1 /* 2 * Copyright (c) 1999, 2007, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package javax.imageio.stream; 27 28 import java.io.Closeable; 29 import java.io.DataInput; 30 import java.io.IOException; 31 import java.nio.ByteOrder; 32 33 /** 34 * A seekable input stream interface for use by 35 * <code>ImageReader</code>s. Various input sources, such as 36 * <code>InputStream</code>s and <code>File</code>s, 37 * as well as future fast I/O sources may be "wrapped" by a suitable 38 * implementation of this interface for use by the Image I/O API. 39 * 40 * @see ImageInputStreamImpl 41 * @see FileImageInputStream 42 * @see FileCacheImageInputStream 43 * @see MemoryCacheImageInputStream 44 * 45 */ 46 public interface ImageInputStream extends DataInput, Closeable { 47 48 /** 49 * Sets the desired byte order for future reads of data values 50 * from this stream. For example, the sequence of bytes '0x01 51 * 0x02 0x03 0x04' if read as a 4-byte integer would have the 52 * value '0x01020304' using network byte order and the value 53 * '0x04030201' under the reverse byte order. 54 * 55 * <p> The enumeration class <code>java.nio.ByteOrder</code> is 56 * used to specify the byte order. A value of 57 * <code>ByteOrder.BIG_ENDIAN</code> specifies so-called 58 * big-endian or network byte order, in which the high-order byte 59 * comes first. Motorola and Sparc processors store data in this 60 * format, while Intel processors store data in the reverse 61 * <code>ByteOrder.LITTLE_ENDIAN</code> order. 62 * 63 * <p> The byte order has no effect on the results returned from 64 * the <code>readBits</code> method (or the value written by 65 * <code>ImageOutputStream.writeBits</code>). 66 * 67 * @param byteOrder one of <code>ByteOrder.BIG_ENDIAN</code> or 68 * <code>java.nio.ByteOrder.LITTLE_ENDIAN</code>, indicating whether 69 * network byte order or its reverse will be used for future 70 * reads. 71 * 72 * @see java.nio.ByteOrder 73 * @see #getByteOrder 74 * @see #readBits(int) 75 */ 76 void setByteOrder(ByteOrder byteOrder); 77 78 /** 79 * Returns the byte order with which data values will be read from 80 * this stream as an instance of the 81 * <code>java.nio.ByteOrder</code> enumeration. 82 * 83 * @return one of <code>ByteOrder.BIG_ENDIAN</code> or 84 * <code>ByteOrder.LITTLE_ENDIAN</code>, indicating which byte 85 * order is being used. 86 * 87 * @see java.nio.ByteOrder 88 * @see #setByteOrder 89 */ 90 ByteOrder getByteOrder(); 91 92 /** 93 * Reads a single byte from the stream and returns it as an 94 * integer between 0 and 255. If the end of the stream is 95 * reached, -1 is returned. 96 * 97 * <p> The bit offset within the stream is reset to zero before 98 * the read occurs. 99 * 100 * @return a byte value from the stream, as an int, or -1 to 101 * indicate EOF. 102 * 103 * @exception IOException if an I/O error occurs. 104 */ 105 int read() throws IOException; 106 107 /** 108 * Reads up to <code>b.length</code> bytes from the stream, and 109 * stores them into <code>b</code> starting at index 0. The 110 * number of bytes read is returned. If no bytes can be read 111 * because the end of the stream has been reached, -1 is returned. 112 * 113 * <p> The bit offset within the stream is reset to zero before 114 * the read occurs. 115 * 116 * @param b an array of bytes to be written to. 117 * 118 * @return the number of bytes actually read, or <code>-1</code> 119 * to indicate EOF. 120 * 121 * @exception NullPointerException if <code>b</code> is 122 * <code>null</code>. 123 * 124 * @exception IOException if an I/O error occurs. 125 */ 126 int read(byte[] b) throws IOException; 127 128 /** 129 * Reads up to <code>len</code> bytes from the stream, and stores 130 * them into <code>b</code> starting at index <code>off</code>. 131 * The number of bytes read is returned. If no bytes can be read 132 * because the end of the stream has been reached, <code>-1</code> 133 * is returned. 134 * 135 * <p> The bit offset within the stream is reset to zero before 136 * the read occurs. 137 * 138 * @param b an array of bytes to be written to. 139 * @param off the starting position within <code>b</code> to write to. 140 * @param len the maximum number of <code>byte</code>s to read. 141 * 142 * @return the number of bytes actually read, or <code>-1</code> 143 * to indicate EOF. 144 * 145 * @exception NullPointerException if <code>b</code> is 146 * <code>null</code>. 147 * @exception IndexOutOfBoundsException if <code>off</code> is 148 * negative, <code>len</code> is negative, or <code>off + 149 * len</code> is greater than <code>b.length</code>. 150 * @exception IOException if an I/O error occurs. 