NotificationColorUtil.java revision ac5f02749a595d39711beb4a1defb01949eb548a
1/* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License 15 */ 16 17package com.android.internal.util; 18 19import android.annotation.ColorInt; 20import android.annotation.FloatRange; 21import android.annotation.IntRange; 22import android.annotation.NonNull; 23import android.app.Notification; 24import android.content.Context; 25import android.content.res.ColorStateList; 26import android.content.res.Resources; 27import android.graphics.Bitmap; 28import android.graphics.Color; 29import android.graphics.drawable.AnimationDrawable; 30import android.graphics.drawable.BitmapDrawable; 31import android.graphics.drawable.Drawable; 32import android.graphics.drawable.Icon; 33import android.graphics.drawable.VectorDrawable; 34import android.text.SpannableStringBuilder; 35import android.text.Spanned; 36import android.text.style.CharacterStyle; 37import android.text.style.ForegroundColorSpan; 38import android.text.style.TextAppearanceSpan; 39import android.util.Log; 40import android.util.Pair; 41 42import java.util.Arrays; 43import java.util.WeakHashMap; 44 45/** 46 * Helper class to process legacy (Holo) notifications to make them look like material notifications. 47 * 48 * @hide 49 */ 50public class NotificationColorUtil { 51 52 private static final String TAG = "NotificationColorUtil"; 53 private static final boolean DEBUG = false; 54 55 private static final Object sLock = new Object(); 56 private static NotificationColorUtil sInstance; 57 58 private final ImageUtils mImageUtils = new ImageUtils(); 59 private final WeakHashMap<Bitmap, Pair<Boolean, Integer>> mGrayscaleBitmapCache = 60 new WeakHashMap<Bitmap, Pair<Boolean, Integer>>(); 61 62 private final int mGrayscaleIconMaxSize; // @dimen/notification_large_icon_width (64dp) 63 64 public static NotificationColorUtil getInstance(Context context) { 65 synchronized (sLock) { 66 if (sInstance == null) { 67 sInstance = new NotificationColorUtil(context); 68 } 69 return sInstance; 70 } 71 } 72 73 private NotificationColorUtil(Context context) { 74 mGrayscaleIconMaxSize = context.getResources().getDimensionPixelSize( 75 com.android.internal.R.dimen.notification_large_icon_width); 76 } 77 78 /** 79 * Checks whether a Bitmap is a small grayscale icon. 80 * Grayscale here means "very close to a perfect gray"; icon means "no larger than 64dp". 81 * 82 * @param bitmap The bitmap to test. 83 * @return True if the bitmap is grayscale; false if it is color or too large to examine. 84 */ 85 public boolean isGrayscaleIcon(Bitmap bitmap) { 86 // quick test: reject large bitmaps 87 if (bitmap.getWidth() > mGrayscaleIconMaxSize 88 || bitmap.getHeight() > mGrayscaleIconMaxSize) { 89 return false; 90 } 91 92 synchronized (sLock) { 93 Pair<Boolean, Integer> cached = mGrayscaleBitmapCache.get(bitmap); 94 if (cached != null) { 95 if (cached.second == bitmap.getGenerationId()) { 96 return cached.first; 97 } 98 } 99 } 100 boolean result; 101 int generationId; 102 synchronized (mImageUtils) { 103 result = mImageUtils.isGrayscale(bitmap); 104 105 // generationId and the check whether the Bitmap is grayscale can't be read atomically 106 // here. However, since the thread is in the process of posting the notification, we can 107 // assume that it doesn't modify the bitmap while we are checking the pixels. 108 generationId = bitmap.getGenerationId(); 109 } 110 synchronized (sLock) { 111 mGrayscaleBitmapCache.put(bitmap, Pair.create(result, generationId)); 112 } 113 return result; 114 } 115 116 /** 117 * Checks whether a Drawable is a small grayscale icon. 118 * Grayscale here means "very close to a perfect gray"; icon means "no larger than 64dp". 119 * 120 * @param d The drawable to test. 121 * @return True if the bitmap is grayscale; false if it is color or too large to examine. 