| /* |
| * Copyright 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package androidx.core.graphics; |
| |
| import android.annotation.SuppressLint; |
| import android.graphics.Color; |
| |
| import androidx.annotation.ColorInt; |
| import androidx.annotation.FloatRange; |
| import androidx.annotation.IntRange; |
| import androidx.annotation.NonNull; |
| import androidx.annotation.RequiresApi; |
| import androidx.annotation.VisibleForTesting; |
| |
| import java.util.Objects; |
| |
| /** |
| * A set of color-related utility methods, building upon those available in {@code Color}. |
| */ |
| public final class ColorUtils { |
| |
| private static final double XYZ_WHITE_REFERENCE_X = 95.047; |
| private static final double XYZ_WHITE_REFERENCE_Y = 100; |
| private static final double XYZ_WHITE_REFERENCE_Z = 108.883; |
| private static final double XYZ_EPSILON = 0.008856; |
| private static final double XYZ_KAPPA = 903.3; |
| |
| private static final int MIN_ALPHA_SEARCH_MAX_ITERATIONS = 10; |
| private static final int MIN_ALPHA_SEARCH_PRECISION = 1; |
| |
| private static final ThreadLocal<double[]> TEMP_ARRAY = new ThreadLocal<>(); |
| |
| private ColorUtils() {} |
| |
| /** |
| * Composite two potentially translucent colors over each other and returns the result. |
| */ |
| public static int compositeColors(@ColorInt int foreground, @ColorInt int background) { |
| int bgAlpha = Color.alpha(background); |
| int fgAlpha = Color.alpha(foreground); |
| int a = compositeAlpha(fgAlpha, bgAlpha); |
| |
| int r = compositeComponent(Color.red(foreground), fgAlpha, |
| Color.red(background), bgAlpha, a); |
| int g = compositeComponent(Color.green(foreground), fgAlpha, |
| Color.green(background), bgAlpha, a); |
| int b = compositeComponent(Color.blue(foreground), fgAlpha, |
| Color.blue(background), bgAlpha, a); |
| |
| return Color.argb(a, r, g, b); |
| } |
| |
| /** |
| * Composites two translucent colors together. More specifically, adds two colors using |
| * the {@linkplain android.graphics.PorterDuff.Mode#SRC_OVER source over} blending mode. The |
| * colors must not be pre-multiplied and the result is a non pre-multiplied color. |
| * <p> |
| * If the two colors have different color spaces, the foreground color is converted to the |
| * color space of the background color. |
| * <p> |
| * The following example creates a purple color by blending opaque blue with |
| * semi-translucent red: |
| * |
| * <pre>{@code |
| * Color purple = ColorUtils.compositeColors( |
| * Color.valueOf(1f, 0f, 0f, 0.5f), |
| * Color.valueOf(0f, 0f, 1f)); |
| * }</pre> |
| * |
| * <em>Note:</em> This method requires API 26 or newer. |
| * |
| * @throws IllegalArgumentException if the |
| * {@linkplain android.graphics.Color#getModel models} of the colors do not match |
| */ |
| @RequiresApi(26) |
| @NonNull |
| public static Color compositeColors(@NonNull Color foreground, @NonNull Color background) { |
| if (!Objects.equals(foreground.getModel(), background.getModel())) { |
| throw new IllegalArgumentException( |
| "Color models must match (" + foreground.getModel() + " vs. " |
| + background.getModel() + ")"); |
| } |
| |
| Color s = Objects.equals(background.getColorSpace(), foreground.getColorSpace()) |
| ? foreground |
| : foreground.convert(background.getColorSpace()); |
| |
| float[] src = s.getComponents(); |
| float[] dst = background.getComponents(); |
| |
| float sa = s.alpha(); |
| // Destination alpha pre-composited |