151 */ 152 int read(byte[] b, int off, int len) throws IOException; 153 154 /** 155 * Reads up to <code>len</code> bytes from the stream, and 156 * modifies the supplied <code>IIOByteBuffer</code> to indicate 157 * the byte array, offset, and length where the data may be found. 158 * The caller should not attempt to modify the data found in the 159 * <code>IIOByteBuffer</code>. 160 * 161 * <p> The bit offset within the stream is reset to zero before 162 * the read occurs. 163 * 164 * @param buf an IIOByteBuffer object to be modified. 165 * @param len the maximum number of <code>byte</code>s to read. 166 * 167 * @exception IndexOutOfBoundsException if <code>len</code> is 168 * negative. 169 * @exception NullPointerException if <code>buf</code> is 170 * <code>null</code>. 171 * 172 * @exception IOException if an I/O error occurs. 173 */ 174 void readBytes(IIOByteBuffer buf, int len) throws IOException; 175 176 /** 177 * Reads a byte from the stream and returns a <code>boolean</code> 178 * value of <code>true</code> if it is nonzero, <code>false</code> 179 * if it is zero. 180 * 181 * <p> The bit offset within the stream is reset to zero before 182 * the read occurs. 183 * 184 * @return a boolean value from the stream. 185 * 186 * @exception EOFException if the end of the stream is reached. 187 * @exception IOException if an I/O error occurs. 188 */ 189 boolean readBoolean() throws IOException; 190 191 /** 192 * Reads a byte from the stream and returns it as a 193 * <code>byte</code> value. Byte values between <code>0x00</code> 194 * and <code>0x7f</code> represent integer values between 195 * <code>0</code> and <code>127</code>. Values between 196 * <code>0x80</code> and <code>0xff</code> represent negative 197 * values from <code>-128</code> to <code>/1</code>. 198 * 199 * <p> The bit offset within the stream is reset to zero before 200 * the read occurs. 201 * 202 * @return a signed byte value from the stream. 203 * 204 * @exception EOFException if the end of the stream is reached. 205 * @exception IOException if an I/O error occurs. 206 */ 207 byte readByte() throws IOException; 208 209 /** 210 * Reads a byte from the stream, and (conceptually) converts it to 211 * an int, masks it with <code>0xff</code> in order to strip off 212 * any sign-extension bits, and returns it as a <code>byte</code> 213 * value. 214 * 215 * <p> Thus, byte values between <code>0x00</code> and 216 * <code>0x7f</code> are simply returned as integer values between 217 * <code>0</code> and <code>127</code>. Values between 218 * <code>0x80</code> and <code>0xff</code>, which normally 219 * represent negative <code>byte</code>values, will be mapped into 220 * positive integers between <code>128</code> and 221 * <code>255</code>. 222 * 223 * <p> The bit offset within the stream is reset to zero before 224 * the read occurs. 225 * 226 * @return an unsigned byte value from the stream. 227 * 228 * @exception EOFException if the end of the stream is reached. 229 * @exception IOException if an I/O error occurs. 230 */ 231 int readUnsignedByte() throws IOException; 232 233 /** 234 * Reads two bytes from the stream, and (conceptually) 235 * concatenates them according to the current byte order, and 236 * returns the result as a <code>short</code> value. 237 * 238 * <p> The bit offset within the stream is reset to zero before 239 * the read occurs. 240 * 241 * @return a signed short value from the stream. 242 * 243 * @exception EOFException if the stream reaches the end before 244 * reading all the bytes. 245 * @exception IOException if an I/O error occurs. 246 * 247 * @see #getByteOrder 248 */ 249 short readShort() throws IOException; 250 251 /** 252 * Reads two bytes from the stream, and (conceptually) 253 * concatenates them according to the current byte order, converts 254 * the resulting value to an <code>int</code>, masks it with 255 * <code>0xffff</code> in order to strip off any sign-extension 256 * buts, and returns the result as an unsigned <code>int</code> 257 * value. 258 * 259 * <p> The bit offset within the stream is reset to zero before 260 * the read occurs. 261 * 262 * @return an unsigned short value from the stream, as an int. 263 * 264 * @exception EOFException if the stream reaches the end before 265 * reading all the bytes. 266 * @exception IOException if an I/O error occurs. 267 * 268 * @see #getByteOrder 269 */ 270 int readUnsignedShort() throws IOException; 271 272 /** 273 * Equivalent to <code>readUnsignedShort</code>, except that the 274 * result is returned using the <code>char</code> datatype. 275 * 276 * <p> The bit offset within the stream is reset to zero before 277 * the read occurs. 278 * 279 * @return an unsigned char value from the stream. 280 * 281 * @exception EOFException if the stream reaches the end before 282 * reading all the bytes. 