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A library jar that provides APIs for Applications written for the Google Android Platform.
/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.transition;
import android.content.Context;
import android.util.SparseArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
* A scene represents the collection of values that various properties in the
* View hierarchy will have when the scene is applied. A Scene can be
* configured to automatically run a Transition when it is applied, which will
* animate the various property changes that take place during the
* scene change.
*/
public final class Scene {
private Context mContext;
private int mLayoutId = -1;
private ViewGroup mSceneRoot;
private View mLayout; // alternative to layoutId
Runnable mEnterAction, mExitAction;
/**
* Returns a Scene described by the resource file associated with the given
* layoutId parameter. If such a Scene has already been created for
* the given sceneRoot, that same Scene will be returned.
* This caching of layoutId-based scenes enables sharing of common scenes
* between those created in code and those referenced by {@link TransitionManager}
* XML resource files.
*
* @param sceneRoot The root of the hierarchy in which scene changes
* and transitions will take place.
* @param layoutId The id of a standard layout resource file.
* @param context The context used in the process of inflating
* the layout resource.
* @return The scene for the given root and layout id
*/
public static Scene getSceneForLayout(ViewGroup sceneRoot, int layoutId, Context context) {
SparseArray scenes = (SparseArray) sceneRoot.getTag(
com.android.internal.R.id.scene_layoutid_cache);
if (scenes == null) {
scenes = new SparseArray();
sceneRoot.setTagInternal(com.android.internal.R.id.scene_layoutid_cache, scenes);
}
Scene scene = scenes.get(layoutId);
if (scene != null) {
return scene;
} else {
scene = new Scene(sceneRoot, layoutId, context);
scenes.put(layoutId, scene);
return scene;
}
}
/**
* Constructs a Scene with no information about how values will change
* when this scene is applied. This constructor might be used when
* a Scene is created with the intention of being dynamically configured,
* through setting {@link #setEnterAction(Runnable)} and possibly
* {@link #setExitAction(Runnable)}.
*
* @param sceneRoot The root of the hierarchy in which scene changes
* and transitions will take place.
*/
public Scene(ViewGroup sceneRoot) {
mSceneRoot = sceneRoot;
}
/**
* Constructs a Scene which, when entered, will remove any
* children from the sceneRoot container and will inflate and add
* the hierarchy specified by the layoutId resource file.
*
* This method is hidden because layoutId-based scenes should be
* created by the caching factory method {@link Scene#getCurrentScene(View)}.
*
* @param sceneRoot The root of the hierarchy in which scene changes
* and transitions will take place.
* @param layoutId The id of a resource file that defines the view
* hierarchy of this scene.
* @param context The context used in the process of inflating
* the layout resource.
*/
private Scene(ViewGroup sceneRoot, int layoutId, Context context) {
mContext = context;
mSceneRoot = sceneRoot;
mLayoutId = layoutId;
}
/**
* Constructs a Scene which, when entered, will remove any
* children from the sceneRoot container and add the layout
* object as a new child of that container.
*
* @param sceneRoot The root of the hierarchy in which scene changes
* and transitions will take place.
* @param layout The view hierarchy of this scene, added as a child
* of sceneRoot when this scene is entered.
*/
public Scene(ViewGroup sceneRoot, View layout) {
mSceneRoot = sceneRoot;
mLayout = layout;
}
/**
* @deprecated use {@link #Scene(ViewGroup, View)}.
*/
@Deprecated
public Scene(ViewGroup sceneRoot, ViewGroup layout) {
mSceneRoot = sceneRoot;
mLayout = layout;
}
/**
* Gets the root of the scene, which is the root of the view hierarchy
* affected by changes due to this scene, and which will be animated
* when this scene is entered.
*
* @return The root of the view hierarchy affected by this scene.
*/
public ViewGroup getSceneRoot() {
return mSceneRoot;
}
/**
* Exits this scene, if it is the current scene
* on the scene's {@link #getSceneRoot() scene root}. The current scene is
* set when {@link #enter() entering} a scene.
