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      1 /*
      2  * Copyright (C) 2016 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 
     17 package com.android.launcher3.dynamicui;
     18 
     19 import android.annotation.TargetApi;
     20 import android.app.WallpaperManager;
     21 import android.app.job.JobInfo;
     22 import android.app.job.JobScheduler;
     23 import android.content.ComponentName;
     24 import android.content.Context;
     25 import android.content.SharedPreferences;
     26 import android.graphics.Color;
     27 import android.os.Build;
     28 import android.support.v4.graphics.ColorUtils;
     29 import android.support.v7.graphics.Palette;
     30 
     31 import com.android.launcher3.Utilities;
     32 import com.android.launcher3.config.FeatureFlags;
     33 
     34 import java.util.List;
     35 
     36 /**
     37  * Contains helper fields and methods related to extracting colors from the wallpaper.
     38  */
     39 public class ExtractionUtils {
     40     public static final String EXTRACTED_COLORS_PREFERENCE_KEY = "pref_extractedColors";
     41     public static final String WALLPAPER_ID_PREFERENCE_KEY = "pref_wallpaperId";
     42 
     43     private static final float MIN_CONTRAST_RATIO = 2f;
     44 
     45     /**
     46      * Extract colors in the :wallpaper-chooser process, if the wallpaper id has changed.
     47      * When the new colors are saved in the LauncherProvider,
     48      * Launcher will be notified in Launcher#onSettingsChanged(String, String).
     49      */
     50     public static void startColorExtractionServiceIfNecessary(final Context context) {
     51         if (FeatureFlags.LAUNCHER3_GRADIENT_ALL_APPS) {
     52             return;
     53         }
     54         // Run on a background thread, since the service is asynchronous anyway.
     55         Utilities.THREAD_POOL_EXECUTOR.execute(new Runnable() {
     56             @Override
     57             public void run() {
     58                 if (hasWallpaperIdChanged(context)) {
     59                     startColorExtractionService(context);
     60                 }
     61             }
     62         });
     63     }
     64 
     65     /** Starts the {@link ColorExtractionService} without checking the wallpaper id */
     66     public static void startColorExtractionService(Context context) {
     67         if (FeatureFlags.LAUNCHER3_GRADIENT_ALL_APPS) {
     68             return;
     69         }
     70         JobScheduler jobScheduler = (JobScheduler) context.getSystemService(
     71                 Context.JOB_SCHEDULER_SERVICE);
     72         jobScheduler.schedule(new JobInfo.Builder(Utilities.COLOR_EXTRACTION_JOB_ID,
     73                 new ComponentName(context, ColorExtractionService.class))
     74                 .setMinimumLatency(0).build());
     75     }
     76 
     77     private static boolean hasWallpaperIdChanged(Context context) {
     78         if (!Utilities.ATLEAST_NOUGAT) {
     79             // TODO: update an id in sharedprefs in onWallpaperChanged broadcast, and read it here.
     80             return false;
     81         }
     82         final SharedPreferences sharedPrefs = Utilities.getPrefs(context);
     83         int wallpaperId = getWallpaperId(WallpaperManager.getInstance(context));
     84         int savedWallpaperId = sharedPrefs.getInt(ExtractionUtils.WALLPAPER_ID_PREFERENCE_KEY, -1);
     85         return wallpaperId != savedWallpaperId;
     86     }
     87 
     88     @TargetApi(Build.VERSION_CODES.N)
     89     public static int getWallpaperId(WallpaperManager wallpaperManager) {
     90         return Utilities.ATLEAST_NOUGAT ?
     91                 wallpaperManager.getWallpaperId(WallpaperManager.FLAG_SYSTEM) : -1;
     92     }
     93 
     94     public static boolean isSuperLight(Palette p) {
     95         return !isLegibleOnWallpaper(Color.WHITE, p.getSwatches());
     96     }
     97 
     98     public static boolean isSuperDark(Palette p) {
     99         return !isLegibleOnWallpaper(Color.BLACK, p.getSwatches());
    100     }
    101 
    102     /**
    103      * Given a color, returns true if that color is legible on
    104      * the given wallpaper color swatches, else returns false.
    105      */
    106     private static boolean isLegibleOnWallpaper(int color, List<Palette.Swatch> wallpaperSwatches) {
    107         int legiblePopulation = 0;
    108         int illegiblePopulation = 0;
    109         for (Palette.Swatch swatch : wallpaperSwatches) {
    110             if (isLegible(color, swatch.getRgb())) {
    111                 legiblePopulation += swatch.getPopulation();
    112             } else {
    113                 illegiblePopulation += swatch.getPopulation();
    114             }
    115         }
    116         return legiblePopulation > illegiblePopulation;
    117     }
    118 
    119     /** @return Whether the foreground color is legible on the background color. */
    120     private static boolean isLegible(int foreground, int background) {
    121         background = ColorUtils.setAlphaComponent(background, 255);
    122         return ColorUtils.calculateContrast(foreground, background) >= MIN_CONTRAST_RATIO;
    123     }
    124 
    125 }
    126