| float da = background.alpha() * (1.0f - sa); |
| |
| // Index of the alpha component |
| @SuppressLint("Range") // TODO Remove after upgrading Android Gradle Plugin to 3.1 or newer. |
| int ai = background.getComponentCount() - 1; |
| |
| // Final alpha: src_alpha + dst_alpha * (1 - src_alpha) |
| dst[ai] = sa + da; |
| |
| // Divide by final alpha to return non pre-multiplied color |
| if (dst[ai] > 0) { |
| sa /= dst[ai]; |
| da /= dst[ai]; |
| } |
| |
| // Composite non-alpha components |
| for (int i = 0; i < ai; i++) { |
| dst[i] = src[i] * sa + dst[i] * da; |
| } |
| |
| return Color.valueOf(dst, background.getColorSpace()); |
| } |
| |
| private static int compositeAlpha(int foregroundAlpha, int backgroundAlpha) { |
| return 0xFF - (((0xFF - backgroundAlpha) * (0xFF - foregroundAlpha)) / 0xFF); |
| } |
| |
| private static int compositeComponent(int fgC, int fgA, int bgC, int bgA, int a) { |
| if (a == 0) return 0; |
| return ((0xFF * fgC * fgA) + (bgC * bgA * (0xFF - fgA))) / (a * 0xFF); |
| } |
| |
| /** |
| * Returns the luminance of a color as a float between {@code 0.0} and {@code 1.0}. |
| * <p>Defined as the Y component in the XYZ representation of {@code color}.</p> |
| */ |
| @FloatRange(from = 0.0, to = 1.0) |
| public static double calculateLuminance(@ColorInt int color) { |
| final double[] result = getTempDouble3Array(); |
| colorToXYZ(color, result); |
| // Luminance is the Y component |
| return result[1] / 100; |
| } |
| |
| /** |
| * Returns the contrast ratio between {@code foreground} and {@code background}. |
| * {@code background} must be opaque. |
| * <p> |
| * Formula defined |
| * <a href="http://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef">here</a>. |
| */ |
| public static double calculateContrast(@ColorInt int foreground, @ColorInt int background) { |
| if (Color.alpha(background) != 255) { |
| throw new IllegalArgumentException("background can not be translucent: #" |
| + Integer.toHexString(background)); |
| } |
| if (Color.alpha(foreground) < 255) { |
| // If the foreground is translucent, composite the foreground over the background |
| foreground = compositeColors(foreground, background); |
| } |
| |
| final double luminance1 = calculateLuminance(foreground) + 0.05; |
| final double luminance2 = calculateLuminance(background) + 0.05; |
| |
| // Now return the lighter luminance divided by the darker luminance |
| return Math.max(luminance1, luminance2) / Math.min(luminance1, luminance2); |
| } |
| |
| /** |
| * Calculates the minimum alpha value which can be applied to {@code foreground} so that would |
| * have a contrast value of at least {@code minContrastRatio} when compared to |
| * {@code background}. |
| * |
| * @param foreground the foreground color |
| * @param background the opaque background color |
| * @param minContrastRatio the minimum contrast ratio |
| * @return the alpha value in the range 0-255, or -1 if no value could be calculated |
| */ |
| public static int calculateMinimumAlpha(@ColorInt int foreground, @ColorInt int background, |
| float minContrastRatio) { |
| if (Color.alpha(background) != 255) { |
| throw new IllegalArgumentException("background can not be translucent: #" |
| + Integer.toHexString(background)); |
| } |
| |
| // First lets check that a fully opaque foreground has sufficient contrast |
| int testForeground = setAlphaComponent(foreground, 255); |
| double testRatio = calculateContrast(testForeground, background); |
