1 /*
   2  * Copyright (c) 2000, 2018, 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 com.sun.imageio.plugins.png;
  27 
  28 import java.awt.Point;
  29 import java.awt.Rectangle;
  30 import java.awt.color.ColorSpace;
  31 import java.awt.image.BufferedImage;
  32 import java.awt.image.DataBuffer;
  33 import java.awt.image.DataBufferByte;
  34 import java.awt.image.DataBufferUShort;
  35 import java.awt.image.Raster;
  36 import java.awt.image.WritableRaster;
  37 import java.io.BufferedInputStream;
  38 import java.io.ByteArrayInputStream;
  39 import java.io.DataInputStream;
  40 import java.io.EOFException;
  41 import java.io.InputStream;
  42 import java.io.IOException;
  43 import java.io.SequenceInputStream;
  44 import java.util.ArrayList;
  45 import java.util.Arrays;
  46 import java.util.Enumeration;
  47 import java.util.Iterator;
  48 import java.util.zip.Inflater;
  49 import java.util.zip.InflaterInputStream;
  50 import javax.imageio.IIOException;
  51 import javax.imageio.ImageReader;
  52 import javax.imageio.ImageReadParam;
  53 import javax.imageio.ImageTypeSpecifier;
  54 import javax.imageio.metadata.IIOMetadata;
  55 import javax.imageio.spi.ImageReaderSpi;
  56 import javax.imageio.stream.ImageInputStream;
  57 import com.sun.imageio.plugins.common.InputStreamAdapter;
  58 import com.sun.imageio.plugins.common.ReaderUtil;
  59 import com.sun.imageio.plugins.common.SubImageInputStream;
  60 import java.io.ByteArrayOutputStream;
  61 import sun.awt.image.ByteInterleavedRaster;
  62 
  63 class PNGImageDataEnumeration implements Enumeration<InputStream> {
  64 
  65     boolean firstTime = true;
  66     ImageInputStream stream;
  67     int length;
  68 
  69     public PNGImageDataEnumeration(ImageInputStream stream)
  70         throws IOException {
  71         this.stream = stream;
  72         this.length = stream.readInt();
  73         int type = stream.readInt(); // skip chunk type
  74     }
  75 
  76     public InputStream nextElement() {
  77         try {
  78             firstTime = false;
  79             ImageInputStream iis = new SubImageInputStream(stream, length);
  80             return new InputStreamAdapter(iis);
  81         } catch (IOException e) {
  82             return null;
  83         }
  84     }
  85 
  86     public boolean hasMoreElements() {
  87         if (firstTime) {
  88             return true;
  89         }
  90 
  91         try {
  92             int crc = stream.readInt();
  93             this.length = stream.readInt();
  94             int type = stream.readInt();
  95             if (type == PNGImageReader.IDAT_TYPE) {
  96                 return true;
  97             } else {
  98                 return false;
  99             }
 100         } catch (IOException e) {
 101             return false;
 102         }
 103     }
 104 }
 105 
 106 public class PNGImageReader extends ImageReader {
 107 
 108     /*
 109      * Note: The following chunk type constants are autogenerated.  Each
 110      * one is derived from the ASCII values of its 4-character name.  For
 111      * example, IHDR_TYPE is calculated as follows:
 112      *            ('I' << 24) | ('H' << 16) | ('D' << 8) | 'R'
 113      */
 114 
 115     // Critical chunks
 116     static final int IHDR_TYPE = 0x49484452;
 117     static final int PLTE_TYPE = 0x504c5445;
 118     static final int IDAT_TYPE = 0x49444154;
 119     static final int IEND_TYPE = 0x49454e44;
 120 
 121     // Ancillary chunks
 122     static final int bKGD_TYPE = 0x624b4744;
 123     static final int cHRM_TYPE = 0x6348524d;
 124     static final int gAMA_TYPE = 0x67414d41;
 125     static final int hIST_TYPE = 0x68495354;
 126     static final int iCCP_TYPE = 0x69434350;
 127     static final int iTXt_TYPE = 0x69545874;
 128     static final int pHYs_TYPE = 0x70485973;
 129     static final int sBIT_TYPE = 0x73424954;
 130     static final int sPLT_TYPE = 0x73504c54;
 131     static final int sRGB_TYPE = 0x73524742;
 132     static final int tEXt_TYPE = 0x74455874;
 133     static final int tIME_TYPE = 0x74494d45;
 134     static final int tRNS_TYPE = 0x74524e53;
 135     static final int zTXt_TYPE = 0x7a545874;
 136 
 137     static final int PNG_COLOR_GRAY = 0;
 138     static final int PNG_COLOR_RGB = 2;
 139     static final int PNG_COLOR_PALETTE = 3;
 140     static final int PNG_COLOR_GRAY_ALPHA = 4;
 141     static final int PNG_COLOR_RGB_ALPHA = 6;
 142 
 143     // The number of bands by PNG color type
 144     static final int[] inputBandsForColorType = {
 145          1, // gray
 146         -1, // unused
 147          3, // rgb
 148          1, // palette
 149          2, // gray + alpha
 150         -1, // unused
 151          4  // rgb + alpha
 152     };
 153 
 154     static final int PNG_FILTER_NONE = 0;
 155     static final int PNG_FILTER_SUB = 1;
 156     static final int PNG_FILTER_UP = 2;
 157     static final int PNG_FILTER_AVERAGE = 3;
 158     static final int PNG_FILTER_PAETH = 4;
 159 
 160     static final int[] adam7XOffset = { 0, 4, 0, 2, 0, 1, 0 };
 161     static final int[] adam7YOffset = { 0, 0, 4, 0, 2, 0, 1 };
 162     static final int[] adam7XSubsampling = { 8, 8, 4, 4, 2, 2, 1, 1 };
 163     static final int[] adam7YSubsampling = { 8, 8, 8, 4, 4, 2, 2, 1 };
 164 
 165     private static final boolean debug = true;
 166 
 167     ImageInputStream stream = null;
 168 
 169     boolean gotHeader = false;
 170     boolean gotMetadata = false;
 171 
 172     ImageReadParam lastParam = null;
 173 
 174     long imageStartPosition = -1L;
 175 
 176     Rectangle sourceRegion = null;
 177     int sourceXSubsampling = -1;
 178     int sourceYSubsampling = -1;
 179     int sourceMinProgressivePass = 0;
 180     int sourceMaxProgressivePass = 6;
 181     int[] sourceBands = null;
 182     int[] destinationBands = null;
 183     Point destinationOffset = new Point(0, 0);
 184 
 185     PNGMetadata metadata = new PNGMetadata();
 186 
 187     DataInputStream pixelStream = null;
 188 
 189     BufferedImage theImage = null;
 190 
 191     // The number of source pixels processed
 192     int pixelsDone = 0;
 193 
 194     // The total number of pixels in the source image
 195     int totalPixels;
 196 
 197     public PNGImageReader(ImageReaderSpi originatingProvider) {
 198         super(originatingProvider);
 199     }
 200 
 201     public void setInput(Object input,
 202                          boolean seekForwardOnly,
 203                          boolean ignoreMetadata) {
 204         super.setInput(input, seekForwardOnly, ignoreMetadata);
 205         this.stream = (ImageInputStream)input; // Always works
 206 
 207         // Clear all values based on the previous stream contents
 208         resetStreamSettings();
 209     }
 210 
 211     private String readNullTerminatedString(String charset, int maxLen) throws IOException {
 212         ByteArrayOutputStream baos = new ByteArrayOutputStream();
 213         int b;
 214         int count = 0;
 215         while ((maxLen > count++) && ((b = stream.read()) != 0)) {
 216             if (b == -1) throw new EOFException();
 217             baos.write(b);
 218         }
 219         return new String(baos.toByteArray(), charset);
 220     }
 221 
 222     private void readHeader() throws IIOException {
 223         if (gotHeader) {
 224             return;
 225         }
 226         if (stream == null) {
 227             throw new IllegalStateException("Input source not set!");
 228         }
 229 
 230         try {
 231             byte[] signature = new byte[8];
 232             stream.readFully(signature);
 233 
 234             if (signature[0] != (byte)137 ||
 235                 signature[1] != (byte)80 ||
 236                 signature[2] != (byte)78 ||
 237                 signature[3] != (byte)71 ||
 238                 signature[4] != (byte)13 ||
 239                 signature[5] != (byte)10 ||