122 */ 123 public boolean isGrayscaleIcon(Drawable d) { 124 if (d == null) { 125 return false; 126 } else if (d instanceof BitmapDrawable) { 127 BitmapDrawable bd = (BitmapDrawable) d; 128 return bd.getBitmap() != null && isGrayscaleIcon(bd.getBitmap()); 129 } else if (d instanceof AnimationDrawable) { 130 AnimationDrawable ad = (AnimationDrawable) d; 131 int count = ad.getNumberOfFrames(); 132 return count > 0 && isGrayscaleIcon(ad.getFrame(0)); 133 } else if (d instanceof VectorDrawable) { 134 // We just assume you're doing the right thing if using vectors 135 return true; 136 } else { 137 return false; 138 } 139 } 140 141 public boolean isGrayscaleIcon(Context context, Icon icon) { 142 if (icon == null) { 143 return false; 144 } 145 switch (icon.getType()) { 146 case Icon.TYPE_BITMAP: 147 return isGrayscaleIcon(icon.getBitmap()); 148 case Icon.TYPE_RESOURCE: 149 return isGrayscaleIcon(context, icon.getResId()); 150 default: 151 return false; 152 } 153 } 154 155 /** 156 * Checks whether a drawable with a resoure id is a small grayscale icon. 157 * Grayscale here means "very close to a perfect gray"; icon means "no larger than 64dp". 158 * 159 * @param context The context to load the drawable from. 160 * @return True if the bitmap is grayscale; false if it is color or too large to examine. 161 */ 162 public boolean isGrayscaleIcon(Context context, int drawableResId) { 163 if (drawableResId != 0) { 164 try { 165 return isGrayscaleIcon(context.getDrawable(drawableResId)); 166 } catch (Resources.NotFoundException ex) { 167 Log.e(TAG, "Drawable not found: " + drawableResId); 168 return false; 169 } 170 } else { 171 return false; 172 } 173 } 174 175 /** 176 * Inverts all the grayscale colors set by {@link android.text.style.TextAppearanceSpan}s on 177 * the text. 178 * 179 * @param charSequence The text to process. 180 * @return The color inverted text. 181 */ 182 public CharSequence invertCharSequenceColors(CharSequence charSequence) { 183 if (charSequence instanceof Spanned) { 184 Spanned ss = (Spanned) charSequence; 185 Object[] spans = ss.getSpans(0, ss.length(), Object.class); 186 SpannableStringBuilder builder = new SpannableStringBuilder(ss.toString()); 187 for (Object span : spans) { 188 Object resultSpan = span; 189 if (resultSpan instanceof CharacterStyle) { 190 resultSpan = ((CharacterStyle) span).getUnderlying(); 191 } 192 if (resultSpan instanceof TextAppearanceSpan) { 193 TextAppearanceSpan processedSpan = processTextAppearanceSpan( 194 (TextAppearanceSpan) span); 195 if (processedSpan != resultSpan) { 196 resultSpan = processedSpan; 197 } else { 198 // we need to still take the orgininal for wrapped spans 199 resultSpan = span; 200 } 201 } else if (resultSpan instanceof ForegroundColorSpan) { 202 ForegroundColorSpan originalSpan = (ForegroundColorSpan) resultSpan; 203 int foregroundColor = originalSpan.getForegroundColor(); 204 resultSpan = new ForegroundColorSpan(processColor(foregroundColor)); 205 } else { 206 resultSpan = span; 207 } 208 builder.setSpan(resultSpan, ss.getSpanStart(span), ss.getSpanEnd(span), 209 ss.getSpanFlags(span)); 210 } 211 return builder; 212 } 213 return charSequence; 214 } 215 216 private TextAppearanceSpan processTextAppearanceSpan(TextAppearanceSpan span) { 217 ColorStateList colorStateList = span.getTextColor(); 218 if (colorStateList != null) { 219 int[] colors = colorStateList.getColors(); 220 boolean changed = false; 221 for (int i = 0; i < colors.length; i++) { 222 if (ImageUtils.isGrayscale(colors[i])) { 223 224 // Allocate a new array so we don't change the colors in the old color state 225 // list. 226 if (!changed) { 227 colors = Arrays.copyOf(colors, colors.length); 228 } 229 colors[i] = processColor(colors[i]); 230 changed = true; 231 } 232 } 233 if (changed) { 234 return new TextAppearanceSpan( 235 span.getFamily(), span.getTextStyle(), span.getTextSize(), 236 new ColorStateList(colorStateList.getStates(), colors), 237 span.getLinkTextColor()); 238 } 239 } 240 return span; 241 } 242 243 private int processColor(int color) { 244 return Color.argb(Color.alpha(color), 245 255 - Color.red(color), 246 255 - Color.green(color), 247 255 - Color.blue(color)); 248 } 249 250 /** 251 * Finds a suitable color such that there's enough contrast. 252 * 253 * @param color the color to start searching from. 254 * @param other the color to ensure contrast against. Assumed to be lighter than {@param color} 255 * @param findFg if true, we assume {@param color} is a foreground, otherwise a background. 256 * @param minRatio the minimum contrast ratio required. 257 * @return a color with the same hue as {@param color}, potentially darkened to meet the 258 * contrast ratio. 