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      1 /*
      2  * Copyright (C) 2008 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;
     18 
     19 import android.app.WallpaperManager;
     20 import android.content.ComponentName;
     21 import android.content.Context;
     22 import android.content.Intent;
     23 import android.content.SharedPreferences;
     24 import android.content.pm.ApplicationInfo;
     25 import android.content.pm.PackageInfo;
     26 import android.content.pm.PackageManager;
     27 import android.content.pm.PackageManager.NameNotFoundException;
     28 import android.content.pm.ResolveInfo;
     29 import android.content.res.Resources;
     30 import android.graphics.Bitmap;
     31 import android.graphics.Color;
     32 import android.graphics.Matrix;
     33 import android.graphics.Paint;
     34 import android.graphics.Rect;
     35 import android.os.Build;
     36 import android.os.Bundle;
     37 import android.os.DeadObjectException;
     38 import android.os.PowerManager;
     39 import android.os.TransactionTooLargeException;
     40 import android.support.v4.os.BuildCompat;
     41 import android.text.Spannable;
     42 import android.text.SpannableString;
     43 import android.text.TextUtils;
     44 import android.text.style.TtsSpan;
     45 import android.util.DisplayMetrics;
     46 import android.util.Log;
     47 import android.util.Pair;
     48 import android.util.SparseArray;
     49 import android.util.TypedValue;
     50 import android.view.View;
     51 import android.view.accessibility.AccessibilityEvent;
     52 import android.view.accessibility.AccessibilityManager;
     53 
     54 import com.android.launcher3.config.ProviderConfig;
     55 
     56 import java.io.ByteArrayOutputStream;
     57 import java.io.Closeable;
     58 import java.io.IOException;
     59 import java.lang.reflect.InvocationTargetException;
     60 import java.lang.reflect.Method;
     61 import java.util.Collection;
     62 import java.util.HashSet;
     63 import java.util.Locale;
     64 import java.util.concurrent.Executor;
     65 import java.util.concurrent.LinkedBlockingQueue;
     66 import java.util.concurrent.ThreadPoolExecutor;
     67 import java.util.concurrent.TimeUnit;
     68 import java.util.regex.Matcher;
     69 import java.util.regex.Pattern;
     70 
     71 /**
     72  * Various utilities shared amongst the Launcher's classes.
     73  */
     74 public final class Utilities {
     75 
     76     private static final String TAG = "Launcher.Utilities";
     77 
     78     private static final Pattern sTrimPattern =
     79             Pattern.compile("^[\\s|\\p{javaSpaceChar}]*(.*)[\\s|\\p{javaSpaceChar}]*$");
     80 
     81     private static final int[] sLoc0 = new int[2];
     82     private static final int[] sLoc1 = new int[2];
     83     private static final float[] sPoint = new float[2];
     84     private static final Matrix sMatrix = new Matrix();
     85     private static final Matrix sInverseMatrix = new Matrix();
     86 
     87     public static boolean isAtLeastO() {
     88         return BuildCompat.isAtLeastO();
     89     }
     90 
     91     public static final boolean ATLEAST_NOUGAT_MR1 =
     92         Build.VERSION.SDK_INT >= Build.VERSION_CODES.N_MR1;
     93 
     94     public static final boolean ATLEAST_NOUGAT =
     95         Build.VERSION.SDK_INT >= Build.VERSION_CODES.N;
     96 
     97     public static final boolean ATLEAST_MARSHMALLOW =
     98             Build.VERSION.SDK_INT >= Build.VERSION_CODES.M;
     99 
    100     public static final boolean ATLEAST_LOLLIPOP_MR1 =
    101             Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1;
    102 
    103     /**
    104      * Indicates if the device has a debug build. Should only be used to store additional info or
    105      * add extra logging and not for changing the app behavior.
    106      */
    107     public static final boolean IS_DEBUG_DEVICE = Build.TYPE.toLowerCase().contains("debug");
    108 
    109     // An intent extra to indicate the horizontal scroll of the wallpaper.
    110     public static final String EXTRA_WALLPAPER_OFFSET = "com.android.launcher3.WALLPAPER_OFFSET";
    111 
    112     public static final int COLOR_EXTRACTION_JOB_ID = 1;
    113 
    114     // These values are same as that in {@link AsyncTask}.
