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      1 /*
      2  * Copyright (C) 2011 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 androidx.core.app;
     18 
     19 import android.app.Activity;
     20 import android.content.Context;
     21 import android.content.Intent;
     22 import android.content.IntentSender;
     23 import android.content.pm.PackageManager;
     24 import android.graphics.Matrix;
     25 import android.graphics.RectF;
     26 import android.net.Uri;
     27 import android.os.Build;
     28 import android.os.Bundle;
     29 import android.os.Handler;
     30 import android.os.Looper;
     31 import android.os.Parcelable;
     32 import android.view.DragEvent;
     33 import android.view.View;
     34 
     35 import androidx.annotation.IdRes;
     36 import androidx.annotation.IntRange;
     37 import androidx.annotation.NonNull;
     38 import androidx.annotation.Nullable;
     39 import androidx.annotation.RequiresApi;
     40 import androidx.annotation.RestrictTo;
     41 import androidx.core.content.ContextCompat;
     42 import androidx.core.view.DragAndDropPermissionsCompat;
     43 
     44 import java.util.List;
     45 import java.util.Map;
     46 
     47 /**
     48  * Helper for accessing features in {@link android.app.Activity}.
     49  */
     50 public class ActivityCompat extends ContextCompat {
     51 
     52     /**
     53      * This interface is the contract for receiving the results for permission requests.
     54      */
     55     public interface OnRequestPermissionsResultCallback {
     56 
     57         /**
     58          * Callback for the result from requesting permissions. This method
     59          * is invoked for every call on {@link #requestPermissions(android.app.Activity,
     60          * String[], int)}.
     61          * <p>
     62          * <strong>Note:</strong> It is possible that the permissions request interaction
     63          * with the user is interrupted. In this case you will receive empty permissions
     64          * and results arrays which should be treated as a cancellation.
     65          * </p>
     66          *
     67          * @param requestCode The request code passed in {@link #requestPermissions(
     68          * android.app.Activity, String[], int)}
     69          * @param permissions The requested permissions. Never null.
     70          * @param grantResults The grant results for the corresponding permissions
     71          *     which is either {@link android.content.pm.PackageManager#PERMISSION_GRANTED}
     72          *     or {@link android.content.pm.PackageManager#PERMISSION_DENIED}. Never null.
     73          *
     74          * @see #requestPermissions(android.app.Activity, String[], int)
     75          */
     76         void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
     77                 @NonNull int[] grantResults);
     78     }
     79 
     80     /**
     81      * Customizable delegate that allows delegating permission compatibility methods to a custom
     82      * implementation.
     83      *
     84      * <p>
     85      *     To delegate permission compatibility methods to a custom class, implement this interface,
     86      *     and call {@code ActivityCompat.setPermissionCompatDelegate(delegate);}. All future calls
     87      *     to the permission compatibility methods in this class will first check whether the
     88      *     delegate can handle the method call, and invoke the corresponding method if it can.
     89      * </p>
     90      */
     91     public interface PermissionCompatDelegate {
     92 
     93         /**
     94          * Determines whether the delegate should handle
     95          * {@link ActivityCompat#requestPermissions(Activity, String[], int)}, and request
     96          * permissions if applicable. If this method returns true, it means that permission
     97          * request is successfully handled by the delegate, and platform should not perform any
     98          * further requests for permission.
     99          *
    100          * @param activity The target activity.
    101          * @param permissions The requested permissions. Must me non-null and not empty.
    102          * @param requestCode Application specific request code to match with a result reported to
    103          *    {@link
    104          *    OnRequestPermissionsResultCallback#onRequestPermissionsResult(int, String[], int[])}.
    105          *    Should be >= 0.
    106          *
    107          * @return Whether the delegate has handled the permission request.
    108          * @see ActivityCompat#requestPermissions(Activity, String[], int)
    109          */
    110         boolean requestPermissions(@NonNull Activity activity,
    111                 @NonNull String[] permissions, @IntRange(from = 0) int requestCode);
    112 
    113         /**
    114          * Determines whether the delegate should handle the permission request as part of
    115          * {@code FragmentActivity#onActivityResult(int, int, Intent)}. If this method returns true,
    116          * it means that activity result is successfully handled by the delegate, and no further
    117          * action is needed on this activity result.
