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.BackgroundColorSpan; 37import android.text.style.CharacterStyle; 38import android.text.style.ForegroundColorSpan; 39import android.text.style.TextAppearanceSpan; 40import android.util.Log; 41import android.util.Pair; 42 43import java.util.Arrays; 44import java.util.WeakHashMap; 45 46/** 47 * Helper class to process legacy (Holo) notifications to make them look like material notifications. 48 * 49 * @hide 50 */ 51public class NotificationColorUtil { 52 53 private static final String TAG = "NotificationColorUtil"; 54 private static final boolean DEBUG = false; 55 56 private static final Object sLock = new Object(); 57 private static NotificationColorUtil sInstance; 58 59 private final ImageUtils mImageUtils = new ImageUtils(); 60 private final WeakHashMap<Bitmap, Pair<Boolean, Integer>> mGrayscaleBitmapCache = 61 new WeakHashMap<Bitmap, Pair<Boolean, Integer>>(); 62 63 private final int mGrayscaleIconMaxSize; // @dimen/notification_large_icon_width (64dp) 64 65 public static NotificationColorUtil getInstance(Context context) { 66 synchronized (sLock) { 67 if (sInstance == null) { 68 sInstance = new NotificationColorUtil(context); 69 } 70 return sInstance; 71 } 72 } 73 74 private NotificationColorUtil(Context context) { 75 mGrayscaleIconMaxSize = context.getResources().getDimensionPixelSize( 76 com.android.internal.R.dimen.notification_large_icon_width); 77 } 78 79 /** 80 * Checks whether a Bitmap is a small grayscale icon. 81 * Grayscale here means "very close to a perfect gray"; icon means "no larger than 64dp". 82 * 83 * @param bitmap The bitmap to test. 84 * @return True if the bitmap is grayscale; false if it is color or too large to examine. 85 */ 86 public boolean isGrayscaleIcon(Bitmap bitmap) { 87 // quick test: reject large bitmaps 88 if (bitmap.getWidth() > mGrayscaleIconMaxSize 89 || bitmap.getHeight() > mGrayscaleIconMaxSize) { 90 return false; 91 } 92 93 synchronized (sLock) { 94 Pair<Boolean, Integer> cached = mGrayscaleBitmapCache.get(bitmap); 95 if (cached != null) { 96 if (cached.second == bitmap.getGenerationId()) { 97 return cached.first; 98 } 99 } 100 } 101 boolean result; 102 int generationId; 103 synchronized (mImageUtils) { 104 result = mImageUtils.isGrayscale(bitmap); 105 106 // generationId and the check whether the Bitmap is grayscale can't be read atomically 107 // here. However, since the thread is in the process of posting the notification, we can 108 // assume that it doesn't modify the bitmap while we are checking the pixels. 109 generationId = bitmap.getGenerationId(); 110 } 111 synchronized (sLock) { 112 mGrayscaleBitmapCache.put(bitmap, Pair.create(result, generationId)); 113 } 114 return result; 115 } 116 117 /** 118 * Checks whether a Drawable is a small grayscale icon. 119 * Grayscale here means "very close to a perfect gray"; icon means "no larger than 64dp". 120 * 121 * @param d The drawable to test. 122 * @return True if the bitmap is grayscale; false if it is color or too large to examine. 123 */ 124 public boolean isGrayscaleIcon(Drawable d) { 125 if (d == null) { 126 return false; 127 } else if (d instanceof BitmapDrawable) { 128 BitmapDrawable bd = (BitmapDrawable) d; 129 return bd.getBitmap() != null && isGrayscaleIcon(bd.getBitmap()); 130 } else if (d instanceof AnimationDrawable) { 131 AnimationDrawable ad = (AnimationDrawable) d; 132 int count = ad.getNumberOfFrames(); 133 return count > 0 && isGrayscaleIcon(ad.getFrame(0)); 134 } else if (d instanceof VectorDrawable) { 135 // We just assume you're doing the right thing if using vectors 136 return true; 137 } else { 138 return false; 139 } 140 } 141 142 public boolean isGrayscaleIcon(Context context, Icon icon) { 143 if (icon == null) { 144 return false; 145 } 146 switch (icon.getType()) { 147 case Icon.TYPE_BITMAP: 148 return isGrayscaleIcon(icon.getBitmap()); 149 case Icon.TYPE_RESOURCE: 150 return isGrayscaleIcon(context, icon.getResId()); 151 default: 152 return false; 153 } 154 } 155 156 /** 157 * Checks whether a drawable with a resoure id is a small grayscale icon. 158 * Grayscale here means "very close to a perfect gray"; icon means "no larger than 64dp". 159 * 160 * @param context The context to load the drawable from. 161 * @return True if the bitmap is grayscale; false if it is color or too large to examine. 162 */ 163 public boolean isGrayscaleIcon(Context context, int drawableResId) { 164 if (drawableResId != 0) { 165 try { 166 return isGrayscaleIcon(context.getDrawable(drawableResId)); 167 } catch (Resources.NotFoundException ex) { 168 Log.e(TAG, "Drawable not found: " + drawableResId); 169 return false; 170 } 171 } else { 172 return false; 173 } 174 } 175 176 /** 177 * Inverts all the grayscale colors set by {@link android.text.style.TextAppearanceSpan}s on 178 * the text. 179 * 180 * @param charSequence The text to process. 