J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1996-2002 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package java.awt.image; |
| 27 | |
| 28 | import java.awt.image.ImageConsumer; |
| 29 | import java.awt.image.ColorModel; |
| 30 | import java.util.Hashtable; |
| 31 | import java.awt.Rectangle; |
| 32 | |
| 33 | /** |
| 34 | * An ImageFilter class for scaling images using a simple area averaging |
| 35 | * algorithm that produces smoother results than the nearest neighbor |
| 36 | * algorithm. |
| 37 | * <p>This class extends the basic ImageFilter Class to scale an existing |
| 38 | * image and provide a source for a new image containing the resampled |
| 39 | * image. The pixels in the source image are blended to produce pixels |
| 40 | * for an image of the specified size. The blending process is analogous |
| 41 | * to scaling up the source image to a multiple of the destination size |
| 42 | * using pixel replication and then scaling it back down to the destination |
| 43 | * size by simply averaging all the pixels in the supersized image that |
| 44 | * fall within a given pixel of the destination image. If the data from |
| 45 | * the source is not delivered in TopDownLeftRight order then the filter |
| 46 | * will back off to a simple pixel replication behavior and utilize the |
| 47 | * requestTopDownLeftRightResend() method to refilter the pixels in a |
| 48 | * better way at the end. |
| 49 | * <p>It is meant to be used in conjunction with a FilteredImageSource |
| 50 | * object to produce scaled versions of existing images. Due to |
| 51 | * implementation dependencies, there may be differences in pixel values |
| 52 | * of an image filtered on different platforms. |
| 53 | * |
| 54 | * @see FilteredImageSource |
| 55 | * @see ReplicateScaleFilter |
| 56 | * @see ImageFilter |
| 57 | * |
| 58 | * @author Jim Graham |
| 59 | */ |
| 60 | public class AreaAveragingScaleFilter extends ReplicateScaleFilter { |
| 61 | private static final ColorModel rgbmodel = ColorModel.getRGBdefault(); |
| 62 | private static final int neededHints = (TOPDOWNLEFTRIGHT |
| 63 | | COMPLETESCANLINES); |
| 64 | |
| 65 | private boolean passthrough; |
| 66 | private float reds[], greens[], blues[], alphas[]; |
| 67 | private int savedy; |
| 68 | private int savedyrem; |
| 69 | |
| 70 | /** |
| 71 | * Constructs an AreaAveragingScaleFilter that scales the pixels from |
| 72 | * its source Image as specified by the width and height parameters. |
| 73 | * @param width the target width to scale the image |
| 74 | * @param height the target height to scale the image |
| 75 | */ |
| 76 | public AreaAveragingScaleFilter(int width, int height) { |
| 77 | super(width, height); |
| 78 | } |
| 79 | |
| 80 | /** |
| 81 | * Detect if the data is being delivered with the necessary hints |
| 82 | * to allow the averaging algorithm to do its work. |
| 83 | * <p> |
| 84 | * Note: This method is intended to be called by the |
| 85 | * <code>ImageProducer</code> of the <code>Image</code> whose |
| 86 | * pixels are being filtered. Developers using |
| 87 | * this class to filter pixels from an image should avoid calling |
| 88 | * this method directly since that operation could interfere |
| 89 | * with the filtering operation. |
| 90 | * @see ImageConsumer#setHints |
