PCHGChunkTest.java
/*
* Copyright (c) 2026, Harald Kuhr
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package com.twelvemonkeys.imageio.plugins.iff;
import com.twelvemonkeys.imageio.stream.ByteArrayImageInputStream;
import org.junit.jupiter.api.Test;
import javax.imageio.IIOException;
import java.awt.image.ColorModel;
import java.awt.image.DataBuffer;
import java.awt.image.IndexColorModel;
import java.io.IOException;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
class PCHGChunkTest {
private static IndexColorModel base() {
return new IndexColorModel(4, 16, new int[16], 0, false, -1, DataBuffer.TYPE_BYTE);
}
private static PCHGChunk parse(final byte[] body) throws IOException {
PCHGChunk chunk = new PCHGChunk(body.length);
chunk.readChunk(new ByteArrayImageInputStream(body));
return chunk;
}
// 20 byte PCHG header followed by 12 bytes of change data:
// uncompressed, 32 bit (BigLineChanges), startLine 0, lineCount 2,
// one changed line (row 1), one change carrying a palette register.
private static byte[] chunkWithRegister(final int reg) {
return new byte[] {
0x00, 0x00, // compression = PCHG_COMP_NONE
0x00, 0x02, // flags = PCHGF_32BIT
0x00, 0x00, // startLine = 0
0x00, 0x02, // lineCount = 2
0x00, 0x01, // changedLines = 1
0x00, 0x00, // minReg = 0
0x00, 0x00, // maxReg = 0
0x00, 0x00, // maxChangesPerLine (ignored)
0x00, 0x00, 0x00, 0x01, // totalChanges = 1
0x40, 0x00, 0x00, 0x00, // line mask: only row 1 changed
0x00, 0x01, // changeCount = 1
(byte) ((reg >> 8) & 0xff), (byte) (reg & 0xff), // register
0x00, 0x11, 0x22, 0x33, // alpha (skipped), r, b, g
};
}
@Test
void specialIngoreRegisterIsIgnored() throws IOException {
// reg 0xffff reads back as a negative short -1; adjustColorMap must not index the palette with it
PCHGChunk chunk = parse(chunkWithRegister(0xffff));
IndexColorModel base = base();
ColorModel palette = assertDoesNotThrow(() -> chunk.getColorModel(base, 1, false));
assertNotNull(palette);
}
@Test
void parseNegativeRegisterThrows() {
// reg 0xfffe reads back as a negative short -2; adjustColorMap must not index the palette with it
assertThrows(IIOException.class, () -> parse(chunkWithRegister(0xfffe)));
}
@Test
void inRangeRegisterIsApplied() throws IOException {
PCHGChunk chunk = parse(chunkWithRegister(5));
IndexColorModel base = base();
ColorModel palette = chunk.getColorModel(base, 1, false);
// r=0x11 b=0x22 g=0x33 -> 0x113322
assertEquals(0x113322, palette.getRGB(5) & 0xffffff);
}
@Test
void truncatedChunkLengthThrows() {
// Declared chunk length shorter than the 20 byte PCHG header: data = new byte[length - 20] must not go negative
PCHGChunk chunk = new PCHGChunk(10);
assertThrows(IIOException.class, () -> chunk.readChunk(new ByteArrayImageInputStream(new byte[24])));
}
@Test
void negativeLineRangeThrows() {
// startLine + lineCount is used as the changes array length, and must not go negative
byte[] body = new byte[32];
body[3] = 0x02; // flags = PCHGF_32BIT
body[4] = (byte) 0xFF; // startLine = -100
body[5] = (byte) 0x9C;
// lineCount = 0
assertThrows(IIOException.class, () -> parse(body));
}
@Test
void invalidInitialRegisterRangeThrows() {
// startLine < 0 allocates initialChanges from maxReg - minReg + 1, which must not go negative
byte[] body = new byte[32];
body[3] = 0x02; // flags = PCHGF_32BIT
body[4] = (byte) 0xFF; // startLine = -1
body[5] = (byte) 0xFF;
body[7] = 0x02; // lineCount = 2
body[9] = 0x01; // changedLines = 1
body[11] = 0x0A; // minReg = 10
// maxReg = 0
assertThrows(IIOException.class, () -> parse(body));
}
@Test
void initialChangeRegisterOutOfRangeThrows() {
// reg is used as initialChanges[reg - minReg]; a register outside [minReg, maxReg] must not index out of bounds
byte[] body = new byte[] {
0x00, 0x00, // compression = PCHG_COMP_NONE
0x00, 0x02, // flags = PCHGF_32BIT
(byte) 0xFF, (byte) 0xFF, // startLine = -1
0x00, 0x02, // lineCount = 2
0x00, 0x01, // changedLines = 1
0x00, 0x00, // minReg = 0
0x00, 0x00, // maxReg = 0 -> initialChanges length 1
0x00, 0x00, // maxChangesPerLine (ignored)
0x00, 0x00, 0x00, 0x01, // totalChanges = 1
(byte) 0x80, 0x00, 0x00, 0x00, // line mask: row -1 changed
0x00, 0x01, // changeCount = 1
0x00, 0x05, // register 5, outside [0, 0]
0x00, 0x11, 0x22, 0x33, // alpha (skipped), r, b, g
};
assertThrows(IIOException.class, () -> parse(body));
}
@Test
void negativeStartLineWithVisibleChangeParses() {
// startLine < 0 with a change on a visible (row >= 0) line: the per-line loop must not index changes[] with a negative row
byte[] body = new byte[] {
0x00, 0x00, // compression = PCHG_COMP_NONE
0x00, 0x02, // flags = PCHGF_32BIT
(byte) 0xFF, (byte) 0xFF, // startLine = -1
0x00, 0x03, // lineCount = 3 -> changes length 2
0x00, 0x02, // changedLines = 2
0x00, 0x00, // minReg = 0
0x00, 0x1F, // maxReg = 31 -> initialChanges length 32
0x00, 0x00, // maxChangesPerLine (ignored)
0x00, 0x00, 0x00, 0x02, // totalChanges = 2
(byte) 0xC0, 0x00, 0x00, 0x00, // line mask: row -1 and the first visible row changed
0x00, 0x01, 0x00, 0x03, 0x00, 0x11, 0x22, 0x33, // initial change, register 3
0x00, 0x01, 0x00, 0x04, 0x00, 0x44, 0x55, 0x66, // visible change, register 4
};
assertDoesNotThrow(() -> parse(body));
}
}