannot be done, returns NULL. */ 138 //TODO: replace with virtual const SkData* getData() 139 virtual const void* getMemoryBase() { return NULL; } 140}; 141 142/** SkStreamRewindable is a SkStream for which rewind and duplicate are required. */ 143class SK_API SkStreamRewindable : public SkStream { 144public: 145 bool rewind() override = 0; 146 SkStreamRewindable* duplicate() const override = 0; 147}; 148 149/** SkStreamSeekable is a SkStreamRewindable for which position, seek, move, and fork are required. */ 150class SK_API SkStreamSeekable : public SkStreamRewindable { 151public: 152 SkStreamSeekable* duplicate() const override = 0; 153 154 bool hasPosition() const override { return true; } 155 size_t getPosition() const override = 0; 156 bool seek(size_t position) override = 0; 157 bool move(long offset) override = 0; 158 SkStreamSeekable* fork() const override = 0; 159}; 160 161/** SkStreamAsset is a SkStreamSeekable for which getLength is required. */ 162class SK_API SkStreamAsset : public SkStreamSeekable { 163public: 164 SkStreamAsset* duplicate() const override = 0; 165 SkStreamAsset* fork() const override = 0; 166 167 bool hasLength() const override { return true; } 168 size_t getLength() const override = 0; 169}; 170 171/** SkStreamMemory is a SkStreamAsset for which getMemoryBase is required. */ 172class SK_API SkStreamMemory : public SkStreamAsset { 173public: 174 SkStreamMemory* duplicate() const override = 0; 175 SkStreamMemory* fork() const override = 0; 176 177 const void* getMemoryBase() override = 0; 178}; 179 180class SK_API SkWStream : SkNoncopyable { 181public: 182 virtual ~SkWStream(); 183 184 /** Called to write bytes to a SkWStream. Returns true on success 185 @param buffer the address of at least size bytes to be written to the stream 186 @param size The number of bytes in buffer to write to the stream 187 @return true on success 188 */ 189 virtual bool write(const void* buffer, size_t size) = 0; 190 virtual void newline(); 191 virtual void flush(); 192 193 virtual size_t bytesWritten() const = 0; 194 195 // helpers 196 197 bool write8(U8CPU); 198 bool write16(U16CPU); 199 bool write32(uint32_t); 200 201 bool writeText(const char text[]) { 202 SkASSERT(text); 203 return this->write(text, strlen(text)); 204 } 205 bool writeDecAsText(int32_t); 206 bool writeBigDecAsText(int64_t, int minDigits = 0); 207 bool writeHexAsText(uint32_t, int minDigits = 0); 208 bool writeScalarAsText(SkScalar); 209 210 bool writeBool(bool v) { return this->write8(v); } 211 bool writeScalar(SkScalar); 212 bool writePackedUInt(size_t); 213 214 bool writeStream(SkStream* input, size_t length); 215 216 /** 217 * This returns the number of bytes in the stream required to store 218 * 'value'. 219 */ 220 static int SizeOfPackedUInt(size_t value); 221}; 222 223//////////////////////////////////////////////////////////////////////////////////////// 224 225#include "SkString.h" 226#include <stdio.h> 227 228/** A stream that wraps a C FILE* file stream. */ 229class SK_API SkFILEStream : public SkStreamAsset { 230public: 231 /** Initialize the stream by calling sk_fopen on the specified path. 232 * This internal stream will be closed in the destructor. 233 */ 234 explicit SkFILEStream(const char path[] = NULL); 235 236 enum Ownership { 237 kCallerPasses_Ownership, 238 kCallerRetains_Ownership 239 }; 240 /** Initialize the stream with an existing C file stream. 241 * While this stream exists, it assumes exclusive access to the C file stream. 242 * The C file stream will be closed in the destructor unless the caller specifies 243 * kCallerRetains_Ownership. 244 */ 245 explicit SkFILEStream(FILE* file, Ownership ownership = kCallerPasses_Ownership); 246 247 virtual ~SkFILEStream(); 248 249 /** Returns true if the current path could be opened. */ 250 bool isValid() const { return fFILE != NULL; } 251 252 /** Close the current file, and open a new file with the specified path. 253 * If path is NULL, just close the current file. 254 */ 255 void setPath(const char path[]); 256 257 size_t read(void* buffer, size_t size) override; 258 bool isAtEnd() const override; 259 260 bool rewind() override; 261 SkStreamAsset* duplicate() const override; 262 263 size_t getPosition() const override; 264 bool seek(size_t position) override; 265 bool move(long offset) override; 266 SkStreamAsset* fork() const override; 267 268 size_t getLength() const override; 269 270 const void* getMemoryBase() override; 271 272private: 273 FILE* fFILE; 274 SkString fName; 275 Ownership fOwnership; 276 // fData is lazilly initialized when needed. 