* Exiting a scene runs the {@link #setExitAction(Runnable) exit action}
* if there is one.
*/
public void exit() {
if (getCurrentScene(mSceneRoot) == this) {
if (mExitAction != null) {
mExitAction.run();
}
}
}
/**
* Enters this scene, which entails changing all values that
* are specified by this scene. These may be values associated
* with a layout view group or layout resource file which will
* now be added to the scene root, or it may be values changed by
* an {@link #setEnterAction(Runnable)} enter action}, or a
* combination of the these. No transition will be run when the
* scene is entered. To get transition behavior in scene changes,
* use one of the methods in {@link TransitionManager} instead.
*/
public void enter() {
// Apply layout change, if any
if (mLayoutId > 0 || mLayout != null) {
// empty out parent container before adding to it
getSceneRoot().removeAllViews();
if (mLayoutId > 0) {
LayoutInflater.from(mContext).inflate(mLayoutId, mSceneRoot);
} else {
mSceneRoot.addView(mLayout);
}
}
// Notify next scene that it is entering. Subclasses may override to configure scene.
if (mEnterAction != null) {
mEnterAction.run();
}
setCurrentScene(mSceneRoot, this);
}
/**
* Set the scene that the given view is in. The current scene is set only
* on the root view of a scene, not for every view in that hierarchy. This
* information is used by Scene to determine whether there is a previous
* scene which should be exited before the new scene is entered.
*
* @param view The view on which the current scene is being set
*/
static void setCurrentScene(View view, Scene scene) {
view.setTagInternal(com.android.internal.R.id.current_scene, scene);
}
/**
* Gets the current {@link Scene} set on the given view. A scene is set on a view
* only if that view is the scene root.
*
* @return The current Scene set on this view. A value of null indicates that
* no Scene is currently set.
*/
static Scene getCurrentScene(View view) {
return (Scene) view.getTag(com.android.internal.R.id.current_scene);
}
/**
* Scenes that are not defined with layout resources or
* hierarchies, or which need to perform additional steps
* after those hierarchies are changed to, should set an enter
* action, and possibly an exit action as well. An enter action
* will cause Scene to call back into application code to do
* anything else the application needs after transitions have
* captured pre-change values and after any other scene changes
* have been applied, such as the layout (if any) being added to
* the view hierarchy. After this method is called, Transitions will
* be played.
*
* @param action The runnable whose {@link Runnable#run() run()} method will
* be called when this scene is entered
* @see #setExitAction(Runnable)
* @see Scene#Scene(ViewGroup, int, Context)
* @see Scene#Scene(ViewGroup, ViewGroup)
*/
public void setEnterAction(Runnable action) {
mEnterAction = action;
}
/**
* Scenes that are not defined with layout resources or
* hierarchies, or which need to perform additional steps
* after those hierarchies are changed to, should set an enter
* action, and possibly an exit action as well. An exit action
* will cause Scene to call back into application code to do
* anything the application needs to do after applicable transitions have
* captured pre-change values, but before any other scene changes
* have been applied, such as the new layout (if any) being added to
* the view hierarchy. After this method is called, the next scene
* will be entered, including a call to {@link #setEnterAction(Runnable)}
* if an enter action is set.
*
* @see #setEnterAction(Runnable)
* @see Scene#Scene(ViewGroup, int, Context)
* @see Scene#Scene(ViewGroup, ViewGroup)
*/
public void setExitAction(Runnable action) {
mExitAction = action;
}
/**
* Returns whether this Scene was created by a layout resource file, determined
* by the layoutId passed into
* {@link #getSceneForLayout(android.view.ViewGroup, int, android.content.Context)}.
* This is called by TransitionManager to determine whether it is safe for views from
* this scene to be removed from their parents when the scene is exited, which is
* used by {@link Fade} to fade these views out (the views must be removed from
* their parent in order to add them to the overlay for fading purposes). If a
* Scene is not based on a resource file, then the impact of removing views
* arbitrarily is unknown and should be avoided.
*/
boolean isCreatedFromLayoutResource() {
return (mLayoutId > 0);
}
}