    115     private static final int CPU_COUNT = Runtime.getRuntime().availableProcessors();
    116     private static final int CORE_POOL_SIZE = CPU_COUNT + 1;
    117     private static final int MAXIMUM_POOL_SIZE = CPU_COUNT * 2 + 1;
    118     private static final int KEEP_ALIVE = 1;
    119     /**
    120      * An {@link Executor} to be used with async task with no limit on the queue size.
    121      */
    122     public static final Executor THREAD_POOL_EXECUTOR = new ThreadPoolExecutor(
    123             CORE_POOL_SIZE, MAXIMUM_POOL_SIZE, KEEP_ALIVE,
    124             TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>());
    125 
    126     public static final String ALLOW_ROTATION_PREFERENCE_KEY = "pref_allowRotation";
    127 
    128     public static boolean isPropertyEnabled(String propertyName) {
    129         return Log.isLoggable(propertyName, Log.VERBOSE);
    130     }
    131 
    132     public static boolean isAllowRotationPrefEnabled(Context context) {
    133         return getPrefs(context).getBoolean(ALLOW_ROTATION_PREFERENCE_KEY,
    134                 getAllowRotationDefaultValue(context));
    135     }
    136 
    137     public static boolean getAllowRotationDefaultValue(Context context) {
    138         if (ATLEAST_NOUGAT) {
    139             // If the device was scaled, used the original dimensions to determine if rotation
    140             // is allowed of not.
    141             Resources res = context.getResources();
    142             int originalSmallestWidth = res.getConfiguration().smallestScreenWidthDp
    143                     * res.getDisplayMetrics().densityDpi / DisplayMetrics.DENSITY_DEVICE_STABLE;
    144             return originalSmallestWidth >= 600;
    145         }
    146         return false;
    147     }
    148 
    149     /**
    150      * Given a coordinate relative to the descendant, find the coordinate in a parent view's
    151      * coordinates.
    152      *
    153      * @param descendant The descendant to which the passed coordinate is relative.
    154      * @param ancestor The root view to make the coordinates relative to.
    155      * @param coord The coordinate that we want mapped.
    156      * @param includeRootScroll Whether or not to account for the scroll of the descendant:
    157      *          sometimes this is relevant as in a child's coordinates within the descendant.
    158      * @return The factor by which this descendant is scaled relative to this DragLayer. Caution
    159      *         this scale factor is assumed to be equal in X and Y, and so if at any point this
    160      *         assumption fails, we will need to return a pair of scale factors.
    161      */
    162     public static float getDescendantCoordRelativeToAncestor(
    163             View descendant, View ancestor, int[] coord, boolean includeRootScroll) {
    164         sPoint[0] = coord[0];
    165         sPoint[1] = coord[1];
    166 
    167         float scale = 1.0f;
    168         View v = descendant;
    169         while(v != ancestor && v != null) {
    170             // For TextViews, scroll has a meaning which relates to the text position
    171             // which is very strange... ignore the scroll.
    172             if (v != descendant || includeRootScroll) {
    173                 sPoint[0] -= v.getScrollX();
    174                 sPoint[1] -= v.getScrollY();
    175             }
    176 
    177             v.getMatrix().mapPoints(sPoint);
    178             sPoint[0] += v.getLeft();
    179             sPoint[1] += v.getTop();
    180             scale *= v.getScaleX();
    181 
    182             v = (View) v.getParent();
    183         }
    184 
    185         coord[0] = Math.round(sPoint[0]);
    186         coord[1] = Math.round(sPoint[1]);
    187         return scale;
    188     }
    189 
    190     /**
    191      * Inverse of {@link #getDescendantCoordRelativeToAncestor(View, View, int[], boolean)}.
    192      */
    193     public static void mapCoordInSelfToDescendant(View descendant, View root, int[] coord) {
    194         sMatrix.reset();
    195         View v = descendant;
    196         while(v != root) {
    197             sMatrix.postTranslate(-v.getScrollX(), -v.getScrollY());
    198             sMatrix.postConcat(v.getMatrix());
    199             sMatrix.postTranslate(v.getLeft(), v.getTop());
    200             v = (View) v.getParent();
    201         }
    202         sMatrix.postTranslate(-v.getScrollX(), -v.getScrollY());
    203         sMatrix.invert(sInverseMatrix);
    204 
    205         sPoint[0] = coord[0];
    206         sPoint[1] = coord[1];
    207         sInverseMatrix.mapPoints(sPoint);
    208         coord[0] = Math.round(sPoint[0]);
    209         coord[1] = Math.round(sPoint[1]);
    210     }
    211 
    212     /**
    213      * Utility method to determine whether the given point, in local coordinates,
    214      * is inside the view, where the area of the view is expanded by the slop factor.