181 * @return The color inverted text. 182 */ 183 public CharSequence invertCharSequenceColors(CharSequence charSequence) { 184 if (charSequence instanceof Spanned) { 185 Spanned ss = (Spanned) charSequence; 186 Object[] spans = ss.getSpans(0, ss.length(), Object.class); 187 SpannableStringBuilder builder = new SpannableStringBuilder(ss.toString()); 188 for (Object span : spans) { 189 Object resultSpan = span; 190 if (resultSpan instanceof CharacterStyle) { 191 resultSpan = ((CharacterStyle) span).getUnderlying(); 192 } 193 if (resultSpan instanceof TextAppearanceSpan) { 194 TextAppearanceSpan processedSpan = processTextAppearanceSpan( 195 (TextAppearanceSpan) span); 196 if (processedSpan != resultSpan) { 197 resultSpan = processedSpan; 198 } else { 199 // we need to still take the orgininal for wrapped spans 200 resultSpan = span; 201 } 202 } else if (resultSpan instanceof ForegroundColorSpan) { 203 ForegroundColorSpan originalSpan = (ForegroundColorSpan) resultSpan; 204 int foregroundColor = originalSpan.getForegroundColor(); 205 resultSpan = new ForegroundColorSpan(processColor(foregroundColor)); 206 } else { 207 resultSpan = span; 208 } 209 builder.setSpan(resultSpan, ss.getSpanStart(span), ss.getSpanEnd(span), 210 ss.getSpanFlags(span)); 211 } 212 return builder; 213 } 214 return charSequence; 215 } 216 217 private TextAppearanceSpan processTextAppearanceSpan(TextAppearanceSpan span) { 218 ColorStateList colorStateList = span.getTextColor(); 219 if (colorStateList != null) { 220 int[] colors = colorStateList.getColors(); 221 boolean changed = false; 222 for (int i = 0; i < colors.length; i++) { 223 if (ImageUtils.isGrayscale(colors[i])) { 224 225 // Allocate a new array so we don't change the colors in the old color state 226 // list. 227 if (!changed) { 228 colors = Arrays.copyOf(colors, colors.length); 229 } 230 colors[i] = processColor(colors[i]); 231 changed = true; 232 } 233 } 234 if (changed) { 235 return new TextAppearanceSpan( 236 span.getFamily(), span.getTextStyle(), span.getTextSize(), 237 new ColorStateList(colorStateList.getStates(), colors), 238 span.getLinkTextColor()); 239 } 240 } 241 return span; 242 } 243 244 /** 245 * Clears all color spans of a text 246 * @param charSequence the input text 247 * @return the same text but without color spans 248 */ 249 public static CharSequence clearColorSpans(CharSequence charSequence) { 250 if (charSequence instanceof Spanned) { 251 Spanned ss = (Spanned) charSequence; 252 Object[] spans = ss.getSpans(0, ss.length(), Object.class); 253 SpannableStringBuilder builder = new SpannableStringBuilder(ss.toString()); 254 for (Object span : spans) { 255 Object resultSpan = span; 256 if (resultSpan instanceof CharacterStyle) { 257 resultSpan = ((CharacterStyle) span).getUnderlying(); 258 } 259 if (resultSpan instanceof TextAppearanceSpan) { 260 TextAppearanceSpan originalSpan = (TextAppearanceSpan) resultSpan; 261 if (originalSpan.getTextColor() != null) { 262 resultSpan = new TextAppearanceSpan( 263 originalSpan.getFamily(), 264 originalSpan.getTextStyle(), 265 originalSpan.getTextSize(), 266 null, 267 originalSpan.getLinkTextColor()); 268 } 269 } else if (resultSpan instanceof ForegroundColorSpan 270 || (resultSpan instanceof BackgroundColorSpan)) { 271 continue; 272 } else { 273 resultSpan = span; 274 } 275 builder.setSpan(resultSpan, ss.getSpanStart(span), ss.getSpanEnd(span), 276 ss.getSpanFlags(span)); 277 } 278 return builder; 279 } 280 return charSequence; 281 } 282 283 private int processColor(int color) { 284 return Color.argb(Color.alpha(color), 285 255 - Color.red(color), 286 255 - Color.green(color), 287 255 - Color.blue(color)); 288 } 289 290 /** 291 * Finds a suitable color such that there's enough contrast. 292 * 293 * @param color the color to start searching from. 294 * @param other the color to ensure contrast against. Assumed to be lighter than {@param color} 295 * @param findFg if true, we assume {@param color} is a foreground, otherwise a background. 296 * @param minRatio the minimum contrast ratio required. 297 * @return a color with the same hue as {@param color}, potentially darkened to meet the 298 * contrast ratio. 