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/*
* 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.graphics.Color;
import android.support.v4.graphics.ColorUtils;
import android.util.Log;
import com.android.launcher3.R;
/**
* 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";
public int backgroundColor;
public int textColor;
public int secondaryColor;
public static IconPalette fromDominantColor(int dominantColor) {
IconPalette palette = new IconPalette();
palette.backgroundColor = getMutedColor(dominantColor);
palette.textColor = getTextColorForBackground(palette.backgroundColor);
palette.secondaryColor = getLowContrastColor(palette.backgroundColor);
return palette;
}
/**
* 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) {
int alpha = (int) (255 * 0.15f);
return ColorUtils.compositeColors(ColorUtils.setAlphaComponent(color, alpha), Color.WHITE);
}
private static int getTextColorForBackground(int backgroundColor) {
return getLighterOrDarkerVersionOfColor(backgroundColor, 3f);
}
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);
}
}
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