2 * This file was adapted from Jason Marshall's PNGImageProducer.java
4 * Copyright (c) 1997, Jason Marshall. All Rights Reserved
6 * The author makes no representations or warranties regarding the suitability,
7 * reliability or stability of this code. This code is provided AS IS. The
8 * author shall not be liable for any damages suffered as a result of using,
9 * modifying or redistributing this software or any derivitives thereof.
10 * Permission to use, reproduce, modify and/or (re)distribute this software is
16 import org.xwt.util.*;
18 import java.util.Hashtable;
19 import java.util.Vector;
20 import java.util.Enumeration;
21 import java.util.zip.*;
23 /** Converts an InputStream carrying a PNG image into an ARGB int[] */
24 public class PNG implements ImageDecoder {
26 // Public Methods ///////////////////////////////////////////////////////////////////////////////
28 /** returns the ARGB int[] representing the last image processed */
29 public final int[] getData() { return data; }
31 /** returns the width of the last image processed */
32 public final int getWidth() { return width; }
34 /** returns the height of the last image processed */
35 public final int getHeight() { return height; }
37 /** process a PNG as an inputstream; returns null if there is an error
38 @param name A string describing the image, to be used when logging errors
40 public static PNG decode(InputStream is, String name) {
42 return new PNG(is, name);
43 } catch (Exception e) {
44 if (Log.on) Log.log(PNG.class, e);
49 private PNG(InputStream is, String name) throws IOException {
50 underlyingStream = is;
52 inputStream = new DataInputStream(underlyingStream);
55 if ((inputStream.read() != 137) || (inputStream.read() != 80) || (inputStream.read() != 78) || (inputStream.read() != 71) ||
56 (inputStream.read() != 13) || (inputStream.read() != 10) || (inputStream.read() != 26) || (inputStream.read() != 10)) {
57 Log.log(this, "PNG: error: input file " + name + " is not a PNG file");
63 DONE: while (!error) {
65 chunkLength = inputStream.readInt();
66 chunkType = inputStream.readInt();
67 needChunkInfo = false;
71 case CHUNK_bKGD: inputStream.skip(chunkLength); break;
72 case CHUNK_cHRM: inputStream.skip(chunkLength); break;
73 case CHUNK_gAMA: inputStream.skip(chunkLength); break;
74 case CHUNK_hIST: inputStream.skip(chunkLength); break;
75 case CHUNK_pHYs: inputStream.skip(chunkLength); break;
76 case CHUNK_sBIT: inputStream.skip(chunkLength); break;
77 case CHUNK_tEXt: inputStream.skip(chunkLength); break;
78 case CHUNK_zTXt: inputStream.skip(chunkLength); break;
79 case CHUNK_tIME: inputStream.skip(chunkLength); break;
81 case CHUNK_IHDR: handleIHDR(); break;
82 case CHUNK_PLTE: handlePLTE(); break;
83 case CHUNK_tRNS: handletRNS(); break;
85 case CHUNK_IDAT: handleIDAT(); break;
87 case CHUNK_IEND: break DONE;
89 System.err.println("unrecognized chunk type " +
90 Integer.toHexString(chunkType) + ". skipping");
91 inputStream.skip(chunkLength);
94 int crc = inputStream.readInt();
99 // Chunk Handlers ///////////////////////////////////////////////////////////////////////
101 /** handle data chunk */
102 private void handleIDAT() throws IOException {
103 if (width == -1 || height == -1) throw new IOException("never got image width/height");
105 case 1: mask = 0x1; break;
106 case 2: mask = 0x3; break;
107 case 4: mask = 0xf; break;
108 case 8: case 16: mask = 0xff; break;
109 default: mask = 0x0; break;
111 if (depth < 8) smask = mask << depth;
112 else smask = mask << 8;
