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A library for adding vector export to Java(R) Graphics2D.
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/*
 * VectorGraphics2D: Vector export for Java(R) Graphics2D
 *
 * (C) Copyright 2010-2017 Erich Seifert ,
 * Michael Seifert 
 *
 * This file is part of VectorGraphics2D.
 *
 * VectorGraphics2D is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * VectorGraphics2D is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with VectorGraphics2D.  If not, see .
 */
package de.erichseifert.vectorgraphics2d.util;

import java.awt.image.BufferedImage;
import java.awt.image.Raster;
import java.io.IOException;
import java.io.InputStream;
import java.util.LinkedList;
import java.util.Queue;

public class ImageDataStream extends InputStream {
	public enum Interleaving {
		SAMPLE,
		ROW,
		WITHOUT_ALPHA,
		ALPHA_ONLY
	}

	private final BufferedImage image;
	private final int width;
	private final int height;
	private final Interleaving interleaving;
	private final Raster raster;
	private final boolean opaque;

	private final Queue byteBuffer;
	private final int[] sampleValues;
	private final int[] sampleSizes;
	private int x;
	private int y;
	//private byte currentBit;

	public ImageDataStream(BufferedImage image, Interleaving interleaving) {
		this.image = image;
		this.interleaving = interleaving;

		width = image.getWidth();
		height = image.getHeight();
		x = -1;
		y = 0;

		Raster alphaRaster = image.getAlphaRaster();
		if (interleaving == Interleaving.ALPHA_ONLY) {
			raster = alphaRaster;
		} else {
			raster = image.getRaster();
		}
		opaque = alphaRaster == null;

		byteBuffer = new LinkedList<>();
		sampleValues = new int[raster.getNumBands()];
		sampleSizes = raster.getSampleModel().getSampleSize();
	}

	public BufferedImage getImage() {
		return image;
	}


	public Interleaving getInterleaving() {
		return interleaving;
	}

	@Override
	public int read() throws IOException {
		if (!byteBuffer.isEmpty()) {
			return byteBuffer.poll();
		} else {
			if (!nextSample()) {
				return -1;
			}
    		int bands = sampleValues.length;
	    	if (interleaving == Interleaving.WITHOUT_ALPHA ||
	    			interleaving == Interleaving.ALPHA_ONLY) {
	    		if (interleaving == Interleaving.WITHOUT_ALPHA && !opaque) {
	    			// Ignore alpha band
	    			bands--;
	    		}
	    		for (int band = 0; band <  bands; band++) {
	    			bufferSampleValue(band);
				}
	    	} else {
	    		if (opaque) {
	        		for (int band = 0; band < bands; band++) {
	        			bufferSampleValue(band);
	    			}
	    		} else {
	        		for (int band = 0; band < bands; band++) {
	        			// Fix order to be ARGB instead of RGBA
	        			if (band == 0) {
	        				bufferSampleValue(bands - 1);
	        			} else {
	        				bufferSampleValue(band - 1);
	        			}
	    			}
	    		}
	    	}
			if (!byteBuffer.isEmpty()) {
				return byteBuffer.poll();
			} else {
				return -1;
			}
		}
	}

	private void bufferSampleValue(int band) {
		if (sampleSizes[band] < 8) {
			// TODO Handle data with sample sizes smaller than 1 byte
			int byteValue = sampleValues[band] & 0xFF;
			byteBuffer.offer(byteValue);
		} else {
			int byteCount = sampleSizes[band]/8;
			for (int i = byteCount - 1; i >= 0; i--) {
				int byteValue = (sampleValues[band] >> i*8) & 0xFF;
				byteBuffer.offer(byteValue);
			}
		}
	}

	private boolean nextSample() {
		if (interleaving == Interleaving.SAMPLE || interleaving == Interleaving.WITHOUT_ALPHA) {
			x++;
			if (x >= width) {
				x = 0;
				y++;
			}
		}
		if (x < 0 || x >= width || y < 0 || y >= height) {
			return false;
		} else {
			raster.getPixel(x, y, sampleValues);
			return true;
		}
	}
}