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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package sun.awt.image;

import java.io.*;
import java.util.*;
import java.util.zip.*;
import java.awt.image.*;
import java.awt.Color;

PNG - Portable Network Graphics - image file reader. See RFC2083 for details.
/** PNG - Portable Network Graphics - image file reader. See <a href=http://www.ietf.org/rfc/rfc2083.txt>RFC2083</a> for details. */
/* this is changed public class PNGImageDecoder extends FilterInputStream implements Runnable { */ public class PNGImageDecoder extends ImageDecoder { private static final int GRAY=0; private static final int PALETTE=1; private static final int COLOR=2; private static final int ALPHA=4; private static final int bKGDChunk = 0x624B4744; private static final int cHRMChunk = 0x6348524D; private static final int gAMAChunk = 0x67414D41; private static final int hISTChunk = 0x68495354; private static final int IDATChunk = 0x49444154; private static final int IENDChunk = 0x49454E44; private static final int IHDRChunk = 0x49484452; private static final int PLTEChunk = 0x504C5445; private static final int pHYsChunk = 0x70485973; private static final int sBITChunk = 0x73424954; private static final int tEXtChunk = 0x74455874; private static final int tIMEChunk = 0x74494D45; private static final int tRNSChunk = 0x74524E53; private static final int zTXtChunk = 0x7A545874; private int width; private int height; private int bitDepth; private int colorType; private int compressionMethod; private int filterMethod; private int interlaceMethod; private int gamma = 100000; private java.util.Hashtable<String, Object> properties; /* this is not needed ImageConsumer target; */ private ColorModel cm; private byte[] red_map, green_map, blue_map, alpha_map; private int transparentPixel = -1; private byte[] transparentPixel_16 = null; // we need 6 bytes to store 16bpp value private static ColorModel greyModels[] = new ColorModel[4]; /* this is not needed PNGImageDecoder next; */ private void property(String key,Object value) { if(value==null) return; if(properties==null) properties=new java.util.Hashtable<>(); properties.put(key,value); } private void property(String key,float value) { property(key, Float.valueOf(value)); } private void pngassert(boolean b) throws IOException { if(!b) { PNGException e = new PNGException("Broken file"); e.printStackTrace(); throw e; } } protected boolean handleChunk(int key, byte[] buf, int st, int len) throws IOException { switch(key) { case bKGDChunk: Color c = null; switch(colorType) { case COLOR: case COLOR|ALPHA: pngassert(len==6); c = new Color(buf[st]&0xff,buf[st+2]&0xff,buf[st+4]&0xff); break; case COLOR|PALETTE: case COLOR|PALETTE|ALPHA: pngassert(len==1); int ix = buf[st]&0xFF; pngassert(red_map!=null && ix<red_map.length); c = new Color(red_map[ix]&0xff,green_map[ix]&0xff,blue_map[ix]&0xff); break; case GRAY: case GRAY|ALPHA: pngassert(len==2); int t = buf[st]&0xFF; c = new Color(t,t,t); break; } if(c!=null) property("background",c); break; case cHRMChunk: property("chromaticities", new Chromaticities( getInt(st), getInt(st+4), getInt(st+8), getInt(st+12), getInt(st+16), getInt(st+20), getInt(st+24), getInt(st+28))); break; case gAMAChunk: if(len!=4) throw new PNGException("bogus gAMA"); gamma = getInt(st); if(gamma!=100000) property("gamma",gamma/100000.0f); break; case hISTChunk: break; case IDATChunk: return false; case IENDChunk: break; case IHDRChunk: if(len!=13 ||(width = getInt(st))==0 ||(height = getInt(st+4))==0 ) throw new PNGException("bogus IHDR"); bitDepth = getByte(st+8); colorType = getByte(st+9); compressionMethod = getByte(st+10); filterMethod = getByte(st+11); interlaceMethod = getByte(st+12); /* this is not needed if(target!