| if (testRatio < minContrastRatio) { |
| // Fully opaque foreground does not have sufficient contrast, return error |
| return -1; |
| } |
| |
| // Binary search to find a value with the minimum value which provides sufficient contrast |
| int numIterations = 0; |
| int minAlpha = 0; |
| int maxAlpha = 255; |
| |
| while (numIterations <= MIN_ALPHA_SEARCH_MAX_ITERATIONS && |
| (maxAlpha - minAlpha) > MIN_ALPHA_SEARCH_PRECISION) { |
| final int testAlpha = (minAlpha + maxAlpha) / 2; |
| |
| testForeground = setAlphaComponent(foreground, testAlpha); |
| testRatio = calculateContrast(testForeground, background); |
| |
| if (testRatio < minContrastRatio) { |
| minAlpha = testAlpha; |
| } else { |
| maxAlpha = testAlpha; |
| } |
| |
| numIterations++; |
| } |
| |
| // Conservatively return the max of the range of possible alphas, which is known to pass. |
| return maxAlpha; |
| } |
| |
| /** |
| * Convert RGB components to HSL (hue-saturation-lightness). |
| * <ul> |
| * <li>outHsl[0] is Hue [0 .. 360)</li> |
| * <li>outHsl[1] is Saturation [0...1]</li> |
| * <li>outHsl[2] is Lightness [0...1]</li> |
| * </ul> |
| * |
| * @param r red component value [0..255] |
| * @param g green component value [0..255] |
| * @param b blue component value [0..255] |
| * @param outHsl 3-element array which holds the resulting HSL components |
| */ |
| public static void RGBToHSL(@IntRange(from = 0x0, to = 0xFF) int r, |
| @IntRange(from = 0x0, to = 0xFF) int g, @IntRange(from = 0x0, to = 0xFF) int b, |
| @NonNull float[] outHsl) { |
| final float rf = r / 255f; |
| final float gf = g / 255f; |
| final float bf = b / 255f; |
| |
| final float max = Math.max(rf, Math.max(gf, bf)); |
| final float min = Math.min(rf, Math.min(gf, bf)); |
| final float deltaMaxMin = max - min; |
| |
| float h, s; |
| float l = (max + min) / 2f; |
| |
| if (max == min) { |
| // Monochromatic |
| h = s = 0f; |
| } else { |
| if (max == rf) { |
| h = ((gf - bf) / deltaMaxMin) % 6f; |
| } else if (max == gf) { |
| h = ((bf - rf) / deltaMaxMin) + 2f; |
| } else { |
| h = ((rf - gf) / deltaMaxMin) + 4f; |
| } |
| |
| s = deltaMaxMin / (1f - Math.abs(2f * l - 1f)); |
| } |
| |
| h = (h * 60f) % 360f; |
| if (h < 0) { |
| h += 360f; |
| } |
| |
| outHsl[0] = constrain(h, 0f, 360f); |
| outHsl[1] = constrain(s, 0f, 1f); |
| outHsl[2] = constrain(l, 0f, 1f); |
| } |
| |
| /** |
| * Convert the ARGB color to its HSL (hue-saturation-lightness) components. |
| * <ul> |
| * <li>outHsl[0] is Hue [0 .. 360)</li> |
| * <li>outHsl[1] is Saturation [0...1]</li> |
| * <li>outHsl[2] is Lightness [0...1]</li> |
| * </ul> |
| * |
| * @param color the ARGB color to convert. The alpha component is ignored |
| * @param outHsl 3-element array which holds the resulting HSL components |
| */ |
| public static void colorToHSL(@ColorInt int color, @NonNull float[] outHsl) { |
| RGBToHSL(Color.red(color), Color.green(color), Color.blue(color), outHsl); |
| } |
| |
| /** |
| * Convert HSL (hue-saturation-lightness) components to a RGB color. |
| * <ul> |
| * <li>hsl[0] is Hue [0 .. 360)</li> |
| * <li>hsl[1] is Saturation [0...1]</li> |
| * <li>hsl[2] is Lightness [0...1]</li> |
| * </ul> |
| * If hsv values are out of range, they are pinned. |
| * |
| * @param hsl 3-element array which holds the input HSL components |
| * @return the resulting RGB color |
| */ |
| @ColorInt |
| public static int HSLToColor(@NonNull float[] hsl) { |
| final float h = hsl[0]; |