259 */ 260 public static int findContrastColor(int color, int other, boolean findFg, double minRatio) { 261 int fg = findFg ? color : other; 262 int bg = findFg ? other : color; 263 if (ColorUtilsFromCompat.calculateContrast(fg, bg) >= minRatio) { 264 return color; 265 } 266 267 double[] lab = new double[3]; 268 ColorUtilsFromCompat.colorToLAB(findFg ? fg : bg, lab); 269 270 double low = 0, high = lab[0]; 271 final double a = lab[1], b = lab[2]; 272 for (int i = 0; i < 15 && high - low > 0.00001; i++) { 273 final double l = (low + high) / 2; 274 if (findFg) { 275 fg = ColorUtilsFromCompat.LABToColor(l, a, b); 276 } else { 277 bg = ColorUtilsFromCompat.LABToColor(l, a, b); 278 } 279 if (ColorUtilsFromCompat.calculateContrast(fg, bg) > minRatio) { 280 low = l; 281 } else { 282 high = l; 283 } 284 } 285 return ColorUtilsFromCompat.LABToColor(low, a, b); 286 } 287 288 /** 289 * Finds a suitable alpha such that there's enough contrast. 290 * 291 * @param color the color to start searching from. 292 * @param backgroundColor the color to ensure contrast against. 293 * @param minRatio the minimum contrast ratio required. 294 * @return the same color as {@param color} with potentially modified alpha to meet contrast 295 */ 296 public static int findAlphaToMeetContrast(int color, int backgroundColor, double minRatio) { 297 int fg = color; 298 int bg = backgroundColor; 299 if (ColorUtilsFromCompat.calculateContrast(fg, bg) >= minRatio) { 300 return color; 301 } 302 int startAlpha = Color.alpha(color); 303 int r = Color.red(color); 304 int g = Color.green(color); 305 int b = Color.blue(color); 306 307 int low = startAlpha, high = 255; 308 for (int i = 0; i < 15 && high - low > 0; i++) { 309 final int alpha = (low + high) / 2; 310 fg = Color.argb(alpha, r, g, b); 311 if (ColorUtilsFromCompat.calculateContrast(fg, bg) > minRatio) { 312 high = alpha; 313 } else { 314 low = alpha; 315 } 316 } 317 return Color.argb(high, r, g, b); 318 } 319 320 /** 321 * Finds a suitable color such that there's enough contrast. 322 * 323 * @param color the color to start searching from. 324 * @param other the color to ensure contrast against. Assumed to be darker than {@param color} 325 * @param findFg if true, we assume {@param color} is a foreground, otherwise a background. 326 * @param minRatio the minimum contrast ratio required. 327 * @return a color with the same hue as {@param color}, potentially darkened to meet the 328 * contrast ratio. 329 */ 330 public static int findContrastColorAgainstDark(int color, int other, boolean findFg, 331 double minRatio) { 332 int fg = findFg ? color : other; 333 int bg = findFg ? other : color; 334 if (ColorUtilsFromCompat.calculateContrast(fg, bg) >= minRatio) { 335 return color; 336 } 337 338 float[] hsl = new float[3]; 339 ColorUtilsFromCompat.colorToHSL(findFg ? fg : bg, hsl); 340 341 float low = hsl[2], high = 1; 342 for (int i = 0; i < 15 && high - low > 0.00001; i++) { 343 final float l = (low + high) / 2; 344 hsl[2] = l; 345 if (findFg) { 346 fg = ColorUtilsFromCompat.HSLToColor(hsl); 347 } else { 348 bg = ColorUtilsFromCompat.HSLToColor(hsl); 349 } 350 if (ColorUtilsFromCompat.calculateContrast(fg, bg) > minRatio) { 351 high = l; 352 } else { 353 low = l; 354 } 355 } 356 return findFg ? fg : bg; 357 } 358 359 public static int ensureTextContrastOnBlack(int color) { 360 return findContrastColorAgainstDark(color, Color.BLACK, true /* fg */, 12); 361 } 362 363 /** 364 * Finds a text color with sufficient contrast over bg that has the same hue as the original 365 * color, assuming it is for large text. 366 */ 367 public static int ensureLargeTextContrast(int color, int bg) { 368 return findContrastColor(color, bg, true, 3); 369 } 370 371 /** 372 * Finds a text color with sufficient contrast over bg that has the same hue as the original 373 * color. 374 */ 375 private static int ensureTextContrast(int color, int bg) { 376 return findContrastColor(color, bg, true, 4.5); 377 } 378 379 /** Finds a background color for a text view with given text color and hint text color, that 380 * has the same hue as the original color. 