=null) target.setDimensions(width,height); */ break; case PLTEChunk: { int tsize = len/3; red_map = new byte[tsize]; green_map = new byte[tsize]; blue_map = new byte[tsize]; for(int i=0,j=st; i<tsize; i++, j+=3) { red_map[i] = buf[j]; green_map[i] = buf[j+1]; blue_map[i] = buf[j+2]; } } break; case pHYsChunk: break; case sBITChunk: break; case tEXtChunk: int klen = 0; while(klen<len && buf[st+klen]!=0) klen++; if(klen<len) { String tkey = new String(buf,st,klen); String tvalue = new String(buf,st+klen+1,len-klen-1); property(tkey,tvalue); } break; case tIMEChunk: property("modtime",new GregorianCalendar( getShort(st+0), getByte(st+2)-1, getByte(st+3), getByte(st+4), getByte(st+5), getByte(st+6)).getTime()); break; case tRNSChunk: switch(colorType) { case PALETTE|COLOR: case PALETTE|COLOR|ALPHA: int alen = len; if(red_map!=null) alen = red_map.length; alpha_map = new byte[alen]; System.arraycopy(buf,st,alpha_map,0,len<alen ? len : alen); while (--alen>=len) alpha_map[alen] = (byte)0xFF; break; case COLOR: // doesn't deal with 16 bit colors properly case COLOR|ALPHA: // doesn't deal with 16 bit colors properly pngassert(len==6); if (bitDepth == 16) { transparentPixel_16 = new byte[6]; for (int i = 0; i < 6; i++) { transparentPixel_16[i] = (byte)getByte(st + i); } } else { transparentPixel = ((getShort(st + 0)&0xFF)<<16) | ((getShort(st + 2)&0xFF)<< 8) | ((getShort(st + 4)&0xFF) ); } break; case GRAY: // doesn't deal with 16 bit colors properly case GRAY|ALPHA: // doesn't deal with 16 bit colors properly pngassert(len==2); /* REMIND: Discarding the LSB for 16 bit depth here * means that the all pixels which match the MSB * will be treated as transparent. */ int t = getShort(st); t = 0xFF & ((bitDepth == 16) ? (t >> 8) : t); transparentPixel = (t<<16) | (t<< 8) | t; break; } break; case zTXtChunk: break; } return true; } @SuppressWarnings("serial") // JDK-implementation class public class PNGException extends IOException { PNGException(String s) { super(s); } } /* this is changed public void run() { */ public void produceImage() throws IOException, ImageFormatException { /* this is not needed ImageConsumer t = target; if(t!=null) try { */ try { for(int i=0; i<signature.length; i++) if((signature[i]&0xFF)!=underlyingInputStream.read()) throw new PNGException("Chunk signature mismatch"); InputStream is = new BufferedInputStream(new InflaterInputStream(inputStream,new Inflater())); getData(); byte[] bPixels = null; int[] wPixels = null; int pixSize = width; int rowStride; int logDepth = 0; switch(bitDepth) { case 1: logDepth = 0; break; case 2: logDepth = 1; break; case 4: logDepth = 2; break; case 8: logDepth = 3; break; case 16: logDepth = 4; break; default: throw new PNGException("invalid depth"); } if(interlaceMethod!=0) {pixSize *= height;rowStride=width;} else rowStride = 0; int combinedType = colorType|(bitDepth<<3); int bitMask = (1<<(bitDepth>=8?8:bitDepth))-1; //Figure out the color model switch(colorType) { case COLOR|PALETTE: case COLOR|PALETTE|ALPHA: if(red_map==null) throw new PNGException("palette expected"); if(alpha_map==null) cm = new IndexColorModel(bitDepth,red_map.length, red_map,green_map,blue_map); else cm = new IndexColorModel(bitDepth,red_map.length, red_map,green_map,blue_map,alpha_map); bPixels = new byte[pixSize]; break; case GRAY: { int llog = logDepth>=4 ? 