299 */ 300 public static int findContrastColor(int color, int other, boolean findFg, double minRatio) { 301 int fg = findFg ? color : other; 302 int bg = findFg ? other : color; 303 if (ColorUtilsFromCompat.calculateContrast(fg, bg) >= minRatio) { 304 return color; 305 } 306 307 double[] lab = new double[3]; 308 ColorUtilsFromCompat.colorToLAB(findFg ? fg : bg, lab); 309 310 double low = 0, high = lab[0]; 311 final double a = lab[1], b = lab[2]; 312 for (int i = 0; i < 15 && high - low > 0.00001; i++) { 313 final double l = (low + high) / 2; 314 if (findFg) { 315 fg = ColorUtilsFromCompat.LABToColor(l, a, b); 316 } else { 317 bg = ColorUtilsFromCompat.LABToColor(l, a, b); 318 } 319 if (ColorUtilsFromCompat.calculateContrast(fg, bg) > minRatio) { 320 low = l; 321 } else { 322 high = l; 323 } 324 } 325 return ColorUtilsFromCompat.LABToColor(low, a, b); 326 } 327 328 /** 329 * Finds a suitable alpha such that there's enough contrast. 330 * 331 * @param color the color to start searching from. 332 * @param backgroundColor the color to ensure contrast against. 333 * @param minRatio the minimum contrast ratio required. 334 * @return the same color as {@param color} with potentially modified alpha to meet contrast 335 */ 336 public static int findAlphaToMeetContrast(int color, int backgroundColor, double minRatio) { 337 int fg = color; 338 int bg = backgroundColor; 339 if (ColorUtilsFromCompat.calculateContrast(fg, bg) >= minRatio) { 340 return color; 341 } 342 int startAlpha = Color.alpha(color); 343 int r = Color.red(color); 344 int g = Color.green(color); 345 int b = Color.blue(color); 346 347 int low = startAlpha, high = 255; 348 for (int i = 0; i < 15 && high - low > 0; i++) { 349 final int alpha = (low + high) / 2; 350 fg = Color.argb(alpha, r, g, b); 351 if (ColorUtilsFromCompat.calculateContrast(fg, bg) > minRatio) { 352 high = alpha; 353 } else { 354 low = alpha; 355 } 356 } 357 return Color.argb(high, r, g, b); 358 } 359 360 /** 361 * Finds a suitable color such that there's enough contrast. 362 * 363 * @param color the color to start searching from. 364 * @param other the color to ensure contrast against. Assumed to be darker than {@param color} 365 * @param findFg if true, we assume {@param color} is a foreground, otherwise a background. 366 * @param minRatio the minimum contrast ratio required. 367 * @return a color with the same hue as {@param color}, potentially darkened to meet the 368 * contrast ratio. 369 */ 370 public static int findContrastColorAgainstDark(int color, int other, boolean findFg, 371 double minRatio) { 372 int fg = findFg ? color : other; 373 int bg = findFg ? other : color; 374 if (ColorUtilsFromCompat.calculateContrast(fg, bg) >= minRatio) { 375 return color; 376 } 377 378 float[] hsl = new float[3]; 379 ColorUtilsFromCompat.colorToHSL(findFg ? fg : bg, hsl); 380 381 float low = hsl[2], high = 1; 382 for (int i = 0; i < 15 && high - low > 0.00001; i++) { 383 final float l = (low + high) / 2; 384 hsl[2] = l; 385 if (findFg) { 386 fg = ColorUtilsFromCompat.HSLToColor(hsl); 387 } else { 388 bg = ColorUtilsFromCompat.HSLToColor(hsl); 389 } 390 if (ColorUtilsFromCompat.calculateContrast(fg, bg) > minRatio) { 391 high = l; 392 } else { 393 low = l; 394 } 395 } 396 return findFg ? fg : bg; 397 } 398 399 public static int ensureTextContrastOnBlack(int color) { 400 return findContrastColorAgainstDark(color, Color.BLACK, true /* fg */, 12); 401 } 402 403 /** 404 * Finds a large text color with sufficient contrast over bg that has the same or darker hue as 405 * the original color, depending on the value of {@code isBgDarker}. 406 * 407 * @param isBgDarker {@code true} if {@code bg} is darker than {@code color}. 408 */ 409 public static int ensureLargeTextContrast(int color, int bg, boolean isBgDarker) { 410 return isBgDarker 411 ? findContrastColorAgainstDark(color, bg, true, 3) 412 : findContrastColor(color, bg, true, 3); 413 } 414 415 /** 416 * Finds a text color with sufficient contrast over bg that has the same or darker hue as the 417 * original color, depending on the value of {@code isBgDarker}. 418 * 419 * @param isBgDarker {@code true} if {@code bg} is darker than {@code color}. 420 */ 421 public static int ensureTextContrast(int color, int bg, boolean isBgDarker) { 422 return ensureContrast(color, bg, isBgDarker, 4.5); 423 } 424 425 /** 426 * Finds a color with sufficient contrast over bg that has the same or darker hue as the 427 * original color, depending on the value of {@code isBgDarker}. 428 * 429 * @param color the color to start searching from 430 * @param bg the color to ensure contrast against 431 * @param isBgDarker {@code true} if {@code bg} is darker than {@code color} 432 * @param minRatio the minimum contrast ratio required 433 */ 434 public static int ensureContrast(int color, int bg, boolean isBgDarker, double minRatio) { 435 return isBgDarker 436 ? findContrastColorAgainstDark(color, bg, true, minRatio) 437 : findContrastColor(color, bg, true, minRatio); 438 } 439 440 /** Finds a background color for a text view with given text color and hint text color, that 441 * has the same hue as the original color. 