    215      * This method is called while processing touch-move events to determine if the event
    216      * is still within the view.
    217      */
    218     public static boolean pointInView(View v, float localX, float localY, float slop) {
    219         return localX >= -slop && localY >= -slop && localX < (v.getWidth() + slop) &&
    220                 localY < (v.getHeight() + slop);
    221     }
    222 
    223     public static int[] getCenterDeltaInScreenSpace(View v0, View v1) {
    224         v0.getLocationInWindow(sLoc0);
    225         v1.getLocationInWindow(sLoc1);
    226 
    227         sLoc0[0] += (v0.getMeasuredWidth() * v0.getScaleX()) / 2;
    228         sLoc0[1] += (v0.getMeasuredHeight() * v0.getScaleY()) / 2;
    229         sLoc1[0] += (v1.getMeasuredWidth() * v1.getScaleX()) / 2;
    230         sLoc1[1] += (v1.getMeasuredHeight() * v1.getScaleY()) / 2;
    231         return new int[] {sLoc1[0] - sLoc0[0], sLoc1[1] - sLoc0[1]};
    232     }
    233 
    234     public static void scaleRectAboutCenter(Rect r, float scale) {
    235         if (scale != 1.0f) {
    236             int cx = r.centerX();
    237             int cy = r.centerY();
    238             r.offset(-cx, -cy);
    239 
    240             r.left = (int) (r.left * scale + 0.5f);
    241             r.top = (int) (r.top * scale + 0.5f);
    242             r.right = (int) (r.right * scale + 0.5f);
    243             r.bottom = (int) (r.bottom * scale + 0.5f);
    244 
    245             r.offset(cx, cy);
    246         }
    247     }
    248 
    249     public static float shrinkRect(Rect r, float scaleX, float scaleY) {
    250         float scale = Math.min(Math.min(scaleX, scaleY), 1.0f);
    251         if (scale < 1.0f) {
    252             int deltaX = (int) (r.width() * (scaleX - scale) * 0.5f);
    253             r.left += deltaX;
    254             r.right -= deltaX;
    255 
    256             int deltaY = (int) (r.height() * (scaleY - scale) * 0.5f);
    257             r.top += deltaY;
    258             r.bottom -= deltaY;
    259         }
    260         return scale;
    261     }
    262 
    263     static boolean isSystemApp(Context context, Intent intent) {
    264         PackageManager pm = context.getPackageManager();
    265         ComponentName cn = intent.getComponent();
    266         String packageName = null;
    267         if (cn == null) {
    268             ResolveInfo info = pm.resolveActivity(intent, PackageManager.MATCH_DEFAULT_ONLY);
    269             if ((info != null) && (info.activityInfo != null)) {
    270                 packageName = info.activityInfo.packageName;
    271             }
    272         } else {
    273             packageName = cn.getPackageName();
    274         }
    275         if (packageName != null) {
    276             try {
    277                 PackageInfo info = pm.getPackageInfo(packageName, 0);
    278                 return (info != null) && (info.applicationInfo != null) &&
    279                         ((info.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0);
    280             } catch (NameNotFoundException e) {
    281                 return false;
    282             }
    283         } else {
    284             return false;
    285         }
    286     }
    287 
    288     /**
    289      * This picks a dominant color, looking for high-saturation, high-value, repeated hues.
    290      * @param bitmap The bitmap to scan
    291      * @param samples The approximate max number of samples to use.
    292      */
    293     public static int findDominantColorByHue(Bitmap bitmap, int samples) {
    294         final int height = bitmap.getHeight();
    295         final int width = bitmap.getWidth();
    296         int sampleStride = (int) Math.sqrt((height * width) / samples);
    297         if (sampleStride < 1) {
    298             sampleStride = 1;
    299         }
    300 
    301         // This is an out-param, for getting the hsv values for an rgb
    302         float[] hsv = new float[3];
    303 
    304         // First get the best hue, by creating a histogram over 360 hue buckets,
    305         // where each pixel contributes a score weighted by saturation, value, and alpha.
    306         float[] hueScoreHistogram = new float[360];
    307         float highScore = -1;
    308         int bestHue = -1;
    309 
    310         for (int y = 0; y < height; y += sampleStride) {
    311             for (int x = 0; x < width; x += sampleStride) {
    312                 int argb = bitmap.getPixel(x, y);
    313                 int alpha = 0xFF & (argb >> 24);
    314                 if (alpha < 0x80) {
    315                     // Drop mostly-transparent pixels.
