| Methods Summary |
|---|
| public static java.awt.image.BufferedImage | decode(java.io.InputStream in)
DataInputStream dataIn = new DataInputStream(in);
readSignature(dataIn);
PNGData chunks = readChunks(dataIn);
long widthLong = chunks.getWidth();
long heightLong = chunks.getHeight();
if (widthLong > Integer.MAX_VALUE || heightLong > Integer.MAX_VALUE)
throw new IOException("That image is too wide or tall.");
int width = (int)widthLong;
int height = (int)heightLong;
ColorModel cm = chunks.getColorModel();
WritableRaster raster = chunks.getRaster();
BufferedImage image = new BufferedImage(cm, raster, false, null);
return image;
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| public static void | main(java.lang.String[] args)
String name = "basn3p08.png";
if (args.length > 0) name = args[0];
InputStream in = PNGDecoder.class.getResourceAsStream(name);
final BufferedImage image = PNGDecoder.decode(in);
in.close();
// Create a Frame to display the image.
Frame f = new ApplicationFrame("PNGDecoder v1.0") {
public void paint(Graphics g) {
Insets insets = getInsets();
g.drawImage(image, insets.left, insets.top, null);
}
};
f.setVisible(true);
Insets insets = f.getInsets();
f.setSize(image.getWidth() + insets.left + insets.right,
image.getHeight() + insets.top + insets.bottom);
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| protected static PNGData | readChunks(java.io.DataInputStream in)
PNGData chunks = new PNGData();
boolean trucking = true;
while (trucking) {
try {
// Read the length.
int length = in.readInt();
if (length < 0)
throw new IOException("Sorry, that file is too long.");
// Read the type.
byte[] typeBytes = new byte[4];
in.readFully(typeBytes);
// Read the data.
byte[] data = new byte[length];
in.readFully(data);
// Read the CRC.
long crc = in.readInt() & 0x00000000ffffffffL; // Make it unsigned.
if (verifyCRC(typeBytes, data, crc) == false)
throw new IOException("That file appears to be corrupted.");
PNGChunk chunk = new PNGChunk(typeBytes, data);
chunks.add(chunk);
}
catch (EOFException eofe) {
trucking = false;
}
}
return chunks;
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| protected static void | readSignature(java.io.DataInputStream in)
long signature = in.readLong();
if (signature != 0x89504e470d0a1a0aL)
throw new IOException("PNG signature not found!");
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| protected static boolean | verifyCRC(byte[] typeBytes, byte[] data, long crc)
CRC32 crc32 = new CRC32();
crc32.update(typeBytes);
crc32.update(data);
long calculated = crc32.getValue();
return (calculated == crc);
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