    118          *
    119          * @param activity    The target Activity.
    120          * @param requestCode The integer request code originally supplied to
    121          *                    {@code startActivityForResult()}, allowing you to identify who this
    122          *                    result came from.
    123          * @param resultCode  The integer result code returned by the child activity
    124          *                    through its {@code }setResult()}.
    125          * @param data        An Intent, which can return result data to the caller
    126          *                    (various data can be attached to Intent "extras").
    127          *
    128          * @return Whether the delegate has handled the activity result.
    129          * @see ActivityCompat#requestPermissions(Activity, String[], int)
    130          */
    131         boolean onActivityResult(@NonNull Activity activity,
    132                 @IntRange(from = 0) int requestCode, int resultCode, @Nullable Intent data);
    133     }
    134 
    135     /**
    136      * @hide
    137      */
    138     @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
    139     public interface RequestPermissionsRequestCodeValidator {
    140         void validateRequestPermissionsRequestCode(int requestCode);
    141     }
    142 
    143     private static PermissionCompatDelegate sDelegate;
    144 
    145     /**
    146      * This class should not be instantiated, but the constructor must be
    147      * visible for the class to be extended (as in support-v13).
    148      */
    149     protected ActivityCompat() {
    150         // Not publicly instantiable, but may be extended.
    151     }
    152 
    153     /**
    154      * Sets the permission delegate for {@code ActivityCompat}. Replaces the previously set
    155      * delegate.
    156      *
    157      * @param delegate The delegate to be set. {@code null} to clear the set delegate.
    158      */
    159     public static void setPermissionCompatDelegate(
    160             @Nullable PermissionCompatDelegate delegate) {
    161         sDelegate = delegate;
    162     }
    163 
    164     /**
    165      * @hide
    166      */
    167     @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
    168     public static PermissionCompatDelegate getPermissionCompatDelegate() {
    169         return sDelegate;
    170     }
    171 
    172     /**
    173      * Invalidate the activity's options menu, if able.
    174      *
    175      * <p>Before API level 11 (Android 3.0/Honeycomb) the lifecycle of the
    176      * options menu was controlled primarily by the user's operation of
    177      * the hardware menu key. When the user presses down on the menu key
    178      * for the first time the menu was created and prepared by calls
    179      * to {@link Activity#onCreateOptionsMenu(android.view.Menu)} and
    180      * {@link Activity#onPrepareOptionsMenu(android.view.Menu)} respectively.
    181      * Subsequent presses of the menu key kept the existing instance of the
    182      * Menu itself and called {@link Activity#onPrepareOptionsMenu(android.view.Menu)}
    183      * to give the activity an opportunity to contextually alter the menu
    184      * before the menu panel was shown.</p>
    185      *
    186      * <p>In Android 3.0+ the Action Bar forces the options menu to be built early
    187      * so that items chosen to show as actions may be displayed when the activity
    188      * first becomes visible. The Activity method invalidateOptionsMenu forces
    189      * the entire menu to be destroyed and recreated from
    190      * {@link Activity#onCreateOptionsMenu(android.view.Menu)}, offering a similar
    191      * though heavier-weight opportunity to change the menu's contents. Normally
    192      * this functionality is used to support a changing configuration of Fragments.</p>
    193      *
    194      * <p>Applications may use this support helper to signal a significant change in
    195      * activity state that should cause the options menu to be rebuilt. If the app
    196      * is running on an older platform version that does not support menu invalidation
    197      * the app will still receive {@link Activity#onPrepareOptionsMenu(android.view.Menu)}
    198      * the next time the user presses the menu key and this method will return false.
    199      * If this method returns true the options menu was successfully invalidated.</p>
    200      *
    201      * @param activity Invalidate the options menu of this activity
    202      * @return true if this operation was supported and it completed; false if it was not available.
