001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.imaging.common;
019
020import java.awt.color.ColorSpace;
021import java.awt.image.BufferedImage;
022import java.awt.image.ColorModel;
023import java.awt.image.DataBuffer;
024import java.awt.image.DataBufferInt;
025import java.awt.image.DirectColorModel;
026import java.awt.image.Raster;
027import java.awt.image.RasterFormatException;
028import java.awt.image.WritableRaster;
029import java.util.Properties;
030
031/*
032 * Development notes:
033 * This class was introduced to the Apache Commons Imaging library in
034 * order to improve performance in building images.  The setRGB method
035 * provided by this class represents a substantial improvement in speed
036 * compared to that of the BufferedImage class that was originally used
037 * in Apache Sanselan.
038 *   This increase is attained because ImageBuilder is a highly specialized
039 * class that does not need to perform the general-purpose logic required
040 * for BufferedImage.  If you need to modify this class to add new
041 * image formats or functionality, keep in mind that some of its methods
042 * are invoked literally millions of times when building an image.
043 * Since even the introduction of something as small as a single conditional
044 * inside of setRGB could result in a noticeable increase in the
045 * time to read a file, changes should be made with care.
046 *    During development, I experimented with inlining the setRGB logic
047 * in some of the code that uses it. This approach did not significantly
048 * improve performance, leading me to speculate that the Java JIT compiler
049 * might have inlined the method at run time.  Further investigation
050 * is required.
051 */
052
053/**
054 * A utility class primary intended for storing data obtained by reading image files.
055 */
056public final class ImageBuilder {
057    private final int[] data;
058    private final int width;
059    private final int height;
060    private final boolean hasAlpha;
061    private final boolean isAlphaPremultiplied;
062
063    /**
064     * Constructs an ImageBuilder instance.
065     *
066     * @param width    the width of the image to be built
067     * @param height   the height of the image to be built
068     * @param hasAlpha indicates whether the image has an alpha channel (the selection of alpha channel does not change the memory requirements for the
069     *                 ImageBuilder or resulting BufferedImage.
070     * @throws RasterFormatException if {@code width} or {@code height} are equal or less than zero
071     */
072    public ImageBuilder(final int width, final int height, final boolean hasAlpha) {
073        this(width, height, hasAlpha, false);
074    }
075
076    /**
077     * Constructs an ImageBuilder instance.
078     *
079     * @param width                the width of the image to be built
080     * @param height               the height of the image to be built
081     * @param hasAlpha             indicates whether the image has an alpha channel (the selection of alpha channel does not change the memory requirements for
082     *                             the ImageBuilder or resulting BufferedImage.
083     * @param isAlphaPremultiplied indicates whether alpha values are pre-multiplied; this setting is relevant only if alpha is true.
084     * @throws RasterFormatException if {@code width} or {@code height} are equal or less than zero
085     */
086    public ImageBuilder(final int width, final int height, final boolean hasAlpha, final boolean isAlphaPremultiplied) {
087        checkDimensions(width, height);
088        data = Allocator.intArray(width * height);
089        this.width = width;
090        this.height = height;
091        this.hasAlpha = hasAlpha;
092        this.isAlphaPremultiplied = isAlphaPremultiplied;
093    }
094
095    /**
096     * Performs a check on the specified sub-region to verify that it is within the constraints of the ImageBuilder bounds.
097     *
098     * @param x the X coordinate of the upper-left corner of the specified rectangular region
099     * @param y the Y coordinate of the upper-left corner of the specified rectangular region
100     * @param w the width of the specified rectangular region
101     * @param h the height of the specified rectangular region
102     * @throws RasterFormatException if width or height are equal or less than zero, or if the subimage is outside raster (on x or y axis)
103     */
104    private void checkBounds(final int x, final int y, final int w, final int h) {
105        if (w <= 0) {
106            throw new RasterFormatException("negative or zero subimage width");
107        }
108        if (h <= 0) {
109            throw new RasterFormatException("negative or zero subimage height");
110        }
111        if (x < 0 || x >= width) {
112            throw new RasterFormatException("subimage x is outside raster");
113        }
114        if (x + w > width) {
115            throw new RasterFormatException("subimage (x+width) is outside raster");
116        }
117        if (y < 0 || y >= height) {
118            throw new RasterFormatException("subimage y is outside raster");
119        }
120        if (y + h > height) {
121            throw new RasterFormatException("subimage (y+height) is outside raster");
122        }
123    }
124
125    /**
126     * Checks for valid dimensions and throws {@link RasterFormatException} if the inputs are invalid.
127     *
128     * @param width  image width (must be greater than zero)
129     * @param height image height (must be greater than zero)
130     * @throws RasterFormatException if {@code width} or {@code height} are equal or less than zero
131     */
132    private void checkDimensions(final int width, final int height) {
133        if (width <= 0) {
134            throw new RasterFormatException("zero or negative width value");
135        }
136        if (height <= 0) {
137            throw new RasterFormatException("zero or negative height value");
138        }
139    }
140
141    /**
142     * Create a BufferedImage using the data stored in the ImageBuilder.
143     *
144     * @return a valid BufferedImage.
