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/*
* Copyright (C) 2016 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.dynamicui;
import android.annotation.TargetApi;
import android.app.WallpaperManager;
import android.app.job.JobInfo;
import android.app.job.JobScheduler;
import android.content.ComponentName;
import android.content.Context;
import android.content.SharedPreferences;
import android.graphics.Color;
import android.os.Build;
import android.support.v4.graphics.ColorUtils;
import android.support.v7.graphics.Palette;
import com.android.launcher3.Utilities;
import java.util.List;
/**
* Contains helper fields and methods related to extracting colors from the wallpaper.
*/
public class ExtractionUtils {
public static final String EXTRACTED_COLORS_PREFERENCE_KEY = "pref_extractedColors";
public static final String WALLPAPER_ID_PREFERENCE_KEY = "pref_wallpaperId";
private static final float MIN_CONTRAST_RATIO = 2f;
/**
* Extract colors in the :wallpaper-chooser process, if the wallpaper id has changed.
* When the new colors are saved in the LauncherProvider,
* Launcher will be notified in Launcher#onSettingsChanged(String, String).
*/
public static void startColorExtractionServiceIfNecessary(final Context context) {
// Run on a background thread, since the service is asynchronous anyway.
Utilities.THREAD_POOL_EXECUTOR.execute(new Runnable() {
@Override
public void run() {
if (hasWallpaperIdChanged(context)) {
startColorExtractionService(context);
}
}
});
}
/** Starts the {@link ColorExtractionService} without checking the wallpaper id */
public static void startColorExtractionService(Context context) {
JobScheduler jobScheduler = (JobScheduler) context.getSystemService(
Context.JOB_SCHEDULER_SERVICE);
jobScheduler.schedule(new JobInfo.Builder(Utilities.COLOR_EXTRACTION_JOB_ID,
new ComponentName(context, ColorExtractionService.class))
.setMinimumLatency(0).build());
}
private static boolean hasWallpaperIdChanged(Context context) {
if (!Utilities.ATLEAST_NOUGAT) {
// TODO: update an id in sharedprefs in onWallpaperChanged broadcast, and read it here.
return false;
}
final SharedPreferences sharedPrefs = Utilities.getPrefs(context);
int wallpaperId = getWallpaperId(WallpaperManager.getInstance(context));
int savedWallpaperId = sharedPrefs.getInt(ExtractionUtils.WALLPAPER_ID_PREFERENCE_KEY, -1);
return wallpaperId != savedWallpaperId;
}
@TargetApi(Build.VERSION_CODES.N)
public static int getWallpaperId(WallpaperManager wallpaperManager) {
return Utilities.ATLEAST_NOUGAT ?
wallpaperManager.getWallpaperId(WallpaperManager.FLAG_SYSTEM) : -1;
}
public static boolean isSuperLight(Palette p) {
return !isLegibleOnWallpaper(Color.WHITE, p.getSwatches());
}
public static boolean isSuperDark(Palette p) {
return !isLegibleOnWallpaper(Color.BLACK, p.getSwatches());
}
/**
* Given a color, returns true if that color is legible on
* the given wallpaper color swatches, else returns false.
*/
private static boolean isLegibleOnWallpaper(int color, List<Palette.Swatch> wallpaperSwatches) {
int legiblePopulation = 0;
int illegiblePopulation = 0;
for (Palette.Swatch swatch : wallpaperSwatches) {
if (isLegible(color, swatch.getRgb())) {
legiblePopulation += swatch.getPopulation();
} else {
illegiblePopulation += swatch.getPopulation();
}
}
return legiblePopulation > illegiblePopulation;
}
/** @return Whether the foreground color is legible on the background color. */
private static boolean isLegible(int foreground, int background) {
background = ColorUtils.setAlphaComponent(background, 255);
return ColorUtils.calculateContrast(foreground, background) >= MIN_CONTRAST_RATIO;
}
}
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