package ar.com.hjg.pngj.chunks;

import ar.com.hjg.pngj.ImageInfo;
import ar.com.hjg.pngj.PngHelperInternal;
import ar.com.hjg.pngj.PngjException;

/**
 * oFFs chunk.
 * <p>
 * see http://www.libpng.org/pub/png/spec/register/pngext-1.3.0-pdg.html#C.oFFs
 */
public class PngChunkOFFS extends PngChunkSingle {
	public final static String ID = "oFFs";

	// http://www.libpng.org/pub/png/spec/register/pngext-1.3.0-pdg.html#C.oFFs
	private long posX;
	private long posY;
	private int units; // 0: pixel 1:micrometer

	public PngChunkOFFS(final ImageInfo info) {
		super(PngChunkOFFS.ID, info);
	}

	@Override
	public ChunkOrderingConstraint getOrderingConstraint() {
		return ChunkOrderingConstraint.BEFORE_IDAT;
	}

	@Override
	public ChunkRaw createRawChunk() {
		final ChunkRaw c = createEmptyChunk(9, true);
		PngHelperInternal.writeInt4tobytes((int) posX, c.data, 0);
		PngHelperInternal.writeInt4tobytes((int) posY, c.data, 4);
		c.data[8] = (byte) units;
		return c;
	}

	@Override
	public void parseFromRaw(final ChunkRaw chunk) {
		if (chunk.len != 9)
			throw new PngjException("bad chunk length " + chunk);
		posX = PngHelperInternal.readInt4fromBytes(chunk.data, 0);
		if (posX < 0)
			posX += 0x100000000L;
		posY = PngHelperInternal.readInt4fromBytes(chunk.data, 4);
		if (posY < 0)
			posY += 0x100000000L;
		units = PngHelperInternal.readInt1fromByte(chunk.data, 8);
	}

	/**
	 * 0: pixel, 1:micrometer
	 */
	public int getUnits() {
		return units;
	}

	/**
	 * 0: pixel, 1:micrometer
	 */
	public void setUnits(final int units) {
		this.units = units;
	}

	public long getPosX() {
		return posX;
	}

	public void setPosX(final long posX) {
		this.posX = posX;
	}

	public long getPosY() {
		return posY;
	}

	public void setPosY(final long posY) {
		this.posY = posY;
	}

}