442 */ 443 public static int ensureTextBackgroundColor(int color, int textColor, int hintColor) { 444 color = findContrastColor(color, hintColor, false, 3.0); 445 return findContrastColor(color, textColor, false, 4.5); 446 } 447 448 private static String contrastChange(int colorOld, int colorNew, int bg) { 449 return String.format("from %.2f:1 to %.2f:1", 450 ColorUtilsFromCompat.calculateContrast(colorOld, bg), 451 ColorUtilsFromCompat.calculateContrast(colorNew, bg)); 452 } 453 454 /** 455 * Resolves {@param color} to an actual color if it is {@link Notification#COLOR_DEFAULT} 456 */ 457 public static int resolveColor(Context context, int color) { 458 if (color == Notification.COLOR_DEFAULT) { 459 return context.getColor(com.android.internal.R.color.notification_default_color_light); 460 } 461 return color; 462 } 463 464 /** 465 * Resolves a Notification's color such that it has enough contrast to be used as the 466 * color for the Notification's action and header text on a background that is lighter than 467 * {@code notificationColor}. 468 * 469 * @see {@link #resolveContrastColor(Context, int, boolean)} 470 */ 471 public static int resolveContrastColor(Context context, int notificationColor, 472 int backgroundColor) { 473 return NotificationColorUtil.resolveContrastColor(context, notificationColor, 474 backgroundColor, false /* isDark */); 475 } 476 477 /** 478 * Resolves a Notification's color such that it has enough contrast to be used as the 479 * color for the Notification's action and header text. 480 * 481 * @param notificationColor the color of the notification or {@link Notification#COLOR_DEFAULT} 482 * @param backgroundColor the background color to ensure the contrast against. 483 * @param isDark whether or not the {@code notificationColor} will be placed on a background 484 * that is darker than the color itself 485 * @return a color of the same hue with enough contrast against the backgrounds. 486 */ 487 public static int resolveContrastColor(Context context, int notificationColor, 488 int backgroundColor, boolean isDark) { 489 final int resolvedColor = resolveColor(context, notificationColor); 490 491 int color = resolvedColor; 492 color = NotificationColorUtil.ensureTextContrast(color, backgroundColor, isDark); 493 494 if (color != resolvedColor) { 495 if (DEBUG){ 496 Log.w(TAG, String.format( 497 "Enhanced contrast of notification for %s" 498 + " and %s (over background) by changing #%s to %s", 499 context.getPackageName(), 500 NotificationColorUtil.contrastChange(resolvedColor, color, backgroundColor), 501 Integer.toHexString(resolvedColor), Integer.toHexString(color))); 502 } 503 } 504 return color; 505 } 506 507 /** 508 * Change a color by a specified value 509 * @param baseColor the base color to lighten 510 * @param amount the amount to lighten the color from 0 to 100. This corresponds to the L 511 * increase in the LAB color space. A negative value will darken the color and 512 * a positive will lighten it. 513 * @return the changed color 514 */ 515 public static int changeColorLightness(int baseColor, int amount) { 516 final double[] result = ColorUtilsFromCompat.getTempDouble3Array(); 517 ColorUtilsFromCompat.colorToLAB(baseColor, result); 518 result[0] = Math.max(Math.min(100, result[0] + amount), 0); 519 return ColorUtilsFromCompat.LABToColor(result[0], result[1], result[2]); 520 } 521 522 public static int resolveAmbientColor(Context context, int notificationColor) { 523 final int resolvedColor = resolveColor(context, notificationColor); 524 525 int color = resolvedColor; 526 color = NotificationColorUtil.ensureTextContrastOnBlack(color); 527 528 if (color != resolvedColor) { 529 if (DEBUG){ 530 Log.w(TAG, String.format( 531 "Ambient contrast of notification for %s is %s (over black)" 532 + " by changing #%s to #%s", 533 context.getPackageName(), 534 NotificationColorUtil.contrastChange(resolvedColor, color, Color.BLACK), 535 Integer.toHexString(resolvedColor), Integer.toHexString(color))); 536 } 537 } 538 return color; 539 } 540 541 public static int resolvePrimaryColor(Context context, int backgroundColor) { 542 boolean useDark = shouldUseDark(backgroundColor); 543 if (useDark) { 544 return context.getColor( 545 com.android.internal.R.color.notification_primary_text_color_light); 546 } else { 547 return