1/*
2 * Copyright (c) 1995, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package java.awt.image;
27
28import java.awt.image.ImageConsumer;
29import java.awt.image.ColorModel;
30import java.util.Hashtable;
31import java.awt.Rectangle;
32
33/**
34 * An ImageFilter class for cropping images.
35 * This class extends the basic ImageFilter Class to extract a given
36 * rectangular region of an existing Image and provide a source for a
37 * new image containing just the extracted region.  It is meant to
38 * be used in conjunction with a FilteredImageSource object to produce
39 * cropped versions of existing images.
40 *
41 * @see FilteredImageSource
42 * @see ImageFilter
43 *
44 * @author      Jim Graham
45 */
46public class CropImageFilter extends ImageFilter {
47    int cropX;
48    int cropY;
49    int cropW;
50    int cropH;
51
52    /**
53     * Constructs a CropImageFilter that extracts the absolute rectangular
54     * region of pixels from its source Image as specified by the x, y,
55     * w, and h parameters.
56     * @param x the x location of the top of the rectangle to be extracted
57     * @param y the y location of the top of the rectangle to be extracted
58     * @param w the width of the rectangle to be extracted
59     * @param h the height of the rectangle to be extracted
60     */
61    public CropImageFilter(int x, int y, int w, int h) {
62        cropX = x;
63        cropY = y;
64        cropW = w;
65        cropH = h;
66    }
67
68    /**
69     * Passes along  the properties from the source object after adding a
70     * property indicating the cropped region.
71     * This method invokes {@code super.setProperties},
72     * which might result in additional properties being added.
73     * <p>
74     * Note: This method is intended to be called by the
75     * {@code ImageProducer} of the {@code Image} whose pixels
76     * are being filtered. Developers using
77     * this class to filter pixels from an image should avoid calling
78     * this method directly since that operation could interfere
79     * with the filtering operation.
80     */
81    public void setProperties(Hashtable<?,?> props) {
82        @SuppressWarnings("unchecked")
83        Hashtable<Object,Object> p = (Hashtable<Object,Object>)props.clone();
84        p.put("croprect", new Rectangle(cropX, cropY, cropW, cropH));
85        super.setProperties(p);
86    }
87
88    /**
89     * Override the source image's dimensions and pass the dimensions
90     * of the rectangular cropped region to the ImageConsumer.
91     * <p>
92     * Note: This method is intended to be called by the
93     * {@code ImageProducer} of the {@code Image} whose
94     * pixels are being filtered. Developers using
95     * this class to filter pixels from an image should avoid calling
96     * this method directly since that operation could interfere
97     * with the filtering operation.
98     * @see ImageConsumer
99     */
100    public void setDimensions(int w, int h) {
101        consumer.setDimensions(cropW, cropH);
102    }
103
104    /**
105     * Determine whether the delivered byte pixels intersect the region to
106     * be extracted and passes through only that subset of pixels that
107     * appear in the output region.
108     * <p>
109     * Note: This method is intended to be called by the
110     * {@code ImageProducer} of the {@code Image} whose
111     * pixels are being filtered. Developers using
112     * this class to filter pixels from an image should avoid calling
113     * this method directly since that operation could interfere
114     * with the filtering operation.
115     */
116    public void setPixels(int x, int y, int w, int h,
117                          ColorModel model, byte pixels[], int off,
118                          int scansize) {
119        int x1 = x;
120        if (x1 < cropX) {
121            x1 = cropX;
122        }
123    int x2 = addWithoutOverflow(x, w);
124        if (x2 > cropX + cropW) {
125            x2 = cropX + cropW;
126        }
127        int y1 = y;
128        if (y1 < cropY) {
129            y1 = cropY;
130        }
131
132    int y2 = addWithoutOverflow(y, h);
133        if (y2 > cropY + cropH) {
134            y2 = cropY + cropH;
135        }
136        if (x1 >= x2 || y1 >= y2) {
137            return;
138        }
139        consumer.setPixels(x1 - cropX, y1 - cropY, (x2 - x1), (y2 - y1),
140                           model, pixels,
141                           off + (y1 - y) * scansize + (x1 - x), scansize);
142    }
143
144    /**
145     * Determine if the delivered int pixels intersect the region to
146     * be extracted and pass through only that subset of pixels that
147     * appear in the output region.
148     * <p>
149     * Note: This method is intended to be called by the
150     * {@code ImageProducer} of the {@code Image} whose
151     * pixels are being filtered. Developers using
152     * this class to filter pixels from an image should avoid calling
153     * this method directly since that operation could interfere
154     * with the filtering operation.
155     */
156    public void setPixels(int x, int y, int w, int h,
157                          ColorModel model, int pixels[], int off,
158                          int scansize) {
159        int x1 = x;
160        if (x1 < cropX) {
161            x1 = cropX;
162        }
163    int x2 = addWithoutOverflow(x, w);
164        if (x2 > cropX + cropW) {
165            x2 = cropX + cropW;
166        }
167        int y1 = y;
168        if (y1 < cropY) {
169            y1 = cropY;
170        }
171
172    int y2 = addWithoutOverflow(y, h);
173        if (y2 > cropY + cropH) {
174            y2 = cropY + cropH;
175        }
176        if (x1 >= x2 || y1 >= y2) {
177            return;
178        }
179        consumer.setPixels(x1 - cropX, y1 - cropY, (x2 - x1), (y2 - y1),
180                           model, pixels,
181                           off + (y1 - y) * scansize + (x1 - x), scansize);
182    }
183
184    //check for potential overflow (see bug 4801285)
185    private int addWithoutOverflow(int x, int w) {
186        int x2 = x + w;
187        if ( x > 0 && w > 0 && x2 < 0 ) {
188            x2 = Integer.MAX_VALUE;
189        } else if( x < 0 && w < 0 && x2 > 0 ) {
190            x2 = Integer.MIN_VALUE;
191        }
192        return x2;
193    }
194}
195