SkStream.h revision 7af21501a61886cac94f0bd5e1c14be2dce9ae63
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 "SkRefCnt.h" 12#include "SkScalar.h" 13 14class SkData; 15 16class SkStream; 17class SkStreamRewindable; 18class SkStreamSeekable; 19class SkStreamAsset; 20class SkStreamMemory; 21 22/** 23 * SkStream -- abstraction for a source of bytes. Subclasses can be backed by 24 * memory, or a file, or something else. 25 * 26 * NOTE: 27 * 28 * Classic "streams" APIs are sort of async, in that on a request for N 29 * bytes, they may return fewer than N bytes on a given call, in which case 30 * the caller can "try again" to get more bytes, eventually (modulo an error) 31 * receiving their total N bytes. 32 * 33 * Skia streams behave differently. They are effectively synchronous, and will 34 * always return all N bytes of the request if possible. If they return fewer 35 * (the read() call returns the number of bytes read) then that means there is 36 * no more data (at EOF or hit an error). The caller should *not* call again 37 * in hopes of fulfilling more of the request. 38 */ 39class SK_API SkStream : public SkNoncopyable { 40public: 41 virtual ~SkStream() {} 42 43 /** 44 * Attempts to open the specified file, and return a stream to it (using 45 * mmap if available). On success, the caller is responsible for deleting. 46 * On failure, returns NULL. 47 */ 48 static SkStreamAsset* NewFromFile(const char path[]); 49 50 /** Reads or skips size number of bytes. 51 * If buffer == NULL, skip size bytes, return how many were skipped. 52 * If buffer != NULL, copy size bytes into buffer, return how many were copied. 53 * @param buffer when NULL skip size bytes, otherwise copy size bytes into buffer 54 * @param size the number of bytes to skip or copy 55 * @return the number of bytes actually read. 56 */ 57 virtual size_t read(void* buffer, size_t size) = 0; 58 59 /** Skip size number of bytes. 60 * @return the actual number bytes that could be skipped. 61 */ 62 size_t skip(size_t size) { 63 return this->read(NULL, size); 64 } 65 66 /** Returns true when all the bytes in the stream have been read. 67 * This may return true early (when there are no more bytes to be read) 68 * or late (after the first unsuccessful read). 69 */ 70 virtual bool isAtEnd() const = 0; 71 72 int8_t readS8(); 73 int16_t readS16(); 74 int32_t readS32(); 75 76 uint8_t readU8() { return (uint8_t)this->readS8(); } 77 uint16_t readU16() { return (uint16_t)this->readS16(); } 78 uint32_t readU32() { return (uint32_t)this->readS32(); } 79 80 bool readBool() { return this->readU8() != 0; } 81 SkScalar readScalar(); 82 size_t readPackedUInt(); 83 84//SkStreamRewindable 85 /** Rewinds to the beginning of the stream. Returns true if the stream is known 86 * to be at the beginning after this call returns. 87 */ 88 virtual bool rewind() { return false; } 89 90 /** Duplicates this stream. If this cannot be done, returns NULL. 91 * The returned stream will be positioned at the beginning of its data. 92 */ 93 virtual SkStreamRewindable* duplicate() const { return NULL; } 94 95//SkStreamSeekable 96 /** Returns true if this stream can report it's current position. */ 97 virtual bool hasPosition() const { return false; } 98 /** Returns the current position in the stream. If this cannot be done, returns 0. */ 99 virtual size_t getPosition() const { return 0; } 100 101 /** Seeks to an absolute position in the stream. If this cannot be done, returns false. 102 * If an attempt is made to seek past the end of the stream, the position will be set 103 * to the end of the stream. 