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package jogamp.opengl.util.pngj.chunks;
// see http://www.libpng.org/pub/png/spec/1.2/PNG-Chunks.html
// http://www.w3.org/TR/PNG/#5Chunk-naming-conventions
// http://www.w3.org/TR/PNG/#table53
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.InflaterInputStream;
import jogamp.opengl.util.pngj.PngHelper;
import jogamp.opengl.util.pngj.PngjException;
public class ChunkHelper {
public static final String IHDR = "IHDR";
public static final String PLTE = "PLTE";
public static final String IDAT = "IDAT";
public static final String IEND = "IEND";
public static final byte[] b_IHDR = toBytes(IHDR);
public static final byte[] b_PLTE = toBytes(PLTE);
public static final byte[] b_IDAT = toBytes(IDAT);
public static final byte[] b_IEND = toBytes(IEND);
public static final String cHRM = "cHRM";
public static final String gAMA = "gAMA";
public static final String iCCP = "iCCP";
public static final String sBIT = "sBIT";
public static final String sRGB = "sRGB";
public static final String bKGD = "bKGD";
public static final String hIST = "hIST";
public static final String tRNS = "tRNS";
public static final String pHYs = "pHYs";
public static final String sPLT = "sPLT";
public static final String tIME = "tIME";
public static final String iTXt = "iTXt";
public static final String tEXt = "tEXt";
public static final String zTXt = "zTXt";
public static Set<String> KNOWN_CHUNKS_CRITICAL = PngHelper.asSet(IHDR, PLTE, IDAT, IEND);
public static byte[] toBytes(String x) {
return x.getBytes(PngHelper.charsetLatin1);
}
public static String toString(byte[] x) {
return new String(x, PngHelper.charsetLatin1);
}
public static boolean isCritical(String id) { // critical chunk ?
// first letter is uppercase
return (Character.isUpperCase(id.charAt(0)));
}
public static boolean isPublic(String id) { // public chunk?
// second letter is uppercase
return (Character.isUpperCase(id.charAt(1)));
}
/**
* "Unknown" just means that our chunk factory (even when it has been augmented by client code) did not recognize its id
*/
public static boolean isUnknown(PngChunk c) {
return c instanceof PngChunkUNKNOWN;
}
public static boolean isSafeToCopy(String id) { // safe to copy?
// fourth letter is lower case
return (!Character.isUpperCase(id.charAt(3)));
}
public static int posNullByte(byte[] b) {
for (int i = 0; i < b.length; i++)
if (b[i] == 0)
return i;
return -1;
}
public static boolean shouldLoad(String id, ChunkLoadBehaviour behav) {
if (isCritical(id))
return true;
boolean kwown = PngChunk.isKnown(id);
switch (behav) {
case LOAD_CHUNK_ALWAYS:
return true;
case LOAD_CHUNK_IF_SAFE:
return kwown || isSafeToCopy(id);
case LOAD_CHUNK_KNOWN:
return kwown;
case LOAD_CHUNK_NEVER:
return false;
}
return false; // should not reach here
}
public final static byte[] compressBytes(byte[] ori, boolean compress) {
return compressBytes(ori, 0, ori.length, compress);
}
public static byte[] compressBytes(byte[] ori, int offset, int len, boolean compress) {
try {
ByteArrayInputStream inb = new ByteArrayInputStream(ori, offset, len);
InputStream in = compress ? inb : new InflaterInputStream(inb);
ByteArrayOutputStream outb = new ByteArrayOutputStream();
OutputStream out = compress ? new DeflaterOutputStream(outb) : outb;
shovelInToOut(in, out);
in.close();
out.close();
return outb.toByteArray();
} catch (Exception e) {
throw new PngjException(e);
}
}
/**
* Shovels all data from an input stream to an output stream.
*/
private static void shovelInToOut(InputStream in, OutputStream out) throws IOException {
byte[] buffer = new byte[1024];
int len;
while ((len = in.read(buffer)) > 0) {
out.write(buffer, 0, len);
}
}
public static boolean maskMatch(int v, int mask) {
return (v & mask) != 0;
}
}
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