| final float s = hsl[1]; |
| final float l = hsl[2]; |
| |
| final float c = (1f - Math.abs(2 * l - 1f)) * s; |
| final float m = l - 0.5f * c; |
| final float x = c * (1f - Math.abs((h / 60f % 2f) - 1f)); |
| |
| final int hueSegment = (int) h / 60; |
| |
| int r = 0, g = 0, b = 0; |
| |
| switch (hueSegment) { |
| case 0: |
| r = Math.round(255 * (c + m)); |
| g = Math.round(255 * (x + m)); |
| b = Math.round(255 * m); |
| break; |
| case 1: |
| r = Math.round(255 * (x + m)); |
| g = Math.round(255 * (c + m)); |
| b = Math.round(255 * m); |
| break; |
| case 2: |
| r = Math.round(255 * m); |
| g = Math.round(255 * (c + m)); |
| b = Math.round(255 * (x + m)); |
| break; |
| case 3: |
| r = Math.round(255 * m); |
| g = Math.round(255 * (x + m)); |
| b = Math.round(255 * (c + m)); |
| break; |
| case 4: |
| r = Math.round(255 * (x + m)); |
| g = Math.round(255 * m); |
| b = Math.round(255 * (c + m)); |
| break; |
| case 5: |
| case 6: |
| r = Math.round(255 * (c + m)); |
| g = Math.round(255 * m); |
| b = Math.round(255 * (x + m)); |
| break; |
| } |
| |
| r = constrain(r, 0, 255); |
| g = constrain(g, 0, 255); |
| b = constrain(b, 0, 255); |
| |
| return Color.rgb(r, g, b); |
| } |
| |
| /** |
| * Set the alpha component of {@code color} to be {@code alpha}. |
| */ |
| @ColorInt |
| public static int setAlphaComponent(@ColorInt int color, |
| @IntRange(from = 0x0, to = 0xFF) int alpha) { |
| if (alpha < 0 || alpha > 255) { |
| throw new IllegalArgumentException("alpha must be between 0 and 255."); |
| } |
| return (color & 0x00ffffff) | (alpha << 24); |
| } |
| |
| /** |
| * Convert the ARGB color to its CIE Lab representative components. |
| * |
| * @param color the ARGB color to convert. The alpha component is ignored |
| * @param outLab 3-element array which holds the resulting LAB components |
| */ |
| public static void colorToLAB(@ColorInt int color, @NonNull double[] outLab) { |
| RGBToLAB(Color.red(color), Color.green(color), Color.blue(color), outLab); |
| } |
| |
| /** |
| * Convert RGB components to its CIE Lab representative components. |
| * |
| * <ul> |
| * <li>outLab[0] is L [0 ...1)</li> |
| * <li>outLab[1] is a [-128...127)</li> |
| * <li>outLab[2] is b [-128...127)</li> |
| * </ul> |
| * |
| * @param r red component value [0..255] |
| * @param g green component value [0..255] |
| * @param b blue component value [0..255] |
| * @param outLab 3-element array which holds the resulting LAB components |
| */ |
| public static void RGBToLAB(@IntRange(from = 0x0, to = 0xFF) int r, |
| @IntRange(from = 0x0, to = 0xFF) int g, @IntRange(from = 0x0, to = 0xFF) int b, |
| @NonNull double[] outLab) { |
| // First we convert RGB to XYZ |
| RGBToXYZ(r, g, b, outLab); |
| // outLab now contains XYZ |
| XYZToLAB(outLab[0], outLab[1], outLab[2], outLab); |
| // outLab now contains LAB representation |
| } |
| |
| /** |
| * Convert the ARGB color to its CIE XYZ representative components. |
| * |
| * <p>The resulting XYZ representation will use the D65 illuminant and the CIE |
| * 2° Standard Observer (1931).</p> |
| * |
| * <ul> |
| * <li>outXyz[0] is X [0 ...95.047)</li> |
| * <li>outXyz[1] is Y [0...100)</li> |
| * <li>outXyz[2] is Z [0...108.883)</li> |
| * </ul> |
| * |
| * @param color the ARGB color to convert. The alpha component is ignored |
| * @param outXyz 3-element array which holds the resulting LAB components |
| */ |
| public static void colorToXYZ(@ColorInt int color, @NonNull double[] outXyz) { |