104 */ 105 virtual bool seek(size_t /*position*/) { return false; } 106 107 /** Seeks to an relative offset in the stream. If this cannot be done, returns false. 108 * If an attempt is made to move to a position outside the stream, the position will be set 109 * to the closest point within the stream (beginning or end). 110 */ 111 virtual bool move(long /*offset*/) { return false; } 112 113 /** Duplicates this stream. If this cannot be done, returns NULL. 114 * The returned stream will be positioned the same as this stream. 115 */ 116 virtual SkStreamSeekable* fork() const { return NULL; } 117 118//SkStreamAsset 119 /** Returns true if this stream can report it's total length. */ 120 virtual bool hasLength() const { return false; } 121 /** Returns the total length of the stream. If this cannot be done, returns 0. */ 122 virtual size_t getLength() const { return 0; } 123 124//SkStreamMemory 125 /** Returns the starting address for the data. If this cannot be done, returns NULL. */ 126 //TODO: replace with virtual const SkData* getData() 127 virtual const void* getMemoryBase() { return NULL; } 128}; 129 130/** SkStreamRewindable is a SkStream for which rewind and duplicate are required. */ 131class SK_API SkStreamRewindable : public SkStream { 132public: 133 bool rewind() SK_OVERRIDE = 0; 134 SkStreamRewindable* duplicate() const SK_OVERRIDE = 0; 135}; 136 137/** SkStreamSeekable is a SkStreamRewindable for which position, seek, move, and fork are required. */ 138class SK_API SkStreamSeekable : public SkStreamRewindable { 139public: 140 SkStreamSeekable* duplicate() const SK_OVERRIDE = 0; 141 142 bool hasPosition() const SK_OVERRIDE { return true; } 143 size_t getPosition() const SK_OVERRIDE = 0; 144 bool seek(size_t position) SK_OVERRIDE = 0; 145 bool move(long offset) SK_OVERRIDE = 0; 146 SkStreamSeekable* fork() const SK_OVERRIDE = 0; 147}; 148 149/** SkStreamAsset is a SkStreamSeekable for which getLength is required. */ 150class SK_API SkStreamAsset : public SkStreamSeekable { 151public: 152 SkStreamAsset* duplicate() const SK_OVERRIDE = 0; 153 SkStreamAsset* fork() const SK_OVERRIDE = 0; 154 155 bool hasLength() const SK_OVERRIDE { return true; } 156 size_t getLength() const SK_OVERRIDE = 0; 157}; 158 159/** SkStreamMemory is a SkStreamAsset for which getMemoryBase is required. */ 160class SK_API SkStreamMemory : public SkStreamAsset { 161public: 162 SkStreamMemory* duplicate() const SK_OVERRIDE = 0; 163 SkStreamMemory* fork() const SK_OVERRIDE = 0; 164 165 const void* getMemoryBase() SK_OVERRIDE = 0; 166}; 167 168class SK_API SkWStream : SkNoncopyable { 169public: 170 SK_DECLARE_INST_COUNT(SkWStream) 171 172 virtual ~SkWStream(); 173 174 /** Called to write bytes to a SkWStream. Returns true on success 175 @param buffer the address of at least size bytes to be written to the stream 176 @param size The number of bytes in buffer to write to the stream 177 @return true on success 178 */ 179 virtual bool write(const void* buffer, size_t size) = 0; 180 virtual void newline(); 181 virtual void flush(); 182 183 virtual size_t bytesWritten() const = 0; 184 185 // helpers 186 187 bool write8(U8CPU); 188 bool write16(U16CPU); 189 bool write32(uint32_t); 190 191 bool writeText(const char text[]); 192 bool writeDecAsText(int32_t); 193 bool writeBigDecAsText(int64_t, int minDigits = 0); 194 bool writeHexAsText(uint32_t, int minDigits = 0); 195 bool writeScalarAsText(SkScalar); 196 197 bool writeBool(bool v) { return this->write8(v); } 198 bool writeScalar(SkScalar); 199 bool writePackedUInt(size_t); 200 201 bool writeStream(SkStream* input, size_t length); 202 203 /** 204 * This returns the number of bytes in the stream required to store 205 * 'value'. 