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 }