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package jogamp.opengl.util.pngj.chunks;
import jogamp.opengl.util.pngj.ImageInfo;
import jogamp.opengl.util.pngj.PngjException;
/**
* PLTE chunk.
* <p>
* see http://www.w3.org/TR/PNG/#11PLTE
* <p>
* Critical chunk
*/
public class PngChunkPLTE extends PngChunkSingle {
public final static String ID = ChunkHelper.PLTE;
// http://www.w3.org/TR/PNG/#11PLTE
private int nentries = 0;
/**
* RGB8 packed in one integer
*/
private int[] entries;
public PngChunkPLTE(final ImageInfo info) {
super(ID, info);
}
@Override
public ChunkOrderingConstraint getOrderingConstraint() {
return ChunkOrderingConstraint.NA;
}
@Override
public ChunkRaw createRawChunk() {
final int len = 3 * nentries;
final int[] rgb = new int[3];
final ChunkRaw c = createEmptyChunk(len, true);
for (int n = 0, i = 0; n < nentries; n++) {
getEntryRgb(n, rgb);
c.data[i++] = (byte) rgb[0];
c.data[i++] = (byte) rgb[1];
c.data[i++] = (byte) rgb[2];
}
return c;
}
@Override
public void parseFromRaw(final ChunkRaw chunk) {
setNentries(chunk.len / 3);
for (int n = 0, i = 0; n < nentries; n++) {
setEntry(n, chunk.data[i++] & 0xff, chunk.data[i++] & 0xff, chunk.data[i++] & 0xff);
}
}
@Override
public void cloneDataFromRead(final PngChunk other) {
final PngChunkPLTE otherx = (PngChunkPLTE) other;
this.setNentries(otherx.getNentries());
System.arraycopy(otherx.entries, 0, entries, 0, nentries);
}
public void setNentries(final int n) {
nentries = n;
if (nentries < 1 || nentries > 256)
throw new PngjException("invalid pallette - nentries=" + nentries);
if (entries == null || entries.length != nentries) { // alloc
entries = new int[nentries];
}
}
public int getNentries() {
return nentries;
}
public void setEntry(final int n, final int r, final int g, final int b) {
entries[n] = ((r << 16) | (g << 8) | b);
}
public int getEntry(final int n) {
return entries[n];
}
public void getEntryRgb(final int n, final int[] rgb) {
getEntryRgb(n, rgb, 0);
}
public void getEntryRgb(final int n, final int[] rgb, final int offset) {
final int v = entries[n];
rgb[offset + 0] = ((v & 0xff0000) >> 16);
rgb[offset + 1] = ((v & 0xff00) >> 8);
rgb[offset + 2] = (v & 0xff);
}
public int minBitDepth() {
if (nentries <= 2)
return 1;
else if (nentries <= 4)
return 2;
else if (nentries <= 16)
return 4;
else
return 8;
}
}
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