com.itextpdf.text.io.WindowRandomAccessSource Maven / Gradle / Ivy
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*
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package com.itextpdf.text.io;
import java.io.IOException;
/**
* A RandomAccessSource that wraps another RandomAccessSouce and provides a window of it at a specific offset and over
* a specific length. Position 0 becomes the offset position in the underlying source.
* @since 5.3.5
*/
public class WindowRandomAccessSource implements RandomAccessSource {
/**
* The source
*/
private final RandomAccessSource source;
/**
* The amount to offset the source by
*/
private final long offset;
/**
* The length
*/
private final long length;
/**
* Constructs a new OffsetRandomAccessSource that extends to the end of the underlying source
* @param source the source
* @param offset the amount of the offset to use
*/
public WindowRandomAccessSource(RandomAccessSource source, long offset) {
this(source, offset, source.length() - offset);
}
/**
* Constructs a new OffsetRandomAccessSource with an explicit length
* @param source the source
* @param offset the amount of the offset to use
* @param length the number of bytes to be included in this RAS
*/
public WindowRandomAccessSource(RandomAccessSource source, long offset, long length) {
this.source = source;
this.offset = offset;
this.length = length;
}
/**
* {@inheritDoc}
* Note that the position will be adjusted to read from the corrected location in the underlying source
*/
public int get(long position) throws IOException {
if (position >= length) return -1;
return source.get(offset + position);
}
/**
* {@inheritDoc}
* Note that the position will be adjusted to read from the corrected location in the underlying source
*/
public int get(long position, byte[] bytes, int off, int len) throws IOException {
if (position >= length)
return -1;
long toRead = Math.min(len, length - position);
return source.get(offset + position, bytes, off, (int)toRead);
}
/**
* {@inheritDoc}
* Note that the length will be adjusted to read from the corrected location in the underlying source
*/
public long length() {
return length;
}
/**
* {@inheritDoc}
*/
public void close() throws IOException {
source.close();
}
}