| 91 | */ |
| 92 | public void setHints(int hints) { |
| 93 | passthrough = ((hints & neededHints) != neededHints); |
| 94 | super.setHints(hints); |
| 95 | } |
| 96 | |
| 97 | private void makeAccumBuffers() { |
| 98 | reds = new float[destWidth]; |
| 99 | greens = new float[destWidth]; |
| 100 | blues = new float[destWidth]; |
| 101 | alphas = new float[destWidth]; |
| 102 | } |
| 103 | |
| 104 | private int[] calcRow() { |
| 105 | float origmult = ((float) srcWidth) * srcHeight; |
| 106 | if (outpixbuf == null || !(outpixbuf instanceof int[])) { |
| 107 | outpixbuf = new int[destWidth]; |
| 108 | } |
| 109 | int[] outpix = (int[]) outpixbuf; |
| 110 | for (int x = 0; x < destWidth; x++) { |
| 111 | float mult = origmult; |
| 112 | int a = Math.round(alphas[x] / mult); |
| 113 | if (a <= 0) { |
| 114 | a = 0; |
| 115 | } else if (a >= 255) { |
| 116 | a = 255; |
| 117 | } else { |
| 118 | // un-premultiply the components (by modifying mult here, we |
| 119 | // are effectively doing the divide by mult and divide by |
| 120 | // alpha in the same step) |
| 121 | mult = alphas[x] / 255; |
| 122 | } |
| 123 | int r = Math.round(reds[x] / mult); |
| 124 | int g = Math.round(greens[x] / mult); |
| 125 | int b = Math.round(blues[x] / mult); |
| 126 | if (r < 0) {r = 0;} else if (r > 255) {r = 255;} |
| 127 | if (g < 0) {g = 0;} else if (g > 255) {g = 255;} |
| 128 | if (b < 0) {b = 0;} else if (b > 255) {b = 255;} |
| 129 | outpix[x] = (a << 24 | r << 16 | g << 8 | b); |
| 130 | } |
| 131 | return outpix; |
| 132 | } |
| 133 | |
| 134 | private void accumPixels(int x, int y, int w, int h, |
| 135 | ColorModel model, Object pixels, int off, |
| 136 | int scansize) { |
| 137 | if (reds == null) { |
| 138 | makeAccumBuffers(); |
| 139 | } |
| 140 | int sy = y; |
| 141 | int syrem = destHeight; |
| 142 | int dy, dyrem; |
| 143 | if (sy == 0) { |
| 144 | dy = 0; |
| 145 | dyrem = 0; |
| 146 | } else { |
| 147 | dy = savedy; |
| 148 | dyrem = savedyrem; |
| 149 | } |
| 150 | while (sy < y + h) { |
| 151 | int amty; |
| 152 | if (dyrem == 0) { |
| 153 | for (int i = 0; i < destWidth; i++) { |
| 154 | alphas[i] = reds[i] = greens[i] = blues[i] = 0f; |
| 155 | } |
| 156 | dyrem = srcHeight; |
| 157 | } |
| 158 | if (syrem < dyrem) { |
| 159 | amty = syrem; |
| 160 | } else { |
| 161 | amty = dyrem; |
| 162 | } |
| 163 | int sx = 0; |
| 164 | int dx = 0; |
| 165 | int sxrem = 0; |
| 166 | int dxrem = srcWidth; |
| 167 | float a = 0f, r = 0f, g = 0f, b = 0f; |
| 168 | while (sx < w) { |
| 169 | if (sxrem == 0) { |
| 170 | sxrem = destWidth; |
| 171 | int rgb; |
| 172 | if (pixels instanceof byte[]) { |
| 173 | rgb = ((byte[]) pixels)[off + sx] & 0xff; |
| 174 | } else { |
| 175 | rgb = ((int[]) pixels)[off + sx]; |
| 176 | } |
| 177 | // getRGB() always returns non-premultiplied components |
| 178 | rgb = model.getRGB(rgb); |
| 179 | a = rgb >>> 24; |
| 180 | r = (rgb >> 16) & 0xff; |
| 181 | g = (rgb >> 8) & 0xff; |
| 182 | b = rgb & 0xff; |
| 183 | // premultiply the components if necessary |
| 184 | if (a != 255.0f) { |
| 185 | float ascale = a / 255.0f; |
| 186 | r *= ascale; |
| 187 | g *= ascale; |
| 188 | b *= ascale; |
| 189 | } |
| 190 | } |
| 191 | int amtx; |
| 192 | if (sxrem < dxrem) { |
| 193 | amtx = sxrem; |
| 194 | } else { |