206 */ 207 static int SizeOfPackedUInt(size_t value); 208}; 209 210//////////////////////////////////////////////////////////////////////////////////////// 211 212#include "SkString.h" 213#include <stdio.h> 214 215struct SkFILE; 216 217/** A stream that wraps a C FILE* file stream. */ 218class SK_API SkFILEStream : public SkStreamAsset { 219public: 220 SK_DECLARE_INST_COUNT(SkFILEStream) 221 222 /** Initialize the stream by calling sk_fopen on the specified path. 223 * This internal stream will be closed in the destructor. 224 */ 225 explicit SkFILEStream(const char path[] = NULL); 226 227 enum Ownership { 228 kCallerPasses_Ownership, 229 kCallerRetains_Ownership 230 }; 231 /** Initialize the stream with an existing C file stream. 232 * While this stream exists, it assumes exclusive access to the C file stream. 233 * The C file stream will be closed in the destructor unless the caller specifies 234 * kCallerRetains_Ownership. 235 */ 236 explicit SkFILEStream(FILE* file, Ownership ownership = kCallerPasses_Ownership); 237 238 virtual ~SkFILEStream(); 239 240 /** Returns true if the current path could be opened. */ 241 bool isValid() const { return fFILE != NULL; } 242 243 /** Close the current file, and open a new file with the specified path. 244 * If path is NULL, just close the current file. 245 */ 246 void setPath(const char path[]); 247 248 size_t read(void* buffer, size_t size) SK_OVERRIDE; 249 bool isAtEnd() const SK_OVERRIDE; 250 251 bool rewind() SK_OVERRIDE; 252 SkStreamAsset* duplicate() const SK_OVERRIDE; 253 254 size_t getPosition() const SK_OVERRIDE; 255 bool seek(size_t position) SK_OVERRIDE; 256 bool move(long offset) SK_OVERRIDE; 257 SkStreamAsset* fork() const SK_OVERRIDE; 258 259 size_t getLength() const SK_OVERRIDE; 260 261 const void* getMemoryBase() SK_OVERRIDE; 262 263private: 264 SkFILE* fFILE; 265 SkString fName; 266 Ownership fOwnership; 267 // fData is lazilly initialized when needed. 268 mutable SkAutoTUnref<SkData> fData; 269 270 typedef SkStreamAsset INHERITED; 271}; 272 273class SK_API SkMemoryStream : public SkStreamMemory { 274public: 275 SK_DECLARE_INST_COUNT(SkMemoryStream) 276 277 SkMemoryStream(); 278 279 /** We allocate (and free) the memory. Write to it via getMemoryBase() */ 280 SkMemoryStream(size_t length); 281 282 /** If copyData is true, the stream makes a private copy of the data. */ 283 SkMemoryStream(const void* data, size_t length, bool copyData = false); 284 285 /** Use the specified data as the memory for this stream. 286 * The stream will call ref() on the data (assuming it is not NULL). 287 */ 288 SkMemoryStream(SkData*); 289 290 virtual ~SkMemoryStream(); 291 292 /** Resets the stream to the specified data and length, 293 just like the constructor. 294 if copyData is true, the stream makes a private copy of the data 295 */ 296 virtual void setMemory(const void* data, size_t length, 297 bool copyData = false); 298 /** Replace any memory buffer with the specified buffer. The caller 299 must have allocated data with sk_malloc or sk_realloc, since it 300 will be freed with sk_free. 301 */ 302 void setMemoryOwned(const void* data, size_t length); 303 304 /** Return the stream's data in a SkData. 305 * The caller must call unref() when it is finished using the data. 306 */ 307 SkData* copyToData() const; 308 309 /** 310 * Use the specified data as the memory for this stream. 311 * The stream will call ref() on the data (assuming it is not NULL). 312 * The function returns the data parameter as a convenience. 