1 /*
2 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
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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).
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25
26 package java.awt.image;
27
28 import java.awt.Transparency;
29 import java.awt.color.ColorSpace;
30 import java.util.Arrays;
31
32 /**
33 * The {@code PackedColorModel} class is an abstract
34 * {@link ColorModel} class that works with pixel values which represent
35 * color and alpha information as separate samples and which pack all
36 * samples for a single pixel into a single int, short, or byte quantity.
37 * This class can be used with an arbitrary {@link ColorSpace}. The number of
38 * color samples in the pixel values must be the same as the number of color
39 * components in the {@code ColorSpace}. There can be a single alpha
40 * sample. The array length is always 1 for those methods that use a
41 * primitive array pixel representation of type {@code transferType}.
42 * The transfer types supported are DataBuffer.TYPE_BYTE,
43 * DataBuffer.TYPE_USHORT, and DataBuffer.TYPE_INT.
44 * Color and alpha samples are stored in the single element of the array
45 * in bits indicated by bit masks. Each bit mask must be contiguous and
46 * masks must not overlap. The same masks apply to the single int
47 * pixel representation used by other methods. The correspondence of
48 * masks and color/alpha samples is as follows:
49 * <ul>
50 * <li> Masks are identified by indices running from 0 through
51 * {@link ColorModel#getNumComponents() getNumComponents} - 1.
52 * <li> The first
53 * {@link ColorModel#getNumColorComponents() getNumColorComponents}
54 * indices refer to color samples.
55 * <li> If an alpha sample is present, it corresponds the last index.
56 * <li> The order of the color indices is specified
57 * by the {@code ColorSpace}. Typically, this reflects the name of
58 * the color space type (for example, TYPE_RGB), index 0
59 * corresponds to red, index 1 to green, and index 2 to blue.
60 * </ul>
61 * <p>
62 * The translation from pixel values to color/alpha components for
63 * display or processing purposes is a one-to-one correspondence of
64 * samples to components.
65 * A {@code PackedColorModel} is typically used with image data
66 * that uses masks to define packed samples. For example, a
67 * {@code PackedColorModel} can be used in conjunction with a
68 * {@link SinglePixelPackedSampleModel} to construct a
69 * {@link BufferedImage}. Normally the masks used by the
70 * {@link SampleModel} and the {@code ColorModel} would be the same.
71 * However, if they are different, the color interpretation of pixel data is
72 * done according to the masks of the {@code ColorModel}.
73 * <p>
74 * A single {@code int} pixel representation is valid for all objects
75 * of this class since it is always possible to represent pixel values
76 * used with this class in a single {@code int}. Therefore, methods
77 * that use this representation do not throw an
78 * {@code IllegalArgumentException} due to an invalid pixel value.
79 * <p>
80 * A subclass of {@code PackedColorModel} is {@link DirectColorModel},
81 * which is similar to an X11 TrueColor visual.
82 *
83 * @see DirectColorModel
84 * @see SinglePixelPackedSampleModel
85 * @see BufferedImage
86 */
87
88 public abstract class PackedColorModel extends ColorModel {
89 int[] maskArray;
90 int[] maskOffsets;
91 float[] scaleFactors;
92
93 /**
94 * Constructs a {@code PackedColorModel} from a color mask array,
95 * which specifies which bits in an {@code int} pixel representation
96 * contain each of the color samples, and an alpha mask. Color
97 * components are in the specified {@code ColorSpace}. The length of
98 * {@code colorMaskArray} should be the number of components in
99 * the {@code ColorSpace}. All of the bits in each mask
100 * must be contiguous and fit in the specified number of least significant
101 * bits of an {@code int} pixel representation. If the
102 * {@code alphaMask} is 0, there is no alpha. If there is alpha,
103 * the {@code boolean isAlphaPremultiplied} specifies
104 * how to interpret color and alpha samples in pixel values. If the
105 * {@code boolean} is {@code true}, color samples are assumed
106 * to have been multiplied by the alpha sample. The transparency,
107 * {@code trans}, specifies what alpha values can be represented
108 * by this color model. The transfer type is the type of primitive
109 * array used to represent pixel values.