114 int count = width * height;
121 ipixels = new int[count];
125 bpixels = new byte[count];
129 throw new IOException("Image has unknown color type");
131 if (interlaceMethod != 0) multipass = true;
135 /** handle header chunk */
136 private void handleIHDR() throws IOException {
137 if (headerFound) throw new IOException("Extraneous IHDR chunk encountered.");
138 if (chunkLength != 13) throw new IOException("IHDR chunk length wrong: " + chunkLength);
139 width = inputStream.readInt();
140 height = inputStream.readInt();
141 depth = inputStream.read();
142 colorType = inputStream.read();
143 compressionMethod = inputStream.read();
144 filterMethod = inputStream.read();
145 interlaceMethod = inputStream.read();
148 /** handle pallette chunk */
149 private void handlePLTE() throws IOException {
150 if (colorType == 3) {
151 palette = new byte[chunkLength];
152 inputStream.readFully(palette);
154 // Ignore suggested palette
155 inputStream.skip(chunkLength);
159 /** handle transparency chunk; modifies palette */
160 private void handletRNS() throws IOException {
161 int chunkLen = chunkLength;
162 if (palette == null) {
163 if (Log.on) Log.log(this, "warning: tRNS chunk encountered before pLTE; ignoring alpha channel");
164 inputStream.skip(chunkLength);
167 int len = palette.length;
168 if (colorType == 3) {
171 int transLength = len/3;
172 byte[] trans = new byte[transLength];
173 for (int i = 0; i < transLength; i++) trans[i] = (byte) 0xff;
174 inputStream.readFully(trans, 0, chunkLength);
176 byte[] newPalette = new byte[len + transLength];
177 for (int i = newPalette.length; i > 0;) {
178 newPalette[--i] = trans[--transLength];
179 newPalette[--i] = palette[--len];
180 newPalette[--i] = palette[--len];
181 newPalette[--i] = palette[--len];
183 palette = newPalette;
186 inputStream.skip(chunkLength);
190 /// Helper functions for IDAT ///////////////////////////////////////////////////////////////////////////////////////////
192 /** Read Image data in off of a compression stream */
193 private void readImageData() throws IOException {
194 InputStream dataStream = new SequenceInputStream(new IDATEnumeration(this));
195 DataInputStream dis = new DataInputStream(new BufferedInputStream(new InflaterInputStream(dataStream, new Inflater())));
196 int bps, filterOffset;
198 case 0: case 3: bps = depth; break;
199 case 2: bps = 3 * depth; break;
200 case 4: bps = depth<<1; break;
201 case 6: bps = depth<<2; break;
202 default: throw new IOException("Unknown color type encountered.");
205 filterOffset = (bps + 7) >> 3;
207 for (pass = (multipass ? 1 : 0); pass < 8; pass++) {
208 int pass = this.pass;
209 int rInc = rowInc[pass];
210 int cInc = colInc[pass];
211 int sCol = startingCol[pass];
212 int val = (width - sCol + cInc - 1) / cInc;
213 int samples = val * filterOffset;
214 int rowSize = (val * bps)>>3;
215 int sRow = startingRow[pass];
216 if (height <= sRow || rowSize == 0) continue;
217 int sInc = rInc * width;
218 byte inbuf[] = new byte[rowSize];
219 int pix[] = new int[rowSize];
221 int temp[] = new int[rowSize];
222 int nextY = sRow; // next Y value and number of rows to report to sendPixels
224 int rowStart = sRow * width;
226 for (int y = sRow; y < height; y += rInc, rowStart += sInc) {
228 int rowFilter = dis.read();
229 dis.readFully(inbuf);
230 if (!filterRow(inbuf, pix, upix, rowFilter, filterOffset)) throw new IOException("Unknown filter type: " + rowFilter);
231 insertPixels(pix, rowStart + sCol, samples);
