102 lines
2.5 KiB
Java
102 lines
2.5 KiB
Java
package ar.com.hjg.pngj;
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import java.io.FilterInputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.util.List;
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import ar.com.hjg.pngj.chunks.PngChunk;
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/**
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* This class allows to use a simple PNG reader as an input filter, wrapping a
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* ChunkSeqReaderPng in callback mode.
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*
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* In this sample implementation, all IDAT chunks are skipped and the rest are
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* stored. An example of use, that lets us
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* grab the Metadata and let the pixels go towards a BufferedImage:
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*
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*
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* <pre class="code">
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* PngReaderFilter reader = new PngReaderFilter(new FileInputStream("image.png"));
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* BufferedImage image1 = ImageIO.read(reader);
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* reader.readUntilEndAndClose(); // in case ImageIO.read() does not read the traling chunks (it happens)
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* System.out.println(reader.getChunksList());
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* </pre>
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*
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*/
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public class PngReaderFilter extends FilterInputStream {
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private final ChunkSeqReaderPng chunkseq;
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public PngReaderFilter(final InputStream arg0) {
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super(arg0);
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chunkseq = createChunkSequenceReader();
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}
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protected ChunkSeqReaderPng createChunkSequenceReader() {
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return new ChunkSeqReaderPng(true) {
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@Override
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public boolean shouldSkipContent(final int len, final String id) {
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return super.shouldSkipContent(len, id) || id.equals("IDAT");
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}
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@Override
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protected boolean shouldCheckCrc(final int len, final String id) {
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return false;
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}
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@Override
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protected void postProcessChunk(final ChunkReader chunkR) {
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super.postProcessChunk(chunkR);
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// System.out.println("processed chunk " + chunkR.getChunkRaw().id);
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}
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};
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}
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@Override
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public void close() throws IOException {
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super.close();
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chunkseq.close();
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}
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@Override
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public int read() throws IOException {
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final int r = super.read();
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if (r > 0)
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chunkseq.feedAll(new byte[] { (byte) r }, 0, 1);
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return r;
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}
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@Override
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public int read(final byte[] b, final int off, final int len) throws IOException {
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final int res = super.read(b, off, len);
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if (res > 0)
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chunkseq.feedAll(b, off, res);
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return res;
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}
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@Override
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public int read(final byte[] b) throws IOException {
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final int res = super.read(b);
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if (res > 0)
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chunkseq.feedAll(b, 0, res);
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return res;
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}
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public void readUntilEndAndClose() throws IOException {
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final BufferedStreamFeeder br = new BufferedStreamFeeder(in);
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while (!chunkseq.isDone() && br.hasMoreToFeed())
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br.feed(chunkseq);
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close();
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}
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public List<PngChunk> getChunksList() {
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return chunkseq.getChunks();
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}
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public ChunkSeqReaderPng getChunkseq() {
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return chunkseq;
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}
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}
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