110 * @param space the specified {@code ColorSpace}
111 * @param bits the number of bits in the pixel values
112 * @param colorMaskArray array that specifies the masks representing
113 * the bits of the pixel values that represent the color
114 * components
115 * @param alphaMask specifies the mask representing
116 * the bits of the pixel values that represent the alpha
117 * component
118 * @param isAlphaPremultiplied {@code true} if color samples are
119 * premultiplied by the alpha sample; {@code false} otherwise
120 * @param trans specifies the alpha value that can be represented by
121 * this color model
122 * @param transferType the type of array used to represent pixel values
123 * @throws IllegalArgumentException if {@code bits} is less than
124 * 1 or greater than 32
125 */
126 public PackedColorModel (ColorSpace space, int bits,
127 int[] colorMaskArray, int alphaMask,
128 boolean isAlphaPremultiplied,
129 int trans, int transferType) {
130 super(bits, PackedColorModel.createBitsArray(colorMaskArray,
131 alphaMask),
132 space, (alphaMask == 0 ? false : true),
133 isAlphaPremultiplied, trans, transferType);
134 if (bits < 1 || bits > 32) {
135 throw new IllegalArgumentException("Number of bits must be between"
136 +" 1 and 32.");
137 }
138 maskArray = new int[numComponents];
139 maskOffsets = new int[numComponents];
140 scaleFactors = new float[numComponents];
141
142 for (int i=0; i < numColorComponents; i++) {
143 // Get the mask offset and #bits
144 DecomposeMask(colorMaskArray[i], i, space.getName(i));
145 }
146 if (alphaMask != 0) {
147 DecomposeMask(alphaMask, numColorComponents, "alpha");
148 if (nBits[numComponents-1] == 1) {
149 transparency = Transparency.BITMASK;
150 }
151 }
152 }
153
154 /**
155 * Constructs a {@code PackedColorModel} from the specified
156 * masks which indicate which bits in an {@code int} pixel
157 * representation contain the alpha, red, green and blue color samples.
158 * Color components are in the specified {@code ColorSpace}, which
159 * must be of type ColorSpace.TYPE_RGB. All of the bits in each
160 * mask must be contiguous and fit in the specified number of
161 * least significant bits of an {@code int} pixel representation. If
162 * {@code amask} is 0, there is no alpha. If there is alpha,
163 * the {@code boolean isAlphaPremultiplied}
164 * specifies how to interpret color and alpha samples
165 * in pixel values. If the {@code boolean} is {@code true},
166 * color samples are assumed to have been multiplied by the alpha sample.
167 * The transparency, {@code trans}, specifies what alpha values
168 * can be represented by this color model.
169 * The transfer type is the type of primitive array used to represent
170 * pixel values.
171 * @param space the specified {@code ColorSpace}
172 * @param bits the number of bits in the pixel values
173 * @param rmask specifies the mask representing
174 * the bits of the pixel values that represent the red
175 * color component
176 * @param gmask specifies the mask representing
177 * the bits of the pixel values that represent the green
178 * color component
179 * @param bmask specifies the mask representing
180 * the bits of the pixel values that represent
181 * the blue color component
182 * @param amask specifies the mask representing
183 * the bits of the pixel values that represent
184 * the alpha component
185 * @param isAlphaPremultiplied {@code true} if color samples are
186 * premultiplied by the alpha sample; {@code false} otherwise
187 * @param trans specifies the alpha value that can be represented by
188 * this color model
189 * @param transferType the type of array used to represent pixel values
190 * @throws IllegalArgumentException if {@code space} is not a
191 * TYPE_RGB space
192 * @see ColorSpace
193 */
194 public PackedColorModel(ColorSpace space, int bits, int rmask, int gmask,
195 int bmask, int amask,
196 boolean isAlphaPremultiplied,
197 int trans, int transferType) {
198 super (bits, PackedColorModel.createBitsArray(rmask, gmask, bmask,
199 amask),
200 space, (amask == 0 ? false : true),
201 isAlphaPremultiplied, trans, transferType);
202
203 if (space.getType() != ColorSpace.TYPE_RGB) {
204 throw new IllegalArgumentException("ColorSpace must be TYPE_RGB.");
205 }
206 maskArray = new int[numComponents];
207 maskOffsets = new int[numComponents];
208 scaleFactors = new float[numComponents];
209
210 DecomposeMask(rmask, 0, "red");
211
212 DecomposeMask(gmask, 1, "green");
213
214 DecomposeMask(bmask, 2, "blue");
215
216 if (amask != 0) {
217 DecomposeMask(amask, 3, "alpha");
218 if (nBits[3] == 1) {
219 transparency = Transparency.BITMASK;
220 }
221 }
222 }
223
224 /**
225 * Returns the mask indicating which bits in a pixel
226 * contain the specified color/alpha sample. For color
227 * samples, {@code index} corresponds to the placement of color
228 * sample names in the color space. Thus, an {@code index}
229 * equal to 0 for a CMYK ColorSpace would correspond to
230 * Cyan and an {@code index} equal to 1 would correspond to
231 * Magenta. If there is alpha, the alpha {@code index} would be:
232 * <pre>
233 * alphaIndex = numComponents() - 1;
234 * </pre>
235 * @param index the specified color or alpha sample
236 * @return the mask, which indicates which bits of the {@code int}
237 * pixel representation contain the color or alpha sample specified
238 * by {@code index}.