283 * @exception IOException if an I/O error occurs. 284 * 285 * @see #readUnsignedShort 286 */ 287 char readChar() throws IOException; 288 289 /** 290 * Reads 4 bytes from the stream, and (conceptually) concatenates 291 * them according to the current byte order and returns the result 292 * as an <code>int</code>. 293 * 294 * <p> The bit offset within the stream is ignored and treated as 295 * though it were zero. 296 * 297 * @return a signed int value from the stream. 298 * 299 * @exception EOFException if the stream reaches the end before 300 * reading all the bytes. 301 * @exception IOException if an I/O error occurs. 302 * 303 * @see #getByteOrder 304 */ 305 int readInt() throws IOException; 306 307 /** 308 * Reads 4 bytes from the stream, and (conceptually) concatenates 309 * them according to the current byte order, converts the result 310 * to a long, masks it with <code>0xffffffffL</code> in order to 311 * strip off any sign-extension bits, and returns the result as an 312 * unsigned <code>long</code> value. 313 * 314 * <p> The bit offset within the stream is reset to zero before 315 * the read occurs. 316 * 317 * @return an unsigned int value from the stream, as a long. 318 * 319 * @exception EOFException if the stream reaches the end before 320 * reading all the bytes. 321 * @exception IOException if an I/O error occurs. 322 * 323 * @see #getByteOrder 324 */ 325 long readUnsignedInt() throws IOException; 326 327 /** 328 * Reads 8 bytes from the stream, and (conceptually) concatenates 329 * them according to the current byte order and returns the result 330 * as a <code>long</code>. 331 * 332 * <p> The bit offset within the stream is reset to zero before 333 * the read occurs. 334 * 335 * @return a signed long value from the stream. 336 * 337 * @exception EOFException if the stream reaches the end before 338 * reading all the bytes. 339 * @exception IOException if an I/O error occurs. 340 * 341 * @see #getByteOrder 342 */ 343 long readLong() throws IOException; 344 345 /** 346 * Reads 4 bytes from the stream, and (conceptually) concatenates 347 * them according to the current byte order and returns the result 348 * as a <code>float</code>. 349 * 350 * <p> The bit offset within the stream is reset to zero before 351 * the read occurs. 352 * 353 * @return a float value from the stream. 354 * 355 * @exception EOFException if the stream reaches the end before 356 * reading all the bytes. 357 * @exception IOException if an I/O error occurs. 358 * 359 * @see #getByteOrder 360 */ 361 float readFloat() throws IOException; 362 363 /** 364 * Reads 8 bytes from the stream, and (conceptually) concatenates 365 * them according to the current byte order and returns the result 366 * as a <code>double</code>. 367 * 368 * <p> The bit offset within the stream is reset to zero before 369 * the read occurs. 370 * 371 * @return a double value from the stream. 372 * 373 * @exception EOFException if the stream reaches the end before 374 * reading all the bytes. 375 * @exception IOException if an I/O error occurs. 376 * 377 * @see #getByteOrder 378 */ 379 double readDouble() throws IOException; 380 381 /** 382 * Reads the next line of text from the input stream. It reads 383 * successive bytes, converting each byte separately into a 384 * character, until it encounters a line terminator or end of 385 * file; the characters read are then returned as a 386 * <code>String</code>. Note that because this method processes 387 * bytes, it does not support input of the full Unicode character 388 * set. 389 * 390 * <p> If end of file is encountered before even one byte can be 391 * read, then <code>null</code> is returned. Otherwise, each byte 392 * that is read is converted to type <code>char</code> by 393 * zero-extension. If the character <code>'\n'</code> is 394 * encountered, it is discarded and reading ceases. If the 395 * character <code>'\r'</code> is encountered, it is discarded 396 * and, if the following byte converts  to the character 397 * <code>'\n'</code>, then that is discarded also; reading then 398 * ceases. If end of file is encountered before either of the 399 * characters <code>'\n'</code> and <code>'\r'</code> is 400 * encountered, reading ceases. Once reading has ceased, a 401 * <code>String</code> is returned that contains all the 402 * characters read and not discarded, taken in order. Note that 403 * every character in this string will have a value less than 404 * <code>\u0100</code>, that is, <code>(char)256</code>. 405 * 406 * <p> The bit offset within the stream is reset to zero before 407 * the read occurs. 408 * 409 * @return a String containing a line of text from the stream. 410 * 411 * @exception IOException if an I/O error occurs. 