    203      * @deprecated Use {@link Activity#invalidateOptionsMenu()} directly.
    204      */
    205     @Deprecated
    206     public static boolean invalidateOptionsMenu(Activity activity) {
    207         activity.invalidateOptionsMenu();
    208         return true;
    209     }
    210 
    211     /**
    212      * Start new activity with options, if able, for which you would like a
    213      * result when it finished.
    214      *
    215      * <p>In Android 4.1+ additional options were introduced to allow for more
    216      * control on activity launch animations. Applications can use this method
    217      * along with {@link ActivityOptionsCompat} to use these animations when
    218      * available. When run on versions of the platform where this feature does
    219      * not exist the activity will be launched normally.</p>
    220      *
    221      * @param activity Origin activity to launch from.
    222      * @param intent The description of the activity to start.
    223      * @param requestCode If >= 0, this code will be returned in
    224      *                   onActivityResult() when the activity exits.
    225      * @param options Additional options for how the Activity should be started.
    226      *                May be null if there are no options. See
    227      *                {@link ActivityOptionsCompat} for how to build the Bundle
    228      *                supplied here; there are no supported definitions for
    229      *                building it manually.
    230      */
    231     public static void startActivityForResult(@NonNull Activity activity, @NonNull Intent intent,
    232             int requestCode, @Nullable Bundle options) {
    233         if (Build.VERSION.SDK_INT >= 16) {
    234             activity.startActivityForResult(intent, requestCode, options);
    235         } else {
    236             activity.startActivityForResult(intent, requestCode);
    237         }
    238     }
    239 
    240     /**
    241      * Start new IntentSender with options, if able, for which you would like a
    242      * result when it finished.
    243      *
    244      * <p>In Android 4.1+ additional options were introduced to allow for more
    245      * control on activity launch animations. Applications can use this method
    246      * along with {@link ActivityOptionsCompat} to use these animations when
    247      * available. When run on versions of the platform where this feature does
    248      * not exist the activity will be launched normally.</p>
    249      *
    250      * @param activity Origin activity to launch from.
    251      * @param intent The IntentSender to launch.
    252      * @param requestCode If >= 0, this code will be returned in
    253      *                   onActivityResult() when the activity exits.
    254      * @param fillInIntent If non-null, this will be provided as the
    255      *                     intent parameter to {@link IntentSender#sendIntent}.
    256      * @param flagsMask Intent flags in the original IntentSender that you
    257      *                  would like to change.
    258      * @param flagsValues Desired values for any bits set in <var>flagsMask</var>
    259      * @param extraFlags Always set to 0.
    260      * @param options Additional options for how the Activity should be started.
    261      *                May be null if there are no options. See
    262      *                {@link ActivityOptionsCompat} for how to build the Bundle
    263      *                supplied here; there are no supported definitions for
    264      *                building it manually.
    265      */
    266     public static void startIntentSenderForResult(@NonNull Activity activity,
    267             @NonNull IntentSender intent, int requestCode, @Nullable Intent fillInIntent,
    268             int flagsMask, int flagsValues, int extraFlags, @Nullable Bundle options)
    269             throws IntentSender.SendIntentException {
    270         if (Build.VERSION.SDK_INT >= 16) {
    271             activity.startIntentSenderForResult(intent, requestCode, fillInIntent, flagsMask,
    272                     flagsValues, extraFlags, options);
    273         } else {
    274             activity.startIntentSenderForResult(intent, requestCode, fillInIntent, flagsMask,
    275                     flagsValues, extraFlags);
    276         }
    277     }
    278 
    279     /**
    280      * Finish this activity, and tries to finish all activities immediately below it
    281      * in the current task that have the same affinity.