 240                 signature[6] != (byte)26 ||
 241                 signature[7] != (byte)10) {
 242                 throw new IIOException("Bad PNG signature!");
 243             }
 244 
 245             int IHDR_length = stream.readInt();
 246             if (IHDR_length != 13) {
 247                 throw new IIOException("Bad length for IHDR chunk!");
 248             }
 249             int IHDR_type = stream.readInt();
 250             if (IHDR_type != IHDR_TYPE) {
 251                 throw new IIOException("Bad type for IHDR chunk!");
 252             }
 253 
 254             this.metadata = new PNGMetadata();
 255 
 256             int width = stream.readInt();
 257             int height = stream.readInt();
 258 
 259             // Re-use signature array to bulk-read these unsigned byte values
 260             stream.readFully(signature, 0, 5);
 261             int bitDepth          = signature[0] & 0xff;
 262             int colorType         = signature[1] & 0xff;
 263             int compressionMethod = signature[2] & 0xff;
 264             int filterMethod      = signature[3] & 0xff;
 265             int interlaceMethod   = signature[4] & 0xff;
 266 
 267             // Skip IHDR CRC
 268             stream.skipBytes(4);
 269 
 270             stream.flushBefore(stream.getStreamPosition());
 271 
 272             if (width <= 0) {
 273                 throw new IIOException("Image width <= 0!");
 274             }
 275             if (height <= 0) {
 276                 throw new IIOException("Image height <= 0!");
 277             }
 278             if (bitDepth != 1 && bitDepth != 2 && bitDepth != 4 &&
 279                 bitDepth != 8 && bitDepth != 16) {
 280                 throw new IIOException("Bit depth must be 1, 2, 4, 8, or 16!");
 281             }
 282             if (colorType != 0 && colorType != 2 && colorType != 3 &&
 283                 colorType != 4 && colorType != 6) {
 284                 throw new IIOException("Color type must be 0, 2, 3, 4, or 6!");
 285             }
 286             if (colorType == PNG_COLOR_PALETTE && bitDepth == 16) {
 287                 throw new IIOException("Bad color type/bit depth combination!");
 288             }
 289             if ((colorType == PNG_COLOR_RGB ||
 290                  colorType == PNG_COLOR_RGB_ALPHA ||
 291                  colorType == PNG_COLOR_GRAY_ALPHA) &&
 292                 (bitDepth != 8 && bitDepth != 16)) {
 293                 throw new IIOException("Bad color type/bit depth combination!");
 294             }
 295             if (compressionMethod != 0) {
 296                 throw new IIOException("Unknown compression method (not 0)!");
 297             }
 298             if (filterMethod != 0) {
 299                 throw new IIOException("Unknown filter method (not 0)!");
 300             }
 301             if (interlaceMethod != 0 && interlaceMethod != 1) {
 302                 throw new IIOException("Unknown interlace method (not 0 or 1)!");
 303             }
 304 
 305             metadata.IHDR_present = true;
 306             metadata.IHDR_width = width;
 307             metadata.IHDR_height = height;
 308             metadata.IHDR_bitDepth = bitDepth;
 309             metadata.IHDR_colorType = colorType;
 310             metadata.IHDR_compressionMethod = compressionMethod;
 311             metadata.IHDR_filterMethod = filterMethod;
 312             metadata.IHDR_interlaceMethod = interlaceMethod;
 313             gotHeader = true;
 314         } catch (IOException e) {
 315             throw new IIOException("I/O error reading PNG header!", e);
 316         }
 317     }
 318 
 319     private void parse_PLTE_chunk(int chunkLength) throws IOException {
 320         if (metadata.PLTE_present) {
 321             processWarningOccurred(
 322 "A PNG image may not contain more than one PLTE chunk.\n" +
 323 "The chunk wil be ignored.");
 324             return;
 325         } else if (metadata.IHDR_colorType == PNG_COLOR_GRAY ||
 326                    metadata.IHDR_colorType == PNG_COLOR_GRAY_ALPHA) {
 327             processWarningOccurred(
 328 "A PNG gray or gray alpha image cannot have a PLTE chunk.\n" +
 329 "The chunk wil be ignored.");
 330             return;
 331         }
 332 
 333         byte[] palette = new byte[chunkLength];
 334         stream.readFully(palette);
 335 
 336         int numEntries = chunkLength/3;
 337         if (metadata.IHDR_colorType == PNG_COLOR_PALETTE) {
 338             int maxEntries = 1 << metadata.IHDR_bitDepth;
 339             if (numEntries > maxEntries) {
 340                 processWarningOccurred(
 341 "PLTE chunk contains too many entries for bit depth, ignoring extras.");
 342                 numEntries = maxEntries;
 343             }
 344             numEntries = Math.min(numEntries, maxEntries);
 345         }
 346 
 347         // Round array sizes up to 2^2^n
 348         int paletteEntries;
 349         if (numEntries > 16) {
 350             paletteEntries = 256;
 351         } else if (numEntries > 4) {
 352             paletteEntries = 16;
 353         } else if (numEntries > 2) {
 354             paletteEntries = 4;
 355         } else {
 356             paletteEntries = 2;
 357         }
 358 
 359         metadata.PLTE_present = true;
 360         metadata.PLTE_red = new byte[paletteEntries];
 361         metadata.PLTE_green = new byte[paletteEntries];
 362         metadata.PLTE_blue = new byte[paletteEntries];
 363 
 364         int index = 0;
 365         for (int i = 0; i < numEntries; i++) {
 366             metadata.PLTE_red[i] = palette[index++];
 367             metadata.PLTE_green[i] = palette[index++];
 368             metadata.PLTE_blue[i] = palette[index++];
 369         }
 370     }
 371 
 372     private void parse_bKGD_chunk() throws IOException {
 373         if (metadata.IHDR_colorType == PNG_COLOR_PALETTE) {
 374             metadata.bKGD_colorType = PNG_COLOR_PALETTE;
 375             metadata.bKGD_index = stream.readUnsignedByte();
 376         } else if (metadata.IHDR_colorType == PNG_COLOR_GRAY ||
 377                    metadata.IHDR_colorType == PNG_COLOR_GRAY_ALPHA) {
 378             metadata.bKGD_colorType = PNG_COLOR_GRAY;
 379             metadata.bKGD_gray = stream.readUnsignedShort();
 380         } else { // RGB or RGB_ALPHA
 381             metadata.bKGD_colorType = PNG_COLOR_RGB;
 382             metadata.bKGD_red = stream.readUnsignedShort();
 383             metadata.bKGD_green = stream.readUnsignedShort();
 384             metadata.bKGD_blue = stream.readUnsignedShort();
 385         }
 386 
 387         metadata.bKGD_present = true;
 388     }
 389 
 390     private void parse_cHRM_chunk() throws IOException {
 391         metadata.cHRM_whitePointX = stream.readInt();
 392         metadata.cHRM_whitePointY = stream.readInt();
 393         metadata.cHRM_redX = stream.readInt();
 394         metadata.cHRM_redY = stream.readInt();
 395         metadata.cHRM_greenX = stream.readInt();
 396         metadata.cHRM_greenY = stream.readInt();
 397         metadata.cHRM_blueX = stream.readInt();
 398         metadata.cHRM_blueY = stream.readInt();
 399 
 400         metadata.cHRM_present = true;
 401     }
 402 
 403     private void parse_gAMA_chunk() throws IOException {
 404         int gamma = stream.readInt();
 405         metadata.gAMA_gamma = gamma;
 406 
 407         metadata.gAMA_present = true;
 408     }
 409 
 410     private void parse_hIST_chunk(int chunkLength) throws IOException,
 411         IIOException
 412     {
 413         if (!metadata.PLTE_present) {
 414             throw new IIOException("hIST chunk without prior PLTE chunk!");
 415         }
 416 
 417         /* According to PNG specification length of
 418          * hIST chunk is specified in bytes and
 419          * hIST chunk consists of 2 byte elements
 420          * (so we expect length is even).