context.getColor( 548 com.android.internal.R.color.notification_primary_text_color_dark); 549 } 550 } 551 552 public static int resolveSecondaryColor(Context context, int backgroundColor) { 553 boolean useDark = shouldUseDark(backgroundColor); 554 if (useDark) { 555 return context.getColor( 556 com.android.internal.R.color.notification_secondary_text_color_light); 557 } else { 558 return context.getColor( 559 com.android.internal.R.color.notification_secondary_text_color_dark); 560 } 561 } 562 563 public static int resolveDefaultColor(Context context, int backgroundColor) { 564 boolean useDark = shouldUseDark(backgroundColor); 565 if (useDark) { 566 return context.getColor( 567 com.android.internal.R.color.notification_default_color_light); 568 } else { 569 return context.getColor( 570 com.android.internal.R.color.notification_default_color_dark); 571 } 572 } 573 574 /** 575 * Get a color that stays in the same tint, but darkens or lightens it by a certain 576 * amount. 577 * This also looks at the lightness of the provided color and shifts it appropriately. 578 * 579 * @param color the base color to use 580 * @param amount the amount from 1 to 100 how much to modify the color 581 * @return the now color that was modified 582 */ 583 public static int getShiftedColor(int color, int amount) { 584 final double[] result = ColorUtilsFromCompat.getTempDouble3Array(); 585 ColorUtilsFromCompat.colorToLAB(color, result); 586 if (result[0] >= 4) { 587 result[0] = Math.max(0, result[0] - amount); 588 } else { 589 result[0] = Math.min(100, result[0] + amount); 590 } 591 return ColorUtilsFromCompat.LABToColor(result[0], result[1], result[2]); 592 } 593 594 private static boolean shouldUseDark(int backgroundColor) { 595 boolean useDark = backgroundColor == Notification.COLOR_DEFAULT; 596 if (!useDark) { 597 useDark = ColorUtilsFromCompat.calculateLuminance(backgroundColor) > 0.5; 598 } 599 return useDark; 600 } 601 602 public static double calculateLuminance(int backgroundColor) { 603 return ColorUtilsFromCompat.calculateLuminance(backgroundColor); 604 } 605 606 607 public static double calculateContrast(int foregroundColor, int backgroundColor) { 608 return ColorUtilsFromCompat.calculateContrast(foregroundColor, backgroundColor); 609 } 610 611 public static boolean satisfiesTextContrast(int backgroundColor, int foregroundColor) { 612 return NotificationColorUtil.calculateContrast(foregroundColor, backgroundColor) >= 4.5; 613 } 614 615 /** 616 * Composite two potentially translucent colors over each other and returns the result. 617 */ 618 public static int compositeColors(int foreground, int background) { 619 return ColorUtilsFromCompat.compositeColors(foreground, background); 620 } 621 622 public static boolean isColorLight(int backgroundColor) { 623 return calculateLuminance(backgroundColor) > 0.5f; 624 } 625 626 /** 627 * Framework copy of functions needed from android.support.v4.graphics.ColorUtils. 628 */ 629 private static class ColorUtilsFromCompat { 630 private static final double XYZ_WHITE_REFERENCE_X = 95.047; 631 private static final double XYZ_WHITE_REFERENCE_Y = 100; 632 private static final double XYZ_WHITE_REFERENCE_Z = 108.883; 633 private static final double XYZ_EPSILON = 0.008856; 634 private static final double XYZ_KAPPA = 903.3; 635 636 private static final int MIN_ALPHA_SEARCH_MAX_ITERATIONS = 10; 637 private static final int MIN_ALPHA_SEARCH_PRECISION = 1; 638 639 private static final ThreadLocal<double[]> TEMP_ARRAY = new ThreadLocal<>(); 640 641 private ColorUtilsFromCompat() {} 642 643 /** 644 * Composite two potentially translucent colors over each other and returns the result. 645 */ 646 public static int compositeColors(@ColorInt int foreground, @ColorInt int background) { 647 int bgAlpha = Color.alpha(background); 648 int fgAlpha = Color.alpha(foreground); 649 int a = compositeAlpha(fgAlpha, bgAlpha); 650 651 int r = compositeComponent(Color.red(foreground), fgAlpha, 652 Color.red(background), bgAlpha, a); 653 int g = compositeComponent(Color.green(foreground), fgAlpha, 654 Color.green(background), bgAlpha, a); 655 int b = compositeComponent(Color.blue(foreground), fgAlpha, 656 Color.blue(background), bgAlpha, a); 657 658 return Color.argb(a, r, g, b); 659 } 660 661 private static int compositeAlpha(int foregroundAlpha, int backgroundAlpha) { 662 return 0xFF - (((0xFF - backgroundAlpha) * (0xFF - foregroundAlpha)) / 0xFF); 663 } 664 665 private static int compositeComponent(int fgC, int fgA, int bgC, int bgA, int a) { 666 if (a == 0) return 0; 667 return ((0xFF * fgC * fgA) + (bgC * bgA * (0xFF - fgA))) / (a * 0xFF); 668 } 669 670 /** 671 * Returns the luminance of a color as a float between {@code 0.0} and {@code 1.0}. 