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 android.view; 18 19 import android.content.Context; 20 import android.util.Log; 21 22 /** 23 * An ActionProvider defines rich menu interaction in a single component. 24 * ActionProvider can generate action views for use in the action bar, 25 * dynamically populate submenus of a MenuItem, and handle default menu 26 * item invocations. 27 * 28 * <p>An ActionProvider can be optionally specified for a {@link MenuItem} and will be 29 * responsible for creating the action view that appears in the {@link android.app.ActionBar} 30 * in place of a simple button in the bar. When the menu item is presented in a way that 31 * does not allow custom action views, (e.g. in an overflow menu,) the ActionProvider 32 * can perform a default action.</p> 33 * 34 * <p>There are two ways to use an action provider: 35 * <ul> 36 * <li> 37 * Set the action provider on a {@link MenuItem} directly by calling 38 * {@link MenuItem#setActionProvider(ActionProvider)}. 39 * </li> 40 * <li> 41 * Declare the action provider in an XML menu resource. For example: 42 * <pre> 43 * <code> 44 * <item android:id="@+id/my_menu_item" 45 * android:title="Title" 46 * android:icon="@drawable/my_menu_item_icon" 47 * android:showAsAction="ifRoom" 48 * android:actionProviderClass="foo.bar.SomeActionProvider" /> 49 * </code> 50 * </pre> 51 * </li> 52 * </ul> 53 * </p> 54 * 55 * @see MenuItem#setActionProvider(ActionProvider) 56 * @see MenuItem#getActionProvider() 57 */ 58 public abstract class ActionProvider { 59 private static final String TAG = "ActionProvider"; 60 private SubUiVisibilityListener mSubUiVisibilityListener; 61 private VisibilityListener mVisibilityListener; 62 63 /** 64 * Creates a new instance. ActionProvider classes should always implement a 65 * constructor that takes a single Context parameter for inflating from menu XML. 66 * 67 * @param context Context for accessing resources. 68 */ 69 public ActionProvider(Context context) { 70 } 71 72 /** 73 * Factory method called by the Android framework to create new action views. 74 * 75 * <p>This method has been deprecated in favor of {@link #onCreateActionView(MenuItem)}. 76 * Newer apps that wish to support platform versions prior to API 16 should also 77 * implement this method to return a valid action view.</p> 78 * 79 * @return A new action view. 80 * 81 * @deprecated use {@link #onCreateActionView(MenuItem)} 82 */ 83 public abstract View onCreateActionView(); 84 85 /** 86 * Factory method called by the Android framework to create new action views. 87 * This method returns a new action view for the given MenuItem. 88 * 89 * <p>If your ActionProvider implementation overrides the deprecated no-argument overload 90 * {@link #onCreateActionView()}, overriding this method for devices running API 16 or later 91 * is recommended but optional. The default implementation calls {@link #onCreateActionView()} 92 * for compatibility with applications written for older platform versions.</p> 93 * 94 * @param forItem MenuItem to create the action view for 95 * @return the new action view 96 */ 97 public View onCreateActionView(MenuItem forItem) { 98 return onCreateActionView(); 99 } 100 101 /** 102 * The result of this method determines whether or not {@link #isVisible()} will be used 103 * by the {@link MenuItem} this ActionProvider is bound to help determine its visibility. 104 * 105 * @return true if this ActionProvider overrides the visibility of the MenuItem 106 * it is bound to, false otherwise. The default implementation returns false. 107 * @see #isVisible() 108 */ 109 public boolean overridesItemVisibility() { 110 return false; 111 } 112 113 /** 114 * If {@link #overridesItemVisibility()} returns true, the return value of this method 115 * will help determine the visibility of the {@link MenuItem} this ActionProvider is bound to. 116 * 117 * <p>If the MenuItem's visibility is explicitly set to false by the application, 118 * the MenuItem will not be shown, even if this method returns true.</p> 119 * 120 * @return true if the MenuItem this ActionProvider is bound to is visible, false if 121 * it is invisible. The default implementation returns true. 122 */ 123 public boolean isVisible() { 124 return true; 125 } 126 127 /** 128 * If this ActionProvider is associated with an item in a menu, 129 * refresh the visibility of the item based on {@link #overridesItemVisibility()} and 130 * {@link #isVisible()}. If {@link #overridesItemVisibility()} returns false, this call 131 * will have no effect. 