313 */ 314 SkData* setData(SkData*); 315 316 void skipToAlign4(); 317 const void* getAtPos(); 318 size_t peek() const { return fOffset; } 319 320 size_t read(void* buffer, size_t size) SK_OVERRIDE; 321 bool isAtEnd() const SK_OVERRIDE; 322 323 bool rewind() SK_OVERRIDE; 324 SkMemoryStream* duplicate() const SK_OVERRIDE; 325 326 size_t getPosition() const SK_OVERRIDE; 327 bool seek(size_t position) SK_OVERRIDE; 328 bool move(long offset) SK_OVERRIDE; 329 SkMemoryStream* fork() const SK_OVERRIDE; 330 331 size_t getLength() const SK_OVERRIDE; 332 333 const void* getMemoryBase() SK_OVERRIDE; 334 335private: 336 SkData* fData; 337 size_t fOffset; 338 339 typedef SkStreamMemory INHERITED; 340}; 341 342///////////////////////////////////////////////////////////////////////////////////////////// 343 344class SK_API SkFILEWStream : public SkWStream { 345public: 346 SK_DECLARE_INST_COUNT(SkFILEWStream) 347 348 SkFILEWStream(const char path[]); 349 virtual ~SkFILEWStream(); 350 351 /** Returns true if the current path could be opened. 352 */ 353 bool isValid() const { return fFILE != NULL; } 354 355 bool write(const void* buffer, size_t size) SK_OVERRIDE; 356 void flush() SK_OVERRIDE; 357 size_t bytesWritten() const SK_OVERRIDE; 358 359private: 360 SkFILE* fFILE; 361 362 typedef SkWStream INHERITED; 363}; 364 365class SkMemoryWStream : public SkWStream { 366public: 367 SK_DECLARE_INST_COUNT(SkMemoryWStream) 368 369 SkMemoryWStream(void* buffer, size_t size); 370 bool write(const void* buffer, size_t size) SK_OVERRIDE; 371 size_t bytesWritten() const SK_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 SK_DECLARE_INST_COUNT(SkDynamicMemoryWStream) 384 385 SkDynamicMemoryWStream(); 386 virtual ~SkDynamicMemoryWStream(); 387 388 bool write(const void* buffer, size_t size) SK_OVERRIDE; 389 size_t bytesWritten() const SK_OVERRIDE { return fBytesWritten; } 390 // random access write 391 // modifies stream and returns true if offset + size is less than or equal to getOffset() 392 bool write(const void* buffer, size_t offset, size_t size); 393 bool read(void* buffer, size_t offset, size_t size); 394 size_t getOffset() const { return fBytesWritten; } 395 396 // copy what has been written to the stream into dst 397 void copyTo(void* dst) const; 398 void writeToStream(SkWStream* dst) const; 399 400 /** 401 * Return a copy of the data written so far. This call is responsible for 402 * calling unref() when they are finished with the data. 403 */ 404 SkData* copyToData() const; 405 406 /** Reset, returning a reader stream with the current content. */ 407 SkStreamAsset* detachAsStream(); 408 409 /** Reset the stream to its original, empty, state. */ 410 void reset(); 411 void padToAlign4(); 412private: 413 struct Block; 414 Block* fHead; 415 Block* fTail; 416 size_t fBytesWritten; 417 mutable SkData* fCopy; // is invalidated if we write after it is created 418 419 void invalidateCopy(); 420 421 // For access to the Block type. 422 friend class SkBlockMemoryStream; 423 friend class SkBlockMemoryRefCnt; 424 425 typedef SkWStream INHERITED; 426}; 427 428 429class SK_API SkDebugWStream : public SkWStream { 430public: 431 SkDebugWStream() : fBytesWritten(0) {} 432 SK_DECLARE_INST_COUNT(SkDebugWStream) 433 434 // overrides 435 bool write(const void* buffer, size_t size) SK_OVERRIDE; 436 void newline() SK_OVERRIDE; 437 size_t bytesWritten() const SK_OVERRIDE { return fBytesWritten; } 438 439private: 440 size_t fBytesWritten; 441 typedef SkWStream INHERITED; 442}; 443 444// for now 445typedef SkFILEStream SkURLStream; 446 447#endif 448