/*
* 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.ArrayMap;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
/**
* This class manages the set of transitions that fire when there is a
* change of {@link Scene}. To use the manager, add scenes along with
* transition objects with calls to {@link #setTransition(Scene, Transition)}
* or {@link #setTransition(Scene, Scene, Transition)}. Setting specific
* transitions for scene changes is not required; by default, a Scene change
* will use {@link AutoTransition} to do something reasonable for most
* situations. Specifying other transitions for particular scene changes is
* only necessary if the application wants different transition behavior
* in these situations.
*
* <p>TransitionManagers can be declared in XML resource files inside the
* <code>res/transition</code> directory. TransitionManager resources consist of
* the <code>transitionManager</code>tag name, containing one or more
* <code>transition</code> tags, each of which describe the relationship of
* that transition to the from/to scene information in that tag.
* For example, here is a resource file that declares several scene
* transitions:</p>
*
* {@sample development/samples/ApiDemos/res/transition/transitions_mgr.xml TransitionManager}
*
* <p>For each of the <code>fromScene</code> and <code>toScene</code> attributes,
* there is a reference to a standard XML layout file. This is equivalent to
* creating a scene from a layout in code by calling
* {@link Scene#getSceneForLayout(ViewGroup, int, Context)}. For the
* <code>transition</code> attribute, there is a reference to a resource
* file in the <code>res/transition</code> directory which describes that
* transition.</p>
*
* Information on XML resource descriptions for transitions can be found for
* {@link android.R.styleable#Transition}, {@link android.R.styleable#TransitionSet},
* {@link android.R.styleable#TransitionTarget}, {@link android.R.styleable#Fade},
* and {@link android.R.styleable#TransitionManager}.
*/
public class TransitionManager {
// TODO: how to handle enter/exit?
private static String LOG_TAG = "TransitionManager";
private static Transition sDefaultTransition = new AutoTransition();
private static final String[] EMPTY_STRINGS = new String[0];
ArrayMap<Scene, Transition> mSceneTransitions = new ArrayMap<Scene, Transition>();
ArrayMap<Scene, ArrayMap<Scene, Transition>> mScenePairTransitions =
new ArrayMap<Scene, ArrayMap<Scene, Transition>>();
private static ThreadLocal<WeakReference<ArrayMap<ViewGroup, ArrayList<Transition>>>>
sRunningTransitions =
new ThreadLocal<WeakReference<ArrayMap<ViewGroup, ArrayList<Transition>>>>();
private static ArrayList<ViewGroup> sPendingTransitions = new ArrayList<ViewGroup>();
/**
* Sets the transition to be used for any scene change for which no
* other transition is explicitly set. The initial value is
* an {@link AutoTransition} instance.
*
* @param transition The default transition to be used for scene changes.
*
* @hide pending later changes
*/
public void setDefaultTransition(Transition transition) {
sDefaultTransition = transition;
}
/**
* Gets the current default transition. The initial value is an {@link
* AutoTransition} instance.
*
* @return The current default transition.
* @see #setDefaultTransition(Transition)
*
* @hide pending later changes
*/
public static Transition getDefaultTransition() {
return sDefaultTransition;
}
/**
* Sets a specific transition to occur when the given scene is entered.
*
* @param scene The scene which, when applied, will cause the given
* transition to run.
* @param transition The transition that will play when the given scene is
* entered. A value of null will result in the default behavior of
* using the default transition instead.
*/
public void setTransition(Scene scene, Transition transition) {
mSceneTransitions.put(scene, transition);
}
/**
* Sets a specific transition to occur when the given pair of scenes is
* exited/entered.
*
* @param fromScene The scene being exited when the given transition will
* be run
* @param toScene The scene being entered when the given transition will
* be run
* @param transition The transition that will play when the given scene is
* entered. A value of null will result in the default behavior of
* using the default transition instead.
*/
public void setTransition(Scene fromScene, Scene toScene, Transition transition) {
ArrayMap<Scene, Transition> sceneTransitionMap = mScenePairTransitions.get(toScene);
if (sceneTransitionMap == null) {
sceneTransitionMap = new ArrayMap<Scene, Transition>();
mScenePairTransitions.put(toScene, sceneTransitionMap);
}
sceneTransitionMap.put(fromScene, transition);
}
/**
* Returns the Transition for the given scene being entered. The result
* depends not only on the given scene, but also the scene which the
* {@link Scene#getSceneRoot() sceneRoot} of the Scene is currently in.
*
* @param scene The scene being entered
* @return The Transition to be used for the given scene change. If no
* Transition was specified for this scene change, the default transition
* will be used instead.
*/
private Transition getTransition(Scene scene) {
Transition transition = null;
ViewGroup sceneRoot = scene.getSceneRoot();
if (sceneRoot != null) {
// TODO: cached in Scene instead? long-term, cache in View itself
Scene currScene = Scene.getCurrentScene(sceneRoot);
if (currScene != null) {
ArrayMap<Scene, Transition> sceneTransitionMap = mScenePairTransitions.get(scene);
if (sceneTransitionMap != null) {
transition = sceneTransitionMap.get(currScene);
if (transition != null) {
return transition;
}
}
}
}
transition = mSceneTransitions.get(scene);
return (transition != null) ? transition : sDefaultTransition;
}
/**
* This is where all of the work of a transition/scene-change is
* orchestrated. This method captures the start values for the given
* transition, exits the current Scene, enters the new scene, captures
* the end values for the transition, and finally plays the
* resulting values-populated transition.