132 */ 133 public void refreshVisibility() { 134 if (mVisibilityListener != null && overridesItemVisibility()) { 135 mVisibilityListener.onActionProviderVisibilityChanged(isVisible()); 136 } 137 } 138 139 /** 140 * Performs an optional default action. 141 * <p> 142 * For the case of an action provider placed in a menu item not shown as an action this 143 * method is invoked if previous callbacks for processing menu selection has handled 144 * the event. 145 * </p> 146 * <p> 147 * A menu item selection is processed in the following order: 148 * <ul> 149 * <li> 150 * Receiving a call to {@link MenuItem.OnMenuItemClickListener#onMenuItemClick 151 * MenuItem.OnMenuItemClickListener.onMenuItemClick}. 152 * </li> 153 * <li> 154 * Receiving a call to {@link android.app.Activity#onOptionsItemSelected(MenuItem) 155 * Activity.onOptionsItemSelected(MenuItem)} 156 * </li> 157 * <li> 158 * Receiving a call to {@link android.app.Fragment#onOptionsItemSelected(MenuItem) 159 * Fragment.onOptionsItemSelected(MenuItem)} 160 * </li> 161 * <li> 162 * Launching the {@link android.content.Intent} set via 163 * {@link MenuItem#setIntent(android.content.Intent) MenuItem.setIntent(android.content.Intent)} 164 * </li> 165 * <li> 166 * Invoking this method. 167 * </li> 168 * </ul> 169 * </p> 170 * <p> 171 * The default implementation does not perform any action and returns false. 172 * </p> 173 */ 174 public boolean onPerformDefaultAction() { 175 return false; 176 } 177 178 /** 179 * Determines if this ActionProvider has a submenu associated with it. 180 * 181 * <p>Associated submenus will be shown when an action view is not. This 182 * provider instance will receive a call to {@link #onPrepareSubMenu(SubMenu)} 183 * after the call to {@link #onPerformDefaultAction()} and before a submenu is 184 * displayed to the user. 185 * 186 * @return true if the item backed by this provider should have an associated submenu 187 */ 188 public boolean hasSubMenu() { 189 return false; 190 } 191 192 /** 193 * Called to prepare an associated submenu for the menu item backed by this ActionProvider. 194 * 195 * <p>if {@link #hasSubMenu()} returns true, this method will be called when the 196 * menu item is selected to prepare the submenu for presentation to the user. Apps 197 * may use this to create or alter submenu content right before display. 198 * 199 * @param subMenu Submenu that will be displayed 200 */ 201 public void onPrepareSubMenu(SubMenu subMenu) { 202 } 203 204 /** 205 * Notify the system that the visibility of an action view's sub-UI such as 206 * an anchored popup has changed. This will affect how other system 207 * visibility notifications occur. 208 * 209 * @hide Pending future API approval 210 */ 211 public void subUiVisibilityChanged(boolean isVisible) { 212 if (mSubUiVisibilityListener != null) { 213 mSubUiVisibilityListener.onSubUiVisibilityChanged(isVisible); 214 } 215 } 216 217 /** 218 * @hide Internal use only 219 */ 220 public void setSubUiVisibilityListener(SubUiVisibilityListener listener) { 221 mSubUiVisibilityListener = listener; 222 } 223 224 /** 225 * Set a listener to be notified when this ActionProvider's overridden visibility changes. 226 * This should only be used by MenuItem implementations. 227 * 228 * @param listener listener to set 229 */ 230 public void setVisibilityListener(VisibilityListener listener) { 231 if (mVisibilityListener != null) { 232 Log.w(TAG, "setVisibilityListener: Setting a new ActionProvider.VisibilityListener " + 233 "when one is already set. Are you reusing this " + getClass().getSimpleName() + 234 " instance while it is still in use somewhere else?"); 235 } 236 mVisibilityListener = listener; 237 } 238 239 /** 240 * @hide 241 */ 242 public void reset() { 243 mVisibilityListener = null; 244 mSubUiVisibilityListener = null; 245 } 246 247 /** 248 * @hide Internal use only 249 */ 250 public interface SubUiVisibilityListener { 251 public void onSubUiVisibilityChanged(boolean isVisible); 252 } 253 254 /** 255 * Listens to changes in visibility as reported by {@link ActionProvider#refreshVisibility()}. 256 * 257 * @see ActionProvider#overridesItemVisibility() 258 * @see ActionProvider#isVisible() 259 */ 260 public interface VisibilityListener { 261 public void onActionProviderVisibilityChanged(boolean isVisible); 262 } 263 } 264
