1 /* 2 * Copyright (C) 2015 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.v7.preference; 18 19 import static android.support.annotation.RestrictTo.Scope.LIBRARY_GROUP; 20 21 import android.content.Context; 22 import android.support.annotation.RestrictTo; 23 import android.support.v4.content.res.TypedArrayUtils; 24 import android.util.AttributeSet; 25 26 /** 27 * Represents a top-level {@link Preference} that 28 * is the root of a Preference hierarchy. A {@link PreferenceFragmentCompat} 29 * points to an instance of this class to show the preferences. To instantiate 30 * this class, use {@link PreferenceManager#createPreferenceScreen(android.content.Context)}. 31 * <ul> 32 * This class can appear in two places: 33 * <li> When a {@link PreferenceFragmentCompat} points to this, it is used as the root 34 * and is not shown (only the contained preferences are shown). 35 * <li> When it appears inside another preference hierarchy, it is shown and 36 * serves as the gateway to another screen of preferences (either by showing 37 * another screen of preferences as a {@link android.app.Dialog} or via a 38 * {@link android.content.Context#startActivity(android.content.Intent)} from the 39 * {@link Preference#getIntent()}). The children of this {@link PreferenceScreen} 40 * are NOT shown in the screen that this {@link PreferenceScreen} is shown in. 41 * Instead, a separate screen will be shown when this preference is clicked. 42 * </ul> 43 * <p>Here's an example XML layout of a PreferenceScreen:</p> 44 * <pre> 45 <PreferenceScreen 46 xmlns:android="http://schemas.android.com/apk/res/android" 47 android:key="first_preferencescreen"> 48 <CheckBoxPreference 49 android:key="wifi enabled" 50 android:title="WiFi" /> 51 <PreferenceScreen 52 android:key="second_preferencescreen" 53 android:title="WiFi settings"> 54 <CheckBoxPreference 55 android:key="prefer wifi" 56 android:title="Prefer WiFi" /> 57 ... other preferences here ... 58 </PreferenceScreen> 59 </PreferenceScreen> </pre> 60 * <p> 61 * In this example, the "first_preferencescreen" will be used as the root of the 62 * hierarchy and given to a {@link android.support.v14.preference.PreferenceFragment} 63 * or {@link PreferenceFragmentCompat}. 64 * The first screen will 65 * show preferences "WiFi" (which can be used to quickly enable/disable WiFi) 66 * and "WiFi settings". The "WiFi settings" is the "second_preferencescreen" and when 67 * clicked will show another screen of preferences such as "Prefer WiFi" (and 68 * the other preferences that are children of the "second_preferencescreen" tag). 69 * 70 * <div class="special reference"> 71 * <h3>Developer Guides</h3> 72 * <p>For information about building a settings UI with Preferences, 73 * read the <a href="{@docRoot}guide/topics/ui/settings.html">Settings</a> 74 * guide.</p> 75 * </div> 76 * 77 * @see PreferenceCategory 78 */ 79 public final class PreferenceScreen extends PreferenceGroup { 80 81 private boolean mShouldUseGeneratedIds = true; 82 83 /** 84 * Do NOT use this constructor, use {@link PreferenceManager#createPreferenceScreen(Context)}. 85 * @hide 86 */ 87 @RestrictTo(LIBRARY_GROUP) PreferenceScreen(Context context, AttributeSet attrs)88 public PreferenceScreen(Context context, AttributeSet attrs) { 89 super(context, attrs, TypedArrayUtils.getAttr(context, R.attr.preferenceScreenStyle, 90 android.R.attr.preferenceScreenStyle)); 91 } 92 93 @Override onClick()94 protected void onClick() { 95 if (getIntent() != null || getFragment() != null || getPreferenceCount() == 0) { 96 return; 97 } 98 final PreferenceManager.OnNavigateToScreenListener listener = 99 getPreferenceManager().getOnNavigateToScreenListener(); 100 if (listener != null) { 101 listener.onNavigateToScreen(this); 102 } 103 } 104 105 @Override isOnSameScreenAsChildren()106 protected boolean isOnSameScreenAsChildren() { 107 return false; 108 } 109 110 /** 111 * See {@link #setShouldUseGeneratedIds(boolean)} 112 * @return {@code true} if the adapter should use the preference IDs generated by 113 * {@link PreferenceGroup#addPreference(Preference)} as stable item IDs 114 */ shouldUseGeneratedIds()115 public boolean shouldUseGeneratedIds() { 116 return mShouldUseGeneratedIds; 117 } 118 119 /** 120 * Set whether the adapter created for this screen should attempt to use the preference IDs 121 * generated by {@link PreferenceGroup#addPreference(Preference)} as stable item IDs. Setting 122 * this to false can suppress unwanted animations if {@link Preference} objects are frequently 123 * removed from and re-added to their containing {@link PreferenceGroup}. 124 * <p> 125 * This method may only be called when the preference screen is not attached to the hierarchy. 126 * <p> 127 * Default value is {@code true}. 128 * 129 * @param shouldUseGeneratedIds {@code true} if the adapter should use the preference ID as a 130 * stable ID, or {@code false} to disable the use of 131 * stable IDs 132 */ setShouldUseGeneratedIds(boolean shouldUseGeneratedIds)133 public void setShouldUseGeneratedIds(boolean shouldUseGeneratedIds) { 134 if (isAttached()) { 135 throw new IllegalStateException("Cannot change the usage of generated IDs while" + 136 " attached to the preference hierarchy"); 137 } 138 mShouldUseGeneratedIds = shouldUseGeneratedIds; 139 } 140 } 141