 421          */
 422         metadata.hIST_histogram = new char[chunkLength/2];
 423         stream.readFully(metadata.hIST_histogram,
 424                          0, metadata.hIST_histogram.length);
 425 
 426         metadata.hIST_present = true;
 427     }
 428 
 429     private void parse_iCCP_chunk(int chunkLength) throws IOException {
 430         String keyword = readNullTerminatedString("ISO-8859-1", 80);
 431         int compressedProfileLength = chunkLength - keyword.length() - 2;
 432         if (compressedProfileLength <= 0) {
 433             throw new IIOException("iCCP chunk length is not proper");
 434         }
 435         metadata.iCCP_profileName = keyword;
 436 
 437         metadata.iCCP_compressionMethod = stream.readUnsignedByte();
 438 
 439         byte[] compressedProfile =
 440           new byte[compressedProfileLength];
 441         stream.readFully(compressedProfile);
 442         metadata.iCCP_compressedProfile = compressedProfile;
 443 
 444         metadata.iCCP_present = true;
 445     }
 446 
 447     private void parse_iTXt_chunk(int chunkLength) throws IOException {
 448         long chunkStart = stream.getStreamPosition();
 449 
 450         String keyword = readNullTerminatedString("ISO-8859-1", 80);
 451         metadata.iTXt_keyword.add(keyword);
 452 
 453         int compressionFlag = stream.readUnsignedByte();
 454         metadata.iTXt_compressionFlag.add(Boolean.valueOf(compressionFlag == 1));
 455 
 456         int compressionMethod = stream.readUnsignedByte();
 457         metadata.iTXt_compressionMethod.add(Integer.valueOf(compressionMethod));
 458 
 459         String languageTag = readNullTerminatedString("UTF8", 80);
 460         metadata.iTXt_languageTag.add(languageTag);
 461 
 462         long pos = stream.getStreamPosition();
 463         int maxLen = (int)(chunkStart + chunkLength - pos);
 464         String translatedKeyword =
 465             readNullTerminatedString("UTF8", maxLen);
 466         metadata.iTXt_translatedKeyword.add(translatedKeyword);
 467 
 468         String text;
 469         pos = stream.getStreamPosition();
 470         int textLength = (int)(chunkStart + chunkLength - pos);
 471         if (textLength <= 0) {
 472             throw new IIOException("iTXt chunk length is not proper");
 473         }
 474         byte[] b = new byte[textLength];
 475         stream.readFully(b);
 476 
 477         if (compressionFlag == 1) { // Decompress the text
 478             text = new String(inflate(b), "UTF8");
 479         } else {
 480             text = new String(b, "UTF8");
 481         }
 482         metadata.iTXt_text.add(text);
 483 
 484         // Check if the text chunk contains image creation time
 485         if (keyword.equals(PNGMetadata.tEXt_creationTimeKey)) {
 486             // Update Standard/Document/ImageCreationTime from text chunk
 487             int index = metadata.iTXt_text.size() - 1;
 488             metadata.decodeImageCreationTimeFromTextChunk(
 489                     metadata.iTXt_text.listIterator(index));
 490         }
 491     }
 492 
 493     private void parse_pHYs_chunk() throws IOException {
 494         metadata.pHYs_pixelsPerUnitXAxis = stream.readInt();
 495         metadata.pHYs_pixelsPerUnitYAxis = stream.readInt();
 496         metadata.pHYs_unitSpecifier = stream.readUnsignedByte();
 497 
 498         metadata.pHYs_present = true;
 499     }
 500 
 501     private void parse_sBIT_chunk() throws IOException {
 502         int colorType = metadata.IHDR_colorType;
 503         if (colorType == PNG_COLOR_GRAY ||
 504             colorType == PNG_COLOR_GRAY_ALPHA) {
 505             metadata.sBIT_grayBits = stream.readUnsignedByte();
 506         } else if (colorType == PNG_COLOR_RGB ||
 507                    colorType == PNG_COLOR_PALETTE ||
 508                    colorType == PNG_COLOR_RGB_ALPHA) {
 509             metadata.sBIT_redBits = stream.readUnsignedByte();
 510             metadata.sBIT_greenBits = stream.readUnsignedByte();
 511             metadata.sBIT_blueBits = stream.readUnsignedByte();
 512         }
 513 
 514         if (colorType == PNG_COLOR_GRAY_ALPHA ||
 515             colorType == PNG_COLOR_RGB_ALPHA) {
 516             metadata.sBIT_alphaBits = stream.readUnsignedByte();
 517         }
 518 
 519         metadata.sBIT_colorType = colorType;
 520         metadata.sBIT_present = true;
 521     }
 522 
 523     private void parse_sPLT_chunk(int chunkLength)
 524         throws IOException, IIOException {
 525         metadata.sPLT_paletteName = readNullTerminatedString("ISO-8859-1", 80);
 526         int remainingChunkLength = chunkLength -
 527                 (metadata.sPLT_paletteName.length() + 1);
 528         if (remainingChunkLength <= 0) {
 529             throw new IIOException("sPLT chunk length is not proper");
 530         }
 531 
 532         int sampleDepth = stream.readUnsignedByte();
 533         metadata.sPLT_sampleDepth = sampleDepth;
 534 
 535         int numEntries = remainingChunkLength/(4*(sampleDepth/8) + 2);
 536         metadata.sPLT_red = new int[numEntries];
 537         metadata.sPLT_green = new int[numEntries];
 538         metadata.sPLT_blue = new int[numEntries];
 539         metadata.sPLT_alpha = new int[numEntries];
 540         metadata.sPLT_frequency = new int[numEntries];
 541 
 542         if (sampleDepth == 8) {
 543             for (int i = 0; i < numEntries; i++) {
 544                 metadata.sPLT_red[i] = stream.readUnsignedByte();
 545                 metadata.sPLT_green[i] = stream.readUnsignedByte();
 546                 metadata.sPLT_blue[i] = stream.readUnsignedByte();
 547                 metadata.sPLT_alpha[i] = stream.readUnsignedByte();
 548                 metadata.sPLT_frequency[i] = stream.readUnsignedShort();
 549             }
 550         } else if (sampleDepth == 16) {
 551             for (int i = 0; i < numEntries; i++) {
 552                 metadata.sPLT_red[i] = stream.readUnsignedShort();
 553                 metadata.sPLT_green[i] = stream.readUnsignedShort();
 554                 metadata.sPLT_blue[i] = stream.readUnsignedShort();
 555                 metadata.sPLT_alpha[i] = stream.readUnsignedShort();
 556                 metadata.sPLT_frequency[i] = stream.readUnsignedShort();
 557             }
 558         } else {
 559             throw new IIOException("sPLT sample depth not 8 or 16!");
 560         }
 561 
 562         metadata.sPLT_present = true;
 563     }
 564 
 565     private void parse_sRGB_chunk() throws IOException {
 566         metadata.sRGB_renderingIntent = stream.readUnsignedByte();
 567 
 568         metadata.sRGB_present = true;
 569     }
 570 
 571     private void parse_tEXt_chunk(int chunkLength) throws IOException {
 572         String keyword = readNullTerminatedString("ISO-8859-1", 80);
 573         int textLength = chunkLength - keyword.length() - 1;
 574         if (textLength <= 0) {
 575             throw new IIOException("tEXt chunk length is not proper");
 576         }
 577         metadata.tEXt_keyword.add(keyword);
 578 
 579         byte[] b = new byte[textLength];
 580         stream.readFully(b);
 581         metadata.tEXt_text.add(new String(b, "ISO-8859-1"));
 582 
 583         // Check if the text chunk contains image creation time
 584         if (keyword.equals(PNGMetadata.tEXt_creationTimeKey)) {
 585             // Update Standard/Document/ImageCreationTime from text chunk
 586             int index = metadata.tEXt_text.size() - 1;
 587             metadata.decodeImageCreationTimeFromTextChunk(
 588                     metadata.tEXt_text.listIterator(index));
 589         }
 590     }
 591 
 592     private void parse_tIME_chunk() throws IOException {
 593         metadata.tIME_year = stream.readUnsignedShort();
 594         metadata.tIME_month = stream.readUnsignedByte();
 595         metadata.tIME_day = stream.readUnsignedByte();
 596         metadata.tIME_hour = stream.readUnsignedByte();
 597         metadata.tIME_minute = stream.readUnsignedByte();
 598         metadata.tIME_second = stream.readUnsignedByte();
 599 
 600         metadata.tIME_present = true;
 601     }
 602 
 603     private void parse_tRNS_chunk(int chunkLength) throws IOException {
 604         int colorType = metadata.IHDR_colorType;
 605         if (colorType == PNG_COLOR_PALETTE) {
 606             if (!metadata.PLTE_present) {
 607                 processWarningOccurred(