232 if (multipass && (pass < 6)) blockFill(rowStart);
237 if (!multipass) break;
239 while(dis.read() != -1) System.err.println("Leftover data encountered.");
241 // 24-bit color is our native format
242 if (colorType == 2 || colorType == 6) {
243 data = (int[])pixels;
244 if (colorType == 2) {
245 for(int i=0; i<data.length; i++)
246 data[i] |= 0xFF000000;
249 } else if (colorType == 3) {
250 byte[] pix = (byte[])pixels;
251 data = new int[pix.length];
252 for(int i=0; i<pix.length; i++) {
255 ((palette[4 * (pix[i] & 0xff) + 3] & 0xff) << 24) |
256 ((palette[4 * (pix[i] & 0xff) + 0] & 0xff) << 16) |
257 ((palette[4 * (pix[i] & 0xff) + 1] & 0xff) << 8) |
258 (palette[4 * (pix[i] & 0xff) + 2] & 0xff);
262 ((palette[3 * (pix[i] & 0xff) + 0] & 0xff) << 16) |
263 ((palette[3 * (pix[i] & 0xff) + 1] & 0xff) << 8) |
264 (palette[3 * (pix[i] & 0xff) + 2] & 0xff);
268 } else if (colorType == 0 || colorType == 4) {
269 if (depth == 16) depth = 8;
270 int[] pix = (int[])pixels;
271 data = new int[pix.length];
272 for(int i=0; i<pix.length; i ++) {
273 if (colorType == 0) {
274 int val = (pix[i] & 0xff) << (8 - depth);
281 int alpha = (pix[i] & mask) << (8 - depth);
282 int val = ((pix[i] & smask) >> depth) << (8 - depth);
294 private void insertGreyPixels(int pix[], int offset, int samples) {
296 int ipix[] = ipixels;
297 int cInc = colInc[pass];
300 if (colorType == 0) {
303 for (int j = 0; j < samples; j++, offset += cInc) {
305 else { rs = 7; p = pix[j>>3]; }
306 ipix[offset] = (p>>rs) & 0x1;
310 for (int j = 0; j < samples; j++, offset += cInc) {
311 if (rs != 0) rs -= 2;
312 else { rs = 6; p = pix[j>>2]; }
313 ipix[offset] = (p>>rs) & 0x3;
317 for (int j = 0; j < samples; j++, offset += cInc) {
319 else { rs = 4; p = pix[j>>1]; }
320 ipix[offset] = (p>>rs) & 0xf;
324 for (int j = 0; j < samples; offset += cInc) ipix[offset] = (byte) pix[j++];
327 samples = samples<<1;
328 for (int j = 0; j < samples; j += 2, offset += cInc) ipix[offset] = pix[j];
332 } else if (colorType == 4) {
334 for (int j = 0; j < samples; offset += cInc) ipix[offset] = (pix[j++]<<8) | pix[j++];
336 samples = samples<<1;
337 for (int j = 0; j < samples; j += 2, offset += cInc) ipix[offset] = (pix[j]<<8) | pix[j+=2];
342 private void insertPalettedPixels(int pix[], int offset, int samples) {
345 byte bpix[] = bpixels;
346 int cInc = colInc[pass];
350 for (int j = 0; j < samples; j++, offset += cInc) {
352 else { rs = 7; p = pix[j>>3]; }
353 bpix[offset] = (byte) ((p>>rs) & 0x1);
357 for (int j = 0; j < samples; j++, offset += cInc) {
358 if (rs != 0) rs -= 2;
359 else { rs = 6; p = pix[j>>2]; }
360 bpix[offset] = (byte) ((p>>rs) & 0x3);
364 for (int j = 0; j < samples; j++, offset += cInc) {
366 else { rs = 4; p = pix[j>>1]; }
367 bpix[offset] = (byte) ((p>>rs) & 0xf);
371 for (int j = 0; j < samples; j++, offset += cInc) bpix[offset] = (byte) pix[j];
376 private void insertPixels(int pix[], int offset, int samples) {
380 insertGreyPixels(pix, offset, samples);
384 int ipix[] = ipixels;
385 int cInc = colInc[pass];
387 for (j = 0; j < samples; offset += cInc)
388 ipix[offset] = (pix[j++]<<16) | (pix[j++]<<8) | pix[j++];
390 samples = samples<<1;
391 for (j = 0; j < samples; j += 2, offset += cInc)
392 ipix[offset] = (pix[j]<<16) | (pix[j+=2]<<8) | pix[j+=2];
396 insertPalettedPixels(pix, offset, samples);
400 int ipix[] = ipixels;
401 int cInc = colInc[pass];
403 for (j = 0; j < samples; offset += cInc) {
404 ipix[offset] = (pix[j++]<<16) | (pix[j++]<<8) | pix[j++] |
408 samples = samples<<1;