    316                     continue;
    317                 }
    318                 // Remove the alpha channel.
    319                 int rgb = argb | 0xFF000000;
    320                 Color.colorToHSV(rgb, hsv);
    321                 // Bucket colors by the 360 integer hues.
    322                 int hue = (int) hsv[0];
    323                 if (hue < 0 || hue >= hueScoreHistogram.length) {
    324                     // Defensively avoid array bounds violations.
    325                     continue;
    326                 }
    327                 float score = hsv[1] * hsv[2];
    328                 hueScoreHistogram[hue] += score;
    329                 if (hueScoreHistogram[hue] > highScore) {
    330                     highScore = hueScoreHistogram[hue];
    331                     bestHue = hue;
    332                 }
    333             }
    334         }
    335 
    336         SparseArray<Float> rgbScores = new SparseArray<Float>();
    337         int bestColor = 0xff000000;
    338         highScore = -1;
    339         // Go back over the RGB colors that match the winning hue,
    340         // creating a histogram of weighted s*v scores, for up to 100*100 [s,v] buckets.
    341         // The highest-scoring RGB color wins.
    342         for (int y = 0; y < height; y += sampleStride) {
    343             for (int x = 0; x < width; x += sampleStride) {
    344                 int rgb = bitmap.getPixel(x, y) | 0xff000000;
    345                 Color.colorToHSV(rgb, hsv);
    346                 int hue = (int) hsv[0];
    347                 if (hue == bestHue) {
    348                     float s = hsv[1];
    349                     float v = hsv[2];
    350                     int bucket = (int) (s * 100) + (int) (v * 10000);
    351                     // Score by cumulative saturation * value.
    352                     float score = s * v;
    353                     Float oldTotal = rgbScores.get(bucket);
    354                     float newTotal = oldTotal == null ? score : oldTotal + score;
    355                     rgbScores.put(bucket, newTotal);
    356                     if (newTotal > highScore) {
    357                         highScore = newTotal;
    358                         // All the colors in the winning bucket are very similar. Last in wins.
    359                         bestColor = rgb;
    360                     }
    361                 }
    362             }
    363         }
    364         return bestColor;
    365     }
    366 
    367     /*
    368      * Finds a system apk which had a broadcast receiver listening to a particular action.
    369      * @param action intent action used to find the apk
    370      * @return a pair of apk package name and the resources.
    371      */
    372     static Pair<String, Resources> findSystemApk(String action, PackageManager pm) {
    373         final Intent intent = new Intent(action);
    374         for (ResolveInfo info : pm.queryBroadcastReceivers(intent, 0)) {
    375             if (info.activityInfo != null &&
    376                     (info.activityInfo.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0) {
    377                 final String packageName = info.activityInfo.packageName;
    378                 try {
    379                     final Resources res = pm.getResourcesForApplication(packageName);
    380                     return Pair.create(packageName, res);
    381                 } catch (NameNotFoundException e) {
    382                     Log.w(TAG, "Failed to find resources for " + packageName);
    383                 }
    384             }
    385         }
    386         return null;
    387     }
    388 
    389     /**
    390      * Compresses the bitmap to a byte array for serialization.
    391      */
    392     public static byte[] flattenBitmap(Bitmap bitmap) {
    393         // Try go guesstimate how much space the icon will take when serialized
    394         // to avoid unnecessary allocations/copies during the write.
    395         int size = bitmap.getWidth() * bitmap.getHeight() * 4;
    396         ByteArrayOutputStream out = new ByteArrayOutputStream(size);
    397         try {
    398             bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
    399             out.flush();
    400             out.close();
    401             return out.toByteArray();
    402         } catch (IOException e) {
    403             Log.w(TAG, "Could not write bitmap");
    404             return null;
    405         }
    406     }
    407 
    408     /**
    409      * Trims the string, removing all whitespace at the beginning and end of the string.
    410      * Non-breaking whitespaces are also removed.
    411      */
    412     public static String trim(CharSequence s) {
    413         if (s == null) {
    414             return null;
    415         }
    416 
    417         // Just strip any sequence of whitespace or java space characters from the beginning and end
    418         Matcher m = sTrimPattern.matcher(s);
    419         return m.replaceAll("$1");
    420     }
    421 
    422     /**
    423      * Calculates the height of a given string at a specific text size.