 608 "tRNS chunk without prior PLTE chunk, ignoring it.");
 609                 return;
 610             }
 611 
 612             // Alpha table may have fewer entries than RGB palette
 613             int maxEntries = metadata.PLTE_red.length;
 614             int numEntries = chunkLength;
 615             if (numEntries > maxEntries && maxEntries > 0) {
 616                 processWarningOccurred(
 617 "tRNS chunk has more entries than prior PLTE chunk, ignoring extras.");
 618                 numEntries = maxEntries;
 619             }
 620             metadata.tRNS_alpha = new byte[numEntries];
 621             metadata.tRNS_colorType = PNG_COLOR_PALETTE;
 622             stream.read(metadata.tRNS_alpha, 0, numEntries);
 623             stream.skipBytes(chunkLength - numEntries);
 624         } else if (colorType == PNG_COLOR_GRAY) {
 625             if (chunkLength != 2) {
 626                 processWarningOccurred(
 627 "tRNS chunk for gray image must have length 2, ignoring chunk.");
 628                 stream.skipBytes(chunkLength);
 629                 return;
 630             }
 631             metadata.tRNS_gray = stream.readUnsignedShort();
 632             metadata.tRNS_colorType = PNG_COLOR_GRAY;
 633         } else if (colorType == PNG_COLOR_RGB) {
 634             if (chunkLength != 6) {
 635                 processWarningOccurred(
 636 "tRNS chunk for RGB image must have length 6, ignoring chunk.");
 637                 stream.skipBytes(chunkLength);
 638                 return;
 639             }
 640             metadata.tRNS_red = stream.readUnsignedShort();
 641             metadata.tRNS_green = stream.readUnsignedShort();
 642             metadata.tRNS_blue = stream.readUnsignedShort();
 643             metadata.tRNS_colorType = PNG_COLOR_RGB;
 644         } else {
 645             processWarningOccurred(
 646 "Gray+Alpha and RGBS images may not have a tRNS chunk, ignoring it.");
 647             return;
 648         }
 649 
 650         metadata.tRNS_present = true;
 651     }
 652 
 653     private static byte[] inflate(byte[] b) throws IOException {
 654         InputStream bais = new ByteArrayInputStream(b);
 655         InputStream iis = new InflaterInputStream(bais);
 656         ByteArrayOutputStream baos = new ByteArrayOutputStream();
 657 
 658         int c;
 659         try {
 660             while ((c = iis.read()) != -1) {
 661                 baos.write(c);
 662             }
 663         } finally {
 664             iis.close();
 665         }
 666         return baos.toByteArray();
 667     }
 668 
 669     private void parse_zTXt_chunk(int chunkLength) throws IOException {
 670         String keyword = readNullTerminatedString("ISO-8859-1", 80);
 671         int textLength = chunkLength - keyword.length() - 2;
 672         if (textLength <= 0) {
 673             throw new IIOException("zTXt chunk length is not proper");
 674         }
 675         metadata.zTXt_keyword.add(keyword);
 676 
 677         int method = stream.readUnsignedByte();
 678         metadata.zTXt_compressionMethod.add(method);
 679 
 680         byte[] b = new byte[textLength];
 681         stream.readFully(b);
 682         metadata.zTXt_text.add(new String(inflate(b), "ISO-8859-1"));
 683 
 684         // Check if the text chunk contains image creation time
 685         if (keyword.equals(PNGMetadata.tEXt_creationTimeKey)) {
 686             // Update Standard/Document/ImageCreationTime from text chunk
 687             int index = metadata.zTXt_text.size() - 1;
 688             metadata.decodeImageCreationTimeFromTextChunk(
 689                     metadata.zTXt_text.listIterator(index));
 690         }
 691     }
 692 
 693     private void readMetadata() throws IIOException {
 694         if (gotMetadata) {
 695             return;
 696         }
 697 
 698         readHeader();
 699 
 700         /*
 701          * Optimization: We can skip the remaining metadata if the
 702          * ignoreMetadata flag is set, and only if this is not a palette
 703          * image (in that case, we need to read the metadata to get the
 704          * tRNS chunk, which is needed for the getImageTypes() method).


 705          */
 706         int colorType = metadata.IHDR_colorType;
 707         if (ignoreMetadata && colorType != PNG_COLOR_PALETTE) {
 708             try {
 709                 while (true) {
 710                     int chunkLength = stream.readInt();
 711 
 712                     // verify the chunk length first
 713                     if (chunkLength < 0 || chunkLength + 4 < 0) {
 714                         throw new IIOException("Invalid chunk length " + chunkLength);
 715                     }
 716 
 717                     int chunkType = stream.readInt();
 718 
 719                     if (chunkType == IDAT_TYPE) {
 720                         // We've reached the image data
 721                         stream.skipBytes(-8);
 722                         imageStartPosition = stream.getStreamPosition();





 723                         break;




 724                     } else {
 725                         // Skip the chunk plus the 4 CRC bytes that follow
 726                         stream.skipBytes(chunkLength + 4);
 727                     }
 728                 }
 729             } catch (IOException e) {
 730                 throw new IIOException("Error skipping PNG metadata", e);
 731             }
 732 
 733             gotMetadata = true;
 734             return;
 735         }
 736 
 737         try {
 738             loop: while (true) {
 739                 int chunkLength = stream.readInt();
 740                 int chunkType = stream.readInt();
 741                 int chunkCRC;
 742 
 743                 // verify the chunk length
 744                 if (chunkLength < 0) {
 745                     throw new IIOException("Invalid chunk length " + chunkLength);
 746                 };
 747 
 748                 try {
 749                     stream.mark();
 750                     stream.seek(stream.getStreamPosition() + chunkLength);
 751                     chunkCRC = stream.readInt();
 752                     stream.reset();
 753                 } catch (IOException e) {
 754                     throw new IIOException("Invalid chunk length " + chunkLength);
 755                 }
 756 
 757                 switch (chunkType) {
 758                 case IDAT_TYPE:
 759                     // If chunk type is 'IDAT', we've reached the image data.
 760                     if (imageStartPosition == -1L) {
 761                         /*
 762                          * The PNG specification mandates that if colorType is
 763                          * PNG_COLOR_PALETTE then the PLTE chunk should appear
 764                          * before the first IDAT chunk.
 765                          */
 766                         if (colorType == PNG_COLOR_PALETTE &&
 767                             !(metadata.PLTE_present))
 768                         {
 769                             throw new IIOException("Required PLTE chunk"
 770                                     + " missing");
 771                         }
 772                         /*
 773                          * PNGs may contain multiple IDAT chunks containing
 774                          * a portion of image data. We store the position of
 775                          * the first IDAT chunk and continue with iteration
 776                          * of other chunks that follow image data.
 777                          */
 778                         imageStartPosition = stream.getStreamPosition() - 8;
 779                     }
 780                     // Move to the CRC byte location.
 781                     stream.skipBytes(chunkLength);
 782                     break;
 783                 case IEND_TYPE:
 784                     /*
 785                      * If the chunk type is 'IEND', we've reached end of image.
 786                      * Seek to the first IDAT chunk for subsequent decoding.
 787                      */
 788                     stream.seek(imageStartPosition);
 789 
 790                     /*
 791                      * flushBefore discards the portion of the stream before
 792                      * the indicated position. Hence this should be used after
 793                      * we complete iteration over available chunks including
 794                      * those that appear after the IDAT.