    282      *
    283      * <p>On Android 4.1+ calling this method will call through to the native version of this
    284      * method. For other platforms {@link Activity#finish()} will be called instead.</p>
    285      */
    286     public static void finishAffinity(@NonNull Activity activity) {
    287         if (Build.VERSION.SDK_INT >= 16) {
    288             activity.finishAffinity();
    289         } else {
    290             activity.finish();
    291         }
    292     }
    293 
    294     /**
    295      * Reverses the Activity Scene entry Transition and triggers the calling Activity
    296      * to reverse its exit Transition. When the exit Transition completes,
    297      * {@link Activity#finish()} is called. If no entry Transition was used, finish() is called
    298      * immediately and the Activity exit Transition is run.
    299      *
    300      * <p>On Android 4.4 or lower, this method only finishes the Activity with no
    301      * special exit transition.</p>
    302      */
    303     public static void finishAfterTransition(@NonNull Activity activity) {
    304         if (Build.VERSION.SDK_INT >= 21) {
    305             activity.finishAfterTransition();
    306         } else {
    307             activity.finish();
    308         }
    309     }
    310 
    311     /**
    312      * Return information about who launched this activity.  If the launching Intent
    313      * contains an {@link Intent#EXTRA_REFERRER Intent.EXTRA_REFERRER},
    314      * that will be returned as-is; otherwise, if known, an
    315      * {@link Intent#URI_ANDROID_APP_SCHEME android-app:} referrer URI containing the
    316      * package name that started the Intent will be returned.  This may return null if no
    317      * referrer can be identified -- it is neither explicitly specified, nor is it known which
    318      * application package was involved.
    319      *
    320      * <p>If called while inside the handling of {@link Activity#onNewIntent}, this function will
    321      * return the referrer that submitted that new intent to the activity.  Otherwise, it
    322      * always returns the referrer of the original Intent.</p>
    323      *
    324      * <p>Note that this is <em>not</em> a security feature -- you can not trust the
    325      * referrer information, applications can spoof it.</p>
    326      */
    327     @Nullable
    328     public static Uri getReferrer(@NonNull Activity activity) {
    329         if (Build.VERSION.SDK_INT >= 22) {
    330             return activity.getReferrer();
    331         }
    332         Intent intent = activity.getIntent();
    333         Uri referrer = intent.getParcelableExtra("android.intent.extra.REFERRER");
    334         if (referrer != null) {
    335             return referrer;
    336         }
    337         String referrerName = intent.getStringExtra("android.intent.extra.REFERRER_NAME");
    338         if (referrerName != null) {
    339             return Uri.parse(referrerName);
    340         }
    341         return null;
    342     }
    343 
    344     /**
    345      * Finds a view that was identified by the {@code android:id} XML attribute that was processed
    346      * in {@link Activity#onCreate}, or throws an IllegalArgumentException if the ID is invalid, or
    347      * there is no matching view in the hierarchy.
    348      * <p>
    349      * <strong>Note:</strong> In most cases -- depending on compiler support --
    350      * the resulting view is automatically cast to the target class type. If
    351      * the target class type is unconstrained, an explicit cast may be
    352      * necessary.
    353      *
    354      * @param id the ID to search for
    355      * @return a view with given ID
    356      * @see Activity#findViewById(int)
    357      * @see androidx.core.view.ViewCompat#requireViewById(View, int)
    358      */
    359     @SuppressWarnings("TypeParameterUnusedInFormals")
    360     @NonNull
    361     public static <T extends View> T requireViewById(@NonNull Activity activity, @IdRes int id) {
    362         // TODO: use and link to Activity#requireViewById() directly, once available
    363         T view = activity.findViewById(id);
    364         if (view == null) {
    365             throw new IllegalArgumentException("ID does not reference a View inside this Activity");
    366         }
    367         return view;
    368     }
    369 
    370     /**
    371      * When {@link android.app.ActivityOptions#makeSceneTransitionAnimation(Activity,
    372      * android.view.View, String)} was used to start an Activity, <var>callback</var>
    373      * will be called to handle shared elements on the <i>launched</i> Activity. This requires
    374      * {@link android.view.Window#FEATURE_CONTENT_TRANSITIONS}.
    375      *
    376      * @param callback Used to manipulate shared element transitions on the launched Activity.