381 */ 382 public static int ensureTextBackgroundColor(int color, int textColor, int hintColor) { 383 color = findContrastColor(color, hintColor, false, 3.0); 384 return findContrastColor(color, textColor, false, 4.5); 385 } 386 387 private static String contrastChange(int colorOld, int colorNew, int bg) { 388 return String.format("from %.2f:1 to %.2f:1", 389 ColorUtilsFromCompat.calculateContrast(colorOld, bg), 390 ColorUtilsFromCompat.calculateContrast(colorNew, bg)); 391 } 392 393 /** 394 * Resolves {@param color} to an actual color if it is {@link Notification#COLOR_DEFAULT} 395 */ 396 public static int resolveColor(Context context, int color) { 397 if (color == Notification.COLOR_DEFAULT) { 398 return context.getColor(com.android.internal.R.color.notification_icon_default_color); 399 } 400 return color; 401 } 402 403 /** 404 * Resolves a Notification's color such that it has enough contrast to be used as the 405 * color for the Notification's action and header text. 406 * 407 * @param notificationColor the color of the notification or {@link Notification#COLOR_DEFAULT} 408 * @param backgroundColor the background color to ensure the contrast against. 409 * @return a color of the same hue with enough contrast against the backgrounds. 410 */ 411 public static int resolveContrastColor(Context context, int notificationColor, 412 int backgroundColor) { 413 final int resolvedColor = resolveColor(context, notificationColor); 414 415 final int actionBg = context.getColor( 416 com.android.internal.R.color.notification_action_list); 417 418 int color = resolvedColor; 419 color = NotificationColorUtil.ensureLargeTextContrast(color, actionBg); 420 color = NotificationColorUtil.ensureTextContrast(color, backgroundColor); 421 422 if (color != resolvedColor) { 423 if (DEBUG){ 424 Log.w(TAG, String.format( 425 "Enhanced contrast of notification for %s %s (over action)" 426 + " and %s (over background) by changing #%s to %s", 427 context.getPackageName(), 428 NotificationColorUtil.contrastChange(resolvedColor, color, actionBg), 429 NotificationColorUtil.contrastChange(resolvedColor, color, backgroundColor), 430 Integer.toHexString(resolvedColor), Integer.toHexString(color))); 431 } 432 } 433 return color; 434 } 435 436 /** 437 * Change a color by a specified value 438 * @param baseColor the base color to lighten 439 * @param amount the amount to lighten the color from 0 to 100. This corresponds to the L 440 * increase in the LAB color space. A negative value will darken the color and 441 * a positive will lighten it. 442 * @return the changed color 443 */ 444 public static int changeColorLightness(int baseColor, int amount) { 445 final double[] result = ColorUtilsFromCompat.getTempDouble3Array(); 446 ColorUtilsFromCompat.colorToLAB(baseColor, result); 447 result[0] = Math.max(Math.min(100, result[0] + amount), 0); 448 return ColorUtilsFromCompat.LABToColor(result[0], result[1], result[2]); 449 } 450 451 public static int resolveAmbientColor(Context context, int notificationColor) { 452 final int resolvedColor = resolveColor(context, notificationColor); 453 454 int color = resolvedColor; 455 color = NotificationColorUtil.ensureTextContrastOnBlack(color); 456 457 if (color != resolvedColor) { 458 if (DEBUG){ 459 Log.w(TAG, String.format( 460 "Ambient contrast of notification for %s is %s (over black)" 461 + " by changing #%s to #%s", 462 context.getPackageName(), 463 NotificationColorUtil.contrastChange(resolvedColor, color, Color.BLACK), 464 Integer.toHexString(resolvedColor), Integer.toHexString(color))); 465 } 466 } 467 return color; 468 } 469 470 public static int resolvePrimaryColor(Context context, int backgroundColor) { 471 boolean useDark = shouldUseDark(backgroundColor); 472 if (useDark) { 473 return context.getColor( 474 com.android.internal.R.color.notification_primary_text_color_light); 475 } else { 476 return context.getColor( 477 com.android.internal.R.color.notification_primary_text_color_dark); 478 } 479 } 480 481 public static int resolveSecondaryColor(Context context, int backgroundColor) { 482 boolean useDark = shouldUseDark(backgroundColor); 483 if (useDark) { 484 return context.getColor( 485 com.android.internal.R.color.notification_secondary_text_color_light); 486 } else { 487 return context.getColor( 488 com.android.internal.R.color.notification_secondary_text_color_dark); 489 } 490 } 491 492 public static int resolveActionBarColor(Context context, int backgroundColor) { 493 if (backgroundColor == Notification.COLOR_DEFAULT) { 494 return context.getColor(com.android.internal.R.color.notification_action_list); 495 } 496 return getShiftedColor(backgroundColor, 7); 497 } 498 499 /** 500 * Get a color that stays in the same tint, but darkens or lightens it by a certain 501 * amount. 