239 * @throws ArrayIndexOutOfBoundsException if {@code index} is
240 * greater than the number of components minus 1 in this
241 * {@code PackedColorModel} or if {@code index} is
242 * less than zero
243 */
244 public final int getMask(int index) {
245 return maskArray[index];
246 }
247
248 /**
249 * Returns a mask array indicating which bits in a pixel
250 * contain the color and alpha samples.
251 * @return the mask array , which indicates which bits of the
252 * {@code int} pixel
253 * representation contain the color or alpha samples.
254 */
255 public final int[] getMasks() {
256 return maskArray.clone();
257 }
258
259 /*
260 * A utility function to compute the mask offset and scalefactor,
261 * store these and the mask in instance arrays, and verify that
262 * the mask fits in the specified pixel size.
263 */
264 private void DecomposeMask(int mask, int idx, String componentName) {
265 int off = 0;
266 int count = nBits[idx];
267
268 // Store the mask
269 maskArray[idx] = mask;
270
271 // Now find the shift
272 if (mask != 0) {
273 while ((mask & 1) == 0) {
274 mask >>>= 1;
275 off++;
276 }
277 }
278
279 if (off + count > pixel_bits) {
280 throw new IllegalArgumentException(componentName + " mask "+
281 Integer.toHexString(maskArray[idx])+
282 " overflows pixel (expecting "+
283 pixel_bits+" bits");
284 }
285
286 maskOffsets[idx] = off;
287 if (count == 0) {
288 // High enough to scale any 0-ff value down to 0.0, but not
289 // high enough to get Infinity when scaling back to pixel bits
290 scaleFactors[idx] = 256.0f;
291 } else {
292 scaleFactors[idx] = 255.0f / ((1 << count) - 1);
293 }
294
295 }
296
297 /**
298 * Creates a {@code SampleModel} with the specified width and
299 * height that has a data layout compatible with this
300 * {@code ColorModel}.
301 * @param w the width (in pixels) of the region of the image data
302 * described
303 * @param h the height (in pixels) of the region of the image data
304 * described
305 * @return the newly created {@code SampleModel}.
306 * @throws IllegalArgumentException if {@code w} or
307 * {@code h} is not greater than 0
308 * @see SampleModel
309 */
310 public SampleModel createCompatibleSampleModel(int w, int h) {
311 return new SinglePixelPackedSampleModel(transferType, w, h,
312 maskArray);
313 }
314
315 /**
316 * Checks if the specified {@code SampleModel} is compatible
317 * with this {@code ColorModel}. If {@code sm} is
318 * {@code null}, this method returns {@code false}.
319 * @param sm the specified {@code SampleModel},
320 * or {@code null}
321 * @return {@code true} if the specified {@code SampleModel}
322 * is compatible with this {@code ColorModel};
323 * {@code false} otherwise.
324 * @see SampleModel
325 */
326 public boolean isCompatibleSampleModel(SampleModel sm) {
327 if (! (sm instanceof SinglePixelPackedSampleModel)) {
328 return false;
329 }
330
331 // Must have the same number of components
332 if (numComponents != sm.getNumBands()) {
333 return false;
334 }
335
336 // Transfer type must be the same
337 if (sm.getTransferType() != transferType) {
338 return false;
339 }
340
341 SinglePixelPackedSampleModel sppsm = (SinglePixelPackedSampleModel) sm;
342 // Now compare the specific masks
343 int[] bitMasks = sppsm.getBitMasks();
344 if (bitMasks.length != maskArray.length) {
345 return false;
346 }
347
348 /* compare 'effective' masks only, i.e. only part of the mask
349 * which fits the capacity of the transfer type.
350 */
351 int maxMask = (int)((1L << DataBuffer.getDataTypeSize(transferType)) - 1);
352 for (int i=0; i < bitMasks.length; i++) {
353 if ((maxMask & bitMasks[i]) != (maxMask & maskArray[i])) {
354 return false;
355 }
356 }
357
358 return true;
359 }
360
361 /**
362 * Returns a {@link WritableRaster} representing the alpha channel of
363 * an image, extracted from the input {@code WritableRaster}.