    377      */
    378     public static void setEnterSharedElementCallback(@NonNull Activity activity,
    379             @Nullable SharedElementCallback callback) {
    380         if (Build.VERSION.SDK_INT >= 23) {
    381             android.app.SharedElementCallback frameworkCallback = callback != null
    382                     ? new SharedElementCallback23Impl(callback)
    383                     : null;
    384             activity.setEnterSharedElementCallback(frameworkCallback);
    385         } else if (Build.VERSION.SDK_INT >= 21) {
    386             android.app.SharedElementCallback frameworkCallback = callback != null
    387                     ? new SharedElementCallback21Impl(callback)
    388                     : null;
    389             activity.setEnterSharedElementCallback(frameworkCallback);
    390         }
    391     }
    392 
    393     /**
    394      * When {@link android.app.ActivityOptions#makeSceneTransitionAnimation(Activity,
    395      * android.view.View, String)} was used to start an Activity, <var>callback</var>
    396      * will be called to handle shared elements on the <i>launching</i> Activity. Most
    397      * calls will only come when returning from the started Activity.
    398      * This requires {@link android.view.Window#FEATURE_CONTENT_TRANSITIONS}.
    399      *
    400      * @param callback Used to manipulate shared element transitions on the launching Activity.
    401      */
    402     public static void setExitSharedElementCallback(@NonNull Activity activity,
    403             @Nullable SharedElementCallback callback) {
    404         if (Build.VERSION.SDK_INT >= 23) {
    405             android.app.SharedElementCallback frameworkCallback = callback != null
    406                     ? new SharedElementCallback23Impl(callback)
    407                     : null;
    408             activity.setExitSharedElementCallback(frameworkCallback);
    409         } else if (Build.VERSION.SDK_INT >= 21) {
    410             android.app.SharedElementCallback frameworkCallback = callback != null
    411                     ? new SharedElementCallback21Impl(callback)
    412                     : null;
    413             activity.setExitSharedElementCallback(frameworkCallback);
    414         }
    415     }
    416 
    417     public static void postponeEnterTransition(@NonNull Activity activity) {
    418         if (Build.VERSION.SDK_INT >= 21) {
    419             activity.postponeEnterTransition();
    420         }
    421     }
    422 
    423     public static void startPostponedEnterTransition(@NonNull Activity activity) {
    424         if (Build.VERSION.SDK_INT >= 21) {
    425             activity.startPostponedEnterTransition();
    426         }
    427     }
    428 
    429     /**
    430      * Requests permissions to be granted to this application. These permissions
    431      * must be requested in your manifest, they should not be granted to your app,
    432      * and they should have protection level {@link android.content.pm.PermissionInfo
    433      * #PROTECTION_DANGEROUS dangerous}, regardless whether they are declared by
    434      * the platform or a third-party app.
    435      * <p>
    436      * Normal permissions {@link android.content.pm.PermissionInfo#PROTECTION_NORMAL}
    437      * are granted at install time if requested in the manifest. Signature permissions
    438      * {@link android.content.pm.PermissionInfo#PROTECTION_SIGNATURE} are granted at
    439      * install time if requested in the manifest and the signature of your app matches
    440      * the signature of the app declaring the permissions.
    441      * </p>
    442      * <p>
    443      * If your app does not have the requested permissions the user will be presented
    444      * with UI for accepting them. After the user has accepted or rejected the
    445      * requested permissions you will receive a callback reporting whether the
    446      * permissions were granted or not. Your activity has to implement {@link
    447      * androidx.core.app.ActivityCompat.OnRequestPermissionsResultCallback}
    448      * and the results of permission requests will be delivered to its {@link
    449      * androidx.core.app.ActivityCompat.OnRequestPermissionsResultCallback#onRequestPermissionsResult(
    450      * int, String[], int[])} method.
    451      * </p>
    452      * <p>
    453      * Note that requesting a permission does not guarantee it will be granted and
    454      * your app should be able to run without having this permission.
