Java tutorial
/* * Copyright (c) 1995, 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 cropping images. * This class extends the basic ImageFilter Class to extract a given * rectangular region of an existing Image and provide a source for a * new image containing just the extracted region. It is meant to * be used in conjunction with a FilteredImageSource object to produce * cropped versions of existing images. * * @see FilteredImageSource * @see ImageFilter * * @author Jim Graham */ public class CropImageFilter extends ImageFilter { int cropX; int cropY; int cropW; int cropH; /** * Constructs a CropImageFilter that extracts the absolute rectangular * region of pixels from its source Image as specified by the x, y, * w, and h parameters. * @param x the x location of the top of the rectangle to be extracted * @param y the y location of the top of the rectangle to be extracted * @param w the width of the rectangle to be extracted * @param h the height of the rectangle to be extracted */ public CropImageFilter(int x, int y, int w, int h) { cropX = x; cropY = y; cropW = w; cropH = h; } /** * Passes along the properties from the source object after adding a * property indicating the cropped region. * 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(); p.put("croprect", new Rectangle(cropX, cropY, cropW, cropH)); super.setProperties(p); } /** * Override the source image's dimensions and pass the dimensions * of the rectangular cropped region 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) { consumer.setDimensions(cropW, cropH); } /** * Determine whether the delivered byte pixels intersect the region to * be extracted and passes through only that subset of pixels that * appear in the output region. * <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) { int x1 = x; if (x1 < cropX) { x1 = cropX; } int x2 = addWithoutOverflow(x, w); if (x2 > cropX + cropW) { x2 = cropX + cropW; } int y1 = y; if (y1 < cropY) { y1 = cropY; } int y2 = addWithoutOverflow(y, h); if (y2 > cropY + cropH) { y2 = cropY + cropH; } if (x1 >= x2 || y1 >= y2) { return; } consumer.setPixels(x1 - cropX, y1 - cropY, (x2 - x1), (y2 - y1), model, pixels, off + (y1 - y) * scansize + (x1 - x), scansize); } /** * Determine if the delivered int pixels intersect the region to * be extracted and pass through only that subset of pixels that * appear in the output region. * <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) { int x1 = x; if (x1 < cropX) { x1 = cropX; } int x2 = addWithoutOverflow(x, w); if (x2 > cropX + cropW) { x2 = cropX + cropW; } int y1 = y; if (y1 < cropY) { y1 = cropY; } int y2 = addWithoutOverflow(y, h); if (y2 > cropY + cropH) { y2 = cropY + cropH; } if (x1 >= x2 || y1 >= y2) { return; } consumer.setPixels(x1 - cropX, y1 - cropY, (x2 - x1), (y2 - y1), model, pixels, off + (y1 - y) * scansize + (x1 - x), scansize); } //check for potential overflow (see bug 4801285) private int addWithoutOverflow(int x, int w) { int x2 = x + w; if (x > 0 && w > 0 && x2 < 0) { x2 = Integer.MAX_VALUE; } else if (x < 0 && w < 0 && x2 > 0) { x2 = Integer.MIN_VALUE; } return x2; } }