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Diffstat (limited to 'gcc-4.4.3/libjava/classpath/gnu/javax/imageio/png/PNGChunk.java')
| -rw-r--r-- | gcc-4.4.3/libjava/classpath/gnu/javax/imageio/png/PNGChunk.java | 283 |
1 files changed, 283 insertions, 0 deletions
diff --git a/gcc-4.4.3/libjava/classpath/gnu/javax/imageio/png/PNGChunk.java b/gcc-4.4.3/libjava/classpath/gnu/javax/imageio/png/PNGChunk.java new file mode 100644 index 000000000..8efbeea72 --- /dev/null +++ b/gcc-4.4.3/libjava/classpath/gnu/javax/imageio/png/PNGChunk.java @@ -0,0 +1,283 @@ +/* PNGChunk.java -- Generic PNG chunk + Copyright (C) 2006 Free Software Foundation + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + +package gnu.javax.imageio.png; + +import java.io.InputStream; +import java.io.OutputStream; +import java.io.IOException; + +/** + * Class to load and validate a generic PNG chunk. + */ +public class PNGChunk +{ + + /** + * CRC table and initialization code. + */ + private static long[] crcTable; + + static + { + long c; + crcTable = new long[256]; + + for(int i = 0; i < 256; i++) + { + c = i; + for(int j = 0; j < 8; j++) + if( (c & 1) == 1 ) + c = 0xEDB88320L ^ (c >> 1); + else + c = c >> 1; + crcTable[i] = c; + } + } + + /** + * (recognized) PNG chunk types. + */ + public static final int TYPE_HEADER = 0x49484452; // 'IHDR' + public static final int TYPE_PALETTE = 0x504c5445;// 'PLTE' + public static final int TYPE_DATA = 0x49444154; // 'IDAT' + public static final int TYPE_TIME = 0x74494d45; // 'tIME' + public static final int TYPE_END = 0x49454e44; // 'IEND' + public static final int TYPE_PHYS = 0x70485973; // 'pHYS' + public static final int TYPE_GAMMA = 0x67414d41; // 'gAMA' + public static final int TYPE_PROFILE = 0x69434350; // 'iCCP' + + /** + * The chunk type - Represented in the file as 4 ASCII bytes, + */ + private int type; + + /** + * The chunk data + */ + protected byte[] data; + + /** + * The chunk's crc + */ + private int crc; + + /** + * Constructor for reading a generic chunk. + */ + protected PNGChunk( int type, byte[] data, int crc ) + { + this.type = type; + this.data = data; + this.crc = crc; + } + + /** + * Constructor for creating new chunks. + * (only used by subclasses - creating a generic chunk is rather useless) + */ + protected PNGChunk( int type ) + { + this.type = type; + } + + /** + * Loads a chunk from an InputStream. Does not perform validation, + * but will throw an IOException if the read fails. + * @param in - th einputstream to read from + * @param strict - if true, a PNGException is thrown on all invalid chunks, + * if false, only critical chunks will throw PNGExceptions. + */ + public static PNGChunk readChunk(InputStream in, boolean strict) + throws IOException, PNGException + { + byte data[] = new byte[4]; + if( in.read( data ) != 4 ) + throw new IOException("Could not read chunk length."); + int length = ((data[0] & 0xFF) << 24) | ((data[1] & 0xFF) << 16 ) | + ((data[2] & 0xFF) << 8) | (data[3] & 0xFF); + + if( in.read( data ) != 4 ) + throw new IOException("Could not read chunk type."); + int type = ((data[0] & 0xFF) << 24) | ((data[1] & 0xFF) << 16 ) | + ((data[2] & 0xFF) << 8) | (data[3] & 0xFF); + + byte[] chkdata = new byte[ length ]; + if( in.read( chkdata ) != length ) + throw new IOException("Could not read chunk data."); + + if( in.read( data ) != 4 ) + throw new IOException("Could not read chunk CRC."); + + int crc = ((data[0] & 0xFF) << 24) | ( (data[1] & 0xFF) << 16 ) | + ((data[2] & 0xFF) << 8) | (data[3] & 0xFF); + + if( strict ) + return getChunk( type, chkdata, crc ); + else + { + try + { + return getChunk( type, chkdata, crc ); + } + catch(PNGException pnge) + { + if( isEssentialChunk( type ) ) + throw pnge; + return null; + } + } + } + + /** + * Returns a specialied object for a chunk, if we have one. + */ + private static PNGChunk getChunk( int type, byte[] data, int crc ) + throws PNGException + { + switch( type ) + { + case TYPE_HEADER: + return new PNGHeader( type, data, crc ); + case TYPE_DATA: + return new PNGData( type, data, crc ); + case TYPE_PALETTE: + return new PNGPalette( type, data, crc ); + case TYPE_TIME: + return new PNGTime( type, data, crc ); + case TYPE_PHYS: + return new PNGPhys( type, data, crc ); + case TYPE_GAMMA: + return new PNGGamma( type, data, crc ); + case TYPE_PROFILE: + return new PNGICCProfile( type, data, crc ); + default: + return new PNGChunk( type, data, crc ); + } + } + + /** + * Returns whether the chunk is essential or not + */ + private static boolean isEssentialChunk( int type ) + { + switch( type ) + { + case TYPE_HEADER: + case TYPE_DATA: + case TYPE_PALETTE: + case TYPE_END: + return true; + default: + return false; + } + } + + /** + * Validates the chunk + */ + public boolean isValidChunk() + { + return (crc == calcCRC()); + } + + /** + * Returns the chunk type. + */ + public int getType() + { + return type; + } + + /** + * Writes a PNG chunk to an output stream, + * performing the CRC calculation as well. + */ + public void writeChunk(OutputStream out) throws IOException + { + out.write( getInt(data.length) ); + out.write( getInt(type) ); + out.write( data ); + out.write( getInt(calcCRC()) ); + } + + /** + * Return whether the chunk contains any data. + */ + public boolean isEmpty() + { + return ( data.length == 0 ); + } + + /** + * Convenience method. Cast an int to four bytes (big endian). + * (Now why doesn't java have a simple way of doing this?) + */ + public static byte[] getInt(int intValue) + { + long i = (intValue & 0xFFFFFFFFL); + byte[] b = new byte[4]; + b[0] = (byte)((i & 0xFF000000L) >> 24); + b[1] = (byte)((i & 0x00FF0000L) >> 16); + b[2] = (byte)((i & 0x0000FF00L) >> 8); + b[3] = (byte)(i & 0x000000FFL); + return b; + } + + /** + * Calculates this chunk's CRC value. + */ + private int calcCRC() + { + long c = 0xFFFFFFFFL; + byte[] t = getInt( type ); + for(int i = 0; i < 4; i++) + c = crcTable[ (int)((c ^ t[i]) & 0xFF) ] ^ (c >> 8); + + for(int i = 0; i < data.length; i++) + c = crcTable[ (int)((c ^ data[i]) & 0xFF) ] ^ (c >> 8); + + return (int)(c ^ 0xFFFFFFFFL); + } + + public String toString() + { + return "PNG Chunk. Type: " + new String( getInt(type) ) + " , CRC: " + + crc + " , calculated CRC: "+calcCRC(); + } + +} |