82 lines
2.3 KiB
Java
82 lines
2.3 KiB
Java
package ar.com.hjg.pngj;
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import ar.com.hjg.pngj.chunks.PngChunkFDAT;
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/**
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*
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* Specialization of ChunkReader, for IDAT-like chunks. These chunks are part of
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* a set of similar chunks (contiguos
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* normally, not necessariyl) which conforms a zlib stream
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*/
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public class DeflatedChunkReader extends ChunkReader {
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protected final DeflatedChunksSet deflatedChunksSet;
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protected boolean alsoBuffer = false;
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protected boolean skipBytes = false; // fDAT (APNG) skips 4 bytes)
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protected byte[] skippedBytes; // only for fDAT
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protected int seqNumExpected = -1; // only for fDAT
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public DeflatedChunkReader(int clen, String chunkid, boolean checkCrc, long offsetInPng, DeflatedChunksSet iDatSet) {
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super(clen, chunkid, offsetInPng, ChunkReaderMode.PROCESS);
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this.deflatedChunksSet = iDatSet;
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if (chunkid.equals(PngChunkFDAT.ID)) {
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skipBytes = true;
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skippedBytes = new byte[4];
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}
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iDatSet.appendNewChunk(this);
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}
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/**
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* Delegates to ChunkReaderDeflatedSet.processData()
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*/
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@Override
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protected void processData(int offsetInchunk, byte[] buf, int off, int len) {
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if (skipBytes && offsetInchunk < 4) {// only for APNG (sigh)
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for (int oc = offsetInchunk; oc < 4 && len > 0; oc++, off++, len--)
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skippedBytes[oc] = buf[off];
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}
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if (len > 0) { // delegate to idatSet
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deflatedChunksSet.processBytes(buf, off, len);
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if (alsoBuffer) { // very rare!
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System.arraycopy(buf, off, getChunkRaw().data, read, len);
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}
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}
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}
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/**
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* only a stupid check for fDAT (I wonder how many APGN readers do this)
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*/
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@Override
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protected void chunkDone() {
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if (skipBytes && getChunkRaw().id.equals(PngChunkFDAT.ID)) {
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if (seqNumExpected >= 0) {
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int seqNum = PngHelperInternal.readInt4fromBytes(skippedBytes, 0);
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if (seqNum != seqNumExpected)
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throw new PngjInputException("bad chunk sequence for fDAT chunk " + seqNum + " expected " + seqNumExpected);
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}
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}
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}
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@Override
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public boolean isFromDeflatedSet() {
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return true;
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}
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/**
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* In some rare cases you might want to also buffer the data?
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*/
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public void setAlsoBuffer() {
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if (read > 0)
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throw new RuntimeException("too late");
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alsoBuffer = true;
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getChunkRaw().allocData();
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}
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/** only relevant for fDAT */
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public void setSeqNumExpected(int seqNumExpected) {
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this.seqNumExpected = seqNumExpected;
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}
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}
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