    424      */
    425     public static int calculateTextHeight(float textSizePx) {
    426         Paint p = new Paint();
    427         p.setTextSize(textSizePx);
    428         Paint.FontMetrics fm = p.getFontMetrics();
    429         return (int) Math.ceil(fm.bottom - fm.top);
    430     }
    431 
    432     /**
    433      * Convenience println with multiple args.
    434      */
    435     public static void println(String key, Object... args) {
    436         StringBuilder b = new StringBuilder();
    437         b.append(key);
    438         b.append(": ");
    439         boolean isFirstArgument = true;
    440         for (Object arg : args) {
    441             if (isFirstArgument) {
    442                 isFirstArgument = false;
    443             } else {
    444                 b.append(", ");
    445             }
    446             b.append(arg);
    447         }
    448         System.out.println(b.toString());
    449     }
    450 
    451     public static boolean isRtl(Resources res) {
    452         return res.getConfiguration().getLayoutDirection() == View.LAYOUT_DIRECTION_RTL;
    453     }
    454 
    455     /**
    456      * Returns true if the intent is a valid launch intent for a launcher activity of an app.
    457      * This is used to identify shortcuts which are different from the ones exposed by the
    458      * applications' manifest file.
    459      *
    460      * @param launchIntent The intent that will be launched when the shortcut is clicked.
    461      */
    462     public static boolean isLauncherAppTarget(Intent launchIntent) {
    463         if (launchIntent != null
    464                 && Intent.ACTION_MAIN.equals(launchIntent.getAction())
    465                 && launchIntent.getComponent() != null
    466                 && launchIntent.getCategories() != null
    467                 && launchIntent.getCategories().size() == 1
    468                 && launchIntent.hasCategory(Intent.CATEGORY_LAUNCHER)
    469                 && TextUtils.isEmpty(launchIntent.getDataString())) {
    470             // An app target can either have no extra or have ItemInfo.EXTRA_PROFILE.
    471             Bundle extras = launchIntent.getExtras();
    472             return extras == null || extras.keySet().isEmpty();
    473         }
    474         return false;
    475     }
    476 
    477     public static float dpiFromPx(int size, DisplayMetrics metrics){
    478         float densityRatio = (float) metrics.densityDpi / DisplayMetrics.DENSITY_DEFAULT;
    479         return (size / densityRatio);
    480     }
    481     public static int pxFromDp(float size, DisplayMetrics metrics) {
    482         return (int) Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
    483                 size, metrics));
    484     }
    485     public static int pxFromSp(float size, DisplayMetrics metrics) {
    486         return (int) Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,
    487                 size, metrics));
    488     }
    489 
    490     public static String createDbSelectionQuery(String columnName, Iterable<?> values) {
    491         return String.format(Locale.ENGLISH, "%s IN (%s)", columnName, TextUtils.join(", ", values));
    492     }
    493 
    494     public static boolean isBootCompleted() {
    495         return "1".equals(getSystemProperty("sys.boot_completed", "1"));
    496     }
    497 
    498     public static String getSystemProperty(String property, String defaultValue) {
    499         try {
    500             Class clazz = Class.forName("android.os.SystemProperties");
    501             Method getter = clazz.getDeclaredMethod("get", String.class);
    502             String value = (String) getter.invoke(null, property);
    503             if (!TextUtils.isEmpty(value)) {
    504                 return value;
    505             }
    506         } catch (Exception e) {
    507             Log.d(TAG, "Unable to read system properties");
    508         }
    509         return defaultValue;
    510     }
    511 
    512     /**
    513      * Ensures that a value is within given bounds. Specifically:
    514      * If value is less than lowerBound, return lowerBound; else if value is greater than upperBound,
    515      * return upperBound; else return value unchanged.
    516      */
    517     public static int boundToRange(int value, int lowerBound, int upperBound) {
    518         return Math.max(lowerBound, Math.min(value, upperBound));
    519     }
    520 
    521     /**
    522      * @see #boundToRange(int, int, int).
    523      */
    524     public static float boundToRange(float value, float lowerBound, float upperBound) {
    525         return Math.max(lowerBound, Math.min(value, upperBound));
    526     }
    527 
    528     /**
    529      * Wraps a message with a TTS span, so that a different message is spoken than
    530      * what is getting displayed.