364 * This method assumes that {@code WritableRaster} objects
365 * associated with this {@code ColorModel} store the alpha band,
366 * if present, as the last band of image data. Returns {@code null}
367 * if there is no separate spatial alpha channel associated with this
368 * {@code ColorModel}. This method creates a new
369 * {@code WritableRaster}, but shares the data array.
370 * @param raster a {@code WritableRaster} containing an image
371 * @return a {@code WritableRaster} that represents the alpha
372 * channel of the image contained in {@code raster}.
373 */
374 public WritableRaster getAlphaRaster(WritableRaster raster) {
375 if (hasAlpha() == false) {
376 return null;
377 }
378
379 int x = raster.getMinX();
380 int y = raster.getMinY();
381 int[] band = new int[1];
382 band[0] = raster.getNumBands() - 1;
383 return raster.createWritableChild(x, y, raster.getWidth(),
384 raster.getHeight(), x, y,
385 band);
386 }
387
388 /**
389 * Tests if the specified {@code Object} equals this
390 * {@code PackedColorModel}.
391 * In order to protect the symmetry property of
392 * {@code (a.equals(b) == b.equals(a))},
393 * the target object must be the exact same class as this
394 * object to evaluate as {equals}.
395 * @param obj the {@code Object} to test for equality
396 * @return {@code true} if the specified {@code Object}
397 * equals this {@code PackedColorModel}; {@code false} otherwise.
398 */
399 @Override
400 public boolean equals(Object obj) {
401 /*
402 * We verify the type of argument obj in super.equals() where we check
403 * for equality of class name.
404 */
405 if (!super.equals(obj)) {
406 return false;
407 }
408
409 PackedColorModel cm = (PackedColorModel) obj;
410 int numC = cm.getNumComponents();
411 for(int i=0; i < numC; i++) {
412 if (maskArray[i] != cm.getMask(i)) {
413 return false;
414 }
415 }
416 return true;
417 }
418
419 /**
420 * Returns the hash code for this PackedColorModel.
421 *
422 * @return a hash code for this PackedColorModel.
423 */
424 @Override
425 public int hashCode() {
426 int hash = super.hashCode();
427 hash = 89 * hash + Arrays.hashCode(this.maskArray);
428 return hash;
429 }
430
431 private static final int[] createBitsArray(int[]colorMaskArray,
432 int alphaMask) {
433 int numColors = colorMaskArray.length;
434 int numAlpha = (alphaMask == 0 ? 0 : 1);
435 int[] arr = new int[numColors+numAlpha];
436 for (int i=0; i < numColors; i++) {
437 arr[i] = countBits(colorMaskArray[i]);
438 if (arr[i] < 0) {
439 throw new IllegalArgumentException("Noncontiguous color mask ("
440 + Integer.toHexString(colorMaskArray[i])+
441 "at index "+i);
442 }
443 }
444 if (alphaMask != 0) {
445 arr[numColors] = countBits(alphaMask);
446 if (arr[numColors] < 0) {
447 throw new IllegalArgumentException("Noncontiguous alpha mask ("
448 + Integer.toHexString(alphaMask));
449 }
450 }
451 return arr;
452 }
453
454 private static final int[] createBitsArray(int rmask, int gmask, int bmask,
455 int amask) {
456 int[] arr = new int[3 + (amask == 0 ? 0 : 1)];
457 arr[0] = countBits(rmask);
458 arr[1] = countBits(gmask);
459 arr[2] = countBits(bmask);
460 if (arr[0] < 0) {
461 throw new IllegalArgumentException("Noncontiguous red mask ("
462 + Integer.toHexString(rmask));
463 }
464 else if (arr[1] < 0) {
465 throw new IllegalArgumentException("Noncontiguous green mask ("
466 + Integer.toHexString(gmask));
467 }
468 else if (arr[2] < 0) {
469 throw new IllegalArgumentException("Noncontiguous blue mask ("
470 + Integer.toHexString(bmask));
471 }
472 if (amask != 0) {
473 arr[3] = countBits(amask);
474 if (arr[3] < 0) {
475 throw new IllegalArgumentException("Noncontiguous alpha mask ("
476 + Integer.toHexString(amask));
477 }
478 }
479 return arr;
480 }
481
482 private static final int countBits(int mask) {
483 int count = 0;
484 if (mask != 0) {
485 while ((mask & 1) == 0) {
486 mask >>>= 1;
487 }
488 while ((mask & 1) == 1) {
489 mask >>>= 1;
490 count++;
491 }
492 }
493 if (mask != 0) {
494 return -1;
495 }
496 return count;
497 }
498
499 }