412 */ 413 String readLine() throws IOException; 414 415 /** 416 * Reads in a string that has been encoded using a 417 * <a href="../../../java/io/DataInput.html#modified-utf-8">modified 418 * UTF-8</a> 419 * format. The general contract of <code>readUTF</code> is that 420 * it reads a representation of a Unicode character string encoded 421 * in modified UTF-8 format; this string of characters is 422 * then returned as a <code>String</code>. 423 * 424 * <p> First, two bytes are read and used to construct an unsigned 425 * 16-bit integer in the manner of the 426 * <code>readUnsignedShort</code> method, using network byte order 427 * (regardless of the current byte order setting). This integer 428 * value is called the <i>UTF length</i> and specifies the number 429 * of additional bytes to be read. These bytes are then converted 430 * to characters by considering them in groups. The length of each 431 * group is computed from the value of the first byte of the 432 * group. The byte following a group, if any, is the first byte of 433 * the next group. 434 * 435 * <p> If the first byte of a group matches the bit pattern 436 * <code>0xxxxxxx</code> (where <code>x</code> means "may be 437 * <code>0</code> or <code>1</code>"), then the group consists of 438 * just that byte. The byte is zero-extended to form a character. 439 * 440 * <p> If the first byte of a group matches the bit pattern 441 * <code>110xxxxx</code>, then the group consists of that byte 442 * <code>a</code> and a second byte <code>b</code>. If there is no 443 * byte <code>b</code> (because byte <code>a</code> was the last 444 * of the bytes to be read), or if byte <code>b</code> does not 445 * match the bit pattern <code>10xxxxxx</code>, then a 446 * <code>UTFDataFormatException</code> is thrown. Otherwise, the 447 * group is converted to the character: 448 * 449 * <p> <pre><code> 450 * (char)(((a& 0x1F) << 6) | (b & 0x3F)) 451 * </code></pre> 452 * 453 * If the first byte of a group matches the bit pattern 454 * <code>1110xxxx</code>, then the group consists of that byte 455 * <code>a</code> and two more bytes <code>b</code> and 456 * <code>c</code>. If there is no byte <code>c</code> (because 457 * byte <code>a</code> was one of the last two of the bytes to be 458 * read), or either byte <code>b</code> or byte <code>c</code> 459 * does not match the bit pattern <code>10xxxxxx</code>, then a 460 * <code>UTFDataFormatException</code> is thrown. Otherwise, the 461 * group is converted to the character: 462 * 463 * <p> <pre><code> 464 * (char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F)) 465 * </code></pre> 466 * 467 * If the first byte of a group matches the pattern 468 * <code>1111xxxx</code> or the pattern <code>10xxxxxx</code>, 469 * then a <code>UTFDataFormatException</code> is thrown. 470 * 471 * <p> If end of file is encountered at any time during this 472 * entire process, then an <code>EOFException</code> is thrown. 473 * 474 * <p> After every group has been converted to a character by this 475 * process, the characters are gathered, in the same order in 476 * which their corresponding groups were read from the input 477 * stream, to form a <code>String</code>, which is returned. 478 * 479 * <p> The current byte order setting is ignored. 480 * 481 * <p> The bit offset within the stream is reset to zero before 482 * the read occurs. 483 * 484 * <p><strong>Note:</strong> This method should not be used in 485 * the implementation of image formats that use standard UTF-8, 486 * because the modified UTF-8 used here is incompatible with 487 * standard UTF-8. 488 * 489 * @return a String read from the stream. 490 * 491 * @exception EOFException if this stream reaches the end 492 * before reading all the bytes. 493 * @exception UTFDataFormatException if the bytes do not represent a 494 * valid modified UTF-8 encoding of a string. 495 * @exception IOException if an I/O error occurs. 496 */ 497 String readUTF() throws IOException; 498 499 /** 500 * Reads <code>len</code> bytes from the stream, and stores them 501 * into <code>b</code> starting at index <code>off</code>. 502 * If the end of the stream is reached, an <code>EOFException</code> 503 * will be thrown. 504 * 505 * <p> The bit offset within the stream is reset to zero before 506 * the read occurs. 507 * 508 * @param b an array of bytes to be written to. 509 * @param off the starting position within <code>b</code> to write to. 510 * @param len the maximum number of <code>byte</code>s to read. 511 * 512 * @exception IndexOutOfBoundsException if <code>off</code> is 513 * negative, <code>len</code> is negative, or <code>off + 514 * len</code> is greater than <code>b.length</code>. 515 * @exception NullPointerException if <code>b</code> is 516 * <code>null</code>. 