PreferenceScreen.java revision 9066cfe9886ac131c34d59ed0e2d287b0e3c0087
1/* 2 * Copyright (C) 2007 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 17package android.preference; 18 19import android.app.Dialog; 20import android.content.Context; 21import android.content.DialogInterface; 22import android.os.Bundle; 23import android.os.Parcel; 24import android.os.Parcelable; 25import android.util.AttributeSet; 26import android.view.View; 27import android.widget.Adapter; 28import android.widget.AdapterView; 29import android.widget.ListAdapter; 30import android.widget.ListView; 31 32/** 33 * Represents a top-level {@link Preference} that 34 * is the root of a Preference hierarchy. A {@link PreferenceActivity} 35 * points to an instance of this class to show the preferences. To instantiate 36 * this class, use {@link PreferenceManager#createPreferenceScreen(Context)}. 37 * <ul> 38 * This class can appear in two places: 39 * <li> When a {@link PreferenceActivity} points to this, it is used as the root 40 * and is not shown (only the contained preferences are shown). 41 * <li> When it appears inside another preference hierarchy, it is shown and 42 * serves as the gateway to another screen of preferences (either by showing 43 * another screen of preferences as a {@link Dialog} or via a 44 * {@link Context#startActivity(android.content.Intent)} from the 45 * {@link Preference#getIntent()}). The children of this {@link PreferenceScreen} 46 * are NOT shown in the screen that this {@link PreferenceScreen} is shown in. 47 * Instead, a separate screen will be shown when this preference is clicked. 48 * </ul> 49 * <p>Here's an example XML layout of a PreferenceScreen:</p> 50 * <pre> 51<PreferenceScreen 52 xmlns:android="http://schemas.android.com/apk/res/android" 53 android:key="first_preferencescreen"> 54 <CheckBoxPreference 55 android:key="wifi enabled" 56 android:title="WiFi" /> 57 <PreferenceScreen 58 android:key="second_preferencescreen" 59 android:title="WiFi settings"> 60 <CheckBoxPreference 61 android:key="prefer wifi" 62 android:title="Prefer WiFi" /> 63 ... other preferences here ... 64 </PreferenceScreen> 65</PreferenceScreen> </pre> 66 * <p> 67 * In this example, the "first_preferencescreen" will be used as the root of the 68 * hierarchy and given to a {@link PreferenceActivity}. The first screen will 69 * show preferences "WiFi" (which can be used to quickly enable/disable WiFi) 70 * and "WiFi settings". The "WiFi settings" is the "second_preferencescreen" and when 71 * clicked will show another screen of preferences such as "Prefer WiFi" (and 72 * the other preferences that are children of the "second_preferencescreen" tag). 73 * 74 * @see PreferenceCategory 75 */ 76public final class PreferenceScreen extends PreferenceGroup implements AdapterView.OnItemClickListener, 77 DialogInterface.OnDismissListener { 78 79 private ListAdapter mRootAdapter; 80 81 private Dialog mDialog; 82 83 /** 84 * Do NOT use this constructor, use {@link PreferenceManager#createPreferenceScreen(Context)}. 85 * @hide- 86 */ 87 public PreferenceScreen(Context context, AttributeSet attrs) { 88 super(context, attrs, com.android.internal.R.attr.preferenceScreenStyle); 89 } 90 91 /** 92 * Returns an adapter that can be attached to a {@link PreferenceActivity} 93 * to show the preferences contained in this {@link PreferenceScreen}. 94 * <p> 95 * This {@link PreferenceScreen} will NOT appear in the returned adapter, instead 96 * it appears in the hierarchy above this {@link PreferenceScreen}. 97 * <p> 98 * This adapter's {@link Adapter#getItem(int)} should always return a 99 * subclass of {@link Preference}. 100 * 101 * @return An adapter that provides the {@link Preference} contained in this 102 * {@link PreferenceScreen}. 103 */ 104 public ListAdapter getRootAdapter() { 105 if (mRootAdapter == null) { 106 mRootAdapter = onCreateRootAdapter(); 107 } 108 109 return mRootAdapter; 110 } 111 112 /** 113 * Creates the root adapter. 