502 * This also looks at the lightness of the provided color and shifts it appropriately. 503 * 504 * @param color the base color to use 505 * @param amount the amount from 1 to 100 how much to modify the color 506 * @return the now color that was modified 507 */ 508 public static int getShiftedColor(int color, int amount) { 509 final double[] result = ColorUtilsFromCompat.getTempDouble3Array(); 510 ColorUtilsFromCompat.colorToLAB(color, result); 511 if (result[0] >= 4) { 512 result[0] = Math.max(0, result[0] - amount); 513 } else { 514 result[0] = Math.min(100, result[0] + amount); 515 } 516 return ColorUtilsFromCompat.LABToColor(result[0], result[1], result[2]); 517 } 518 519 private static boolean shouldUseDark(int backgroundColor) { 520 boolean useDark = backgroundColor == Notification.COLOR_DEFAULT; 521 if (!useDark) { 522 useDark = ColorUtilsFromCompat.calculateLuminance(backgroundColor) > 0.5; 523 } 524 return useDark; 525 } 526 527 public static double calculateLuminance(int backgroundColor) { 528 return ColorUtilsFromCompat.calculateLuminance(backgroundColor); 529 } 530 531 532 public static double calculateContrast(int foregroundColor, int backgroundColor) { 533 return ColorUtilsFromCompat.calculateContrast(foregroundColor, backgroundColor); 534 } 535 536 /** 537 * Composite two potentially translucent colors over each other and returns the result. 538 */ 539 public static int compositeColors(int foreground, int background) { 540 return ColorUtilsFromCompat.compositeColors(foreground, background); 541 } 542 543 /** 544 * Framework copy of functions needed from android.support.v4.graphics.ColorUtils. 545 */ 546 private static class ColorUtilsFromCompat { 547 private static final double XYZ_WHITE_REFERENCE_X = 95.047; 548 private static final double XYZ_WHITE_REFERENCE_Y = 100; 549 private static final double XYZ_WHITE_REFERENCE_Z = 108.883; 550 private static final double XYZ_EPSILON = 0.008856; 551 private static final double XYZ_KAPPA = 903.3; 552 553 private static final int MIN_ALPHA_SEARCH_MAX_ITERATIONS = 10; 554 private static final int MIN_ALPHA_SEARCH_PRECISION = 1; 555 556 private static final ThreadLocal<double[]> TEMP_ARRAY = new ThreadLocal<>(); 557 558 private ColorUtilsFromCompat() {} 559 560 /** 561 * Composite two potentially translucent colors over each other and returns the result. 562 */ 563 public static int compositeColors(@ColorInt int foreground, @ColorInt int background) { 564 int bgAlpha = Color.alpha(background); 565 int fgAlpha = Color.alpha(foreground); 566 int a = compositeAlpha(fgAlpha, bgAlpha); 567 568 int r = compositeComponent(Color.red(foreground), fgAlpha, 569 Color.red(background), bgAlpha, a); 570 int g = compositeComponent(Color.green(foreground), fgAlpha, 571 Color.green(background), bgAlpha, a); 572 int b = compositeComponent(Color.blue(foreground), fgAlpha, 573 Color.blue(background), bgAlpha, a); 574 575 return Color.argb(a, r, g, b); 576 } 577 578 private static int compositeAlpha(int foregroundAlpha, int backgroundAlpha) { 579 return 0xFF - (((0xFF - backgroundAlpha) * (0xFF - foregroundAlpha)) / 0xFF); 580 } 581 582 private static int compositeComponent(int fgC, int fgA, int bgC, int bgA, int a) { 583 if (a == 0) return 0; 584 return ((0xFF * fgC * fgA) + (bgC * bgA * (0xFF - fgA))) / (a * 0xFF); 585 } 586 587 /** 588 * Returns the luminance of a color as a float between {@code 0.0} and {@code 1.0}. 589 * <p>Defined as the Y component in the XYZ representation of {@code color}.</p> 590 */ 591 @FloatRange(from = 0.0, to = 1.0) 592 public static double calculateLuminance(@ColorInt int color) { 593 final double[] result = getTempDouble3Array(); 594 colorToXYZ(color, result); 595 // Luminance is the Y component 596 return result[1] / 100; 597 } 598 599 /** 600 * Returns the contrast ratio between {@code foreground} and {@code background}. 601 * {@code background} must be opaque. 602 * <p> 603 * Formula defined 604 * <a href="http://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef">here</a>. 