| RGBToXYZ(Color.red(color), Color.green(color), Color.blue(color), outXyz); |
| } |
| |
| /** |
| * Convert RGB components to its CIE XYZ representative components. |
| * |
| * <p>The resulting XYZ representation will use the D65 illuminant and the CIE |
| * 2° Standard Observer (1931).</p> |
| * |
| * <ul> |
| * <li>outXyz[0] is X [0 ...95.047)</li> |
| * <li>outXyz[1] is Y [0...100)</li> |
| * <li>outXyz[2] is Z [0...108.883)</li> |
| * </ul> |
| * |
| * @param r red component value [0..255] |
| * @param g green component value [0..255] |
| * @param b blue component value [0..255] |
| * @param outXyz 3-element array which holds the resulting XYZ components |
| */ |
| public static void RGBToXYZ(@IntRange(from = 0x0, to = 0xFF) int r, |
| @IntRange(from = 0x0, to = 0xFF) int g, @IntRange(from = 0x0, to = 0xFF) int b, |
| @NonNull double[] outXyz) { |
| if (outXyz.length != 3) { |
| throw new IllegalArgumentException("outXyz must have a length of 3."); |
| } |
| |
| double sr = r / 255.0; |
| sr = sr < 0.04045 ? sr / 12.92 : Math.pow((sr + 0.055) / 1.055, 2.4); |
| double sg = g / 255.0; |
| sg = sg < 0.04045 ? sg / 12.92 : Math.pow((sg + 0.055) / 1.055, 2.4); |
| double sb = b / 255.0; |
| sb = sb < 0.04045 ? sb / 12.92 : Math.pow((sb + 0.055) / 1.055, 2.4); |
| |
| outXyz[0] = 100 * (sr * 0.4124 + sg * 0.3576 + sb * 0.1805); |
| outXyz[1] = 100 * (sr * 0.2126 + sg * 0.7152 + sb * 0.0722); |
| outXyz[2] = 100 * (sr * 0.0193 + sg * 0.1192 + sb * 0.9505); |
| } |
| |
| /** |
| * Converts a color from CIE XYZ to CIE Lab representation. |
| * |
| * <p>This method expects the XYZ representation to use the D65 illuminant and the CIE |
| * 2° Standard Observer (1931).</p> |
| * |
| * <ul> |
| * <li>outLab[0] is L [0 ...1)</li> |
| * <li>outLab[1] is a [-128...127)</li> |
| * <li>outLab[2] is b [-128...127)</li> |
| * </ul> |
| * |
| * @param x X component value [0...95.047) |
| * @param y Y component value [0...100) |
| * @param z Z component value [0...108.883) |
| * @param outLab 3-element array which holds the resulting Lab components |
| */ |
| public static void XYZToLAB(@FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_X) double x, |
| @FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_Y) double y, |
| @FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_Z) double z, |
| @NonNull double[] outLab) { |
| if (outLab.length != 3) { |
| throw new IllegalArgumentException("outLab must have a length of 3."); |
| } |
| x = pivotXyzComponent(x / XYZ_WHITE_REFERENCE_X); |
| y = pivotXyzComponent(y / XYZ_WHITE_REFERENCE_Y); |
| z = pivotXyzComponent(z / XYZ_WHITE_REFERENCE_Z); |
| outLab[0] = Math.max(0, 116 * y - 16); |
| outLab[1] = 500 * (x - y); |
| outLab[2] = 200 * (y - z); |
| } |
| |
| /** |
| * Converts a color from CIE Lab to CIE XYZ representation. |
| * |
| * <p>The resulting XYZ representation will use the D65 illuminant and the CIE |
| * 2° Standard Observer (1931).</p> |
| * |
| * <ul> |
| * <li>outXyz[0] is X [0 ...95.047)</li> |
| * <li>outXyz[1] is Y [0...100)</li> |
| * <li>outXyz[2] is Z [0...108.883)</li> |
| * </ul> |
| * |
| * @param l L component value [0...100) |
| * @param a A component value [-128...127) |
| * @param b B component value [-128...127) |
| * @param outXyz 3-element array which holds the resulting XYZ components |
| */ |
| public static void LABToXYZ(@FloatRange(from = 0f, to = 100) final double l, |
