src/com/android/launcher3/graphics/IconPalette.java - platform/packages/apps/Launcher3 - Git at Google

 /*
  * Copyright (C) 2017 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 com.android.launcher3.graphics;

 import android.app.Notification;
 import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Color;
 import android.graphics.ColorMatrix;
 import android.graphics.ColorMatrixColorFilter;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.v4.graphics.ColorUtils;
 import android.util.Log;

 import com.android.launcher3.R;
 import com.android.launcher3.util.Themes;

 /**
  * Contains colors based on the dominant color of an icon.
  */
 public class IconPalette {

     private static final boolean DEBUG = false;
     private static final String TAG = "IconPalette";

     private static final float MIN_PRELOAD_COLOR_SATURATION = 0.2f;
     private static final float MIN_PRELOAD_COLOR_LIGHTNESS = 0.6f;

     private static IconPalette sBadgePalette;
     private static IconPalette sFolderBadgePalette;

     public final int dominantColor;
     public final int backgroundColor;
     public final ColorMatrixColorFilter backgroundColorMatrixFilter;
     public final ColorMatrixColorFilter saturatedBackgroundColorMatrixFilter;
     public final int textColor;
     public final int secondaryColor;

     private IconPalette(int color, boolean desaturateBackground) {
         dominantColor = color;
         backgroundColor = desaturateBackground ? getMutedColor(dominantColor, 0.87f) : dominantColor;
         ColorMatrix backgroundColorMatrix = new ColorMatrix();
         Themes.setColorScaleOnMatrix(backgroundColor, backgroundColorMatrix);
         backgroundColorMatrixFilter = new ColorMatrixColorFilter(backgroundColorMatrix);
         if (!desaturateBackground) {
             saturatedBackgroundColorMatrixFilter = backgroundColorMatrixFilter;
         } else {
             // Get slightly more saturated background color.
             Themes.setColorScaleOnMatrix(getMutedColor(dominantColor, 0.54f), backgroundColorMatrix);
             saturatedBackgroundColorMatrixFilter = new ColorMatrixColorFilter(backgroundColorMatrix);
         }
         textColor = getTextColorForBackground(backgroundColor);
         secondaryColor = getLowContrastColor(backgroundColor);
     }

     /**
      * Returns a color suitable for the progress bar color of preload icon.
      */
     public int getPreloadProgressColor(Context context) {
         int result = dominantColor;

         // Make sure that the dominant color has enough saturation to be visible properly.
         float[] hsv = new float[3];
         Color.colorToHSV(result, hsv);
         if (hsv[1] < MIN_PRELOAD_COLOR_SATURATION) {
             result = Themes.getColorAccent(context);
         } else {
             hsv[2] = Math.max(MIN_PRELOAD_COLOR_LIGHTNESS, hsv[2]);
             result = Color.HSVToColor(hsv);
         }
         return result;
     }

     public static IconPalette fromDominantColor(int dominantColor, boolean desaturateBackground) {
         return new IconPalette(dominantColor, desaturateBackground);
     }

     /**
      * Returns an IconPalette based on the badge_color in colors.xml.
      * If that color is Color.TRANSPARENT, then returns null instead.
      */
     public static @Nullable IconPalette getBadgePalette(Resources resources) {
         int badgeColor = resources.getColor(R.color.badge_color);
         if (badgeColor == Color.TRANSPARENT) {
             // Colors will be extracted per app icon, so a static palette won't work.
             return null;
         }
         if (sBadgePalette == null) {
             sBadgePalette = fromDominantColor(badgeColor, false);
         }
         return sBadgePalette;
     }

     /**
      * Returns an IconPalette based on the folder_badge_color in colors.xml.
      */
     public static @NonNull IconPalette getFolderBadgePalette(Resources resources) {
         if (sFolderBadgePalette == null) {
             int badgeColor = resources.getColor(R.color.folder_badge_color);
             sFolderBadgePalette = fromDominantColor(badgeColor, false);
         }
         return sFolderBadgePalette;
     }

