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      1 package ${packageName}.util;
      2 
      3 import android.app.Activity;
      4 import android.os.Build;
      5 import android.view.View;
      6 
      7 /**
      8  * A utility class that helps with showing and hiding system UI such as the
      9  * status bar and navigation/system bar. This class uses backward-compatibility
     10  * techniques described in <a href=
     11  * "http://developer.android.com/training/backward-compatible-ui/index.html">
     12  * Creating Backward-Compatible UIs</a> to ensure that devices running any
     13  * version of ndroid OS are supported. More specifically, there are separate
     14  * implementations of this abstract class: for newer devices,
     15  * {@link #getInstance} will return a {@link SystemUiHiderHoneycomb} instance,
     16  * while on older devices {@link #getInstance} will return a
     17  * {@link SystemUiHiderBase} instance.
     18  * <p>
     19  * For more on system bars, see <a href=
     20  * "http://developer.android.com/design/get-started/ui-overview.html#system-bars"
     21  * > System Bars</a>.
     22  * 
     23  * @see android.view.View#setSystemUiVisibility(int)
     24  * @see android.view.WindowManager.LayoutParams#FLAG_FULLSCREEN
     25  */
     26 public abstract class SystemUiHider {
     27     /**
     28      * When this flag is set, the
     29      * {@link android.view.WindowManager.LayoutParams#FLAG_LAYOUT_IN_SCREEN}
     30      * flag will be set on older devices, making the status bar "float" on top
     31      * of the activity layout. This is most useful when there are no controls at
     32      * the top of the activity layout.
     33      * <p>
     34      * This flag isn't used on newer devices because the <a
     35      * href="http://developer.android.com/design/patterns/actionbar.html">action
     36      * bar</a>, the most important structural element of an Android app, should
     37      * be visible and not obscured by the system UI.
     38      */
     39     public static final int FLAG_LAYOUT_IN_SCREEN_OLDER_DEVICES = 0x1;
     40 
     41     /**
     42      * When this flag is set, {@link #show()} and {@link #hide()} will toggle
     43      * the visibility of the status bar. If there is a navigation bar, show and
     44      * hide will toggle low profile mode.
     45      */
     46     public static final int FLAG_FULLSCREEN = 0x2;
     47 
     48     /**
     49      * When this flag is set, {@link #show()} and {@link #hide()} will toggle
     50      * the visibility of the navigation bar, if it's present on the device and
     51      * the device allows hiding it. In cases where the navigation bar is present
     52      * but cannot be hidden, show and hide will toggle low profile mode.
     53      */
     54     public static final int FLAG_HIDE_NAVIGATION = FLAG_FULLSCREEN | 0x4;
     55 
     56     /**
     57      * The activity associated with this UI hider object.
     58      */
     59     protected Activity mActivity;
     60 
     61     /**
     62      * The view on which {@link View#setSystemUiVisibility(int)} will be called.
     63      */
     64     protected View mAnchorView;
     65 
     66     /**
     67      * The current UI hider flags.
     68      * 
     69      * @see #FLAG_FULLSCREEN
     70      * @see #FLAG_HIDE_NAVIGATION
     71      * @see #FLAG_LAYOUT_IN_SCREEN_OLDER_DEVICES
     72      */
     73     protected int mFlags;
     74 
     75     /**
     76      * The current visibility callback.
     77      */
     78     protected OnVisibilityChangeListener mOnVisibilityChangeListener = sDummyListener;
     79 
     80     /**
     81      * Creates and returns an instance of {@link SystemUiHider} that is
     82      * appropriate for this device. The object will be either a
     83      * {@link SystemUiHiderBase} or {@link SystemUiHiderHoneycomb} depending on
     84      * the device.
     85      * 
     86      * @param activity The activity whose window's system UI should be
     87      *            controlled by this class.
     88      * @param anchorView The view on which
     89      *            {@link View#setSystemUiVisibility(int)} will be called.
     90      * @param flags Either 0 or any combination of {@link #FLAG_FULLSCREEN},
     91      *            {@link #FLAG_HIDE_NAVIGATION}, and
     92      *            {@link #FLAG_LAYOUT_IN_SCREEN_OLDER_DEVICES}.
     93      */
     94     public static SystemUiHider getInstance(Activity activity, View anchorView, int flags) {
     95         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
     96             return new SystemUiHiderHoneycomb(activity, anchorView, flags);
     97         } else {
     98             return new SystemUiHiderBase(activity, anchorView, flags);
     99         }
    100     }
    101 
    102     protected SystemUiHider(Activity activity, View anchorView, int flags) {
    103         mActivity = activity;
    104         mAnchorView = anchorView;
    105         mFlags = flags;
    106     }
    107 
    108     /**
    109      * Sets up the system UI hider. Should be called from
    110      * {@link Activity#onCreate}.
    111      */
    112     public abstract void setup();
    113 
    114     /**
    115      * Returns whether or not the system UI is visible.
    116      */
    117     public abstract boolean isVisible();
    118 
    119     /**
    120      * Hide the system UI.
    121      */
    122     public abstract void hide();
    123 
    124     /**
    125      * Show the system UI.
    126      */
    127     public abstract void show();
    128 
    129     /**
    130      * Toggle the visibility of the system UI.
    131      */
    132     public void toggle() {
    133         if (isVisible()) {
    134             hide();
    135         } else {
    136             show();
    137         }
    138     }
    139 
    140     /**
    141      * Registers a callback, to be triggered when the system UI visibility
    142      * changes.
    143      */
    144     public void setOnVisibilityChangeListener(OnVisibilityChangeListener listener) {
    145         if (listener == null) {
    146             listener = sDummyListener;
    147         }
    148 
    149         mOnVisibilityChangeListener = listener;
    150     }
    151 
    152     /**
    153      * A dummy no-op callback for use when there is no other listener set.
    154      */
    155     private static OnVisibilityChangeListener sDummyListener = new OnVisibilityChangeListener() {
    156         @Override
    157         public void onVisibilityChange(boolean visible) {
    158         }
    159     };
    160 
    161     /**
    162      * A callback interface used to listen for system UI visibility changes.
    163      */
    164     public interface OnVisibilityChangeListener {
    165         /**
    166          * Called when the system UI visibility has changed.
    167          * 
    168          * @param visible True if the system UI is visible.
    169          */
    170         public void onVisibilityChange(boolean visible);
    171     }
    172 }
    173