3 : logDepth; if((cm=greyModels[llog]) == null) { int size = 1<<(1<<llog); byte ramp[] = new byte[size]; for(int i = 0; i<size; i++) ramp[i] = (byte)(255*i/(size-1)); if (transparentPixel == -1) { cm = new IndexColorModel(bitDepth,ramp.length,ramp,ramp,ramp); } else { cm = new IndexColorModel(bitDepth,ramp.length,ramp,ramp,ramp, (transparentPixel & 0xFF)); } greyModels[llog] = cm; } } bPixels = new byte[pixSize]; break; case COLOR: case COLOR|ALPHA: case GRAY|ALPHA: cm = ColorModel.getRGBdefault(); wPixels = new int[pixSize]; break; default: throw new PNGException("invalid color type"); } /* this is going to be set in the pixel store t.setColorModel(cm); t.setHints(interlaceMethod !=0 ? ImageConsumer.TOPDOWNLEFTRIGHT | ImageConsumer.COMPLETESCANLINES : ImageConsumer.TOPDOWNLEFTRIGHT | ImageConsumer.COMPLETESCANLINES | ImageConsumer.SINGLEPASS | ImageConsumer.SINGLEFRAME); */ // code added to make it work with ImageDecoder architecture setDimensions(width, height); setColorModel(cm); int flags = (interlaceMethod !=0 ? ImageConsumer.TOPDOWNLEFTRIGHT | ImageConsumer.COMPLETESCANLINES : ImageConsumer.TOPDOWNLEFTRIGHT | ImageConsumer.COMPLETESCANLINES | ImageConsumer.SINGLEPASS | ImageConsumer.SINGLEFRAME); setHints(flags); headerComplete(); // end of adding int samplesPerPixel = ((colorType&PALETTE)!=0 ? 1 : ((colorType&COLOR)!=0 ? 3 : 1)+((colorType&ALPHA)!=0?1:0)); int bitsPerPixel = samplesPerPixel*bitDepth; int bytesPerPixel = (bitsPerPixel+7)>>3; int pass, passLimit; if(interlaceMethod==0) { pass = -1; passLimit = 0; } else { pass = 0; passLimit = 7; } // These loops are far from being tuned. They're this way to make them easy to // debug. Tuning comes later. /* code changed. target not needed here while(++pass<=passLimit && (t=target)!=null) { */ while(++pass<=passLimit) { int row = startingRow[pass]; int rowInc = rowIncrement[pass]; int colInc = colIncrement[pass]; int bWidth = blockWidth[pass]; int bHeight = blockHeight[pass]; int sCol = startingCol[pass]; int rowPixelWidth = (width-sCol+(colInc-1))/colInc; int rowByteWidth = ((rowPixelWidth*bitsPerPixel)+7)>>3; if(rowByteWidth==0) continue; int pixelBufferInc = interlaceMethod==0 ? rowInc*width : 0; int rowOffset = rowStride*row; boolean firstRow = true; byte[] rowByteBuffer = new byte[rowByteWidth]; byte[] prevRowByteBuffer = new byte[rowByteWidth]; /* code changed. target not needed here while (row < height && (t=target)!=null) { */ while (row < height) { int rowFilter = is.read(); for (int rowFillPos=0;rowFillPos<rowByteWidth; ) { int n = is.read(rowByteBuffer,rowFillPos,rowByteWidth-rowFillPos); if(n<=0) throw new PNGException("missing data"); rowFillPos+=n; } filterRow(rowByteBuffer, firstRow ? null : prevRowByteBuffer, rowFilter, rowByteWidth, bytesPerPixel); int col = sCol; int spos=0; int pixel = 0; while (col < width) { if(wPixels !=null) { switch(combinedType) { case COLOR|ALPHA|(8<<3): wPixels[col+rowOffset] = ((rowByteBuffer[spos ]&0xFF)<<16) | ((rowByteBuffer[spos+1]&0xFF)<< 8) | ((rowByteBuffer[spos+2]&0xFF) ) | ((rowByteBuffer[spos+3]&0xFF)<<24); spos+=4; break; case COLOR|ALPHA|(16<<3): wPixels[col+rowOffset] = ((rowByteBuffer[spos ]&0xFF)<<16) | ((rowByteBuffer[spos+2]&0xFF)<< 8) | ((rowByteBuffer[spos+4]&0xFF) ) | ((rowByteBuffer[spos+6]&0xFF)<<24); spos+=8; break; case COLOR|(8<<3): pixel = ((rowByteBuffer[spos ]&0xFF)<<16) | ((rowByteBuffer[spos+1]&0xFF)<< 8) | ((rowByteBuffer[spos+2]&0xFF) ); if (pixel != transparentPixel) { pixel |= 0xff000000; } wPixels[col+rowOffset] = pixel; spos+=3; break; case COLOR|(16<<3): pixel = ((rowByteBuffer[spos ]&0xFF)<<16) | ((rowByteBuffer[spos+2]&0xFF)<< 8) | ((rowByteBuffer[spos+4]&0xFF) ); boolean isTransparent = (transparentPixel_16 != null); for (int i = 0; isTransparent && (i < 6); i++) { isTransparent &= (rowByteBuffer[spos + i] & 0xFF) == (transparentPixel_16[i] & 0xFF); } if (!isTransparent) { pixel |= 0xff000000; } wPixels[col+rowOffset] = pixel; spos+=6; break; case GRAY|ALPHA|(8<<3): { int tx = rowByteBuffer[spos]&0xFF; wPixels[col+rowOffset] = (tx<<16)|(tx<<8)|tx |((rowByteBuffer[spos+1]&0xFF)<<24); } spos+=2; break; case GRAY|ALPHA|(16<<3): { int tx = rowByteBuffer[spos]&0xFF; wPixels[col+rowOffset] = (tx<<16)|(tx<<8)|tx |((rowByteBuffer[spos+2]&0xFF)<<24); } spos+=4; break; default: throw new PNGException("illegal type/depth"); } } else switch(bitDepth) { case 1: bPixels[col+rowOffset] = (byte)((rowByteBuffer[spos>>3]>>(7-(spos&7)))&1); spos++; break; case 2: bPixels[col+rowOffset] = (byte)((rowByteBuffer[spos>>2]>>((3-(spos&3))*2))&3); spos++; break; case 4: bPixels[col+rowOffset] = (byte)((rowByteBuffer[spos>>1]>>((1-(spos&1))*4))&15); spos++; break; case 8: bPixels[col+rowOffset] = rowByteBuffer[spos++]; break; case 16: bPixels[col+rowOffset] = rowByteBuffer[spos]; spos+=2; break; default: throw new PNGException("illegal type/depth"); } /*visit (row, col, min (bHeight, height - row), min (bWidth, width - col)); */ col += colInc; } if(interlaceMethod==0) if(wPixels!=null) { /* code changed. target not needed here t.setPixels(0,row,width,1,cm,wPixels,0,width); */ // code added to make it work with ImageDecoder arch sendPixels(0,row,width,1,wPixels,0,width); // end of adding } else { /* code changed. target not needed here t.setPixels(0,row,width,1,cm,bPixels,0,width); */ // code added to make it work with ImageDecoder arch sendPixels(0,row,width,1,bPixels,0,width); //end of adding } row += rowInc; rowOffset += rowInc*rowStride; byte[] T = rowByteBuffer; rowByteBuffer = prevRowByteBuffer; prevRowByteBuffer = T; firstRow = false; } if(interlaceMethod!=0) if(wPixels!=null) { /* code changed. target not needed here t.setPixels(0,0,width,height,cm,wPixels,0,width); */ // code added to make it work with ImageDecoder arch sendPixels(0,0,width,height,wPixels,0,width); //end of adding } else { /* code changed. target not needed here t.setPixels(0,0,width,height,cm,bPixels,0,width); */ // code added to make it work with ImageDecoder arch sendPixels(0,0,width,height,bPixels,0,width); //end of adding } } /* Here, the function "visit(row,column,height,width)" obtains the next transmitted pixel and paints a rectangle of the specified height and width, whose upper-left corner is at the specified row and column, using the color indicated by the pixel. Note that row and column are measured from 0,0 at the upper left corner. */ /* code not needed, don't deal with target if((t=target)!=null) { if(properties!=null) t.setProperties(properties); t.imageComplete(ImageConsumer.STATICIMAGEDONE); */ imageComplete(ImageConsumer.STATICIMAGEDONE, true); /* code not needed } is.close(); */ } catch(IOException e) { if(!aborted) { /* code not needed if((t=target)!=null) { PNGEncoder.prChunk(e.toString(),inbuf,pos,limit-pos,true); */ property("error", e); /* code not needed t.setProperties(properties); t.imageComplete(ImageConsumer.IMAGEERROR|ImageConsumer.STATICIMAGEDONE); */ imageComplete(ImageConsumer.IMAGEERROR|ImageConsumer.STATICIMAGEDONE, true); throw e; } } finally { try { close(); } catch(Throwable e){} /* code not needed target = null; endTurn(); */ } } private boolean sendPixels(int x, int y, int w, int h, int[] pixels, int offset, int pixlength) { int count = setPixels(x, y, w, h, cm, pixels, offset, pixlength); if (count <= 0) { aborted = true; } return !aborted; } private boolean sendPixels(int x, int y, int w, int h, byte[] pixels, int offset, int pixlength) { int count = setPixels(x, y, w, h, cm, pixels, offset, pixlength); if (count <= 0) { aborted = true; } return !aborted; } private void filterRow(byte rowByteBuffer[], byte[] prevRow, int rowFilter, int rowByteWidth, int bytesPerSample) throws IOException { int x = 0; switch (rowFilter) { case 0: break; case 1: for (x = bytesPerSample; x < rowByteWidth; x++) rowByteBuffer[x] += rowByteBuffer[x - bytesPerSample]; break; case 2: if (prevRow != null) for ( ; x < rowByteWidth; x++) rowByteBuffer[x] += prevRow[x]; break; case 3: if (prevRow != null) { for ( ; x < bytesPerSample; x++) rowByteBuffer[x] += (0xff & prevRow[x])>>1; for ( ; x < rowByteWidth; x++) rowByteBuffer[x] += ((prevRow[x]&0xFF) + (rowByteBuffer[x - bytesPerSample]&0xFF))>>1; } else for (x = bytesPerSample; x < rowByteWidth; x++) rowByteBuffer[x] += (rowByteBuffer[x - bytesPerSample]&0xFF)>>1; break; case 4: if (prevRow != null) { for ( ; x < bytesPerSample; x++) rowByteBuffer[x] += prevRow[x]; for ( ; x < rowByteWidth; x++) { int a, b, c, p, pa, pb, pc, rval; a = rowByteBuffer[x - bytesPerSample]&0xFF; b = prevRow[x]&0xFF; c = prevRow[x - bytesPerSample]&0xFF; p = a + b - c; pa = p > a ? p - a : a - p; pb = p > b ? p - b : b - p; pc = p > c ? p - c : c - p; rowByteBuffer[x] += (pa <= pb) && (pa <= pc) ? a : pb <= pc ? b : c; } } else for (x = bytesPerSample; x < rowByteWidth; x++) rowByteBuffer[x] += rowByteBuffer[x - bytesPerSample]; break; default: throw new PNGException("Illegal filter"); } } private static final byte[] startingRow = { 0, 0, 0, 4, 0, 2, 0, 1 }; private static final byte[] startingCol = { 0, 0, 4, 0, 2, 0, 1, 0 }; private static final byte[] rowIncrement = { 1, 8, 8, 8, 4, 4, 2, 2 }; private static final byte[] colIncrement = { 1, 8, 8, 4, 4, 2, 2, 1 }; private static final byte[] blockHeight = { 1, 8, 8, 4, 4, 2, 2, 1 }; private static final byte[] blockWidth = { 1, 8, 4, 4, 2, 2, 1, 1 }; //abstract public class ChunkReader extends FilterInputStream { int pos, limit; int chunkStart; int chunkKey, chunkLength, chunkCRC; boolean seenEOF; private static final byte[] signature = { (byte) 137, (byte) 80, (byte) 78, (byte) 71, (byte) 13, (byte) 10, (byte) 26, (byte) 10 }; PNGFilterInputStream inputStream; InputStream underlyingInputStream; /* code changed public PNGImageDecoder(InputStream in, ImageConsumer t) throws IOException { */ public PNGImageDecoder(InputStreamImageSource src, InputStream input) throws IOException { // code added super(src, input); inputStream = new PNGFilterInputStream(this, input); underlyingInputStream = inputStream.underlyingInputStream; // end of adding /* code changed super(in); target = t; waitTurn(); new Thread(this).start(); */ } /* code changed to make it work with ImageDecoder architecture static int ThreadLimit = 10; private static synchronized void waitTurn() { try { while(ThreadLimit<=0) PNGImageDecoder.class.wait(1000); } catch(InterruptedException e){} ThreadLimit--; } private static synchronized void endTurn() { if(ThreadLimit<=0) PNGImageDecoder.class.notify(); ThreadLimit++; } */ byte[] inbuf = new byte[4096]; private void fill() throws IOException { if(!seenEOF) { if(pos>0 && pos<limit) { System.arraycopy(inbuf,pos,inbuf,0,limit-pos); limit = limit-pos; pos = 0; } else if(pos>=limit) { pos = 0; limit = 0; } int bsize = inbuf.length; while(limit<bsize) { int n = underlyingInputStream.read(inbuf,limit,bsize-limit); if(n<=0) { seenEOF=true; break; } limit += n; } } } private boolean need(int n) throws IOException { if(limit-pos>=n) return true; fill(); if(limit-pos>=n) return true; if(seenEOF) return false; byte nin[] = new byte[n+100]; System.arraycopy(inbuf,pos,nin,0,limit-pos); limit = limit-pos; pos = 0; inbuf = nin; fill(); return limit-pos>=n; } private int getInt(int pos) { return ((inbuf[pos ]&0xFF)<<24) | ((inbuf[pos+1]&0xFF)<<16) | ((inbuf[pos+2]&0xFF)<< 8) | ((inbuf[pos+3]&0xFF) ); } private int getShort(int pos) { return (short)(((inbuf[pos ]&0xFF)<<8) | ((inbuf[pos+1]&0xFF) )); } private int getByte(int pos) { return inbuf[pos]&0xFF; } private boolean getChunk() throws IOException { chunkLength = 0; if (!need(8)) return false; chunkLength = getInt(pos); chunkKey = getInt(pos+4); if(chunkLength<0) throw new PNGException("bogus length: "+chunkLength); if (!need(chunkLength+12)) return false; chunkCRC = getInt(pos+8+chunkLength); chunkStart = pos+8; int calcCRC = crc(inbuf,pos+4,chunkLength+4); if(chunkCRC!