672 * <p>Defined as the Y component in the XYZ representation of {@code color}.</p> 673 */ 674 @FloatRange(from = 0.0, to = 1.0) 675 public static double calculateLuminance(@ColorInt int color) { 676 final double[] result = getTempDouble3Array(); 677 colorToXYZ(color, result); 678 // Luminance is the Y component 679 return result[1] / 100; 680 } 681 682 /** 683 * Returns the contrast ratio between {@code foreground} and {@code background}. 684 * {@code background} must be opaque. 685 * <p> 686 * Formula defined 687 * <a href="http://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef">here</a>. 688 */ 689 public static double calculateContrast(@ColorInt int foreground, @ColorInt int background) { 690 if (Color.alpha(background) != 255) { 691 Log.wtf(TAG, "background can not be translucent: #" 692 + Integer.toHexString(background)); 693 } 694 if (Color.alpha(foreground) < 255) { 695 // If the foreground is translucent, composite the foreground over the background 696 foreground = compositeColors(foreground, background); 697 } 698 699 final double luminance1 = calculateLuminance(foreground) + 0.05; 700 final double luminance2 = calculateLuminance(background) + 0.05; 701 702 // Now return the lighter luminance divided by the darker luminance 703 return Math.max(luminance1, luminance2) / Math.min(luminance1, luminance2); 704 } 705 706 /** 707 * Convert the ARGB color to its CIE Lab representative components. 708 * 709 * @param color the ARGB color to convert. The alpha component is ignored 710 * @param outLab 3-element array which holds the resulting LAB components 711 */ 712 public static void colorToLAB(@ColorInt int color, @NonNull double[] outLab) { 713 RGBToLAB(Color.red(color), Color.green(color), Color.blue(color), outLab); 714 } 715 716 /** 717 * Convert RGB components to its CIE Lab representative components. 718 * 719 * <ul> 720 * <li>outLab[0] is L [0 ...100)</li> 721 * <li>outLab[1] is a [-128...127)</li> 722 * <li>outLab[2] is b [-128...127)</li> 723 * </ul> 724 * 725 * @param r red component value [0..255] 726 * @param g green component value [0..255] 727 * @param b blue component value [0..255] 728 * @param outLab 3-element array which holds the resulting LAB components 729 */ 730 public static void RGBToLAB(@IntRange(from = 0x0, to = 0xFF) int r, 731 @IntRange(from = 0x0, to = 0xFF) int g, @IntRange(from = 0x0, to = 0xFF) int b, 732 @NonNull double[] outLab) { 733 // First we convert RGB to XYZ 734 RGBToXYZ(r, g, b, outLab); 735 // outLab now contains XYZ 736 XYZToLAB(outLab[0], outLab[1], outLab[2], outLab); 737 // outLab now contains LAB representation 738 } 739 740 /** 741 * Convert the ARGB color to it's CIE XYZ representative components. 742 * 743 * <p>The resulting XYZ representation will use the D65 illuminant and the CIE 744 * 2° Standard Observer (1931).</p> 745 * 746 * <ul> 747 * <li>outXyz[0] is X [0 ...95.047)</li> 748 * <li>outXyz[1] is Y [0...100)</li> 749 * <li>outXyz[2] is Z [0...108.883)</li> 750 * </ul> 751 * 752 * @param color the ARGB color to convert. The alpha component is ignored 753 * @param outXyz 3-element array which holds the resulting LAB components 754 */ 755 public static void colorToXYZ(@ColorInt int color, @NonNull double[] outXyz) { 756 RGBToXYZ(Color.red(color), Color.green(color), Color.blue(color), outXyz); 757 } 758 759 /** 760 * Convert RGB components to it's CIE XYZ representative components. 761 * 762 * <p>The resulting XYZ representation will use the D65 illuminant and the CIE 763 * 2° Standard Observer (1931).</p> 764 * 765 * <ul> 766 * <li>outXyz[0] is X [0 ...95.047)</li> 767 * <li>outXyz[1] is Y [0...100)</li> 768 * <li>outXyz[2] is Z [0...108.883)</li> 769 * </ul> 770 * 771 * @param r red component value [0..255] 772 * @param g green component value [0..255] 773 * @param b blue component value [0..255] 774 * @param outXyz 3-element array which holds the resulting XYZ components 775 */ 776 public static void RGBToXYZ(@IntRange(from = 0x0, to = 0xFF) int r, 777 @IntRange(from = 0x0, to = 0xFF) int g, @IntRange(from = 0x0, to = 0xFF) int b, 778 @NonNull double[] outXyz) { 779 if (outXyz.length != 3) { 780 throw new IllegalArgumentException("outXyz must have a length of 3."); 781 } 782 783 double sr = r / 255.0; 784 sr = sr < 0.04045 ? sr / 12.92 : Math.pow((sr + 0.055) / 1.055, 2.4); 785 double sg = g / 255.0; 786 sg = sg < 0.04045 ? sg / 12.92 : Math.pow((sg + 0.055) / 1.055, 2.4); 787 double sb = b / 255.0; 788 sb = sb < 0.04045 ? sb / 12.92 : Math.pow((sb + 0.055) / 1.055, 2.4); 789 790 outXyz[0] = 100 * (sr * 0.4124 + sg * 0.3576 + sb * 0.1805); 791 outXyz[1] = 100 * (sr * 0.2126 + sg * 0.7152 + sb * 0.0722); 792 outXyz[2] = 100 * (sr * 0.0193 + sg * 0.1192 + sb * 0.9505); 793 } 794 795 /** 796 * Converts a color from CIE XYZ to CIE Lab representation. 