    455      * </p>
    456      * <p>
    457      * This method may start an activity allowing the user to choose which permissions
    458      * to grant and which to reject. Hence, you should be prepared that your activity
    459      * may be paused and resumed. Further, granting some permissions may require
    460      * a restart of you application. In such a case, the system will recreate the
    461      * activity stack before delivering the result to your
    462      * {@link OnRequestPermissionsResultCallback#onRequestPermissionsResult(int, String[], int[])}.
    463      * </p>
    464      * <p>
    465      * When checking whether you have a permission you should use {@link
    466      * #checkSelfPermission(android.content.Context, String)}.
    467      * </p>
    468      * <p>
    469      * Calling this API for permissions already granted to your app would show UI
    470      * to the user to decided whether the app can still hold these permissions. This
    471      * can be useful if the way your app uses the data guarded by the permissions
    472      * changes significantly.
    473      * </p>
    474      * <p>
    475      * You cannot request a permission if your activity sets {@link
    476      * android.R.attr#noHistory noHistory} to <code>true</code> in the manifest
    477      * because in this case the activity would not receive result callbacks including
    478      * {@link OnRequestPermissionsResultCallback#onRequestPermissionsResult(int, String[], int[])}.
    479      * </p>
    480      * <p>
    481      * The <a href="http://developer.android.com/samples/RuntimePermissions/index.html">
    482      * RuntimePermissions</a> sample app demonstrates how to use this method to
    483      * request permissions at run time.
    484      * </p>
    485      *
    486      * @param activity The target activity.
    487      * @param permissions The requested permissions. Must me non-null and not empty.
    488      * @param requestCode Application specific request code to match with a result
    489      *    reported to {@link OnRequestPermissionsResultCallback#onRequestPermissionsResult(int, String[], int[])}.
    490      *    Should be >= 0.
    491      *
    492      * @see OnRequestPermissionsResultCallback#onRequestPermissionsResult(int, String[], int[])
    493      * @see #checkSelfPermission(android.content.Context, String)
    494      * @see #shouldShowRequestPermissionRationale(android.app.Activity, String)
    495      */
    496     public static void requestPermissions(final @NonNull Activity activity,
    497             final @NonNull String[] permissions, final @IntRange(from = 0) int requestCode) {
    498         if (sDelegate != null
    499                 && sDelegate.requestPermissions(activity, permissions, requestCode)) {
    500             // Delegate has handled the permission request.
    501             return;
    502         }
    503 
    504         if (Build.VERSION.SDK_INT >= 23) {
    505             if (activity instanceof RequestPermissionsRequestCodeValidator) {
    506                 ((RequestPermissionsRequestCodeValidator) activity)
    507                         .validateRequestPermissionsRequestCode(requestCode);
    508             }
    509             activity.requestPermissions(permissions, requestCode);
    510         } else if (activity instanceof OnRequestPermissionsResultCallback) {
    511             Handler handler = new Handler(Looper.getMainLooper());
    512             handler.post(new Runnable() {
    513                 @Override
    514                 public void run() {
    515                     final int[] grantResults = new int[permissions.length];
    516 
    517                     PackageManager packageManager = activity.getPackageManager();
    518                     String packageName = activity.getPackageName();
    519 
    520                     final int permissionCount = permissions.length;
    521                     for (int i = 0; i < permissionCount; i++) {
    522                         grantResults[i] = packageManager.checkPermission(
    523                                 permissions[i], packageName);
    524                     }
    525 
    526                     ((OnRequestPermissionsResultCallback) activity).onRequestPermissionsResult(
    527                             requestCode, permissions, grantResults);
    528                 }
    529             });
    530         }
    531     }
    532 
    533     /**
    534      * Gets whether you should show UI with rationale for requesting a permission.
    535      * You should do this only if you do not have the permission and the context in
    536      * which the permission is requested does not clearly communicate to the user
    537      * what would be the benefit from granting this permission.
    538      * <p>
    539      * For example, if you write a camera app, requesting the camera permission
    540      * would be expected by the user and no rationale for why it is requested is
    541      * needed. If however, the app needs location for tagging photos then a non-tech
    542      * savvy user may wonder how location is related to taking photos. In this case
    543      * you may choose to show UI with rationale of requesting this permission.