    531      * @param msg original message
    532      * @param ttsMsg message to be spoken
    533      */
    534     public static CharSequence wrapForTts(CharSequence msg, String ttsMsg) {
    535         SpannableString spanned = new SpannableString(msg);
    536         spanned.setSpan(new TtsSpan.TextBuilder(ttsMsg).build(),
    537                 0, spanned.length(), Spannable.SPAN_INCLUSIVE_INCLUSIVE);
    538         return spanned;
    539     }
    540 
    541     /**
    542      * Replacement for Long.compare() which was added in API level 19.
    543      */
    544     public static int longCompare(long lhs, long rhs) {
    545         return lhs < rhs ? -1 : (lhs == rhs ? 0 : 1);
    546     }
    547 
    548     public static SharedPreferences getPrefs(Context context) {
    549         return context.getSharedPreferences(
    550                 LauncherFiles.SHARED_PREFERENCES_KEY, Context.MODE_PRIVATE);
    551     }
    552 
    553     public static boolean isPowerSaverOn(Context context) {
    554         PowerManager powerManager = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
    555         return powerManager.isPowerSaveMode();
    556     }
    557 
    558     public static boolean isWallpaperAllowed(Context context) {
    559         if (ATLEAST_NOUGAT) {
    560             try {
    561                 WallpaperManager wm = context.getSystemService(WallpaperManager.class);
    562                 return (Boolean) wm.getClass().getDeclaredMethod("isSetWallpaperAllowed")
    563                         .invoke(wm);
    564             } catch (Exception e) { }
    565         }
    566         return true;
    567     }
    568 
    569     public static void closeSilently(Closeable c) {
    570         if (c != null) {
    571             try {
    572                 c.close();
    573             } catch (IOException e) {
    574                 if (ProviderConfig.IS_DOGFOOD_BUILD) {
    575                     Log.d(TAG, "Error closing", e);
    576                 }
    577             }
    578         }
    579     }
    580 
    581     /**
    582      * Returns true if {@param original} contains all entries defined in {@param updates} and
    583      * have the same value.
    584      * The comparison uses {@link Object#equals(Object)} to compare the values.
    585      */
    586     public static boolean containsAll(Bundle original, Bundle updates) {
    587         for (String key : updates.keySet()) {
    588             Object value1 = updates.get(key);
    589             Object value2 = original.get(key);
    590             if (value1 == null) {
    591                 if (value2 != null) {
    592                     return false;
    593                 }
    594             } else if (!value1.equals(value2)) {
    595                 return false;
    596             }
    597         }
    598         return true;
    599     }
    600 
    601     /** Returns whether the collection is null or empty. */
    602     public static boolean isEmpty(Collection c) {
    603         return c == null || c.isEmpty();
    604     }
    605 
    606     public static void sendCustomAccessibilityEvent(View target, int type, String text) {
    607         AccessibilityManager accessibilityManager = (AccessibilityManager)
    608                 target.getContext().getSystemService(Context.ACCESSIBILITY_SERVICE);
    609         if (accessibilityManager.isEnabled()) {
    610             AccessibilityEvent event = AccessibilityEvent.obtain(type);
    611             target.onInitializeAccessibilityEvent(event);
    612             event.getText().add(text);
    613             accessibilityManager.sendAccessibilityEvent(event);
    614         }
    615     }
    616 
    617     public static boolean isBinderSizeError(Exception e) {
    618         return e.getCause() instanceof TransactionTooLargeException
    619                 || e.getCause() instanceof DeadObjectException;
    620     }
    621 
    622     public static <T> T getOverrideObject(Class<T> clazz, Context context, int resId) {
    623         String className = context.getString(resId);
    624         if (!TextUtils.isEmpty(className)) {
    625             try {
    626                 Class<?> cls = Class.forName(className);
    627                 return (T) cls.getDeclaredConstructor(Context.class).newInstance(context);
    628             } catch (ClassNotFoundException | InstantiationException | IllegalAccessException
    629                     | ClassCastException | NoSuchMethodException | InvocationTargetException e) {
    630                 Log.e(TAG, "Bad overriden class", e);
    631             }
    632         }
    633 
    634         try {
    635             return clazz.newInstance();
    636         } catch (InstantiationException|IllegalAccessException e) {
    637             throw new RuntimeException(e);
    638         }
    639     }
    640 
    641     /**
    642      * Returns a HashSet with a single element. We use this instead of Collections.singleton()
    643      * because HashSet ensures all operations, such as remove, are supported.
    644      */
    645     public static <T> HashSet<T> singletonHashSet(T elem) {
    646         HashSet<T> hashSet = new HashSet<>(1);
    647         hashSet.add(elem);
    648         return hashSet;
    649     }
    650 }
    651