605 */ 606 public static double calculateContrast(@ColorInt int foreground, @ColorInt int background) { 607 if (Color.alpha(background) != 255) { 608 throw new IllegalArgumentException("background can not be translucent: #" 609 + Integer.toHexString(background)); 610 } 611 if (Color.alpha(foreground) < 255) { 612 // If the foreground is translucent, composite the foreground over the background 613 foreground = compositeColors(foreground, background); 614 } 615 616 final double luminance1 = calculateLuminance(foreground) + 0.05; 617 final double luminance2 = calculateLuminance(background) + 0.05; 618 619 // Now return the lighter luminance divided by the darker luminance 620 return Math.max(luminance1, luminance2) / Math.min(luminance1, luminance2); 621 } 622 623 /** 624 * Convert the ARGB color to its CIE Lab representative components. 625 * 626 * @param color the ARGB color to convert. The alpha component is ignored 627 * @param outLab 3-element array which holds the resulting LAB components 628 */ 629 public static void colorToLAB(@ColorInt int color, @NonNull double[] outLab) { 630 RGBToLAB(Color.red(color), Color.green(color), Color.blue(color), outLab); 631 } 632 633 /** 634 * Convert RGB components to its CIE Lab representative components. 635 * 636 * <ul> 637 * <li>outLab[0] is L [0 ...100)</li> 638 * <li>outLab[1] is a [-128...127)</li> 639 * <li>outLab[2] is b [-128...127)</li> 640 * </ul> 641 * 642 * @param r red component value [0..255] 643 * @param g green component value [0..255] 644 * @param b blue component value [0..255] 645 * @param outLab 3-element array which holds the resulting LAB components 646 */ 647 public static void RGBToLAB(@IntRange(from = 0x0, to = 0xFF) int r, 648 @IntRange(from = 0x0, to = 0xFF) int g, @IntRange(from = 0x0, to = 0xFF) int b, 649 @NonNull double[] outLab) { 650 // First we convert RGB to XYZ 651 RGBToXYZ(r, g, b, outLab); 652 // outLab now contains XYZ 653 XYZToLAB(outLab[0], outLab[1], outLab[2], outLab); 654 // outLab now contains LAB representation 655 } 656 657 /** 658 * Convert the ARGB color to it's CIE XYZ representative components. 659 * 660 * <p>The resulting XYZ representation will use the D65 illuminant and the CIE 661 * 2° Standard Observer (1931).</p> 662 * 663 * <ul> 664 * <li>outXyz[0] is X [0 ...95.047)</li> 665 * <li>outXyz[1] is Y [0...100)</li> 666 * <li>outXyz[2] is Z [0...108.883)</li> 667 * </ul> 668 * 669 * @param color the ARGB color to convert. The alpha component is ignored 670 * @param outXyz 3-element array which holds the resulting LAB components 671 */ 672 public static void colorToXYZ(@ColorInt int color, @NonNull double[] outXyz) { 673 RGBToXYZ(Color.red(color), Color.green(color), Color.blue(color), outXyz); 674 } 675 676 /** 677 * Convert RGB components to it's CIE XYZ representative components. 678 * 679 * <p>The resulting XYZ representation will use the D65 illuminant and the CIE 680 * 2° Standard Observer (1931).</p> 681 * 682 * <ul> 683 * <li>outXyz[0] is X [0 ...95.047)</li> 684 * <li>outXyz[1] is Y [0...100)</li> 685 * <li>outXyz[2] is Z [0...108.883)</li> 686 * </ul> 687 * 688 * @param r red component value [0..255] 689 * @param g green component value [0..255] 690 * @param b blue component value [0..255] 691 * @param outXyz 3-element array which holds the resulting XYZ components 692 */ 693 public static void RGBToXYZ(@IntRange(from = 0x0, to = 0xFF) int r, 694 @IntRange(from = 0x0, to = 0xFF) int g, @IntRange(from = 0x0, to = 0xFF) int b, 695 @NonNull double[] outXyz) { 696 if (outXyz.length != 3) { 697 throw new IllegalArgumentException("outXyz must have a length of 3."); 698 } 699 700 double sr = r / 255.0; 701 sr = sr < 0.04045 ? sr / 12.92 : Math.pow((sr + 0.055) / 1.055, 2.4); 702 double sg = g / 255.0; 703 sg = sg < 0.04045 ? sg / 12.92 : Math.pow((sg + 0.055) / 1.055, 2.4); 704 double sb = b / 255.0; 705 sb = sb < 0.04045 ? sb / 12.92 : Math.pow((sb + 0.055) / 1.055, 2.4); 706 707 outXyz[0] = 100 * (sr * 0.4124 + sg * 0.3576 + sb * 0.1805); 708 outXyz[1] = 100 * (sr * 0.2126 + sg * 0.7152 + sb * 0.0722); 709 outXyz[2] = 100 * (sr * 0.0193 + sg * 0.1192 + sb * 0.9505); 710 } 711 712 /** 713 * Converts a color from CIE XYZ to CIE Lab representation. 714 * 715 * <p>This method expects the XYZ representation to use the D65 illuminant and the CIE 716 * 2° Standard Observer (1931).