    544      * </p>
    545      *
    546      * @param activity The target activity.
    547      * @param permission A permission your app wants to request.
    548      * @return Whether you can show permission rationale UI.
    549      *
    550      * @see #checkSelfPermission(android.content.Context, String)
    551      * @see #requestPermissions(android.app.Activity, String[], int)
    552      */
    553     public static boolean shouldShowRequestPermissionRationale(@NonNull Activity activity,
    554             @NonNull String permission) {
    555         if (Build.VERSION.SDK_INT >= 23) {
    556             return activity.shouldShowRequestPermissionRationale(permission);
    557         }
    558         return false;
    559     }
    560 
    561     /**
    562      * Create {@link DragAndDropPermissionsCompat} object bound to this activity and controlling
    563      * the access permissions for content URIs associated with the {@link android.view.DragEvent}.
    564      * @param dragEvent Drag event to request permission for
    565      * @return The {@link DragAndDropPermissionsCompat} object used to control access to the content
    566      * URIs. {@code null} if no content URIs are associated with the event or if permissions could
    567      * not be granted.
    568      */
    569     @Nullable
    570     public static DragAndDropPermissionsCompat requestDragAndDropPermissions(Activity activity,
    571             DragEvent dragEvent) {
    572         return DragAndDropPermissionsCompat.request(activity, dragEvent);
    573     }
    574 
    575     @RequiresApi(21)
    576     private static class SharedElementCallback21Impl extends android.app.SharedElementCallback {
    577 
    578         protected SharedElementCallback mCallback;
    579 
    580         SharedElementCallback21Impl(SharedElementCallback callback) {
    581             mCallback = callback;
    582         }
    583 
    584         @Override
    585         public void onSharedElementStart(List<String> sharedElementNames,
    586                 List<View> sharedElements, List<View> sharedElementSnapshots) {
    587             mCallback.onSharedElementStart(sharedElementNames, sharedElements,
    588                     sharedElementSnapshots);
    589         }
    590 
    591         @Override
    592         public void onSharedElementEnd(List<String> sharedElementNames, List<View> sharedElements,
    593                 List<View> sharedElementSnapshots) {
    594             mCallback.onSharedElementEnd(sharedElementNames, sharedElements,
    595                     sharedElementSnapshots);
    596         }
    597 
    598         @Override
    599         public void onRejectSharedElements(List<View> rejectedSharedElements) {
    600             mCallback.onRejectSharedElements(rejectedSharedElements);
    601         }
    602 
    603         @Override
    604         public void onMapSharedElements(List<String> names, Map<String, View> sharedElements) {
    605             mCallback.onMapSharedElements(names, sharedElements);
    606         }
    607 
    608         @Override
    609         public Parcelable onCaptureSharedElementSnapshot(View sharedElement,
    610                 Matrix viewToGlobalMatrix, RectF screenBounds) {
    611             return mCallback.onCaptureSharedElementSnapshot(sharedElement, viewToGlobalMatrix,
    612                     screenBounds);
    613         }
    614 
    615         @Override
    616         public View onCreateSnapshotView(Context context, Parcelable snapshot) {
    617             return mCallback.onCreateSnapshotView(context, snapshot);
    618         }
    619     }
    620 
    621     @RequiresApi(23)
    622     private static class SharedElementCallback23Impl extends SharedElementCallback21Impl {
    623         SharedElementCallback23Impl(SharedElementCallback callback) {
    624             super(callback);
    625         }
    626 
    627         @Override
    628         public void onSharedElementsArrived(List<String> sharedElementNames,
    629                 List<View> sharedElements, final OnSharedElementsReadyListener listener) {
    630             mCallback.onSharedElementsArrived(sharedElementNames, sharedElements,
    631                     new SharedElementCallback.OnSharedElementsReadyListener() {
    632                         @Override
    633                         public void onSharedElementsReady() {
    634                             listener.onSharedElementsReady();
    635                         }
    636                     });
    637         }
    638     }
    639 }
    640