145     */
146    public BufferedImage getBufferedImage() {
147        return makeBufferedImage(data, width, height, hasAlpha);
148    }
149
150    /**
151     * Gets the height of the ImageBuilder pixel field
152     *
153     * @return a positive integer
154     */
155    public int getHeight() {
156        return height;
157    }
158
159    /**
160     * Gets the RGB or ARGB value for the pixel at the position (x,y) within the image builder pixel field. For performance reasons no bounds checking is
161     * applied.
162     *
163     * @param x the X coordinate of the pixel to be read
164     * @param y the Y coordinate of the pixel to be read
165     * @return the RGB or ARGB pixel value
166     */
167    public int getRgb(final int x, final int y) {
168        final int rowOffset = y * width;
169        return data[rowOffset + x];
170    }
171
172    /**
173     * Gets a subimage from the ImageBuilder using the specified parameters. If the parameters specify a rectangular region that is not entirely contained
174     * within the bounds defined by the ImageBuilder, this method will throw a RasterFormatException. This runtime-exception behavior is consistent with the
175     * behavior of the getSubimage method provided by BufferedImage.
176     *
177     * @param x the X coordinate of the upper-left corner of the specified rectangular region
178     * @param y the Y coordinate of the upper-left corner of the specified rectangular region
179     * @param w the width of the specified rectangular region
180     * @param h the height of the specified rectangular region
181     * @return a BufferedImage that constructed from the data within the specified rectangular region
182     * @throws RasterFormatException f the specified area is not contained within this ImageBuilder
183     */
184    public BufferedImage getSubimage(final int x, final int y, final int w, final int h) {
185        checkBounds(x, y, w, h);
186
187        // Transcribe the data to an output image array
188        final int[] argb = Allocator.intArray(w * h);
189        int k = 0;
190        for (int iRow = 0; iRow < h; iRow++) {
191            final int dIndex = (iRow + y) * width + x;
192            System.arraycopy(this.data, dIndex, argb, k, w);
193            k += w;
194
195        }
196
197        return makeBufferedImage(argb, w, h, hasAlpha);
198
199    }
200
201    /**
202     * Gets a subset of the ImageBuilder content using the specified parameters to indicate an area of interest. If the parameters specify a rectangular region
203     * that is not entirely contained within the bounds defined by the ImageBuilder, this method will throw a RasterFormatException. This run- time exception is
204     * consistent with the behavior of the getSubimage method provided by BufferedImage.
205     *
206     * @param x the X coordinate of the upper-left corner of the specified rectangular region
207     * @param y the Y coordinate of the upper-left corner of the specified rectangular region
208     * @param w the width of the specified rectangular region
209     * @param h the height of the specified rectangular region
210     * @return a valid instance of the specified width and height.
211     * @throws RasterFormatException if the specified area is not contained within this ImageBuilder
212     */
213    public ImageBuilder getSubset(final int x, final int y, final int w, final int h) {
214        checkBounds(x, y, w, h);
215        final ImageBuilder b = new ImageBuilder(w, h, hasAlpha, isAlphaPremultiplied);
216        for (int i = 0; i < h; i++) {
217            final int srcDex = (i + y) * width + x;
218            final int outDex = i * w;
219            System.arraycopy(data, srcDex, b.data, outDex, w);
220        }
221        return b;
222    }
223
224    /**
225     * Gets the width of the ImageBuilder pixel field
226     *
227     * @return a positive integer
228     */
229    public int getWidth() {
230        return width;
231    }
232
233    private BufferedImage makeBufferedImage(final int[] argb, final int w, final int h, final boolean useAlpha) {
234        final ColorModel colorModel;
235        final WritableRaster raster;
236        final DataBufferInt buffer = new DataBufferInt(argb, w * h);
237        if (useAlpha) {
238            colorModel = new DirectColorModel(ColorSpace.getInstance(ColorSpace.CS_sRGB), 32, 0x00ff0000, 0x0000ff00, 0x000000ff, 0xff000000,
239                    isAlphaPremultiplied, DataBuffer.TYPE_INT);
240            raster = Raster.createPackedRaster(buffer, w, h, w, new int[] { 0x00ff0000, 0x0000ff00, 0x000000ff, 0xff000000 }, null);
241        } else {
242            colorModel = new DirectColorModel(24, 0x00ff0000, 0x0000ff00, 0x000000ff);
243            raster = Raster.createPackedRaster(buffer, w, h, w, new int[] { 0x00ff0000, 0x0000ff00, 0x000000ff }, null);
244        }
245        return new BufferedImage(colorModel, raster, colorModel.isAlphaPremultiplied(), new Properties());
246    }
247
248    /**
249     * Sets the RGB or ARGB value for the pixel at position (x,y) within the image builder pixel field. For performance reasons, no bounds checking is applied.
250     *
251     * @param x    the X coordinate of the pixel to be set.
252     * @param y    the Y coordinate of the pixel to be set.
253     * @param argb the RGB or ARGB value to be stored.
254     * @throws ArithmeticException      if the index computation overflows an int.
255     * @throws IllegalArgumentException if the resulting index is illegal.
256     */
257    public void setRgb(final int x, final int y, final int argb) {
258        // Throw ArithmeticException if the result overflows an int.
259        final int rowOffset = Math.multiplyExact(y, width);
260        // Throw ArithmeticException if the result overflows an int.
261        final int index = Math.addExact(rowOffset, x);
262        if (index > data.length) {
263            throw new IllegalArgumentException("setRGB: Illegal array index.");
264        }
265        data[index] = argb;
266    }
267}