     /**
      * Resolves a color such that it has enough contrast to be used as the
      * color of an icon or text on the given background color.
      *
      * @return a color of the same hue with enough contrast against the background.
      *
      * This was copied from com.android.internal.util.NotificationColorUtil.
      */
     public static int resolveContrastColor(Context context, int color, int background) {
         final int resolvedColor = resolveColor(context, color);

         int contrastingColor = ensureTextContrast(resolvedColor, background);

         if (contrastingColor != resolvedColor) {
             if (DEBUG){
                 Log.w(TAG, String.format(
                         "Enhanced contrast of notification for %s " +
                                 "%s (over background) by changing #%s to %s",
                         context.getPackageName(),
                         contrastChange(resolvedColor, contrastingColor, background),
                         Integer.toHexString(resolvedColor), Integer.toHexString(contrastingColor)));
             }
         }
         return contrastingColor;
     }

     /**
      * Resolves {@param color} to an actual color if it is {@link Notification#COLOR_DEFAULT}
      *
      * This was copied from com.android.internal.util.NotificationColorUtil.
      */
     private static int resolveColor(Context context, int color) {
         if (color == Notification.COLOR_DEFAULT) {
             return context.getColor(R.color.notification_icon_default_color);
         }
         return color;
     }

     /** For debugging. This was copied from com.android.internal.util.NotificationColorUtil. */
     private static String contrastChange(int colorOld, int colorNew, int bg) {
         return String.format("from %.2f:1 to %.2f:1",
                 ColorUtils.calculateContrast(colorOld, bg),
                 ColorUtils.calculateContrast(colorNew, bg));
     }

     /**
      * Finds a text color with sufficient contrast over bg that has the same hue as the original
      * color.
      *
      * This was copied from com.android.internal.util.NotificationColorUtil.
      */
     private static int ensureTextContrast(int color, int bg) {
         return findContrastColor(color, bg, true, 4.5);
     }
     /**
      * Finds a suitable color such that there's enough contrast.
      *
      * @param color the color to start searching from.
      * @param other the color to ensure contrast against. Assumed to be lighter than {@param color}
      * @param findFg if true, we assume {@param color} is a foreground, otherwise a background.
      * @param minRatio the minimum contrast ratio required.
      * @return a color with the same hue as {@param color}, potentially darkened to meet the
      *          contrast ratio.
      *
      * This was copied from com.android.internal.util.NotificationColorUtil.
      */
     private static int findContrastColor(int color, int other, boolean findFg, double minRatio) {
         int fg = findFg ? color : other;
         int bg = findFg ? other : color;
         if (ColorUtils.calculateContrast(fg, bg) >= minRatio) {
             return color;
         }

         double[] lab = new double[3];
         ColorUtils.colorToLAB(findFg ? fg : bg, lab);

         double low = 0, high = lab[0];
         final double a = lab[1], b = lab[2];
         for (int i = 0; i < 15 && high - low > 0.00001; i++) {
             final double l = (low + high) / 2;
             if (findFg) {
                 fg = ColorUtils.LABToColor(l, a, b);
             } else {
                 bg = ColorUtils.LABToColor(l, a, b);
             }
             if (ColorUtils.calculateContrast(fg, bg) > minRatio) {
                 low = l;
             } else {
                 high = l;
             }
         }
         return ColorUtils.LABToColor(low, a, b);
     }

     private static int getMutedColor(int color, float whiteScrimAlpha) {
         int whiteScrim = ColorUtils.setAlphaComponent(Color.WHITE, (int) (255 * whiteScrimAlpha));
         return ColorUtils.compositeColors(whiteScrim, color);
     }

     private static int getTextColorForBackground(int backgroundColor) {
         return getLighterOrDarkerVersionOfColor(backgroundColor, 4.5f);
     }

     private static int getLowContrastColor(int color) {
         return getLighterOrDarkerVersionOfColor(color, 1.5f);
     }

     private static int getLighterOrDarkerVersionOfColor(int color, float contrastRatio) {
         int whiteMinAlpha = ColorUtils.calculateMinimumAlpha(Color.WHITE, color, contrastRatio);
         int blackMinAlpha = ColorUtils.calculateMinimumAlpha(Color.BLACK, color, contrastRatio);
         int translucentWhiteOrBlack;
         if (whiteMinAlpha >= 0) {
             translucentWhiteOrBlack = ColorUtils.setAlphaComponent(Color.WHITE, whiteMinAlpha);
         } else if (blackMinAlpha >= 0) {
             translucentWhiteOrBlack = ColorUtils.setAlphaComponent(Color.BLACK, blackMinAlpha);
         } else {
             translucentWhiteOrBlack = Color.WHITE;
         }
         return ColorUtils.compositeColors(translucentWhiteOrBlack, color);
     }
 }
	/*
	* Copyright (C) 2017 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 com.android.launcher3.graphics;

	import android.app.Notification;
	import android.content.Context;
	import android.content.res.Resources;
	import android.graphics.Color;
	import android.graphics.ColorMatrix;
	import android.graphics.ColorMatrixColorFilter;
	import android.support.annotation.NonNull;
	import android.support.annotation.Nullable;
	import android.support.v4.graphics.ColorUtils;
	import android.util.Log;

	import com.android.launcher3.R;
	import com.android.launcher3.util.Themes;

