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.transition; 18 19 import android.annotation.NonNull; 20 import android.annotation.Nullable; 21 import android.compat.annotation.UnsupportedAppUsage; 22 import android.content.Context; 23 import android.os.Build; 24 import android.util.SparseArray; 25 import android.view.LayoutInflater; 26 import android.view.View; 27 import android.view.ViewGroup; 28 29 /** 30 * A scene represents the collection of values that various properties in the 31 * View hierarchy will have when the scene is applied. A Scene can be 32 * configured to automatically run a Transition when it is applied, which will 33 * animate the various property changes that take place during the 34 * scene change. 35 */ 36 public final class Scene { 37 38 private Context mContext; 39 private int mLayoutId = -1; 40 private ViewGroup mSceneRoot; 41 private View mLayout; // alternative to layoutId 42 @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P) 43 Runnable mEnterAction; 44 @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P) 45 Runnable mExitAction; 46 47 /** 48 * Returns a Scene described by the resource file associated with the given 49 * <code>layoutId</code> parameter. If such a Scene has already been created for 50 * the given <code>sceneRoot</code>, that same Scene will be returned. 51 * This caching of layoutId-based scenes enables sharing of common scenes 52 * between those created in code and those referenced by {@link TransitionManager} 53 * XML resource files. 54 * 55 * @param sceneRoot The root of the hierarchy in which scene changes 56 * and transitions will take place. 57 * @param layoutId The id of a standard layout resource file. 58 * @param context The context used in the process of inflating 59 * the layout resource. 60 * @return The scene for the given root and layout id 61 */ getSceneForLayout(ViewGroup sceneRoot, int layoutId, Context context)62 public static Scene getSceneForLayout(ViewGroup sceneRoot, int layoutId, Context context) { 63 SparseArray<Scene> scenes = (SparseArray<Scene>) sceneRoot.getTag( 64 com.android.internal.R.id.scene_layoutid_cache); 65 if (scenes == null) { 66 scenes = new SparseArray<Scene>(); 67 sceneRoot.setTagInternal(com.android.internal.R.id.scene_layoutid_cache, scenes); 68 } 69 Scene scene = scenes.get(layoutId); 70 if (scene != null) { 71 return scene; 72 } else { 73 scene = new Scene(sceneRoot, layoutId, context); 74 scenes.put(layoutId, scene); 75 return scene; 76 } 77 } 78 79 /** 80 * Constructs a Scene with no information about how values will change 81 * when this scene is applied. This constructor might be used when 82 * a Scene is created with the intention of being dynamically configured, 83 * through setting {@link #setEnterAction(Runnable)} and possibly 84 * {@link #setExitAction(Runnable)}. 85 * 86 * @param sceneRoot The root of the hierarchy in which scene changes 87 * and transitions will take place. 88 */ Scene(ViewGroup sceneRoot)89 public Scene(ViewGroup sceneRoot) { 90 mSceneRoot = sceneRoot; 91 } 92 93 /** 94 * Constructs a Scene which, when entered, will remove any 95 * children from the sceneRoot container and will inflate and add 96 * the hierarchy specified by the layoutId resource file. 97 * 98 * <p>This method is hidden because layoutId-based scenes should be 99 * created by the caching factory method {@link Scene#getCurrentScene(ViewGroup)}.</p> 100 * 101 * @param sceneRoot The root of the hierarchy in which scene changes 102 * and transitions will take place. 103 * @param layoutId The id of a resource file that defines the view 104 * hierarchy of this scene. 105 * @param context The context used in the process of inflating 106 * the layout resource. 107 */ Scene(ViewGroup sceneRoot, int layoutId, Context context)108 private Scene(ViewGroup sceneRoot, int layoutId, Context context) { 109 mContext = context; 110 mSceneRoot = sceneRoot; 111 mLayoutId = layoutId; 112 } 113 114 /** 115 * Constructs a Scene which, when entered, will remove any 116 * children from the sceneRoot container and add the layout 117 * object as a new child of that container. 118 * 119 * @param sceneRoot The root of the hierarchy in which scene changes 120 * and transitions will take place. 121 * @param layout The view hierarchy of this scene, added as a child 122 * of sceneRoot when this scene is entered. 123 */ Scene(ViewGroup sceneRoot, View layout)124 public Scene(ViewGroup sceneRoot, View layout) { 125 mSceneRoot = sceneRoot; 126 mLayout = layout; 127 } 128 129 /** 130 * @deprecated use {@link #Scene(ViewGroup, View)}. 131 */ 132 @Deprecated Scene(ViewGroup sceneRoot, ViewGroup layout)133 public Scene(ViewGroup sceneRoot, ViewGroup layout) { 134 mSceneRoot = sceneRoot; 135 mLayout = layout; 136 } 137 138 /** 139 * Gets the root of the scene, which is the root of the view hierarchy 140 * affected by changes due to this scene, and which will be animated 141 * when this scene is entered. 142 * 143 * @return The root of the view hierarchy affected by this scene. 144 */ getSceneRoot()145 public ViewGroup getSceneRoot() { 146 return mSceneRoot; 147 } 148 149 /** 150 * Exits this scene, if it is the current scene 151 * on the scene's {@link #getSceneRoot() scene root}. The current scene is 152 * set when {@link #enter() entering} a scene. 