SkStream.h revision 884300dca5531f60535501424bbd86b30e20450a
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 value) { 198 uint8_t v = SkToU8(value); 199 return this->write(&v, 1); 200 } 201 bool write16(U16CPU value) { 202 uint16_t v = SkToU16(value); 203 return this->write(&v, 2); 204 } 205 bool write32(uint32_t v) { 206 return this->write(&v, 4); 207 } 208 209 bool writeText(const char text[]) { 210 SkASSERT(text); 211 return this->write(text, strlen(text)); 212 } 213 bool writeDecAsText(int32_t); 214 bool writeBigDecAsText(int64_t, int minDigits = 0); 215 bool writeHexAsText(uint32_t, int minDigits = 0); 216 bool writeScalarAsText(SkScalar); 217 218 bool writeBool(bool v) { return this->write8(v); } 219 bool writeScalar(SkScalar); 220 bool writePackedUInt(size_t); 221 222 bool writeStream(SkStream* input, size_t length); 223 224 /** 225 * This returns the number of bytes in the stream required to store 226 * 'value'. 227 */ 228 static int SizeOfPackedUInt(size_t value); 229}; 230 231//////////////////////////////////////////////////////////////////////////////////////// 232 233#include "SkString.h" 234#include <stdio.h> 235 236/** A stream that wraps a C FILE* file stream. */ 237class SK_API SkFILEStream : public SkStreamAsset { 238public: 239 /** Initialize the stream by calling sk_fopen on the specified path. 240 * This internal stream will be closed in the destructor. 241 */ 242 explicit SkFILEStream(const char path[] = NULL); 243 244 enum Ownership { 245 kCallerPasses_Ownership, 246 kCallerRetains_Ownership 247 }; 248 /** Initialize the stream with an existing C file stream. 249 * While this stream exists, it assumes exclusive access to the C file stream. 250 * The C file stream will be closed in the destructor unless the caller specifies 251 * kCallerRetains_Ownership. 252 */ 253 explicit SkFILEStream(FILE* file, Ownership ownership = kCallerPasses_Ownership); 254 255 virtual ~SkFILEStream(); 256 257 /** Returns true if the current path could be opened. */ 258 bool isValid() const { return fFILE != NULL; } 259 260 /** Close the current file, and open a new file with the specified path. 261 * If path is NULL, just close the current file. 262 */ 263 void setPath(const char path[]); 264 265 size_t read(void* buffer, size_t size) override; 266 bool isAtEnd() const override; 267 268 bool rewind() override; 269 SkStreamAsset* duplicate() const override; 270 271 size_t getPosition() const override; 272 bool seek(size_t position) override; 273 bool move(long offset) override; 274 SkStreamAsset* fork() const override; 275 276 size_t getLength() const override; 277 278 const void* getMemoryBase() override; 279 280private: 281 FILE* fFILE; 282 SkString fName; 283 Ownership fOwnership; 284 // fData is lazilly initialized when needed. 285 mutable sk_sp<SkData> fData; 286 287 typedef SkStreamAsset INHERITED; 288}; 289 290class SK_API SkMemoryStream : public SkStreamMemory { 291public: 292 SkMemoryStream(); 293 294 /** We allocate (and free) the memory. Write to it via getMemoryBase() */ 295 SkMemoryStream(size_t length); 296 297 /** If copyData is true, the stream makes a private copy of the data. */ 298 SkMemoryStream(const void* data, size_t length, bool copyData = false); 299 300 /** Creates the stream to read from the specified data */ 301 SkMemoryStream(sk_sp<SkData>); 302 303 /** Resets the stream to the specified data and length, 304 just like the constructor. 305 if copyData is true, the stream makes a private copy of the data 306 */ 307 virtual void setMemory(const void* data, size_t length, 308 bool copyData = false); 309 /** Replace any memory buffer with the specified buffer. The caller 310 must have allocated data with sk_malloc or sk_realloc, since it 311 will be freed with sk_free. 312 */ 313 void setMemoryOwned(const void* data, size_t length); 314 315 sk_sp<SkData> asData() const { return fData; } 316 void setData(sk_sp<SkData>); 317 318 void skipToAlign4(); 319 const void* getAtPos(); 320 321 size_t read(void* buffer, size_t size) override; 322 bool isAtEnd() const override; 323 324 size_t peek(void* buffer, size_t size) const override; 325 326 bool rewind() override; 327 SkMemoryStream* duplicate() const override; 328 329 size_t getPosition() const override; 330 bool seek(size_t position) override; 331 bool move(long offset) override; 332 SkMemoryStream* fork() const override; 333 334 size_t getLength() const override; 335 336 const void* getMemoryBase() override; 337 338private: 339 sk_sp<SkData> fData; 340 size_t fOffset; 341 342 typedef SkStreamMemory INHERITED; 343}; 344 345///////////////////////////////////////////////////////////////////////////////////////////// 346 347class SK_API SkFILEWStream : public SkWStream { 348public: 349 SkFILEWStream(const char path[]); 350 virtual ~SkFILEWStream(); 351 352 /** Returns true if the current path could be opened. 353 */ 354 bool isValid() const { return fFILE != NULL; } 355 356 bool write(const void* buffer, size_t size) override; 357 void flush() override; 358 void fsync(); 359 size_t bytesWritten() const override; 360 361private: 362 FILE* fFILE; 363 364 typedef SkWStream INHERITED; 365}; 366 367class SK_API SkMemoryWStream : public SkWStream { 368public: 369 SkMemoryWStream(void* buffer, size_t size); 370 bool write(const void* buffer, size_t size) override; 371 size_t bytesWritten() const override { return fBytesWritten; } 372 373private: 374 char* fBuffer; 375 size_t fMaxLength; 376 size_t fBytesWritten; 377 378 typedef SkWStream INHERITED; 379}; 380 381class SK_API SkDynamicMemoryWStream : public SkWStream { 382public: 383 SkDynamicMemoryWStream(); 384 virtual ~SkDynamicMemoryWStream(); 385 386 bool write(const void* buffer, size_t size) override; 387 size_t bytesWritten() const override; 388 389 bool read(void* buffer, size_t offset, size_t size); 390 391 /** More efficient version of read(dst, 0, bytesWritten()). */ 392 void copyTo(void* dst) const; 393 void writeToStream(SkWStream* dst) const; 394 395 /** Return the contents as SkData, and then reset the stream. */ 396 sk_sp<SkData> detachAsData(); 397 398 /** Reset, returning a reader stream with the current content. */ 399 SkStreamAsset* detachAsStream(); 400 401 /** Reset the stream to its original, empty, state. */ 402 void reset(); 403 void padToAlign4(); 404private: 405 struct Block; 406 Block* fHead; 407 Block* fTail; 408 size_t fBytesWrittenBeforeTail; 409 410#ifdef SK_DEBUG 411 void validate() const; 412#else 413 void validate() const {} 414#endif 415 416 // For access to the Block type. 417 friend class SkBlockMemoryStream; 418 friend class SkBlockMemoryRefCnt; 419 420 typedef SkWStream INHERITED; 421}; 422 423 424class SK_API SkDebugWStream : public SkWStream { 425public: 426 SkDebugWStream() : fBytesWritten(0) {} 427 428 // overrides 429 bool write(const void* buffer, size_t size) override; 430 void newline() override; 431 size_t bytesWritten() const override { return fBytesWritten; } 432 433private: 434 size_t fBytesWritten; 435 typedef SkWStream INHERITED; 436}; 437 438// for now 439typedef SkFILEStream SkURLStream; 440 441#endif 442