 795                      */
 796                     stream.flushBefore(stream.getStreamPosition());
 797                     break loop;
 798                 case PLTE_TYPE:
 799                     parse_PLTE_chunk(chunkLength);
 800                     break;
 801                 case bKGD_TYPE:
 802                     parse_bKGD_chunk();
 803                     break;
 804                 case cHRM_TYPE:
 805                     parse_cHRM_chunk();
 806                     break;
 807                 case gAMA_TYPE:
 808                     parse_gAMA_chunk();
 809                     break;
 810                 case hIST_TYPE:
 811                     parse_hIST_chunk(chunkLength);
 812                     break;
 813                 case iCCP_TYPE:
 814                     parse_iCCP_chunk(chunkLength);
 815                     break;
 816                 case iTXt_TYPE:
 817                     if (ignoreMetadata) {
 818                         stream.skipBytes(chunkLength);
 819                     } else {
 820                         parse_iTXt_chunk(chunkLength);
 821                     }
 822                     break;
 823                 case pHYs_TYPE:
 824                     parse_pHYs_chunk();
 825                     break;
 826                 case sBIT_TYPE:
 827                     parse_sBIT_chunk();
 828                     break;
 829                 case sPLT_TYPE:
 830                     parse_sPLT_chunk(chunkLength);
 831                     break;
 832                 case sRGB_TYPE:
 833                     parse_sRGB_chunk();
 834                     break;
 835                 case tEXt_TYPE:
 836                     parse_tEXt_chunk(chunkLength);
 837                     break;
 838                 case tIME_TYPE:
 839                     parse_tIME_chunk();
 840                     break;
 841                 case tRNS_TYPE:
 842                     parse_tRNS_chunk(chunkLength);
 843                     break;
 844                 case zTXt_TYPE:
 845                     if (ignoreMetadata) {
 846                         stream.skipBytes(chunkLength);
 847                     } else {
 848                         parse_zTXt_chunk(chunkLength);
 849                     }
 850                     break;
 851                 default:
 852                     // Read an unknown chunk
 853                     byte[] b = new byte[chunkLength];
 854                     stream.readFully(b);
 855 
 856                     StringBuilder chunkName = new StringBuilder(4);
 857                     chunkName.append((char)(chunkType >>> 24));
 858                     chunkName.append((char)((chunkType >> 16) & 0xff));
 859                     chunkName.append((char)((chunkType >> 8) & 0xff));
 860                     chunkName.append((char)(chunkType & 0xff));
 861 
 862                     int ancillaryBit = chunkType >>> 28;
 863                     if (ancillaryBit == 0) {
 864                         processWarningOccurred(
 865 "Encountered unknown chunk with critical bit set!");
 866                     }
 867 
 868                     metadata.unknownChunkType.add(chunkName.toString());
 869                     metadata.unknownChunkData.add(b);
 870                     break;
 871                 }
 872 
 873                 // double check whether all chunk data were consumed
 874                 if (chunkCRC != stream.readInt()) {
 875                     throw new IIOException("Failed to read a chunk of type " +
 876                             chunkType);
 877                 }
 878             }
 879         } catch (IOException e) {
 880             throw new IIOException("Error reading PNG metadata", e);
 881         }
 882 
 883         gotMetadata = true;
 884     }
 885 
 886     // Data filtering methods
 887 
 888     private static void decodeSubFilter(byte[] curr, int coff, int count,
 889                                         int bpp) {
 890         for (int i = bpp; i < count; i++) {
 891             int val;
 892 
 893             val = curr[i + coff] & 0xff;
 894             val += curr[i + coff - bpp] & 0xff;
 895 
 896             curr[i + coff] = (byte)val;
 897         }
 898     }
 899 
 900     private static void decodeUpFilter(byte[] curr, int coff,
 901                                        byte[] prev, int poff,
 902                                        int count) {
 903         for (int i = 0; i < count; i++) {
 904             int raw = curr[i + coff] & 0xff;
 905             int prior = prev[i + poff] & 0xff;
 906 
 907             curr[i + coff] = (byte)(raw + prior);
 908         }
 909     }
 910 
 911     private static void decodeAverageFilter(byte[] curr, int coff,
 912                                             byte[] prev, int poff,
 913                                             int count, int bpp) {
 914         int raw, priorPixel, priorRow;
 915 
 916         for (int i = 0; i < bpp; i++) {
 917             raw = curr[i + coff] & 0xff;
 918             priorRow = prev[i + poff] & 0xff;
 919 
 920             curr[i + coff] = (byte)(raw + priorRow/2);
 921         }
 922 
 923         for (int i = bpp; i < count; i++) {
 924             raw = curr[i + coff] & 0xff;
 925             priorPixel = curr[i + coff - bpp] & 0xff;
 926             priorRow = prev[i + poff] & 0xff;
 927 
 928             curr[i + coff] = (byte)(raw + (priorPixel + priorRow)/2);
 929         }
 930     }
 931 
 932     private static int paethPredictor(int a, int b, int c) {
 933         int p = a + b - c;
 934         int pa = Math.abs(p - a);
 935         int pb = Math.abs(p - b);
 936         int pc = Math.abs(p - c);
 937 
 938         if ((pa <= pb) && (pa <= pc)) {
 939             return a;
 940         } else if (pb <= pc) {
 941             return b;
 942         } else {
 943             return c;
 944         }
 945     }
 946 
 947     private static void decodePaethFilter(byte[] curr, int coff,
 948                                           byte[] prev, int poff,
 949                                           int count, int bpp) {
 950         int raw, priorPixel, priorRow, priorRowPixel;
 951 
 952         for (int i = 0; i < bpp; i++) {
 953             raw = curr[i + coff] & 0xff;
 954             priorRow = prev[i + poff] & 0xff;
 955 
 956             curr[i + coff] = (byte)(raw + priorRow);
 957         }
 958 
 959         for (int i = bpp; i < count; i++) {
 960             raw = curr[i + coff] & 0xff;
 961             priorPixel = curr[i + coff - bpp] & 0xff;
 962             priorRow = prev[i + poff] & 0xff;
 963             priorRowPixel = prev[i + poff - bpp] & 0xff;
 964 
 965             curr[i + coff] = (byte)(raw + paethPredictor(priorPixel,
 966                                                          priorRow,
 967                                                          priorRowPixel));
 968         }
 969     }
 970 
 971     private static final int[][] bandOffsets = {
 972         null,
 973         { 0 }, // G
 974         { 0, 1 }, // GA in GA order
 975         { 0, 1, 2 }, // RGB in RGB order
 976         { 0, 1, 2, 3 } // RGBA in RGBA order
 977     };
 978 
 979     private WritableRaster createRaster(int width, int height, int bands,
 980                                         int scanlineStride,
 981                                         int bitDepth) {
 982 
 983         DataBuffer dataBuffer;
 984         WritableRaster ras = null;
 985         Point origin = new Point(0, 0);
 986         if ((bitDepth < 8) && (bands == 1)) {
 987             dataBuffer = new DataBufferByte(height*scanlineStride);
 988             ras = Raster.createPackedRaster(dataBuffer,
 989                                             width, height,
 990                                             bitDepth,
 991                                             origin);
 992         } else if (bitDepth <= 8) {
 993             dataBuffer = new DataBufferByte(height*scanlineStride);
 994             ras = Raster.createInterleavedRaster(dataBuffer,
 995                                                  width, height,
 996                                                  scanlineStride,
 997                                                  bands,
 998                                                  bandOffsets[bands],
 999                                                  origin);
1000         } else {
1001             dataBuffer = new DataBufferUShort(height*scanlineStride);
1002             ras = Raster.createInterleavedRaster(dataBuffer,
1003                                                  width, height,
1004                                                  scanlineStride,
1005                                                  bands,
1006                                                  bandOffsets[bands],
1007                                                  origin);
1008         }
1009 
1010         return ras;
1011     }
1012 
1013     private void skipPass(int passWidth, int passHeight)
1014         throws IOException, IIOException  {
1015         if ((passWidth == 0) || (passHeight == 0)) {
1016             return;
1017         }
1018 
1019         int inputBands = inputBandsForColorType[metadata.IHDR_colorType];
1020         int bitsPerRow = Math.