153 * Exiting a scene runs the {@link #setExitAction(Runnable) exit action} 154 * if there is one. 155 */ exit()156 public void exit() { 157 if (getCurrentScene(mSceneRoot) == this) { 158 if (mExitAction != null) { 159 mExitAction.run(); 160 } 161 } 162 } 163 164 /** 165 * Enters this scene, which entails changing all values that 166 * are specified by this scene. These may be values associated 167 * with a layout view group or layout resource file which will 168 * now be added to the scene root, or it may be values changed by 169 * an {@link #setEnterAction(Runnable)} enter action}, or a 170 * combination of the these. No transition will be run when the 171 * scene is entered. To get transition behavior in scene changes, 172 * use one of the methods in {@link TransitionManager} instead. 173 */ enter()174 public void enter() { 175 176 // Apply layout change, if any 177 if (mLayoutId > 0 || mLayout != null) { 178 // empty out parent container before adding to it 179 getSceneRoot().removeAllViews(); 180 181 if (mLayoutId > 0) { 182 LayoutInflater.from(mContext).inflate(mLayoutId, mSceneRoot); 183 } else { 184 mSceneRoot.addView(mLayout); 185 } 186 } 187 188 // Notify next scene that it is entering. Subclasses may override to configure scene. 189 if (mEnterAction != null) { 190 mEnterAction.run(); 191 } 192 193 setCurrentScene(mSceneRoot, this); 194 } 195 196 /** 197 * Set the scene that the given ViewGroup is in. The current scene is set only 198 * on the root ViewGroup of a scene, not for every view in that hierarchy. This 199 * information is used by Scene to determine whether there is a previous 200 * scene which should be exited before the new scene is entered. 201 * 202 * @param sceneRoot The ViewGroup on which the current scene is being set 203 */ 204 @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P) setCurrentScene(@onNull ViewGroup sceneRoot, @Nullable Scene scene)205 static void setCurrentScene(@NonNull ViewGroup sceneRoot, @Nullable Scene scene) { 206 sceneRoot.setTagInternal(com.android.internal.R.id.current_scene, scene); 207 } 208 209 /** 210 * Gets the current {@link Scene} set on the given ViewGroup. A scene is set on a ViewGroup 211 * only if that ViewGroup is the scene root. 212 * 213 * @param sceneRoot The ViewGroup on which the current scene will be returned 214 * @return The current Scene set on this ViewGroup. A value of null indicates that 215 * no Scene is currently set. 216 */ 217 @Nullable getCurrentScene(@onNull ViewGroup sceneRoot)218 public static Scene getCurrentScene(@NonNull ViewGroup sceneRoot) { 219 return (Scene) sceneRoot.getTag(com.android.internal.R.id.current_scene); 220 } 221 222 /** 223 * Scenes that are not defined with layout resources or 224 * hierarchies, or which need to perform additional steps 225 * after those hierarchies are changed to, should set an enter 226 * action, and possibly an exit action as well. An enter action 227 * will cause Scene to call back into application code to do 228 * anything else the application needs after transitions have 229 * captured pre-change values and after any other scene changes 230 * have been applied, such as the layout (if any) being added to 231 * the view hierarchy. After this method is called, Transitions will 232 * be played. 233 * 234 * @param action The runnable whose {@link Runnable#run() run()} method will 235 * be called when this scene is entered 236 * @see #setExitAction(Runnable) 237 * @see Scene#Scene(ViewGroup, View) 238 */ setEnterAction(Runnable action)239 public void setEnterAction(Runnable action) { 240 mEnterAction = action; 241 } 242 243 /** 244 * Scenes that are not defined with layout resources or 245 * hierarchies, or which need to perform additional steps 246 * after those hierarchies are changed to, should set an enter 247 * action, and possibly an exit action as well. An exit action 248 * will cause Scene to call back into application code to do 249 * anything the application needs to do after applicable transitions have 250 * captured pre-change values, but before any other scene changes 251 * have been applied, such as the new layout (if any) being added to 252 * the view hierarchy. After this method is called, the next scene 253 * will be entered, including a call to {@link #setEnterAction(Runnable)} 254 * if an enter action is set. 255 * 256 * @see #setEnterAction(Runnable) 257 * @see Scene#Scene(ViewGroup, View) 258 */ setExitAction(Runnable action)259 public void setExitAction(Runnable action) { 260 mExitAction = action; 261 } 262 263 264 /** 265 * Returns whether this Scene was created by a layout resource file, determined 266 * by the layoutId passed into 267 * {@link #getSceneForLayout(android.view.ViewGroup, int, android.content.Context)}. 268 * This is called by TransitionManager to determine whether it is safe for views from 269 * this scene to be removed from their parents when the scene is exited, which is 270 * used by {@link Fade} to fade these views out (the views must be removed from 271 * their parent in order to add them to the overlay for fading purposes). If a 272 * Scene is not based on a resource file, then the impact of removing views 273 * arbitrarily is unknown and should be avoided. 274 */ isCreatedFromLayoutResource()275 boolean isCreatedFromLayoutResource() { 276 return (mLayoutId > 0); 277 } 278 } 279