409 for (j = 0; j < samples; j += 2, offset += cInc) {
410 ipix[offset] = (pix[j]<<16) | (pix[j+=2]<<8) | pix[j+=2] |
420 private void blockFill(int rowStart) {
423 int pass = this.pass;
424 int w = blockWidth[pass];
425 int sCol = startingCol[pass];
426 int cInc = colInc[pass];
428 int maxW = rowStart + dw - w;
430 int h = blockHeight[pass];
431 int maxH = rowStart + (dw * h);
432 int startPos = rowStart + sCol;
435 if (colorType == 3) {
436 byte bpix[] = bpixels;
439 for (; counter <= maxW;) {
440 int end = counter + w;
441 pixel = bpix[counter++];
442 for (; counter < end; counter++) bpix[counter] = pixel;
447 for (pixel = bpix[counter++]; counter < maxW; counter++)
448 bpix[counter] = pixel;
449 if (len < maxH) maxH = len;
450 for (counter = startPos + dw; counter < maxH; counter += dw)
451 System.arraycopy(bpix, startPos, bpix, counter, dw - sCol);
453 int ipix[] = ipixels;
456 for (; counter <= maxW;) {
457 int end = counter + w;
458 pixel = ipix[counter++];
459 for (; counter < end; counter++)
460 ipix[counter] = pixel;
465 for (pixel = ipix[counter++]; counter < maxW; counter++)
466 ipix[counter] = pixel;
467 if (len < maxH) maxH = len;
468 for (counter = startPos + dw; counter < maxH; counter += dw)
469 System.arraycopy(ipix, startPos, ipix, counter, dw - sCol);
473 private boolean filterRow(byte inbuf[], int pix[], int upix[], int rowFilter, int boff) {
474 int rowWidth = pix.length;
477 for (int x = 0; x < rowWidth; x++) pix[x] = 0xff & inbuf[x];
481 for ( ; x < boff; x++) pix[x] = 0xff & inbuf[x];
482 for ( ; x < rowWidth; x++) pix[x] = 0xff & (inbuf[x] + pix[x - boff]);
486 for (int x = 0; x < rowWidth; x++)
487 pix[x] = 0xff & (upix[x] + inbuf[x]);
489 for (int x = 0; x < rowWidth; x++)
490 pix[x] = 0xff & inbuf[x];
496 for ( ; x < boff; x++) {
498 pix[x] = 0xff & ((rval>>1) + inbuf[x]);
500 for ( ; x < rowWidth; x++) {
501 int rval = upix[x] + pix[x - boff];
502 pix[x] = 0xff & ((rval>>1) + inbuf[x]);
506 for ( ; x < boff; x++) pix[x] = 0xff & inbuf[x];
507 for ( ; x < rowWidth; x++) {
508 int rval = pix[x - boff];
509 pix[x] = 0xff & ((rval>>1) + inbuf[x]);
516 for ( ; x < boff; x++) pix[x] = 0xff & (upix[x] + inbuf[x]);
517 for ( ; x < rowWidth; x++) {
518 int a, b, c, p, pa, pb, pc, rval;
523 pa = p > a ? p - a : a - p;
524 pb = p > b ? p - b : b - p;
525 pc = p > c ? p - c : c - p;
526 if ((pa <= pb) && (pa <= pc)) rval = a;
527 else if (pb <= pc) rval = b;
529 pix[x] = 0xff & (rval + inbuf[x]);
533 for ( ; x < boff; x++) pix[x] = 0xff & inbuf[x];
534 for ( ; x < rowWidth; x++) {
535 int rval = pix[x - boff];
536 pix[x] = 0xff & (rval + inbuf[x]);
540 default: return false;
545 // Private Data ///////////////////////////////////////////////////////////////////////////////////////
547 private int target_offset = 0;
548 private int width = -1;
549 private int height = -1;
550 private int sigmask = 0xffff;
551 private Object pixels = null;
552 private int ipixels[] = null;
553 private byte bpixels[] = null;
554 private boolean multipass = false;
555 private boolean complete = false;
556 private boolean error = false;
558 private int[] data = null;
560 private InputStream underlyingStream = null;
561 private DataInputStream inputStream = null;
562 private Thread controlThread = null;
563 private boolean infoAvailable = false;
564 private int updateDelay = 750;
566 // Image decoding state variables
567 private boolean headerFound = false;
568 private int compressionMethod = -1;
569 private int depth = -1;
570 private int colorType = -1;