1021                 multiplyExact((inputBands * metadata.IHDR_bitDepth), passWidth);
1022         int bytesPerRow = (bitsPerRow + 7) / 8;
1023 
1024         // Read the image row-by-row
1025         for (int srcY = 0; srcY < passHeight; srcY++) {
1026             // Skip filter byte and the remaining row bytes
1027             pixelStream.skipBytes(1 + bytesPerRow);
1028         }
1029     }
1030 
1031     private void updateImageProgress(int newPixels) {
1032         pixelsDone += newPixels;
1033         processImageProgress(100.0F*pixelsDone/totalPixels);
1034     }
1035 
1036     private void decodePass(int passNum,
1037                             int xStart, int yStart,
1038                             int xStep, int yStep,
1039                             int passWidth, int passHeight) throws IOException {
1040 
1041         if ((passWidth == 0) || (passHeight == 0)) {
1042             return;
1043         }
1044 
1045         WritableRaster imRas = theImage.getWritableTile(0, 0);
1046         int dstMinX = imRas.getMinX();
1047         int dstMaxX = dstMinX + imRas.getWidth() - 1;
1048         int dstMinY = imRas.getMinY();
1049         int dstMaxY = dstMinY + imRas.getHeight() - 1;
1050 
1051         // Determine which pixels will be updated in this pass
1052         int[] vals =
1053           ReaderUtil.computeUpdatedPixels(sourceRegion,
1054                                           destinationOffset,
1055                                           dstMinX, dstMinY,
1056                                           dstMaxX, dstMaxY,
1057                                           sourceXSubsampling,
1058                                           sourceYSubsampling,
1059                                           xStart, yStart,
1060                                           passWidth, passHeight,
1061                                           xStep, yStep);
1062         int updateMinX = vals[0];
1063         int updateMinY = vals[1];
1064         int updateWidth = vals[2];
1065         int updateXStep = vals[4];
1066         int updateYStep = vals[5];
1067 
1068         int bitDepth = metadata.IHDR_bitDepth;
1069         int inputBands = inputBandsForColorType[metadata.IHDR_colorType];
1070         int bytesPerPixel = (bitDepth == 16) ? 2 : 1;
1071         bytesPerPixel *= inputBands;
1072 
1073         int bitsPerRow = Math.multiplyExact((inputBands * bitDepth), passWidth);
1074         int bytesPerRow = (bitsPerRow + 7) / 8;
1075         int eltsPerRow = (bitDepth == 16) ? bytesPerRow/2 : bytesPerRow;
1076 
1077         // If no pixels need updating, just skip the input data
1078         if (updateWidth == 0) {
1079             for (int srcY = 0; srcY < passHeight; srcY++) {
1080                 // Update count of pixels read
1081                 updateImageProgress(passWidth);
1082                 /*
1083                  * If read has been aborted, just return
1084                  * processReadAborted will be called later
1085                  */
1086                 if (abortRequested()) {
1087                     return;
1088                 }
1089                 // Skip filter byte and the remaining row bytes
1090                 pixelStream.skipBytes(1 + bytesPerRow);
1091             }
1092             return;
1093         }
1094 
1095         // Backwards map from destination pixels
1096         // (dstX = updateMinX + k*updateXStep)
1097         // to source pixels (sourceX), and then
1098         // to offset and skip in passRow (srcX and srcXStep)
1099         int sourceX =
1100             (updateMinX - destinationOffset.x)*sourceXSubsampling +
1101             sourceRegion.x;
1102         int srcX = (sourceX - xStart)/xStep;
1103 
1104         // Compute the step factor in the source
1105         int srcXStep = updateXStep*sourceXSubsampling/xStep;
1106 
1107         byte[] byteData = null;
1108         short[] shortData = null;
1109         byte[] curr = new byte[bytesPerRow];
1110         byte[] prior = new byte[bytesPerRow];
1111 
1112         // Create a 1-row tall Raster to hold the data
1113         WritableRaster passRow = createRaster(passWidth, 1, inputBands,
1114                                               eltsPerRow,
1115                                               bitDepth);
1116 
1117         // Create an array suitable for holding one pixel
1118         int[] ps = passRow.getPixel(0, 0, (int[])null);
1119 
1120         DataBuffer dataBuffer = passRow.getDataBuffer();
1121         int type = dataBuffer.getDataType();
1122         if (type == DataBuffer.TYPE_BYTE) {
1123             byteData = ((DataBufferByte)dataBuffer).getData();
1124         } else {
1125             shortData = ((DataBufferUShort)dataBuffer).getData();
1126         }
1127 
1128         processPassStarted(theImage,
1129                            passNum,
1130                            sourceMinProgressivePass,
1131                            sourceMaxProgressivePass,
1132                            updateMinX, updateMinY,
1133                            updateXStep, updateYStep,
1134                            destinationBands);
1135 
1136         // Handle source and destination bands
1137         if (sourceBands != null) {
1138             passRow = passRow.createWritableChild(0, 0,
1139                                                   passRow.getWidth(), 1,
1140                                                   0, 0,
1141                                                   sourceBands);
1142         }
1143         if (destinationBands != null) {
1144             imRas = imRas.createWritableChild(0, 0,
1145                                               imRas.getWidth(),
1146                                               imRas.getHeight(),
1147                                               0, 0,
1148                                               destinationBands);
1149         }
1150 
1151         // Determine if all of the relevant output bands have the
1152         // same bit depth as the source data
1153         boolean adjustBitDepths = false;
1154         int[] outputSampleSize = imRas.getSampleModel().getSampleSize();
1155         int numBands = outputSampleSize.length;
1156         for (int b = 0; b < numBands; b++) {
1157             if (outputSampleSize[b] != bitDepth) {
1158                 adjustBitDepths = true;
1159                 break;
1160             }
1161         }
1162 
1163         // If the bit depths differ, create a lookup table per band to perform
1164         // the conversion
1165         int[][] scale = null;
1166         if (adjustBitDepths) {
1167             int maxInSample = (1 << bitDepth) - 1;
1168             int halfMaxInSample = maxInSample/2;
1169             scale = new int[numBands][];
1170             for (int b = 0; b < numBands; b++) {
1171                 int maxOutSample = (1 << outputSampleSize[b]) - 1;
1172                 scale[b] = new int[maxInSample + 1];
1173                 for (int s = 0; s <= maxInSample; s++) {
1174                     scale[b][s] =
1175                         (s*maxOutSample + halfMaxInSample)/maxInSample;
1176                 }
1177             }
1178         }
1179 
1180         // Limit passRow to relevant area for the case where we
1181         // will can setRect to copy a contiguous span
1182         boolean useSetRect = srcXStep == 1 &&
1183             updateXStep == 1 &&
1184             !adjustBitDepths &&
1185             (imRas instanceof ByteInterleavedRaster);
1186 
1187         if (useSetRect) {
1188             passRow = passRow.createWritableChild(srcX, 0,
1189                                                   updateWidth, 1,
1190                                                   0, 0,
1191                                                   null);
1192         }
1193 
1194         // Decode the (sub)image row-by-row
1195         for (int srcY = 0; srcY < passHeight; srcY++) {
1196             // Update count of pixels read
1197             updateImageProgress(passWidth);
1198             /*
1199              * If read has been aborted, just return
1200              * processReadAborted will be called later
1201              */
1202             if (abortRequested()) {
1203                 return;
1204             }
1205             // Read the filter type byte and a row of data
1206             int filter = pixelStream.read();
1207             try {
1208                 // Swap curr and prior
1209                 byte[] tmp = prior;
1210                 prior = curr;
1211                 curr = tmp;
1212 
1213                 pixelStream.readFully(curr, 0, bytesPerRow);
1214             } catch (java.util.zip.ZipException ze) {
1215                 // TODO - throw a more meaningful exception
1216                 throw ze;
1217             }
1218 
1219             switch (filter) {
1220             case PNG_FILTER_NONE:
1221                 break;
1222             case PNG_FILTER_SUB:
1223                 decodeSubFilter(curr, 0, bytesPerRow, bytesPerPixel);
1224                 break;
1225             case PNG_FILTER_UP:
1226                 decodeUpFilter(curr, 0, prior, 0, bytesPerRow);
1227                 break;
1228             case PNG_FILTER_AVERAGE:
1229                 decodeAverageFilter(curr, 0, prior, 0, bytesPerRow,
1230                                     bytesPerPixel);
1231                 break;
1232             case PNG_FILTER_PAETH:
1233                 decodePaethFilter(curr, 0, prior, 0, bytesPerRow,
1234                                   bytesPerPixel);
1235                 break;
1236             default:
1237                 throw new IIOException("Unknown row filter type (= " +
1238                                        filter + ")!");
1239             }
1240 
1241             // Copy data into passRow byte by byte
1242             if (bitDepth < 16) {
1243                 System.arraycopy(curr, 0, byteData, 0, bytesPerRow);
1244             } else {
1245                 int idx = 0;
1246                 for (int j = 0; j < eltsPerRow; j++) {
1247                     shortData[j] =
1248                         (short)((curr[idx] << 8) | (curr[idx + 1] & 0xff));
1249                     idx += 2;
1250                 }
1251             }
1252 
1253             // True Y position in source
1254             int sourceY = srcY*yStep + yStart;
1255             if ((sourceY >= sourceRegion.y) &&
1256                 (sourceY < sourceRegion.y + sourceRegion.height) &&
1257                 (((sourceY - sourceRegion.y) %
1258                   sourceYSubsampling) == 0)) {
1259 
1260                 int dstY = destinationOffset.y +
1261                     (sourceY - sourceRegion.y)/sourceYSubsampling;
1262                 if (dstY < dstMinY) {
1263                     continue;
1264                 }
1265                 if (dstY > dstMaxY) {
1266                     break;
1267                 }
1268 
1269                 if (useSetRect) {










1270                     imRas.setRect(updateMinX, dstY, passRow);
1271                 } else {
1272                     int newSrcX = srcX;
1273 






1274                     for (int dstX = updateMinX;
1275                          dstX < updateMinX + updateWidth;
1276                          dstX += updateXStep) {
1277 
1278                         passRow.getPixel(newSrcX, 0, ps);
1279                         if (adjustBitDepths) {
1280                             for (int b = 0; b < numBands; b++) {