517 * @exception EOFException if the stream reaches the end before 518 * reading all the bytes. 519 * @exception IOException if an I/O error occurs. 520 */ 521 void readFully(byte[] b, int off, int len) throws IOException; 522 523 /** 524 * Reads <code>b.length</code> bytes from the stream, and stores them 525 * into <code>b</code> starting at index <code>0</code>. 526 * If the end of the stream is reached, an <code>EOFException</code> 527 * will be thrown. 528 * 529 * <p> The bit offset within the stream is reset to zero before 530 * the read occurs. 531 * 532 * @param b an array of <code>byte</code>s. 533 * 534 * @exception NullPointerException if <code>b</code> is 535 * <code>null</code>. 536 * @exception EOFException if the stream reaches the end before 537 * reading all the bytes. 538 * @exception IOException if an I/O error occurs. 539 */ 540 void readFully(byte[] b) throws IOException; 541 542 /** 543 * Reads <code>len</code> shorts (signed 16-bit integers) from the 544 * stream according to the current byte order, and 545 * stores them into <code>s</code> starting at index 546 * <code>off</code>. If the end of the stream is reached, an 547 * <code>EOFException</code> will be thrown. 548 * 549 * <p> The bit offset within the stream is reset to zero before 550 * the read occurs. 551 * 552 * @param s an array of shorts to be written to. 553 * @param off the starting position withinb to write to. 554 * @param len the maximum number of <code>short</code>s to read. 555 * 556 * @exception IndexOutOfBoundsException if <code>off</code> is 557 * negative, <code>len</code> is negative, or <code>off + 558 * len</code> is greater than <code>s.length</code>. 559 * @exception NullPointerException if <code>s</code> is 560 * <code>null</code>. 561 * @exception EOFException if the stream reaches the end before 562 * reading all the bytes. 563 * @exception IOException if an I/O error occurs. 564 */ 565 void readFully(short[] s, int off, int len) throws IOException; 566 567 /** 568 * Reads <code>len</code> chars (unsigned 16-bit integers) from the 569 * stream according to the current byte order, and 570 * stores them into <code>c</code> starting at index 571 * <code>off</code>. If the end of the stream is reached, an 572 * <code>EOFException</code> will be thrown. 573 * 574 * <p> The bit offset within the stream is reset to zero before 575 * the read occurs. 576 * 577 * @param c an array of chars to be written to. 578 * @param off the starting position withinb to write to. 579 * @param len the maximum number of <code>char</code>s to read. 580 * 581 * @exception IndexOutOfBoundsException if <code>off</code> is 582 * negative, <code>len</code> is negative, or <code>off + 583 * len</code> is greater than <code>c.length</code>. 584 * @exception NullPointerException if <code>c</code> is 585 * <code>null</code>. 586 * @exception EOFException if the stream reaches the end before 587 * reading all the bytes. 588 * @exception IOException if an I/O error occurs. 589 */ 590 void readFully(char[] c, int off, int len) throws IOException; 591 592 /** 593 * Reads <code>len</code> ints (signed 32-bit integers) from the 594 * stream according to the current byte order, and 595 * stores them into <code>i</code> starting at index 596 * <code>off</code>. If the end of the stream is reached, an 597 * <code>EOFException</code> will be thrown. 598 * 599 * <p> The bit offset within the stream is reset to zero before 600 * the read occurs. 601 * 602 * @param i an array of ints to be written to. 603 * @param off the starting position withinb to write to. 604 * @param len the maximum number of <code>int</code>s to read. 605 * 606 * @exception IndexOutOfBoundsException if <code>off</code> is 607 * negative, <code>len</code> is negative, or <code>off + 608 * len</code> is greater than <code>i.length</code>. 609 * @exception NullPointerException if <code>i</code> is 610 * <code>null</code>. 611 * @exception EOFException if the stream reaches the end before 612 * reading all the bytes. 613 * @exception IOException if an I/O error occurs. 614 */ 615 void readFully(int[] i, int off, int len) throws IOException; 616 617 /** 618 * Reads <code>len</code> longs (signed 64-bit integers) from the 619 * stream according to the current byte order, and 620 * stores them into <code>l</code> starting at index 621 * <code>off</code>. If the end of the stream is reached, an 622 * <code>EOFException</code> will be thrown. 623 * 624 * <p> The bit offset within the stream is reset to zero before 625 * the read occurs. 626 * 627 * @param l an array of longs to be written to. 628 * @param off the starting position withinb to write to. 629 * @param len the maximum number of <code>long</code>s to read. 630 * 631 * @exception IndexOutOfBoundsException if <code>off</code> is 632 * negative, <code>len</code> is negative, or <code>off + 633 * len</code> is greater than <code>l.length</code>. 