571 private int filterMethod = -1;
572 private int interlaceMethod = -1;
573 private int pass = 0;
574 private byte palette[] = null;
575 private int mask = 0x0;
576 private int smask = 0x0;
577 private boolean transparency = false;
579 private int chunkLength = 0;
580 private int chunkType = 0;
581 private boolean needChunkInfo = true;
583 private static final int CHUNK_bKGD = 0x624B4744; // "bKGD"
584 private static final int CHUNK_cHRM = 0x6348524D; // "cHRM"
585 private static final int CHUNK_gAMA = 0x67414D41; // "gAMA"
586 private static final int CHUNK_hIST = 0x68495354; // "hIST"
587 private static final int CHUNK_IDAT = 0x49444154; // "IDAT"
588 private static final int CHUNK_IEND = 0x49454E44; // "IEND"
589 private static final int CHUNK_IHDR = 0x49484452; // "IHDR"
590 private static final int CHUNK_PLTE = 0x504C5445; // "PLTE"
591 private static final int CHUNK_pHYs = 0x70485973; // "pHYs"
592 private static final int CHUNK_sBIT = 0x73424954; // "sBIT"
593 private static final int CHUNK_tEXt = 0x74455874; // "tEXt"
594 private static final int CHUNK_tIME = 0x74494D45; // "tIME"
595 private static final int CHUNK_tRNS = 0x74524E53; // "tIME"
596 private static final int CHUNK_zTXt = 0x7A545874; // "zTXt"
598 private static final int startingRow[] = { 0, 0, 0, 4, 0, 2, 0, 1 };
599 private static final int startingCol[] = { 0, 0, 4, 0, 2, 0, 1, 0 };
600 private static final int rowInc[] = { 1, 8, 8, 8, 4, 4, 2, 2 };
601 private static final int colInc[] = { 1, 8, 8, 4, 4, 2, 2, 1 };
602 private static final int blockHeight[] = { 1, 8, 8, 4, 4, 2, 2, 1 };
603 private static final int blockWidth[] = { 1, 8, 4, 4, 2, 2, 1, 1 };
605 // Helper Classes ////////////////////////////////////////////////////////////////////
607 private static class MeteredInputStream extends FilterInputStream {
611 public MeteredInputStream(InputStream in, int size) {
616 public final int read() throws IOException {
619 if (val != -1) bytesLeft--;
625 public final int read(byte b[]) throws IOException {
626 return read(b, 0, b.length);
629 public final int read(byte b[], int off, int len) throws IOException {
631 len = (len > bytesLeft ? bytesLeft : len);
632 int read = in.read(b, off, len);
633 if (read > 0) bytesLeft -= read;
639 public final long skip(long n) throws IOException {
640 n = (n > bytesLeft ? bytesLeft : n);
641 long skipped = in.skip(n);
642 if (skipped > 0) bytesLeft -= skipped;
646 public final int available() throws IOException {
647 int n = in.available();
648 return (n > bytesLeft ? bytesLeft : n);
651 public final void close() throws IOException { /* Eat this */ }
653 public final void mark(int readlimit) {
658 public final void reset() throws IOException {
663 public final boolean markSupported() { return in.markSupported(); }
666 /** Support class, used to eat the IDAT headers dividing up the deflated stream */
667 private static class IDATEnumeration implements Enumeration {
668 InputStream underlyingStream;
670 boolean firstStream = true;
672 public IDATEnumeration(PNG owner) {
674 this.underlyingStream = owner.underlyingStream;
677 public Object nextElement() {
679 return new MeteredInputStream(underlyingStream, owner.chunkLength);
682 public boolean hasMoreElements() {
683 DataInputStream dis = new DataInputStream(underlyingStream);
686 int crc = dis.readInt();
687 owner.needChunkInfo = false;
688 owner.chunkLength = dis.readInt();
689 owner.chunkType = dis.readInt();
690 } catch (IOException ioe) {
694 if (owner.chunkType == PNG.CHUNK_IDAT) return true;