114 * 115 * @return An adapter that contains the preferences contained in this {@link PreferenceScreen}. 116 * @see #getRootAdapter() 117 */ 118 protected ListAdapter onCreateRootAdapter() { 119 return new PreferenceGroupAdapter(this); 120 } 121 122 /** 123 * Binds a {@link ListView} to the preferences contained in this {@link PreferenceScreen} via 124 * {@link #getRootAdapter()}. It also handles passing list item clicks to the corresponding 125 * {@link Preference} contained by this {@link PreferenceScreen}. 126 * 127 * @param listView The list view to attach to. 128 */ 129 public void bind(ListView listView) { 130 listView.setOnItemClickListener(this); 131 listView.setAdapter(getRootAdapter()); 132 133 onAttachedToActivity(); 134 } 135 136 @Override 137 protected void onClick() { 138 if (getIntent() != null || getPreferenceCount() == 0) { 139 return; 140 } 141 142 showDialog(null); 143 } 144 145 private void showDialog(Bundle state) { 146 Context context = getContext(); 147 ListView listView = new ListView(context); 148 bind(listView); 149 150 Dialog dialog = mDialog = new Dialog(context, com.android.internal.R.style.Theme_NoTitleBar); 151 dialog.setContentView(listView); 152 dialog.setOnDismissListener(this); 153 if (state != null) { 154 dialog.onRestoreInstanceState(state); 155 } 156 157 // Add the screen to the list of preferences screens opened as dialogs 158 getPreferenceManager().addPreferencesScreen(dialog); 159 160 dialog.show(); 161 } 162 163 public void onDismiss(DialogInterface dialog) { 164 mDialog = null; 165 getPreferenceManager().removePreferencesScreen(dialog); 166 } 167 168 /** 169 * Used to get a handle to the dialog. 170 * This is useful for cases where we want to manipulate the dialog 171 * as we would with any other activity or view. 172 */ 173 public Dialog getDialog() { 174 return mDialog; 175 } 176 177 public void onItemClick(AdapterView parent, View view, int position, long id) { 178 Object item = getRootAdapter().getItem(position); 179 if (!(item instanceof Preference)) return; 180 181 final Preference preference = (Preference) item; 182 preference.performClick(this); 183 } 184 185 @Override 186 protected boolean isOnSameScreenAsChildren() { 187 return false; 188 } 189 190 @Override 191 protected Parcelable onSaveInstanceState() { 192 final Parcelable superState = super.onSaveInstanceState(); 193 final Dialog dialog = mDialog; 194 if (dialog == null || !dialog.isShowing()) { 195 return superState; 196 } 197 198 final SavedState myState = new SavedState(superState); 199 myState.isDialogShowing = true; 200 myState.dialogBundle = dialog.onSaveInstanceState(); 201 return myState; 202 } 203 204 @Override 205 protected void onRestoreInstanceState(Parcelable state) { 206 if (state == null || !state.getClass().equals(SavedState.class)) { 207 // Didn't save state for us in onSaveInstanceState 208 super.onRestoreInstanceState(state); 209 return; 210 } 211 212 SavedState myState = (SavedState) state; 213 super.onRestoreInstanceState(myState.getSuperState()); 214 if (myState.isDialogShowing) { 215 showDialog(myState.dialogBundle); 216 } 217 } 218 219 private static class SavedState extends BaseSavedState { 220 boolean isDialogShowing; 221 Bundle dialogBundle; 222 223 public SavedState(Parcel source) { 224 super(source); 225 isDialogShowing = source.readInt() == 1; 226 dialogBundle = source.readBundle(); 227 } 228 229 @Override 230 public void writeToParcel(Parcel dest, int flags) { 231 super.writeToParcel(dest, flags); 232 dest.writeInt(isDialogShowing ? 1 : 0); 233 dest.writeBundle(dialogBundle); 234 } 235 236 public SavedState(Parcelable superState) { 237 super(superState); 238 } 239 240 public static final Parcelable.Creator<SavedState> CREATOR = 241 new Parcelable.Creator<SavedState>() { 242 public SavedState createFromParcel(Parcel in) { 243 return new SavedState(in); 244 } 245 246 public SavedState[] newArray(int size) { 247 return new SavedState[size]; 248 } 249 }; 250 } 251 252} 253