=calcCRC && checkCRC) throw new PNGException("crc corruption"); pos+=chunkLength+12; return true; } private void readAll() throws IOException { while(getChunk()) handleChunk(chunkKey,inbuf,chunkStart,chunkLength); } boolean getData() throws IOException { while(chunkLength==0 && getChunk()) if(handleChunk(chunkKey,inbuf,chunkStart,chunkLength)) chunkLength = 0; return chunkLength>0; } //abstract protected boolean handleChunk(int key, byte[] buf, int st, int len) // throws IOException; private static boolean checkCRC = true; public static boolean getCheckCRC() { return checkCRC; } public static void setCheckCRC(boolean c) { checkCRC = c; } protected void wrc(int c) { c = c&0xFF; if(c<=' '||c>'z') c = '?'; System.out.write(c); } protected void wrk(int n) { wrc(n>>24); wrc(n>>16); wrc(n>>8); wrc(n); } public void print() { wrk(chunkKey); System.out.print(" "+chunkLength+"\n"); } /* Table of CRCs of all 8-bit messages. */ private static final int[] crc_table = new int[256]; /* Make the table for a fast CRC. */ static { for (int n = 0; n < 256; n++) { int c = n; for (int k = 0; k < 8; k++) if ((c & 1) != 0) c = 0xedb88320 ^ (c >>> 1); else c = c >>> 1; crc_table[n] = c; } } /* Update a running CRC with the bytes buf[0..len-1]--the CRC should be initialized to all 1's, and the transmitted value is the 1's complement of the final running CRC (see the crc() routine below)). */ private static int update_crc(int crc, byte[] buf, int offset, int len) { int c = crc; while (--len>=0) c = crc_table[(c ^ buf[offset++]) & 0xff] ^ (c >>> 8); return c; } /* Return the CRC of the bytes buf[0..len-1]. */ private static int crc(byte[] buf, int offset, int len) { return update_crc(0xffffffff, buf, offset, len) ^ 0xffffffff; } public static class Chromaticities { public float whiteX, whiteY, redX, redY, greenX, greenY, blueX, blueY; Chromaticities(int wx, int wy, int rx, int ry, int gx, int gy, int bx, int by) { whiteX = wx/100000.0f; whiteY = wy/100000.0f; redX = rx/100000.0f; redY = ry/100000.0f; greenX = gx/100000.0f; greenY = gy/100000.0f; blueX = bx/100000.0f; blueY = by/100000.0f; } public String toString() { return "Chromaticities(white="+whiteX+","+whiteY+";red="+ redX+","+redY+";green="+ greenX+","+greenY+";blue="+ blueX+","+blueY+")"; } } } // the following class are added to make it work with ImageDecoder architecture class PNGFilterInputStream extends FilterInputStream { PNGImageDecoder owner; public InputStream underlyingInputStream; public PNGFilterInputStream(PNGImageDecoder owner, InputStream is) { super(is); underlyingInputStream = in; this.owner = owner; } public int available() throws IOException { return owner.limit-owner.pos+in.available();} public boolean markSupported() { return false; } public int read() throws IOException { if(owner.chunkLength<=0) if(!owner.getData()) return -1; owner.chunkLength--; return owner.inbuf[owner.chunkStart++]&0xFF; } public int read(byte[] b) throws IOException{return read(b,0,b.length);} public int read(byte[] b, int st, int len) throws IOException { if(owner.chunkLength<=0) if(!owner.getData()) return -1; if(owner.chunkLength<len) len = owner.chunkLength; System.arraycopy(owner.inbuf,owner.chunkStart,b,st,len); owner.chunkLength-=len; owner.chunkStart+=len; return len; } public long skip(long n) throws IOException { int i; for(i = 0; i<n && read()>=0; i++); return i; } }