| @FloatRange(from = -128, to = 127) final double a, |
| @FloatRange(from = -128, to = 127) final double b, |
| @NonNull double[] outXyz) { |
| final double fy = (l + 16) / 116; |
| final double fx = a / 500 + fy; |
| final double fz = fy - b / 200; |
| |
| double tmp = Math.pow(fx, 3); |
| final double xr = tmp > XYZ_EPSILON ? tmp : (116 * fx - 16) / XYZ_KAPPA; |
| final double yr = l > XYZ_KAPPA * XYZ_EPSILON ? Math.pow(fy, 3) : l / XYZ_KAPPA; |
| |
| tmp = Math.pow(fz, 3); |
| final double zr = tmp > XYZ_EPSILON ? tmp : (116 * fz - 16) / XYZ_KAPPA; |
| |
| outXyz[0] = xr * XYZ_WHITE_REFERENCE_X; |
| outXyz[1] = yr * XYZ_WHITE_REFERENCE_Y; |
| outXyz[2] = zr * XYZ_WHITE_REFERENCE_Z; |
| } |
| |
| /** |
| * Converts a color from CIE XYZ to its RGB representation. |
| * |
| * <p>This method expects the XYZ representation to use the D65 illuminant and the CIE |
| * 2° Standard Observer (1931).</p> |
| * |
| * @param x X component value [0...95.047) |
| * @param y Y component value [0...100) |
| * @param z Z component value [0...108.883) |
| * @return int containing the RGB representation |
| */ |
| @ColorInt |
| public static int XYZToColor(@FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_X) double x, |
| @FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_Y) double y, |
| @FloatRange(from = 0f, to = XYZ_WHITE_REFERENCE_Z) double z) { |
| double r = (x * 3.2406 + y * -1.5372 + z * -0.4986) / 100; |
| double g = (x * -0.9689 + y * 1.8758 + z * 0.0415) / 100; |
| double b = (x * 0.0557 + y * -0.2040 + z * 1.0570) / 100; |
| |
| r = r > 0.0031308 ? 1.055 * Math.pow(r, 1 / 2.4) - 0.055 : 12.92 * r; |
| g = g > 0.0031308 ? 1.055 * Math.pow(g, 1 / 2.4) - 0.055 : 12.92 * g; |
| b = b > 0.0031308 ? 1.055 * Math.pow(b, 1 / 2.4) - 0.055 : 12.92 * b; |
| |
| return Color.rgb( |
| constrain((int) Math.round(r * 255), 0, 255), |
| constrain((int) Math.round(g * 255), 0, 255), |
| constrain((int) Math.round(b * 255), 0, 255)); |
| } |
| |
| /** |
| * Converts a color from CIE Lab to its RGB representation. |
| * |
| * @param l L component value [0...100] |
| * @param a A component value [-128...127] |
| * @param b B component value [-128...127] |
| * @return int containing the RGB representation |
| */ |
| @ColorInt |
| public static int LABToColor(@FloatRange(from = 0f, to = 100) final double l, |
| @FloatRange(from = -128, to = 127) final double a, |
| @FloatRange(from = -128, to = 127) final double b) { |
| final double[] result = getTempDouble3Array(); |
| LABToXYZ(l, a, b, result); |
| return XYZToColor(result[0], result[1], result[2]); |
| } |
| |
| /** |
| * Returns the euclidean distance between two LAB colors. |
| */ |
| public static double distanceEuclidean(@NonNull double[] labX, @NonNull double[] labY) { |
| return Math.sqrt(Math.pow(labX[0] - labY[0], 2) |
| + Math.pow(labX[1] - labY[1], 2) |
| + Math.pow(labX[2] - labY[2], 2)); |
| } |
| |
| private static float constrain(float amount, float low, float high) { |
| return amount < low ? low : (amount > high ? high : amount); |
| } |
| |
| private static int constrain(int amount, int low, int high) { |
| return amount < low ? low : (amount > high ? high : amount); |
| } |
| |
| private static double pivotXyzComponent(double component) { |
| return component > XYZ_EPSILON |
| ? Math.pow(component, 1 / 3.0) |
| : (XYZ_KAPPA * component + 16) / 116; |
| } |
| |
| /** |
| * Blend between two ARGB colors using the given ratio. |
| * |