634 * @exception NullPointerException if <code>l</code> is 635 * <code>null</code>. 636 * @exception EOFException if the stream reaches the end before 637 * reading all the bytes. 638 * @exception IOException if an I/O error occurs. 639 */ 640 void readFully(long[] l, int off, int len) throws IOException; 641 642 /** 643 * Reads <code>len</code> floats (32-bit IEEE single-precision 644 * floats) from the stream according to the current byte order, 645 * and stores them into <code>f</code> starting at 646 * index <code>off</code>. If the end of the stream is reached, 647 * an <code>EOFException</code> will be thrown. 648 * 649 * <p> The bit offset within the stream is reset to zero before 650 * the read occurs. 651 * 652 * @param f an array of floats to be written to. 653 * @param off the starting position withinb to write to. 654 * @param len the maximum number of <code>float</code>s to read. 655 * 656 * @exception IndexOutOfBoundsException if <code>off</code> is 657 * negative, <code>len</code> is negative, or <code>off + 658 * len</code> is greater than <code>f.length</code>. 659 * @exception NullPointerException if <code>f</code> is 660 * <code>null</code>. 661 * @exception EOFException if the stream reaches the end before 662 * reading all the bytes. 663 * @exception IOException if an I/O error occurs. 664 */ 665 void readFully(float[] f, int off, int len) throws IOException; 666 667 /** 668 * Reads <code>len</code> doubles (64-bit IEEE double-precision 669 * floats) from the stream according to the current byte order, 670 * and stores them into <code>d</code> starting at 671 * index <code>off</code>. If the end of the stream is reached, 672 * an <code>EOFException</code> will be thrown. 673 * 674 * <p> The bit offset within the stream is reset to zero before 675 * the read occurs. 676 * 677 * @param d an array of doubles to be written to. 678 * @param off the starting position withinb to write to. 679 * @param len the maximum number of <code>double</code>s to read. 680 * 681 * @exception IndexOutOfBoundsException if <code>off</code> is 682 * negative, <code>len</code> is negative, or <code>off + 683 * len</code> is greater than <code>d.length</code>. 684 * @exception NullPointerException if <code>d</code> is 685 * <code>null</code>. 686 * @exception EOFException if the stream reaches the end before 687 * reading all the bytes. 688 * @exception IOException if an I/O error occurs. 689 */ 690 void readFully(double[] d, int off, int len) throws IOException; 691 692 /** 693 * Returns the current byte position of the stream. The next read 694 * will take place starting at this offset. 695 * 696 * @return a long containing the position of the stream. 697 * 698 * @exception IOException if an I/O error occurs. 699 */ 700 long getStreamPosition() throws IOException; 701 702 /** 703 * Returns the current bit offset, as an integer between 0 and 7, 704 * inclusive. The bit offset is updated implicitly by calls to 705 * the <code>readBits</code> method. A value of 0 indicates the 706 * most-significant bit, and a value of 7 indicates the least 707 * significant bit, of the byte being read. 708 * 709 * <p> The bit offset is set to 0 when a stream is first 710 * opened, and is reset to 0 by calls to <code>seek</code>, 711 * <code>skipBytes</code>, or any <code>read</code> or 712 * <code>readFully</code> method. 713 * 714 * @return an <code>int</code> containing the bit offset between 715 * 0 and 7, inclusive. 716 * 717 * @exception IOException if an I/O error occurs. 718 * 719 * @see #setBitOffset 720 */ 721 int getBitOffset() throws IOException; 722 723 /** 724 * Sets the bit offset to an integer between 0 and 7, inclusive. 725 * The byte offset within the stream, as returned by 726 * <code>getStreamPosition</code>, is left unchanged. 727 * A value of 0 indicates the 728 * most-significant bit, and a value of 7 indicates the least 729 * significant bit, of the byte being read. 730 * 731 * @param bitOffset the desired offset, as an <code>int</code> 732 * between 0 and 7, inclusive. 733 * 734 * @exception IllegalArgumentException if <code>bitOffset</code> 735 * is not between 0 and 7, inclusive. 736 * @exception IOException if an I/O error occurs. 737 * 738 * @see #getBitOffset 739 */ 740 void setBitOffset(int bitOffset) throws IOException; 741 742 /** 743 * Reads a single bit from the stream and returns it as an 744 * <code>int</code> with the value <code>0</code> or 745 * <code>1</code>. The bit offset is advanced by one and reduced 746 * modulo 8. 747 * 748 * @return an <code>int</code> containing the value <code>0</code> 749 * or <code>1</code>. 