1281                                 ps[b] = scale[b][ps[b]];
1282                             }
1283                         }























1284                         imRas.setPixel(dstX, dstY, ps);

1285                         newSrcX += srcXStep;
1286                     }
1287                 }
1288 
1289                 processImageUpdate(theImage,
1290                                    updateMinX, dstY,
1291                                    updateWidth, 1,
1292                                    updateXStep, updateYStep,
1293                                    destinationBands);
1294             }
1295         }
1296 
1297         processPassComplete(theImage);
1298     }
1299 
1300     private void decodeImage()
1301         throws IOException, IIOException  {
1302         int width = metadata.IHDR_width;
1303         int height = metadata.IHDR_height;
1304 
1305         this.pixelsDone = 0;
1306         this.totalPixels = width*height;
1307 
1308         if (metadata.IHDR_interlaceMethod == 0) {
1309             decodePass(0, 0, 0, 1, 1, width, height);
1310         } else {
1311             for (int i = 0; i <= sourceMaxProgressivePass; i++) {
1312                 int XOffset = adam7XOffset[i];
1313                 int YOffset = adam7YOffset[i];
1314                 int XSubsampling = adam7XSubsampling[i];
1315                 int YSubsampling = adam7YSubsampling[i];
1316                 int xbump = adam7XSubsampling[i + 1] - 1;
1317                 int ybump = adam7YSubsampling[i + 1] - 1;
1318 
1319                 if (i >= sourceMinProgressivePass) {
1320                     decodePass(i,
1321                                XOffset,
1322                                YOffset,
1323                                XSubsampling,
1324                                YSubsampling,
1325                                (width + xbump)/XSubsampling,
1326                                (height + ybump)/YSubsampling);
1327                 } else {
1328                     skipPass((width + xbump)/XSubsampling,
1329                              (height + ybump)/YSubsampling);
1330                 }
1331 
1332                 /*
1333                  * If read has been aborted, just return
1334                  * processReadAborted will be called later
1335                  */
1336                 if (abortRequested()) {
1337                     return;
1338                 }
1339             }
1340         }
1341     }
1342 
1343     private void readImage(ImageReadParam param) throws IIOException {
1344         readMetadata();
1345 
1346         int width = metadata.IHDR_width;
1347         int height = metadata.IHDR_height;
1348 
1349         // Init default values
1350         sourceXSubsampling = 1;
1351         sourceYSubsampling = 1;
1352         sourceMinProgressivePass = 0;
1353         sourceMaxProgressivePass = 6;
1354         sourceBands = null;
1355         destinationBands = null;
1356         destinationOffset = new Point(0, 0);
1357 
1358         // If an ImageReadParam is available, get values from it
1359         if (param != null) {
1360             sourceXSubsampling = param.getSourceXSubsampling();
1361             sourceYSubsampling = param.getSourceYSubsampling();
1362 
1363             sourceMinProgressivePass =
1364                 Math.max(param.getSourceMinProgressivePass(), 0);
1365             sourceMaxProgressivePass =
1366                 Math.min(param.getSourceMaxProgressivePass(), 6);
1367 
1368             sourceBands = param.getSourceBands();
1369             destinationBands = param.getDestinationBands();
1370             destinationOffset = param.getDestinationOffset();
1371         }
1372         Inflater inf = null;
1373         try {
1374             stream.seek(imageStartPosition);
1375 
1376             Enumeration<InputStream> e = new PNGImageDataEnumeration(stream);
1377             InputStream is = new SequenceInputStream(e);
1378 
1379            /* InflaterInputStream uses an Inflater instance which consumes
1380             * native (non-GC visible) resources. This is normally implicitly
1381             * freed when the stream is closed. However since the
1382             * InflaterInputStream wraps a client-supplied input stream,
1383             * we cannot close it.
1384             * But the app may depend on GC finalization to close the stream.
1385             * Therefore to ensure timely freeing of native resources we
1386             * explicitly create the Inflater instance and free its resources
1387             * when we are done with the InflaterInputStream by calling
1388             * inf.end();
1389             */
1390             inf = new Inflater();
1391             is = new InflaterInputStream(is, inf);
1392             is = new BufferedInputStream(is);
1393             this.pixelStream = new DataInputStream(is);
1394 
1395             /*
1396              * PNG spec declares that valid range for width
1397              * and height is [1, 2^31-1], so here we may fail to allocate
1398              * a buffer for destination image due to memory limitation.
1399              *
1400              * If the read operation triggers OutOfMemoryError, the same
1401              * will be wrapped in an IIOException at PNGImageReader.read
1402              * method.
1403              *
1404              * The recovery strategy for this case should be defined at
1405              * the level of application, so we will not try to estimate
1406              * the required amount of the memory and/or handle OOM in
1407              * any way.
1408              */
1409             theImage = getDestination(param,
1410                                       getImageTypes(0),
1411                                       width,
1412                                       height);
1413 
1414             Rectangle destRegion = new Rectangle(0, 0, 0, 0);
1415             sourceRegion = new Rectangle(0, 0, 0, 0);
1416             computeRegions(param, width, height,
1417                            theImage,
1418                            sourceRegion, destRegion);
1419             destinationOffset.setLocation(destRegion.getLocation());
1420 
1421             // At this point the header has been read and we know
1422             // how many bands are in the image, so perform checking
1423             // of the read param.
1424             int colorType = metadata.IHDR_colorType;







1425             checkReadParamBandSettings(param,
1426                                        inputBandsForColorType[colorType],
1427                                       theImage.getSampleModel().getNumBands());

1428 
1429             clearAbortRequest();
1430             processImageStarted(0);
1431             if (abortRequested()) {
1432                 processReadAborted();
1433             } else {
1434                 decodeImage();
1435                 if (abortRequested()) {
1436                     processReadAborted();
1437                 } else {
1438                     processImageComplete();
1439                 }
1440             }
1441 
1442         } catch (IOException e) {
1443             throw new IIOException("Error reading PNG image data", e);
1444         } finally {
1445             if (inf != null) {
1446                 inf.end();
1447             }
1448         }
1449     }
1450 
1451     public int getNumImages(boolean allowSearch) throws IIOException {
1452         if (stream == null) {
1453             throw new IllegalStateException("No input source set!");
1454         }
1455         if (seekForwardOnly && allowSearch) {
1456             throw new IllegalStateException
1457                 ("seekForwardOnly and allowSearch can't both be true!");
1458         }
1459         return 1;
1460     }
1461 
1462     public int getWidth(int imageIndex) throws IIOException {
1463         if (imageIndex != 0) {
1464             throw new IndexOutOfBoundsException("imageIndex != 0!");
1465         }
1466 
1467         readHeader();
1468 
1469         return metadata.IHDR_width;
1470     }
1471 
1472     public int getHeight(int imageIndex) throws IIOException {
1473         if (imageIndex != 0) {
1474             throw new IndexOutOfBoundsException("imageIndex != 0!");
1475         }
1476 
1477         readHeader();
1478 
1479         return metadata.IHDR_height;
1480     }
1481 
1482     public Iterator<ImageTypeSpecifier> getImageTypes(int imageIndex)
1483       throws IIOException
1484     {
1485         if (imageIndex != 0) {
1486             throw new IndexOutOfBoundsException("imageIndex != 0!");
1487         }
1488 
1489         readHeader();
1490 
1491         ArrayList<ImageTypeSpecifier> l =
1492             new ArrayList<ImageTypeSpecifier>(1);
1493 
1494         ColorSpace rgb;
1495         ColorSpace gray;
1496         int[] bandOffsets;
1497 
1498         int bitDepth = metadata.IHDR_bitDepth;
1499         int colorType = metadata.IHDR_colorType;
1500 
1501         int dataType;
1502         if (bitDepth <= 8) {
1503             dataType = DataBuffer.TYPE_BYTE;
1504         } else {
1505             dataType = DataBuffer.TYPE_USHORT;
1506         }
1507 
1508         switch (colorType) {






1509         case PNG_COLOR_GRAY:













1510             // Packed grayscale
1511             l.add(ImageTypeSpecifier.createGrayscale(bitDepth,
1512                                                      dataType,
1513                                                      false));
1514             break;
1515 
1516         case PNG_COLOR_RGB:


1517             if (bitDepth == 8) {




1518                 // some standard types of buffered images
1519                 // which can be used as destination
1520                 l.add(ImageTypeSpecifier.createFromBufferedImageType(
1521                           BufferedImage.TYPE_3BYTE_BGR));
1522 
1523                 l.add(ImageTypeSpecifier.createFromBufferedImageType(
1524                           BufferedImage.TYPE_INT_RGB));
1525 
1526                 l.add(ImageTypeSpecifier.createFromBufferedImageType(
1527                           BufferedImage.TYPE_INT_BGR));
1528 













1529             }
1530             // Component R, G, B
1531             rgb = ColorSpace.getInstance(ColorSpace.CS_sRGB);
1532             bandOffsets = new int[3];
1533             bandOffsets[0] = 0;
1534             bandOffsets[1] = 1;
1535             bandOffsets[2] = 2;
1536             l.add(ImageTypeSpecifier.createInterleaved(rgb,
1537                                                        bandOffsets,
1538                                                        dataType,
1539                                                        false,
1540                                                        false));
1541             break;
1542 
1543         case PNG_COLOR_PALETTE:
1544             readMetadata(); // Need tRNS chunk
1545 
1546             /*
1547              * The PLTE chunk spec says:
1548              *
1549              * The number of palette entries must not exceed the range that
1550              * can be represented in the image bit depth (for example, 2^4 = 16
1551              * for a bit depth of 4). It is permissible to have fewer entries
1552              * than the bit depth would allow. In that case, any out-of-range
1553              * pixel value found in the image data is an error.
