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