109 lines
3.1 KiB
Java
109 lines
3.1 KiB
Java
package com.webcodepro.shrinkit.io;
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import java.io.ByteArrayInputStream;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.OutputStream;
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/**
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* Exercise the RLE encoder and decoders.
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*
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* @author robgreene@users.sourceforge.net
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*/
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public class RleTest extends TestCaseHelper {
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/**
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* Test the RleInputStream to verify decoding.
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*/
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public void testInputStream() throws IOException {
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InputStream is = new RleInputStream(new ByteArrayInputStream(getPatternFileRle()));
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ByteArrayOutputStream os = new ByteArrayOutputStream();
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copy(is,os);
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byte[] expected = getPatternFileUncompressed();
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byte[] actual = os.toByteArray();
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assertEquals(expected, actual);
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}
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/**
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* Test the RleOutputStream to verify compression.
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*/
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public void testOutputStream() throws IOException {
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ByteArrayOutputStream baos = new ByteArrayOutputStream();
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RleOutputStream os = new RleOutputStream(baos);
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ByteArrayInputStream is = new ByteArrayInputStream(getPatternFileUncompressed());
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copy(is,os);
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byte[] expected = getPatternFileRle();
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byte[] actual = baos.toByteArray();
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assertEquals(expected, actual);
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}
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/**
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* Test the RleOutputStream with the escape character to ensure it <em>always</em> is encoded.
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* Note that a file with lots of 0xdb codes will grow.
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*/
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public void testOutputStreamEscapeCharacter() throws IOException {
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ByteArrayOutputStream baos = new ByteArrayOutputStream();
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RleOutputStream os = new RleOutputStream(baos);
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ByteArrayInputStream is = new ByteArrayInputStream(new byte[] { (byte)0xdb, (byte)0xdb, 0x00, (byte)0xdb });
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copy(is,os);
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byte[] expected = new byte[] { (byte)0xdb, (byte)0xdb, 0x01, 0x00, (byte)0xdb, (byte)0xdb, 0x00 };
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byte[] actual = baos.toByteArray();
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assertEquals(expected, actual);
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}
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/**
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* Copy the input stream to the output stream.
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*/
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private void copy(InputStream is, OutputStream os) throws IOException {
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int b = is.read();
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while (b != -1) {
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os.write(b);
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b = is.read();
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}
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is.close();
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os.close();
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}
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/**
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* This the RLE compressed pattern file that happens to not compress via LZW.
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*/
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private byte[] getPatternFileRle() {
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return new byte[] {
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(byte)0xdb, 0x01, (byte)0xfd,
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(byte)0xdb, 0x02, (byte)0xfc,
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(byte)0xdb, 0x03, (byte)0xfb,
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(byte)0xdb, 0x04, (byte)0xfa,
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(byte)0xdb, 0x05, (byte)0xf9,
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(byte)0xdb, 0x06, (byte)0xf8,
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(byte)0xdb, 0x07, (byte)0xf7,
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(byte)0xdb, 0x08, (byte)0xf6,
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(byte)0xdb, 0x09, (byte)0xf5,
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(byte)0xdb, 0x0a, (byte)0xf4,
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(byte)0xdb, 0x0b, (byte)0xf3,
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(byte)0xdb, 0x0c, (byte)0xf2,
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(byte)0xdb, 0x0d, (byte)0xf1,
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(byte)0xdb, 0x0e, (byte)0xf0,
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(byte)0xdb, 0x0f, (byte)0xef,
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(byte)0xdb, 0x10, (byte)0xee,
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(byte)0xdb, 0x11, (byte)0x97
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};
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}
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/**
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* This is the uncompressed pattern file that happens to not compress via LZW.
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*/
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private byte[] getPatternFileUncompressed() {
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byte[] data = new byte[4096];
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int value = 0x01;
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int nextCount = 0xfd;
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int count = 0xfe;
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for (int i=0; i<data.length; i++) {
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data[i] = (byte)(value & 0xff);
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count--;
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if (count == 0) {
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count = nextCount;
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nextCount--;
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value++;
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}
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}
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return data;
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}
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}
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