1554              *
1555              * http://www.libpng.org/pub/png/spec/1.2/PNG-Chunks.html#C.PLTE
1556              *
1557              * Consequently, the case when the palette length is smaller than
1558              * 2^bitDepth is legal in the view of PNG spec.
1559              *
1560              * However the spec of createIndexed() method demands the exact
1561              * equality of the palette lengh and number of possible palette
1562              * entries (2^bitDepth).
1563              *
1564              * {@link javax.imageio.ImageTypeSpecifier.html#createIndexed}
1565              *
1566              * In order to avoid this contradiction we need to extend the
1567              * palette arrays to the limit defined by the bitDepth.
1568              */
1569 
1570             int plength = 1 << bitDepth;
1571 
1572             byte[] red = metadata.PLTE_red;
1573             byte[] green = metadata.PLTE_green;
1574             byte[] blue = metadata.PLTE_blue;
1575 
1576             if (metadata.PLTE_red.length < plength) {
1577                 red = Arrays.copyOf(metadata.PLTE_red, plength);
1578                 Arrays.fill(red, metadata.PLTE_red.length, plength,
1579                             metadata.PLTE_red[metadata.PLTE_red.length - 1]);
1580 
1581                 green = Arrays.copyOf(metadata.PLTE_green, plength);
1582                 Arrays.fill(green, metadata.PLTE_green.length, plength,
1583                             metadata.PLTE_green[metadata.PLTE_green.length - 1]);
1584 
1585                 blue = Arrays.copyOf(metadata.PLTE_blue, plength);
1586                 Arrays.fill(blue, metadata.PLTE_blue.length, plength,
1587                             metadata.PLTE_blue[metadata.PLTE_blue.length - 1]);
1588 
1589             }
1590 
1591             // Alpha from tRNS chunk may have fewer entries than
1592             // the RGB LUTs from the PLTE chunk; if so, pad with
1593             // 255.
1594             byte[] alpha = null;
1595             if (metadata.tRNS_present && (metadata.tRNS_alpha != null)) {
1596                 if (metadata.tRNS_alpha.length == red.length) {
1597                     alpha = metadata.tRNS_alpha;
1598                 } else {
1599                     alpha = Arrays.copyOf(metadata.tRNS_alpha, red.length);
1600                     Arrays.fill(alpha,
1601                                 metadata.tRNS_alpha.length,
1602                                 red.length, (byte)255);
1603                 }
1604             }
1605 
1606             l.add(ImageTypeSpecifier.createIndexed(red, green,
1607                                                    blue, alpha,
1608                                                    bitDepth,
1609                                                    DataBuffer.TYPE_BYTE));
1610             break;
1611 
1612         case PNG_COLOR_GRAY_ALPHA:
1613             // Component G, A
1614             gray = ColorSpace.getInstance(ColorSpace.CS_GRAY);
1615             bandOffsets = new int[2];
1616             bandOffsets[0] = 0;
1617             bandOffsets[1] = 1;
1618             l.add(ImageTypeSpecifier.createInterleaved(gray,
1619                                                        bandOffsets,
1620                                                        dataType,
1621                                                        true,
1622                                                        false));
1623             break;
1624 
1625         case PNG_COLOR_RGB_ALPHA:
1626             if (bitDepth == 8) {
1627                 // some standard types of buffered images
1628                 // wich can be used as destination
1629                 l.add(ImageTypeSpecifier.createFromBufferedImageType(
1630                           BufferedImage.TYPE_4BYTE_ABGR));
1631 
1632                 l.add(ImageTypeSpecifier.createFromBufferedImageType(
1633                           BufferedImage.TYPE_INT_ARGB));
1634             }
1635 
1636             // Component R, G, B, A (non-premultiplied)
1637             rgb = ColorSpace.getInstance(ColorSpace.CS_sRGB);
1638             bandOffsets = new int[4];
1639             bandOffsets[0] = 0;
1640             bandOffsets[1] = 1;
1641             bandOffsets[2] = 2;
1642             bandOffsets[3] = 3;
1643 
1644             l.add(ImageTypeSpecifier.createInterleaved(rgb,
1645                                                        bandOffsets,
1646                                                        dataType,
1647                                                        true,
1648                                                        false));
1649             break;
1650 
1651         default:
1652             break;
1653         }
1654 
1655         return l.iterator();
1656     }
1657 
1658     /*
1659      * Super class implementation uses first element
1660      * of image types list as raw image type.
1661      *
1662      * Also, super implementation uses first element of this list
1663      * as default destination type image read param does not specify
1664      * anything other.
1665      *
1666      * However, in case of RGB and RGBA color types, raw image type
1667      * produces buffered image of custom type. It causes some
1668      * performance degradation of subsequent rendering operations.
1669      *
1670      * To resolve this contradiction we put standard image types
1671      * at the first positions of image types list (to produce standard
1672      * images by default) and put raw image type (which is custom)
1673      * at the last position of this list.
1674      *
1675      * After this changes we should override getRawImageType()
1676      * to return last element of image types list.
1677      */
1678     public ImageTypeSpecifier getRawImageType(int imageIndex)
1679       throws IOException {
1680 
1681         Iterator<ImageTypeSpecifier> types = getImageTypes(imageIndex);
1682         ImageTypeSpecifier raw = null;
1683         do {
1684             raw = types.next();
1685         } while (types.hasNext());
1686         return raw;
1687     }
1688 
1689     public ImageReadParam getDefaultReadParam() {
1690         return new ImageReadParam();
1691     }
1692 
1693     public IIOMetadata getStreamMetadata()
1694         throws IIOException {
1695         return null;
1696     }
1697 
1698     public IIOMetadata getImageMetadata(int imageIndex) throws IIOException {
1699         if (imageIndex != 0) {
1700             throw new IndexOutOfBoundsException("imageIndex != 0!");
1701         }
1702         readMetadata();
1703         return metadata;
1704     }
1705 
1706     public BufferedImage read(int imageIndex, ImageReadParam param)
1707         throws IIOException {
1708         if (imageIndex != 0) {
1709             throw new IndexOutOfBoundsException("imageIndex != 0!");
1710         }
1711 
1712         try {
1713             readImage(param);
1714         } catch (IOException |
1715                  IllegalStateException |
1716                  IllegalArgumentException e)
1717         {
1718             throw e;
1719         } catch (Throwable e) {
1720             throw new IIOException("Caught exception during read: ", e);
1721         }
1722         return theImage;
1723     }
1724 
1725     public void reset() {
1726         super.reset();
1727         resetStreamSettings();
1728     }
1729 
1730     private void resetStreamSettings() {
1731         gotHeader = false;
1732         gotMetadata = false;
1733         metadata = null;
1734         pixelStream = null;
1735         imageStartPosition = -1L;
1736     }
1737 }
--- EOF ---