</p> 717 * 718 * <ul> 719 * <li>outLab[0] is L [0 ...100)</li> 720 * <li>outLab[1] is a [-128...127)</li> 721 * <li>outLab[2] is b [-128...127)</li> 722 * </ul> 723 * 724 * @param x X component value [0...95.047) 725 * @param y Y component value [0...100) 726 * @param z Z component value [0...108.883) 727 * @param outLab 3-element array which holds the resulting Lab components 728 */ 729 public static void XYZToLAB(@FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_X) double x, 730 @FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_Y) double y, 731 @FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_Z) double z, 732 @NonNull double[] outLab) { 733 if (outLab.length != 3) { 734 throw new IllegalArgumentException("outLab must have a length of 3."); 735 } 736 x = pivotXyzComponent(x / XYZ_WHITE_REFERENCE_X); 737 y = pivotXyzComponent(y / XYZ_WHITE_REFERENCE_Y); 738 z = pivotXyzComponent(z / XYZ_WHITE_REFERENCE_Z); 739 outLab[0] = Math.max(0, 116 * y - 16); 740 outLab[1] = 500 * (x - y); 741 outLab[2] = 200 * (y - z); 742 } 743 744 /** 745 * Converts a color from CIE Lab to CIE XYZ representation. 746 * 747 * <p>The resulting XYZ representation will use the D65 illuminant and the CIE 748 * 2° Standard Observer (1931).</p> 749 * 750 * <ul> 751 * <li>outXyz[0] is X [0 ...95.047)</li> 752 * <li>outXyz[1] is Y [0...100)</li> 753 * <li>outXyz[2] is Z [0...108.883)</li> 754 * </ul> 755 * 756 * @param l L component value [0...100) 757 * @param a A component value [-128...127) 758 * @param b B component value [-128...127) 759 * @param outXyz 3-element array which holds the resulting XYZ components 760 */ 761 public static void LABToXYZ(@FloatRange(from = 0f, to = 100) final double l, 762 @FloatRange(from = -128, to = 127) final double a, 763 @FloatRange(from = -128, to = 127) final double b, 764 @NonNull double[] outXyz) { 765 final double fy = (l + 16) / 116; 766 final double fx = a / 500 + fy; 767 final double fz = fy - b / 200; 768 769 double tmp = Math.pow(fx, 3); 770 final double xr = tmp > XYZ_EPSILON ? tmp : (116 * fx - 16) / XYZ_KAPPA; 771 final double yr = l > XYZ_KAPPA * XYZ_EPSILON ? Math.pow(fy, 3) : l / XYZ_KAPPA; 772 773 tmp = Math.pow(fz, 3); 774 final double zr = tmp > XYZ_EPSILON ? tmp : (116 * fz - 16) / XYZ_KAPPA; 775 776 outXyz[0] = xr * XYZ_WHITE_REFERENCE_X; 777 outXyz[1] = yr * XYZ_WHITE_REFERENCE_Y; 778 outXyz[2] = zr * XYZ_WHITE_REFERENCE_Z; 779 } 780 781 /** 782 * Converts a color from CIE XYZ to its RGB representation. 783 * 784 * <p>This method expects the XYZ representation to use the D65 illuminant and the CIE 785 * 2° Standard Observer (1931).</p> 786 * 787 * @param x X component value [0...95.047) 788 * @param y Y component value [0...100) 789 * @param z Z component value [0...108.883) 790 * @return int containing the RGB representation 791 */ 792 @ColorInt 793 public static int XYZToColor(@FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_X) double x, 794 @FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_Y) double y, 795 @FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_Z) double z) { 796 double r = (x * 3.2406 + y * -1.5372 + z * -0.4986) / 100; 797 double g = (x * -0.9689 + y * 1.8758 + z * 0.0415) / 100; 798 double b = (x * 0.0557 + y * -0.2040 + z * 1.0570) / 100; 799 800 r = r > 0.0031308 ? 1.055 * Math.pow(r, 1 / 2.4) - 0.055 : 12.92 * r; 801 g = g > 0.0031308 ? 1.055 * Math.pow(g, 1 / 2.4) - 0.055 : 12.92 * g; 802 b = b > 0.0031308 ? 1.055 * Math.pow(b, 1 / 2.4) - 0.055 : 12.92 * b; 803 804 return Color.rgb( 805 constrain((int) Math.round(r * 255), 0, 255), 806 constrain((int) Math.round(g * 255), 0, 255), 807 constrain((int) Math.round(b * 255), 0, 255)); 808 } 809 810 /** 811 * Converts a color from CIE Lab to its RGB representation. 812 * 813 * @param l L component value [0...100] 814 * @param a A component value [-128...127] 815 * @param b B component value [-128...127] 816 * @return int containing the RGB representation 817 */ 818 @ColorInt 819 public static int LABToColor(@FloatRange(from = 0f, to = 100) final double l, 820 @FloatRange(from = -128, to = 127) final double a, 821 @FloatRange(from = -128, to = 127) final double b) { 822 final double[] result = getTempDouble3Array(); 823 LABToXYZ(l, a, b, result); 824 return XYZToColor(result[0], result[1], result[2]); 825 } 826 827 private static int constrain(int amount, int low, int high) { 828 return amount < low ? low : (amount > high ? high : amount); 829 } 830 831 private static float constrain(float amount, float low, float high) { 832 return amount < low ? low : (amount > high ? high : amount); 833 } 834 835 private static double pivotXyzComponent(double component) { 836 return component > XYZ_EPSILON 837 ? Math.pow(component, 1 / 3.0) 838 : (XYZ_KAPPA * component + 16) / 116; 839 } 840 841 public static double[] getTempDouble3Array() { 842 double[] result = TEMP_ARRAY.get(); 843 if (result == null) { 844 result = new double[3]; 845 TEMP_ARRAY.set(result); 846 } 847 return result; 848 } 849 850 /** 851 * Convert HSL (hue-saturation-lightness) components to a RGB color. 