| * <p>A blend ratio of 0.0 will result in {@code color1}, 0.5 will give an even blend, |
| * 1.0 will result in {@code color2}.</p> |
| * |
| * @param color1 the first ARGB color |
| * @param color2 the second ARGB color |
| * @param ratio the blend ratio of {@code color1} to {@code color2} |
| */ |
| @ColorInt |
| public static int blendARGB(@ColorInt int color1, @ColorInt int color2, |
| @FloatRange(from = 0.0, to = 1.0) float ratio) { |
| final float inverseRatio = 1 - ratio; |
| float a = Color.alpha(color1) * inverseRatio + Color.alpha(color2) * ratio; |
| float r = Color.red(color1) * inverseRatio + Color.red(color2) * ratio; |
| float g = Color.green(color1) * inverseRatio + Color.green(color2) * ratio; |
| float b = Color.blue(color1) * inverseRatio + Color.blue(color2) * ratio; |
| return Color.argb((int) a, (int) r, (int) g, (int) b); |
| } |
| |
| /** |
| * Blend between {@code hsl1} and {@code hsl2} using the given ratio. This will interpolate |
| * the hue using the shortest angle. |
| * |
| * <p>A blend ratio of 0.0 will result in {@code hsl1}, 0.5 will give an even blend, |
| * 1.0 will result in {@code hsl2}.</p> |
| * |
| * @param hsl1 3-element array which holds the first HSL color |
| * @param hsl2 3-element array which holds the second HSL color |
| * @param ratio the blend ratio of {@code hsl1} to {@code hsl2} |
| * @param outResult 3-element array which holds the resulting HSL components |
| */ |
| public static void blendHSL(@NonNull float[] hsl1, @NonNull float[] hsl2, |
| @FloatRange(from = 0.0, to = 1.0) float ratio, @NonNull float[] outResult) { |
| if (outResult.length != 3) { |
| throw new IllegalArgumentException("result must have a length of 3."); |
| } |
| final float inverseRatio = 1 - ratio; |
| // Since hue is circular we will need to interpolate carefully |
| outResult[0] = circularInterpolate(hsl1[0], hsl2[0], ratio); |
| outResult[1] = hsl1[1] * inverseRatio + hsl2[1] * ratio; |
| outResult[2] = hsl1[2] * inverseRatio + hsl2[2] * ratio; |
| } |
| |
| /** |
| * Blend between two CIE-LAB colors using the given ratio. |
| * |
| * <p>A blend ratio of 0.0 will result in {@code lab1}, 0.5 will give an even blend, |
| * 1.0 will result in {@code lab2}.</p> |
| * |
| * @param lab1 3-element array which holds the first LAB color |
| * @param lab2 3-element array which holds the second LAB color |
| * @param ratio the blend ratio of {@code lab1} to {@code lab2} |
| * @param outResult 3-element array which holds the resulting LAB components |
| */ |
| public static void blendLAB(@NonNull double[] lab1, @NonNull double[] lab2, |
| @FloatRange(from = 0.0, to = 1.0) double ratio, @NonNull double[] outResult) { |
| if (outResult.length != 3) { |
| throw new IllegalArgumentException("outResult must have a length of 3."); |
| } |
| final double inverseRatio = 1 - ratio; |
| outResult[0] = lab1[0] * inverseRatio + lab2[0] * ratio; |
| outResult[1] = lab1[1] * inverseRatio + lab2[1] * ratio; |
| outResult[2] = lab1[2] * inverseRatio + lab2[2] * ratio; |
| } |
| |
| @VisibleForTesting |
| static float circularInterpolate(float a, float b, float f) { |
| if (Math.abs(b - a) > 180) { |
| if (b > a) { |
| a += 360; |
| } else { |
| b += 360; |
| } |
| } |
| return (a + ((b - a) * f)) % 360; |
| } |
| |
| private static double[] getTempDouble3Array() { |
| double[] result = TEMP_ARRAY.get(); |
| if (result == null) { |
| result = new double[3]; |
| TEMP_ARRAY.set(result); |
| } |
| return result; |
| } |
| |
| } |