277 mutable sk_sp<SkData> fData; 278 279 typedef SkStreamAsset INHERITED; 280}; 281 282class SK_API SkMemoryStream : public SkStreamMemory { 283public: 284 SkMemoryStream(); 285 286 /** We allocate (and free) the memory. Write to it via getMemoryBase() */ 287 SkMemoryStream(size_t length); 288 289 /** If copyData is true, the stream makes a private copy of the data. */ 290 SkMemoryStream(const void* data, size_t length, bool copyData = false); 291 292 /** Creates the stream to read from the specified data */ 293 SkMemoryStream(sk_sp<SkData>); 294 295 /** Resets the stream to the specified data and length, 296 just like the constructor. 297 if copyData is true, the stream makes a private copy of the data 298 */ 299 virtual void setMemory(const void* data, size_t length, 300 bool copyData = false); 301 /** Replace any memory buffer with the specified buffer. The caller 302 must have allocated data with sk_malloc or sk_realloc, since it 303 will be freed with sk_free. 304 */ 305 void setMemoryOwned(const void* data, size_t length); 306 307 sk_sp<SkData> asData() const { return fData; } 308 void setData(sk_sp<SkData>); 309 310 void skipToAlign4(); 311 const void* getAtPos(); 312 313 size_t read(void* buffer, size_t size) override; 314 bool isAtEnd() const override; 315 316 size_t peek(void* buffer, size_t size) const override; 317 318 bool rewind() override; 319 SkMemoryStream* duplicate() const override; 320 321 size_t getPosition() const override; 322 bool seek(size_t position) override; 323 bool move(long offset) override; 324 SkMemoryStream* fork() const override; 325 326 size_t getLength() const override; 327 328 const void* getMemoryBase() override; 329 330private: 331 sk_sp<SkData> fData; 332 size_t fOffset; 333 334 typedef SkStreamMemory INHERITED; 335}; 336 337///////////////////////////////////////////////////////////////////////////////////////////// 338 339class SK_API SkFILEWStream : public SkWStream { 340public: 341 SkFILEWStream(const char path[]); 342 virtual ~SkFILEWStream(); 343 344 /** Returns true if the current path could be opened. 345 */ 346 bool isValid() const { return fFILE != NULL; } 347 348 bool write(const void* buffer, size_t size) override; 349 void flush() override; 350 void fsync(); 351 size_t bytesWritten() const override; 352 353private: 354 FILE* fFILE; 355 356 typedef SkWStream INHERITED; 357}; 358 359class SK_API SkMemoryWStream : public SkWStream { 360public: 361 SkMemoryWStream(void* buffer, size_t size); 362 bool write(const void* buffer, size_t size) override; 363 size_t bytesWritten() const override { return fBytesWritten; } 364 365private: 366 char* fBuffer; 367 size_t fMaxLength; 368 size_t fBytesWritten; 369 370 typedef SkWStream INHERITED; 371}; 372 373class SK_API SkDynamicMemoryWStream : public SkWStream { 374public: 375 SkDynamicMemoryWStream(); 376 virtual ~SkDynamicMemoryWStream(); 377 378 bool write(const void* buffer, size_t size) override; 379 size_t bytesWritten() const override { return fBytesWritten; } 380 // random access write 381 // modifies stream and returns true if offset + size is less than or equal to getOffset() 382 bool write(const void* buffer, size_t offset, size_t size); 383 bool read(void* buffer, size_t offset, size_t size); 384 size_t getOffset() const { return fBytesWritten; } 385 386 // copy what has been written to the stream into dst 387 void copyTo(void* dst) const; 388 void writeToStream(SkWStream* dst) const; 389 390 sk_sp<SkData> snapshotAsData() const; 391 // Return the contents as SkData, and then reset the stream. 392 sk_sp<SkData> detachAsData(); 393 394 /** Reset, returning a reader stream with the current content. */ 395 SkStreamAsset* detachAsStream(); 396 397 /** Reset the stream to its original, empty, state. */ 398 void reset(); 399 void padToAlign4(); 400private: 401 struct Block; 402 Block* fHead; 403 Block* fTail; 404 size_t fBytesWritten; 405 mutable sk_sp<SkData> fCopy; // is invalidated if we write after it is created 406 407 void invalidateCopy(); 408 409 // For access to the Block type. 410 friend class SkBlockMemoryStream; 411 friend class SkBlockMemoryRefCnt; 412 413 typedef SkWStream INHERITED; 414}; 415 416 417class SK_API SkDebugWStream : public SkWStream { 418public: 419 SkDebugWStream() : fBytesWritten(0) {} 420 421 // overrides 422 bool write(const void* buffer, size_t size) override; 423 void newline() override; 424 size_t bytesWritten() const override { return fBytesWritten; } 425 426private: 427 size_t fBytesWritten; 428 typedef SkWStream INHERITED; 429}; 430 431// for now 432typedef SkFILEStream SkURLStream; 433 434#endif 435