Java tutorial
/* * Copyright (c) 1996, 2018, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.awt.image; import java.awt.image.ImageConsumer; import java.awt.image.ColorModel; import java.util.Hashtable; import java.awt.Rectangle; /** * An ImageFilter class for scaling images using the simplest algorithm. * This class extends the basic ImageFilter Class to scale an existing * image and provide a source for a new image containing the resampled * image. The pixels in the source image are sampled to produce pixels * for an image of the specified size by replicating rows and columns of * pixels to scale up or omitting rows and columns of pixels to scale * down. * <p>It is meant to be used in conjunction with a FilteredImageSource * object to produce scaled versions of existing images. Due to * implementation dependencies, there may be differences in pixel values * of an image filtered on different platforms. * * @see FilteredImageSource * @see ImageFilter * * @author Jim Graham */ public class ReplicateScaleFilter extends ImageFilter { /** * The width of the source image. */ protected int srcWidth; /** * The height of the source image. */ protected int srcHeight; /** * The target width to scale the image. */ protected int destWidth; /** * The target height to scale the image. */ protected int destHeight; /** * An {@code int} array containing information about a * row of pixels. */ protected int[] srcrows; /** * An {@code int} array containing information about a * column of pixels. */ protected int[] srccols; /** * A {@code byte} array initialized with a size of * {@link #destWidth} and used to deliver a row of pixel * data to the {@link ImageConsumer}. */ protected Object outpixbuf; /** * Constructs a ReplicateScaleFilter that scales the pixels from * its source Image as specified by the width and height parameters. * @param width the target width to scale the image * @param height the target height to scale the image * @throws IllegalArgumentException if {@code width} equals * zero or {@code height} equals zero */ public ReplicateScaleFilter(int width, int height) { if (width == 0 || height == 0) { throw new IllegalArgumentException( "Width (" + width + ") and height (" + height + ") must be non-zero"); } destWidth = width; destHeight = height; } /** * Passes along the properties from the source object after adding a * property indicating the scale applied. * This method invokes {@code super.setProperties}, * which might result in additional properties being added. * <p> * Note: This method is intended to be called by the * {@code ImageProducer} of the {@code Image} whose pixels * are being filtered. Developers using * this class to filter pixels from an image should avoid calling * this method directly since that operation could interfere * with the filtering operation. */ public void setProperties(Hashtable<?, ?> props) { @SuppressWarnings("unchecked") Hashtable<Object, Object> p = (Hashtable<Object, Object>) props.clone(); String key = "rescale"; String val = destWidth + "x" + destHeight; Object o = p.get(key); if (o != null && o instanceof String) { val = ((String) o) + ", " + val; } p.put(key, val); super.setProperties(p); } /** * Override the dimensions of the source image and pass the dimensions * of the new scaled size to the ImageConsumer. * <p> * Note: This method is intended to be called by the * {@code ImageProducer} of the {@code Image} whose pixels * are being filtered. Developers using * this class to filter pixels from an image should avoid calling * this method directly since that operation could interfere * with the filtering operation. * @see ImageConsumer */ public void setDimensions(int w, int h) { srcWidth = w; srcHeight = h; if (destWidth < 0) { if (destHeight < 0) { destWidth = srcWidth; destHeight = srcHeight; } else { destWidth = srcWidth * destHeight / srcHeight; } } else if (destHeight < 0) { destHeight = srcHeight * destWidth / srcWidth; } consumer.setDimensions(destWidth, destHeight); } private void calculateMaps() { srcrows = new int[destHeight + 1]; for (int y = 0; y <= destHeight; y++) { srcrows[y] = (2 * y * srcHeight + srcHeight) / (2 * destHeight); } srccols = new int[destWidth + 1]; for (int x = 0; x <= destWidth; x++) { srccols[x] = (2 * x * srcWidth + srcWidth) / (2 * destWidth); } } /** * Choose which rows and columns of the delivered byte pixels are * needed for the destination scaled image and pass through just * those rows and columns that are needed, replicated as necessary. * <p> * Note: This method is intended to be called by the * {@code ImageProducer} of the {@code Image} whose pixels * are being filtered. Developers using * this class to filter pixels from an image should avoid calling * this method directly since that operation could interfere * with the filtering operation. */ public void setPixels(int x, int y, int w, int h, ColorModel model, byte[] pixels, int off, int scansize) { if (srcrows == null || srccols == null) { calculateMaps(); } int sx, sy; int dx1 = (2 * x * destWidth + srcWidth - 1) / (2 * srcWidth); int dy1 = (2 * y * destHeight + srcHeight - 1) / (2 * srcHeight); byte[] outpix; if (outpixbuf != null && outpixbuf instanceof byte[]) { outpix = (byte[]) outpixbuf; } else { outpix = new byte[destWidth]; outpixbuf = outpix; } for (int dy = dy1; (sy = srcrows[dy]) < y + h; dy++) { int srcoff = off + scansize * (sy - y); int dx; for (dx = dx1; (sx = srccols[dx]) < x + w; dx++) { outpix[dx] = pixels[srcoff + sx - x]; } if (dx > dx1) { consumer.setPixels(dx1, dy, dx - dx1, 1, model, outpix, dx1, destWidth); } } } /** * Choose which rows and columns of the delivered int pixels are * needed for the destination scaled image and pass through just * those rows and columns that are needed, replicated as necessary. * <p> * Note: This method is intended to be called by the * {@code ImageProducer} of the {@code Image} whose pixels * are being filtered. Developers using * this class to filter pixels from an image should avoid calling * this method directly since that operation could interfere * with the filtering operation. */ public void setPixels(int x, int y, int w, int h, ColorModel model, int[] pixels, int off, int scansize) { if (srcrows == null || srccols == null) { calculateMaps(); } int sx, sy; int dx1 = (2 * x * destWidth + srcWidth - 1) / (2 * srcWidth); int dy1 = (2 * y * destHeight + srcHeight - 1) / (2 * srcHeight); int[] outpix; if (outpixbuf != null && outpixbuf instanceof int[]) { outpix = (int[]) outpixbuf; } else { outpix = new int[destWidth]; outpixbuf = outpix; } for (int dy = dy1; (sy = srcrows[dy]) < y + h; dy++) { int srcoff = off + scansize * (sy - y); int dx; for (dx = dx1; (sx = srccols[dx]) < x + w; dx++) { outpix[dx] = pixels[srcoff + sx - x]; } if (dx > dx1) { consumer.setPixels(dx1, dy, dx - dx1, 1, model, outpix, dx1, destWidth); } } } }