| 195 | amtx = dxrem; |
| 196 | } |
| 197 | float mult = ((float) amtx) * amty; |
| 198 | alphas[dx] += mult * a; |
| 199 | reds[dx] += mult * r; |
| 200 | greens[dx] += mult * g; |
| 201 | blues[dx] += mult * b; |
| 202 | if ((sxrem -= amtx) == 0) { |
| 203 | sx++; |
| 204 | } |
| 205 | if ((dxrem -= amtx) == 0) { |
| 206 | dx++; |
| 207 | dxrem = srcWidth; |
| 208 | } |
| 209 | } |
| 210 | if ((dyrem -= amty) == 0) { |
| 211 | int outpix[] = calcRow(); |
| 212 | do { |
| 213 | consumer.setPixels(0, dy, destWidth, 1, |
| 214 | rgbmodel, outpix, 0, destWidth); |
| 215 | dy++; |
| 216 | } while ((syrem -= amty) >= amty && amty == srcHeight); |
| 217 | } else { |
| 218 | syrem -= amty; |
| 219 | } |
| 220 | if (syrem == 0) { |
| 221 | syrem = destHeight; |
| 222 | sy++; |
| 223 | off += scansize; |
| 224 | } |
| 225 | } |
| 226 | savedyrem = dyrem; |
| 227 | savedy = dy; |
| 228 | } |
| 229 | |
| 230 | /** |
| 231 | * Combine the components for the delivered byte pixels into the |
| 232 | * accumulation arrays and send on any averaged data for rows of |
| 233 | * pixels that are complete. If the correct hints were not |
| 234 | * specified in the setHints call then relay the work to our |
| 235 | * superclass which is capable of scaling pixels regardless of |
| 236 | * the delivery hints. |
| 237 | * <p> |
| 238 | * Note: This method is intended to be called by the |
| 239 | * <code>ImageProducer</code> of the <code>Image</code> |
| 240 | * whose pixels are being filtered. Developers using |
| 241 | * this class to filter pixels from an image should avoid calling |
| 242 | * this method directly since that operation could interfere |
| 243 | * with the filtering operation. |
| 244 | * @see ReplicateScaleFilter |
| 245 | */ |
| 246 | public void setPixels(int x, int y, int w, int h, |
| 247 | ColorModel model, byte pixels[], int off, |
| 248 | int scansize) { |
| 249 | if (passthrough) { |
| 250 | super.setPixels(x, y, w, h, model, pixels, off, scansize); |
| 251 | } else { |
| 252 | accumPixels(x, y, w, h, model, pixels, off, scansize); |
| 253 | } |
| 254 | } |
| 255 | |
| 256 | /** |
| 257 | * Combine the components for the delivered int pixels into the |
| 258 | * accumulation arrays and send on any averaged data for rows of |
| 259 | * pixels that are complete. If the correct hints were not |
| 260 | * specified in the setHints call then relay the work to our |
| 261 | * superclass which is capable of scaling pixels regardless of |
| 262 | * the delivery hints. |
| 263 | * <p> |
| 264 | * Note: This method is intended to be called by the |
| 265 | * <code>ImageProducer</code> of the <code>Image</code> |
| 266 | * whose pixels are being filtered. Developers using |
| 267 | * this class to filter pixels from an image should avoid calling |
| 268 | * this method directly since that operation could interfere |
| 269 | * with the filtering operation. |
| 270 | * @see ReplicateScaleFilter |
| 271 | */ |
| 272 | public void setPixels(int x, int y, int w, int h, |
| 273 | ColorModel model, int pixels[], int off, |
| 274 | int scansize) { |
| 275 | if (passthrough) { |
| 276 | super.setPixels(x, y, w, h, model, pixels, off, scansize); |
| 277 | } else { |
| 278 | accumPixels(x, y, w, h, model, pixels, off, scansize); |
| 279 | } |
| 280 | } |
| 281 | } |