	/**
	* Contains colors based on the dominant color of an icon.
	*/
	public class IconPalette {

	private static final boolean DEBUG = false;
	private static final String TAG = "IconPalette";

	private static final float MIN_PRELOAD_COLOR_SATURATION = 0.2f;
	private static final float MIN_PRELOAD_COLOR_LIGHTNESS = 0.6f;

	private static IconPalette sBadgePalette;
	private static IconPalette sFolderBadgePalette;

	public final int dominantColor;
	public final int backgroundColor;
	public final ColorMatrixColorFilter backgroundColorMatrixFilter;
	public final ColorMatrixColorFilter saturatedBackgroundColorMatrixFilter;
	public final int textColor;
	public final int secondaryColor;

	private IconPalette(int color, boolean desaturateBackground) {
	dominantColor = color;
	backgroundColor = desaturateBackground ? getMutedColor(dominantColor, 0.87f) : dominantColor;
	ColorMatrix backgroundColorMatrix = new ColorMatrix();
	Themes.setColorScaleOnMatrix(backgroundColor, backgroundColorMatrix);
	backgroundColorMatrixFilter = new ColorMatrixColorFilter(backgroundColorMatrix);
	if (!desaturateBackground) {
	saturatedBackgroundColorMatrixFilter = backgroundColorMatrixFilter;
	} else {
	// Get slightly more saturated background color.
	Themes.setColorScaleOnMatrix(getMutedColor(dominantColor, 0.54f), backgroundColorMatrix);
	saturatedBackgroundColorMatrixFilter = new ColorMatrixColorFilter(backgroundColorMatrix);
	}
	textColor = getTextColorForBackground(backgroundColor);
	secondaryColor = getLowContrastColor(backgroundColor);
	}

	/**
	* Returns a color suitable for the progress bar color of preload icon.
	*/
	public int getPreloadProgressColor(Context context) {
	int result = dominantColor;

	// Make sure that the dominant color has enough saturation to be visible properly.
	float[] hsv = new float[3];
	Color.colorToHSV(result, hsv);
	if (hsv[1] < MIN_PRELOAD_COLOR_SATURATION) {
	result = Themes.getColorAccent(context);
	} else {
	hsv[2] = Math.max(MIN_PRELOAD_COLOR_LIGHTNESS, hsv[2]);
	result = Color.HSVToColor(hsv);
	}
	return result;
	}

	public static IconPalette fromDominantColor(int dominantColor, boolean desaturateBackground) {
	return new IconPalette(dominantColor, desaturateBackground);
	}

	/**
	* Returns an IconPalette based on the badge_color in colors.xml.
	* If that color is Color.TRANSPARENT, then returns null instead.
	*/
	public static @Nullable IconPalette getBadgePalette(Resources resources) {
	int badgeColor = resources.getColor(R.color.badge_color);
	if (badgeColor == Color.TRANSPARENT) {
	// Colors will be extracted per app icon, so a static palette won't work.
	return null;
	}
	if (sBadgePalette == null) {
	sBadgePalette = fromDominantColor(badgeColor, false);
	}
	return sBadgePalette;
	}

	/**
	* Returns an IconPalette based on the folder_badge_color in colors.xml.
	*/
	public static @NonNull IconPalette getFolderBadgePalette(Resources resources) {
	if (sFolderBadgePalette == null) {
	int badgeColor = resources.getColor(R.color.folder_badge_color);
	sFolderBadgePalette = fromDominantColor(badgeColor, false);
	}
	return sFolderBadgePalette;
	}