797 * 798 * <p>This method expects the XYZ representation to use the D65 illuminant and the CIE 799 * 2° Standard Observer (1931).</p> 800 * 801 * <ul> 802 * <li>outLab[0] is L [0 ...100)</li> 803 * <li>outLab[1] is a [-128...127)</li> 804 * <li>outLab[2] is b [-128...127)</li> 805 * </ul> 806 * 807 * @param x X component value [0...95.047) 808 * @param y Y component value [0...100) 809 * @param z Z component value [0...108.883) 810 * @param outLab 3-element array which holds the resulting Lab components 811 */ 812 public static void XYZToLAB(@FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_X) double x, 813 @FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_Y) double y, 814 @FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_Z) double z, 815 @NonNull double[] outLab) { 816 if (outLab.length != 3) { 817 throw new IllegalArgumentException("outLab must have a length of 3."); 818 } 819 x = pivotXyzComponent(x / XYZ_WHITE_REFERENCE_X); 820 y = pivotXyzComponent(y / XYZ_WHITE_REFERENCE_Y); 821 z = pivotXyzComponent(z / XYZ_WHITE_REFERENCE_Z); 822 outLab[0] = Math.max(0, 116 * y - 16); 823 outLab[1] = 500 * (x - y); 824 outLab[2] = 200 * (y - z); 825 } 826 827 /** 828 * Converts a color from CIE Lab to CIE XYZ representation. 829 * 830 * <p>The resulting XYZ representation will use the D65 illuminant and the CIE 831 * 2° Standard Observer (1931).</p> 832 * 833 * <ul> 834 * <li>outXyz[0] is X [0 ...95.047)</li> 835 * <li>outXyz[1] is Y [0...100)</li> 836 * <li>outXyz[2] is Z [0...108.883)</li> 837 * </ul> 838 * 839 * @param l L component value [0...100) 840 * @param a A component value [-128...127) 841 * @param b B component value [-128...127) 842 * @param outXyz 3-element array which holds the resulting XYZ components 843 */ 844 public static void LABToXYZ(@FloatRange(from = 0f, to = 100) final double l, 845 @FloatRange(from = -128, to = 127) final double a, 846 @FloatRange(from = -128, to = 127) final double b, 847 @NonNull double[] outXyz) { 848 final double fy = (l + 16) / 116; 849 final double fx = a / 500 + fy; 850 final double fz = fy - b / 200; 851 852 double tmp = Math.pow(fx, 3); 853 final double xr = tmp > XYZ_EPSILON ? tmp : (116 * fx - 16) / XYZ_KAPPA; 854 final double yr = l > XYZ_KAPPA * XYZ_EPSILON ? Math.pow(fy, 3) : l / XYZ_KAPPA; 855 856 tmp = Math.pow(fz, 3); 857 final double zr = tmp > XYZ_EPSILON ? tmp : (116 * fz - 16) / XYZ_KAPPA; 858 859 outXyz[0] = xr * XYZ_WHITE_REFERENCE_X; 860 outXyz[1] = yr * XYZ_WHITE_REFERENCE_Y; 861 outXyz[2] = zr * XYZ_WHITE_REFERENCE_Z; 862 } 863 864 /** 865 * Converts a color from CIE XYZ to its RGB representation. 866 * 867 * <p>This method expects the XYZ representation to use the D65 illuminant and the CIE 868 * 2° Standard Observer (1931).</p> 869 * 870 * @param x X component value [0...95.047) 871 * @param y Y component value [0...100) 872 * @param z Z component value [0...108.883) 873 * @return int containing the RGB representation 874 */ 875 @ColorInt 876 public static int XYZToColor(@FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_X) double x, 877 @FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_Y) double y, 878 @FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_Z) double z) { 879 double r = (x * 3.2406 + y * -1.5372 + z * -0.4986) / 100; 880 double g = (x * -0.9689 + y * 1.8758 + z * 0.0415) / 100; 881 double b = (x * 0.0557 + y * -0.2040 + z * 1.0570) / 100; 882 883 r = r > 0.0031308 ? 1.055 * Math.pow(r, 1 / 2.4) - 0.055 : 12.92 * r; 884 g = g > 0.0031308 ? 1.055 * Math.pow(g, 1 / 2.4) - 0.055 : 12.92 * g; 885 b = b > 0.0031308 ? 1.055 * Math.pow(b, 1 / 2.4) - 0.055 : 12.92 * b; 886 887 return Color.rgb( 888 constrain((int) Math.round(r * 255), 0, 255), 889 constrain((int) Math.round(g * 255), 0, 255), 890 constrain((int) Math.round(b * 255), 0, 255)); 891 } 892 893 /** 894 * Converts a color from CIE Lab to its RGB representation. 