750 * 751 * @exception EOFException if the stream reaches the end before 752 * reading all the bits. 753 * @exception IOException if an I/O error occurs. 754 */ 755 int readBit() throws IOException; 756 757 /** 758 * Reads a bitstring from the stream and returns it as a 759 * <code>long</code>, with the first bit read becoming the most 760 * significant bit of the output. The read starts within the byte 761 * indicated by <code>getStreamPosition</code>, at the bit given 762 * by <code>getBitOffset</code>. The bit offset is advanced by 763 * <code>numBits</code> and reduced modulo 8. 764 * 765 * <p> The byte order of the stream has no effect on this 766 * method. The return value of this method is constructed as 767 * though the bits were read one at a time, and shifted into 768 * the right side of the return value, as shown by the following 769 * pseudo-code: 770 * 771 * <pre> 772 * long accum = 0L; 773 * for (int i = 0; i < numBits; i++) { 774 * accum <<= 1; // Shift left one bit to make room 775 * accum |= readBit(); 776 * } 777 * </pre> 778 * 779 * Note that the result of <code>readBits(32)</code> may thus not 780 * be equal to that of <code>readInt()</code> if a reverse network 781 * byte order is being used (i.e., <code>getByteOrder() == 782 * false</code>). 783 * 784 * <p> If the end of the stream is encountered before all the bits 785 * have been read, an <code>EOFException</code> is thrown. 786 * 787 * @param numBits the number of bits to read, as an <code>int</code> 788 * between 0 and 64, inclusive. 789 * @return the bitstring, as a <code>long</code> with the last bit 790 * read stored in the least significant bit. 791 * 792 * @exception IllegalArgumentException if <code>numBits</code> 793 * is not between 0 and 64, inclusive. 794 * @exception EOFException if the stream reaches the end before 795 * reading all the bits. 796 * @exception IOException if an I/O error occurs. 797 */ 798 long readBits(int numBits) throws IOException; 799 800 /** 801 * Returns the total length of the stream, if known. Otherwise, 802 * <code>-1</code> is returned. 803 * 804 * @return a <code>long</code> containing the length of the 805 * stream, if known, or else <code>-1</code>. 806 * 807 * @exception IOException if an I/O error occurs. 808 */ 809 long length() throws IOException; 810 811 /** 812 * Moves the stream position forward by a given number of bytes. It 813 * is possible that this method will only be able to skip forward 814 * by a smaller number of bytes than requested, for example if the 815 * end of the stream is reached. In all cases, the actual number 816 * of bytes skipped is returned. The bit offset is set to zero 817 * prior to advancing the position. 818 * 819 * @param n an <code>int</code> containing the number of bytes to 820 * be skipped. 821 * 822 * @return an <code>int</code> representing the number of bytes skipped. 823 * 824 * @exception IOException if an I/O error occurs. 825 */ 826 int skipBytes(int n) throws IOException; 827 828 /** 829 * Moves the stream position forward by a given number of bytes. 830 * This method is identical to <code>skipBytes(int)</code> except 831 * that it allows for a larger skip distance. 832 * 833 * @param n a <code>long</code> containing the number of bytes to 834 * be skipped. 835 * 836 * @return a <code>long</code> representing the number of bytes 837 * skipped. 838 * 839 * @exception IOException if an I/O error occurs. 840 */ 841 long skipBytes(long n) throws IOException; 842 843 /** 844 * Sets the current stream position to the desired location. The 845 * next read will occur at this location. The bit offset is set 846 * to 0. 847 * 848 * <p> An <code>IndexOutOfBoundsException</code> will be thrown if 849 * <code>pos</code> is smaller than the flushed position (as 850 * returned by <code>getflushedPosition</code>). 851 * 852 * <p> It is legal to seek past the end of the file; an 853 * <code>EOFException</code> will be thrown only if a read is 854 * performed. 855 * 856 * @param pos a <code>long</code> containing the desired file 857 * pointer position. 858 * 859 * @exception IndexOutOfBoundsException if <code>pos</code> is smaller 860 * than the flushed position. 861 * @exception IOException if any other I/O error occurs. 862 */ 863 void seek(long pos) throws IOException; 864 865 /** 866 * Marks a position in the stream to be returned to by a 867 * subsequent call to <code>reset</code>. Unlike a standard 868 * <code>InputStream</code>, all <code>ImageInputStream</code>s 869 * support marking. Additionally, calls to <code>mark</code> and 870 * <code>reset</code> may be nested arbitrarily. 