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      1 /*
      2  * Copyright (C) 2013 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 android.support.v4.hardware.display;
     18 
     19 import android.content.Context;
     20 import android.view.Display;
     21 import android.view.WindowManager;
     22 
     23 import java.util.WeakHashMap;
     24 
     25 /**
     26  * Helper for accessing features in {@link android.hardware.display.DisplayManager}
     27  * introduced after API level 4 in a backwards compatible fashion.
     28  */
     29 public abstract class DisplayManagerCompat {
     30     private static final WeakHashMap<Context, DisplayManagerCompat> sInstances =
     31             new WeakHashMap<Context, DisplayManagerCompat>();
     32 
     33     /**
     34      * Display category: Presentation displays.
     35      * <p>
     36      * This category can be used to identify secondary displays that are suitable for
     37      * use as presentation displays.
     38      * </p>
     39      *
     40      * @see android.app.Presentation for information about presenting content
     41      * on secondary displays.
     42      * @see #getDisplays(String)
     43      */
     44     public static final String DISPLAY_CATEGORY_PRESENTATION =
     45             "android.hardware.display.category.PRESENTATION";
     46 
     47     DisplayManagerCompat() {
     48     }
     49 
     50     /**
     51      * Gets an instance of the display manager given the context.
     52      */
     53     public static DisplayManagerCompat getInstance(Context context) {
     54         synchronized (sInstances) {
     55             DisplayManagerCompat instance = sInstances.get(context);
     56             if (instance == null) {
     57                 final int version = android.os.Build.VERSION.SDK_INT;
     58                 if (version >= 17) {
     59                     instance = new JellybeanMr1Impl(context);
     60                 } else {
     61                     instance = new LegacyImpl(context);
     62                 }
     63                 sInstances.put(context, instance);
     64             }
     65             return instance;
     66         }
     67     }
     68 
     69     /**
     70      * Gets information about a logical display.
     71      *
     72      * The display metrics may be adjusted to provide compatibility
     73      * for legacy applications.
     74      *
     75      * @param displayId The logical display id.
     76      * @return The display object, or null if there is no valid display with the given id.
     77      */
     78     public abstract Display getDisplay(int displayId);
     79 
     80     /**
     81      * Gets all currently valid logical displays.
     82      *
     83      * @return An array containing all displays.
     84      */
     85     public abstract Display[] getDisplays();
     86 
     87     /**
     88      * Gets all currently valid logical displays of the specified category.
     89      * <p>
     90      * When there are multiple displays in a category the returned displays are sorted
     91      * of preference.  For example, if the requested category is
     92      * {@link #DISPLAY_CATEGORY_PRESENTATION} and there are multiple presentation displays
     93      * then the displays are sorted so that the first display in the returned array
     94      * is the most preferred presentation display.  The application may simply
     95      * use the first display or allow the user to choose.
     96      * </p>
     97      *
     98      * @param category The requested display category or null to return all displays.
     99      * @return An array containing all displays sorted by order of preference.
    100      *
    101      * @see #DISPLAY_CATEGORY_PRESENTATION
    102      */
    103     public abstract Display[] getDisplays(String category);
    104 
    105     private static class LegacyImpl extends DisplayManagerCompat {
    106         private final WindowManager mWindowManager;
    107 
    108         public LegacyImpl(Context context) {
    109             mWindowManager = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
    110         }
    111 
    112         @Override
    113         public Display getDisplay(int displayId) {
    114             Display display = mWindowManager.getDefaultDisplay();
    115             if (display.getDisplayId() == displayId) {
    116                 return display;
    117             }
    118             return null;
    119         }
    120 
    121         @Override
    122         public Display[] getDisplays() {
    123             return new Display[] { mWindowManager.getDefaultDisplay() };
    124         }
    125 
    126         @Override
    127         public Display[] getDisplays(String category) {
    128             return category == null ? getDisplays() : new Display[0];
    129         }
    130     }
    131 
    132     private static class JellybeanMr1Impl extends DisplayManagerCompat {
    133         private final Object mDisplayManagerObj;
    134 
    135         public JellybeanMr1Impl(Context context) {
    136             mDisplayManagerObj = DisplayManagerJellybeanMr1.getDisplayManager(context);
    137         }
    138 
    139         @Override
    140         public Display getDisplay(int displayId) {
    141             return DisplayManagerJellybeanMr1.getDisplay(mDisplayManagerObj, displayId);
    142         }
    143 
    144         @Override
    145         public Display[] getDisplays() {
    146             return DisplayManagerJellybeanMr1.getDisplays(mDisplayManagerObj);
    147         }
    148 
    149         @Override
    150         public Display[] getDisplays(String category) {
    151             return DisplayManagerJellybeanMr1.getDisplays(mDisplayManagerObj, category);
    152         }
    153     }
    154 }
    155