852 * <ul> 853 * <li>hsl[0] is Hue [0 .. 360)</li> 854 * <li>hsl[1] is Saturation [0...1]</li> 855 * <li>hsl[2] is Lightness [0...1]</li> 856 * </ul> 857 * If hsv values are out of range, they are pinned. 858 * 859 * @param hsl 3-element array which holds the input HSL components 860 * @return the resulting RGB color 861 */ 862 @ColorInt 863 public static int HSLToColor(@NonNull float[] hsl) { 864 final float h = hsl[0]; 865 final float s = hsl[1]; 866 final float l = hsl[2]; 867 868 final float c = (1f - Math.abs(2 * l - 1f)) * s; 869 final float m = l - 0.5f * c; 870 final float x = c * (1f - Math.abs((h / 60f % 2f) - 1f)); 871 872 final int hueSegment = (int) h / 60; 873 874 int r = 0, g = 0, b = 0; 875 876 switch (hueSegment) { 877 case 0: 878 r = Math.round(255 * (c + m)); 879 g = Math.round(255 * (x + m)); 880 b = Math.round(255 * m); 881 break; 882 case 1: 883 r = Math.round(255 * (x + m)); 884 g = Math.round(255 * (c + m)); 885 b = Math.round(255 * m); 886 break; 887 case 2: 888 r = Math.round(255 * m); 889 g = Math.round(255 * (c + m)); 890 b = Math.round(255 * (x + m)); 891 break; 892 case 3: 893 r = Math.round(255 * m); 894 g = Math.round(255 * (x + m)); 895 b = Math.round(255 * (c + m)); 896 break; 897 case 4: 898 r = Math.round(255 * (x + m)); 899 g = Math.round(255 * m); 900 b = Math.round(255 * (c + m)); 901 break; 902 case 5: 903 case 6: 904 r = Math.round(255 * (c + m)); 905 g = Math.round(255 * m); 906 b = Math.round(255 * (x + m)); 907 break; 908 } 909 910 r = constrain(r, 0, 255); 911 g = constrain(g, 0, 255); 912 b = constrain(b, 0, 255); 913 914 return Color.rgb(r, g, b); 915 } 916 917 /** 918 * Convert the ARGB color to its HSL (hue-saturation-lightness) components. 919 * <ul> 920 * <li>outHsl[0] is Hue [0 .. 360)</li> 921 * <li>outHsl[1] is Saturation [0...1]</li> 922 * <li>outHsl[2] is Lightness [0...1]</li> 923 * </ul> 924 * 925 * @param color the ARGB color to convert. The alpha component is ignored 926 * @param outHsl 3-element array which holds the resulting HSL components 927 */ 928 public static void colorToHSL(@ColorInt int color, @NonNull float[] outHsl) { 929 RGBToHSL(Color.red(color), Color.green(color), Color.blue(color), outHsl); 930 } 931 932 /** 933 * Convert RGB components to HSL (hue-saturation-lightness). 934 * <ul> 935 * <li>outHsl[0] is Hue [0 .. 360)</li> 936 * <li>outHsl[1] is Saturation [0...1]</li> 937 * <li>outHsl[2] is Lightness [0...1]</li> 938 * </ul> 939 * 940 * @param r red component value [0..255] 941 * @param g green component value [0..255] 942 * @param b blue component value [0..255] 943 * @param outHsl 3-element array which holds the resulting HSL components 944 */ 945 public static void RGBToHSL(@IntRange(from = 0x0, to = 0xFF) int r, 946 @IntRange(from = 0x0, to = 0xFF) int g, @IntRange(from = 0x0, to = 0xFF) int b, 947 @NonNull float[] outHsl) { 948 final float rf = r / 255f; 949 final float gf = g / 255f; 950 final float bf = b / 255f; 951 952 final float max = Math.max(rf, Math.max(gf, bf)); 953 final float min = Math.min(rf, Math.min(gf, bf)); 954 final float deltaMaxMin = max - min; 955 956 float h, s; 957 float l = (max + min) / 2f; 958 959 if (max == min) { 960 // Monochromatic 961 h = s = 0f; 962 } else { 963 if (max == rf) { 964 h = ((gf - bf) / deltaMaxMin) % 6f; 965 } else if (max == gf) { 966 h = ((bf - rf) / deltaMaxMin) + 2f; 967 } else { 968 h = ((rf - gf) / deltaMaxMin) + 4f; 969 } 970 971 s = deltaMaxMin / (1f - Math.abs(2f * l - 1f)); 972 } 973 974 h = (h * 60f) % 360f; 975 if (h < 0) { 976 h += 360f; 977 } 978 979 outHsl[0] = constrain(h, 0f, 360f); 980 outHsl[1] = constrain(s, 0f, 1f); 981 outHsl[2] = constrain(l, 0f, 1f); 982 } 983 984 } 985} 986