895 * 896 * @param l L component value [0...100] 897 * @param a A component value [-128...127] 898 * @param b B component value [-128...127] 899 * @return int containing the RGB representation 900 */ 901 @ColorInt 902 public static int LABToColor(@FloatRange(from = 0f, to = 100) final double l, 903 @FloatRange(from = -128, to = 127) final double a, 904 @FloatRange(from = -128, to = 127) final double b) { 905 final double[] result = getTempDouble3Array(); 906 LABToXYZ(l, a, b, result); 907 return XYZToColor(result[0], result[1], result[2]); 908 } 909 910 private static int constrain(int amount, int low, int high) { 911 return amount < low ? low : (amount > high ? high : amount); 912 } 913 914 private static float constrain(float amount, float low, float high) { 915 return amount < low ? low : (amount > high ? high : amount); 916 } 917 918 private static double pivotXyzComponent(double component) { 919 return component > XYZ_EPSILON 920 ? Math.pow(component, 1 / 3.0) 921 : (XYZ_KAPPA * component + 16) / 116; 922 } 923 924 public static double[] getTempDouble3Array() { 925 double[] result = TEMP_ARRAY.get(); 926 if (result == null) { 927 result = new double[3]; 928 TEMP_ARRAY.set(result); 929 } 930 return result; 931 } 932 933 /** 934 * Convert HSL (hue-saturation-lightness) components to a RGB color. 935 * <ul> 936 * <li>hsl[0] is Hue [0 .. 360)</li> 937 * <li>hsl[1] is Saturation [0...1]</li> 938 * <li>hsl[2] is Lightness [0...1]</li> 939 * </ul> 940 * If hsv values are out of range, they are pinned. 941 * 942 * @param hsl 3-element array which holds the input HSL components 943 * @return the resulting RGB color 944 */ 945 @ColorInt 946 public static int HSLToColor(@NonNull float[] hsl) { 947 final float h = hsl[0]; 948 final float s = hsl[1]; 949 final float l = hsl[2]; 950 951 final float c = (1f - Math.abs(2 * l - 1f)) * s; 952 final float m = l - 0.5f * c; 953 final float x = c * (1f - Math.abs((h / 60f % 2f) - 1f)); 954 955 final int hueSegment = (int) h / 60; 956 957 int r = 0, g = 0, b = 0; 958 959 switch (hueSegment) { 960 case 0: 961 r = Math.round(255 * (c + m)); 962 g = Math.round(255 * (x + m)); 963 b = Math.round(255 * m); 964 break; 965 case 1: 966 r = Math.round(255 * (x + m)); 967 g = Math.round(255 * (c + m)); 968 b = Math.round(255 * m); 969 break; 970 case 2: 971 r = Math.round(255 * m); 972 g = Math.round(255 * (c + m)); 973 b = Math.round(255 * (x + m)); 974 break; 975 case 3: 976 r = Math.round(255 * m); 977 g = Math.round(255 * (x + m)); 978 b = Math.round(255 * (c + m)); 979 break; 980 case 4: 981 r = Math.round(255 * (x + m)); 982 g = Math.round(255 * m); 983 b = Math.round(255 * (c + m)); 984 break; 985 case 5: 986 case 6: 987 r = Math.round(255 * (c + m)); 988 g = Math.round(255 * m); 989 b = Math.round(255 * (x + m)); 990 break; 991 } 992 993 r = constrain(r, 0, 255); 994 g = constrain(g, 0, 255); 995 b = constrain(b, 0, 255); 996 997 return Color.rgb(r, g, b); 998 } 999 1000 /** 1001 * Convert the ARGB color to its HSL (hue-saturation-lightness) components. 1002 * <ul> 1003 * <li>outHsl[0] is Hue [0 .. 360)</li> 1004 * <li>outHsl[1] is Saturation [0...1]</li> 1005 * <li>outHsl[2] is Lightness [0...1]</li> 1006 * </ul> 1007 * 1008 * @param color the ARGB color to convert. The alpha component is ignored 1009 * @param outHsl 3-element array which holds the resulting HSL components 1010 */ 1011 public static void colorToHSL(@ColorInt int color, @NonNull float[] outHsl) { 1012 RGBToHSL(Color.red(color), Color.green(color), Color.blue(color), outHsl); 1013 } 1014 1015 /** 1016 * Convert RGB components to HSL (hue-saturation-lightness). 1017 * <ul> 1018 * <li>outHsl[0] is Hue [0 .. 360)</li> 1019 * <li>outHsl[1] is Saturation [0...1]</li> 1020 * <li>outHsl[2] is Lightness [0...1]</li> 1021 * </ul> 1022 * 1023 * @param r red component value [0..255] 1024 * @param g green component value [0..255] 1025 * @param b blue component value [0..255] 1026 * @param outHsl 3-element array which holds the resulting HSL components 1027 */ 1028 public static void RGBToHSL(@IntRange(from = 0x0, to = 0xFF) int r, 1029 @IntRange(from = 0x0, to = 0xFF) int g, @IntRange(from = 0x0, to = 0xFF) int b, 1030 @NonNull float[] outHsl) { 1031 final float rf = r / 255f; 1032 final float gf = g / 255f; 1033 final float bf = b / 255f; 1034 1035 final float max = Math.max(rf, Math.max(gf, bf)); 1036 final float min = Math.min(rf, Math.min(gf, bf)); 1037 final float deltaMaxMin = max - min; 1038 1039 float h, s; 1040 float l = (max + min) / 2f; 1041 1042 if (max == min) { 1043 // Monochromatic 1044 h = s = 0f; 1045 } else { 1046 if (max == rf) { 1047 h = ((gf - bf) / deltaMaxMin) % 6f; 1048 } else if (max == gf) { 1049 h = ((bf - rf) / deltaMaxMin) + 2f; 1050 } else { 1051 h = ((rf - gf) / deltaMaxMin) + 4f; 1052 } 1053 1054 s = deltaMaxMin / (1f - Math.abs(2f * l - 1f)); 1055 } 1056 1057 h = (h * 60f) % 360f; 1058 if (h < 0) { 1059 h += 360f; 1060 } 1061 1062 outHsl[0] = constrain(h, 0f, 360f); 1063 outHsl[1] = constrain(s, 0f, 1f); 1064 outHsl[2] = constrain(l, 0f, 1f); 1065 } 1066 1067 } 1068} 1069