	/**
	* Resolves a color such that it has enough contrast to be used as the
	* color of an icon or text on the given background color.
	*
	* @return a color of the same hue with enough contrast against the background.
	*
	* This was copied from com.android.internal.util.NotificationColorUtil.
	*/
	public static int resolveContrastColor(Context context, int color, int background) {
	final int resolvedColor = resolveColor(context, color);

	int contrastingColor = ensureTextContrast(resolvedColor, background);

	if (contrastingColor != resolvedColor) {
	if (DEBUG){
	Log.w(TAG, String.format(
	"Enhanced contrast of notification for %s " +
	"%s (over background) by changing #%s to %s",
	context.getPackageName(),
	contrastChange(resolvedColor, contrastingColor, background),
	Integer.toHexString(resolvedColor), Integer.toHexString(contrastingColor)));
	}
	}
	return contrastingColor;
	}

	/**
	* Resolves {@param color} to an actual color if it is {@link Notification#COLOR_DEFAULT}
	*
	* This was copied from com.android.internal.util.NotificationColorUtil.
	*/
	private static int resolveColor(Context context, int color) {
	if (color == Notification.COLOR_DEFAULT) {
	return context.getColor(R.color.notification_icon_default_color);
	}
	return color;
	}

	/** For debugging. This was copied from com.android.internal.util.NotificationColorUtil. */
	private static String contrastChange(int colorOld, int colorNew, int bg) {
	return String.format("from %.2f:1 to %.2f:1",
	ColorUtils.calculateContrast(colorOld, bg),
	ColorUtils.calculateContrast(colorNew, bg));
	}

	/**
	* Finds a text color with sufficient contrast over bg that has the same hue as the original
	* color.
	*
	* This was copied from com.android.internal.util.NotificationColorUtil.
	*/
	private static int ensureTextContrast(int color, int bg) {
	return findContrastColor(color, bg, true, 4.5);
	}
	/**
	* Finds a suitable color such that there's enough contrast.
	*
	* @param color the color to start searching from.
	* @param other the color to ensure contrast against. Assumed to be lighter than {@param color}
	* @param findFg if true, we assume {@param color} is a foreground, otherwise a background.
	* @param minRatio the minimum contrast ratio required.
	* @return a color with the same hue as {@param color}, potentially darkened to meet the
	* contrast ratio.
	*
	* This was copied from com.android.internal.util.NotificationColorUtil.
	*/
	private static int findContrastColor(int color, int other, boolean findFg, double minRatio) {
	int fg = findFg ? color : other;
	int bg = findFg ? other : color;
	if (ColorUtils.calculateContrast(fg, bg) >= minRatio) {
	return color;
	}

	double[] lab = new double[3];
	ColorUtils.colorToLAB(findFg ? fg : bg, lab);

	double low = 0, high = lab[0];
	final double a = lab[1], b = lab[2];
	for (int i = 0; i < 15 && high - low > 0.00001; i++) {
	final double l = (low + high) / 2;
	if (findFg) {
	fg = ColorUtils.LABToColor(l, a, b);
	} else {
	bg = ColorUtils.LABToColor(l, a, b);
	}
	if (ColorUtils.calculateContrast(fg, bg) > minRatio) {
	low = l;
	} else {
	high = l;
	}
	}
	return ColorUtils.LABToColor(low, a, b);
	}

	private static int getMutedColor(int color, float whiteScrimAlpha) {
	int whiteScrim = ColorUtils.setAlphaComponent(Color.WHITE, (int) (255 * whiteScrimAlpha));
	return ColorUtils.compositeColors(whiteScrim, color);
	}

	private static int getTextColorForBackground(int backgroundColor) {
	return getLighterOrDarkerVersionOfColor(backgroundColor, 4.5f);
	}

	private static int getLowContrastColor(int color) {
	return getLighterOrDarkerVersionOfColor(color, 1.5f);
	}

	private static int getLighterOrDarkerVersionOfColor(int color, float contrastRatio) {
	int whiteMinAlpha = ColorUtils.calculateMinimumAlpha(Color.WHITE, color, contrastRatio);
	int blackMinAlpha = ColorUtils.calculateMinimumAlpha(Color.BLACK, color, contrastRatio);
	int translucentWhiteOrBlack;
	if (whiteMinAlpha >= 0) {
	translucentWhiteOrBlack = ColorUtils.setAlphaComponent(Color.WHITE, whiteMinAlpha);
	} else if (blackMinAlpha >= 0) {
	translucentWhiteOrBlack = ColorUtils.setAlphaComponent(Color.BLACK, blackMinAlpha);
	} else {
	translucentWhiteOrBlack = Color.WHITE;
	}
	return ColorUtils.compositeColors(translucentWhiteOrBlack, color);
	}
	}