871 * 872 * <p> Unlike the <code>mark</code> methods declared by the 873 * <code>Reader</code> and <code>InputStream</code> interfaces, no 874 * <code>readLimit</code> parameter is used. An arbitrary amount 875 * of data may be read following the call to <code>mark</code>. 876 * 877 * <p> The bit position used by the <code>readBits</code> method 878 * is saved and restored by each pair of calls to 879 * <code>mark</code> and <code>reset</code>. 880 * 881 * <p> Note that it is valid for an <code>ImageReader</code> to call 882 * <code>flushBefore</code> as part of a read operation. 883 * Therefore, if an application calls <code>mark</code> prior to 884 * passing that stream to an <code>ImageReader</code>, the application 885 * should not assume that the marked position will remain valid after 886 * the read operation has completed. 887 */ 888 void mark(); 889 890 /** 891 * Returns the stream pointer to its previous position, including 892 * the bit offset, at the time of the most recent unmatched call 893 * to <code>mark</code>. 894 * 895 * <p> Calls to <code>reset</code> without a corresponding call 896 * to <code>mark</code> have no effect. 897 * 898 * <p> An <code>IOException</code> will be thrown if the previous 899 * marked position lies in the discarded portion of the stream. 900 * 901 * @exception IOException if an I/O error occurs. 902 */ 903 void reset() throws IOException; 904 905 /** 906 * Discards the initial portion of the stream prior to the 907 * indicated postion. Attempting to seek to an offset within the 908 * flushed portion of the stream will result in an 909 * <code>IndexOutOfBoundsException</code>. 910 * 911 * <p> Calling <code>flushBefore</code> may allow classes 912 * implementing this interface to free up resources such as memory 913 * or disk space that are being used to store data from the 914 * stream. 915 * 916 * @param pos a <code>long</code> containing the length of the 917 * stream prefix that may be flushed. 918 * 919 * @exception IndexOutOfBoundsException if <code>pos</code> lies 920 * in the flushed portion of the stream or past the current stream 921 * position. 922 * @exception IOException if an I/O error occurs. 923 */ 924 void flushBefore(long pos) throws IOException; 925 926 /** 927 * Discards the initial position of the stream prior to the current 928 * stream position. Equivalent to 929 * <code>flushBefore(getStreamPosition())</code>. 930 * 931 * @exception IOException if an I/O error occurs. 932 */ 933 void flush() throws IOException; 934 935 /** 936 * Returns the earliest position in the stream to which seeking 937 * may be performed. The returned value will be the maximum of 938 * all values passed into previous calls to 939 * <code>flushBefore</code>. 940 * 941 * @return the earliest legal position for seeking, as a 942 * <code>long</code>. 943 */ 944 long getFlushedPosition(); 945 946 /** 947 * Returns <code>true</code> if this <code>ImageInputStream</code> 948 * caches data itself in order to allow seeking backwards. 949 * Applications may consult this in order to decide how frequently, 950 * or whether, to flush in order to conserve cache resources. 951 * 952 * @return <code>true</code> if this <code>ImageInputStream</code> 953 * caches data. 954 * 955 * @see #isCachedMemory 956 * @see #isCachedFile 957 */ 958 boolean isCached(); 959 960 /** 961 * Returns <code>true</code> if this <code>ImageInputStream</code> 962 * caches data itself in order to allow seeking backwards, and 963 * the cache is kept in main memory. Applications may consult 964 * this in order to decide how frequently, or whether, to flush 965 * in order to conserve cache resources. 966 * 967 * @return <code>true</code> if this <code>ImageInputStream</code> 968 * caches data in main memory. 969 * 970 * @see #isCached 971 * @see #isCachedFile 972 */ 973 boolean isCachedMemory(); 974 975 /** 976 * Returns <code>true</code> if this <code>ImageInputStream</code> 977 * caches data itself in order to allow seeking backwards, and 978 * the cache is kept in a temporary file. Applications may consult 979 * this in order to decide how frequently, or whether, to flush 980 * in order to conserve cache resources. 981 * 982 * @return <code>true</code> if this <code>ImageInputStream</code> 983 * caches data in a temporary file. 984 * 985 * @see #isCached 986 * @see #isCachedMemory 987 */ 988 boolean isCachedFile(); 989 990 /** 991 * Closes the stream. Attempts to access a stream that has been 992 * closed may result in <code>IOException</code>s or incorrect 993 * behavior. Calling this method may allow classes implementing 994 * this interface to release resources associated with the stream 995 * such as memory, disk space, or file descriptors. 996 * 997 * @exception IOException if an I/O error occurs. 998 */ 999 void close() throws IOException; 1000 }