*
* @param scene The scene being entered
* @param transition The transition to play for this scene change
*/
private static void changeScene(Scene scene, Transition transition) {
final ViewGroup sceneRoot = scene.getSceneRoot();
Transition transitionClone = null;
if (transition != null) {
transitionClone = transition.clone();
transitionClone.setSceneRoot(sceneRoot);
}
Scene oldScene = Scene.getCurrentScene(sceneRoot);
if (oldScene != null && transitionClone != null &&
oldScene.isCreatedFromLayoutResource()) {
transitionClone.setCanRemoveViews(true);
}
sceneChangeSetup(sceneRoot, transitionClone);
scene.enter();
sceneChangeRunTransition(sceneRoot, transitionClone);
}
private static ArrayMap<ViewGroup, ArrayList<Transition>> getRunningTransitions() {
WeakReference<ArrayMap<ViewGroup, ArrayList<Transition>>> runningTransitions =
sRunningTransitions.get();
if (runningTransitions == null || runningTransitions.get() == null) {
ArrayMap<ViewGroup, ArrayList<Transition>> transitions =
new ArrayMap<ViewGroup, ArrayList<Transition>>();
runningTransitions = new WeakReference<ArrayMap<ViewGroup, ArrayList<Transition>>>(
transitions);
sRunningTransitions.set(runningTransitions);
}
return runningTransitions.get();
}
private static void sceneChangeRunTransition(final ViewGroup sceneRoot,
final Transition transition) {
if (transition != null && sceneRoot != null) {
MultiListener listener = new MultiListener(transition, sceneRoot);
sceneRoot.addOnAttachStateChangeListener(listener);
sceneRoot.getViewTreeObserver().addOnPreDrawListener(listener);
}
}
/**
* This private utility class is used to listen for both OnPreDraw and
* OnAttachStateChange events. OnPreDraw events are the main ones we care
* about since that's what triggers the transition to take place.
* OnAttachStateChange events are also important in case the view is removed
* from the hierarchy before the OnPreDraw event takes place; it's used to
* clean up things since the OnPreDraw listener didn't get called in time.
*/
private static class MultiListener implements ViewTreeObserver.OnPreDrawListener,
View.OnAttachStateChangeListener {
Transition mTransition;
ViewGroup mSceneRoot;
MultiListener(Transition transition, ViewGroup sceneRoot) {
mTransition = transition;
mSceneRoot = sceneRoot;
}
private void removeListeners() {
mSceneRoot.getViewTreeObserver().removeOnPreDrawListener(this);
mSceneRoot.removeOnAttachStateChangeListener(this);
}
@Override
public void onViewAttachedToWindow(View v) {
}
@Override
public void onViewDetachedFromWindow(View v) {
removeListeners();
sPendingTransitions.remove(mSceneRoot);
ArrayList<Transition> runningTransitions = getRunningTransitions().get(mSceneRoot);
if (runningTransitions != null && runningTransitions.size() > 0) {
for (Transition runningTransition : runningTransitions) {
runningTransition.resume(mSceneRoot);
}
}
mTransition.clearValues(true);
}
@Override
public boolean onPreDraw() {
removeListeners();
sPendingTransitions.remove(mSceneRoot);
// Add to running list, handle end to remove it
final ArrayMap<ViewGroup, ArrayList<Transition>> runningTransitions =
getRunningTransitions();
ArrayList<Transition> currentTransitions = runningTransitions.get(mSceneRoot);
ArrayList<Transition> previousRunningTransitions = null;
if (currentTransitions == null) {
currentTransitions = new ArrayList<Transition>();
runningTransitions.put(mSceneRoot, currentTransitions);
} else if (currentTransitions.size() > 0) {
previousRunningTransitions = new ArrayList<Transition>(currentTransitions);
}
currentTransitions.add(mTransition);
mTransition.addListener(new Transition.TransitionListenerAdapter() {
@Override
public void onTransitionEnd(Transition transition) {
ArrayList<Transition> currentTransitions =
runningTransitions.get(mSceneRoot);
currentTransitions.remove(transition);
}
});
mTransition.captureValues(mSceneRoot, false);
if (previousRunningTransitions != null) {
for (Transition runningTransition : previousRunningTransitions) {
runningTransition.resume(mSceneRoot);
}
}
mTransition.playTransition(mSceneRoot);
return true;
}
};
private static void sceneChangeSetup(ViewGroup sceneRoot, Transition transition) {
// Capture current values
ArrayList<Transition> runningTransitions = getRunningTransitions().get(sceneRoot);
if (runningTransitions != null && runningTransitions.size() > 0) {
for (Transition runningTransition : runningTransitions) {
runningTransition.pause(sceneRoot);
}
}
if (transition != null) {
transition.captureValues(sceneRoot, true);
}
// Notify previous scene that it is being exited
Scene previousScene = Scene.getCurrentScene(sceneRoot);
if (previousScene != null) {
previousScene.exit();
}
}
/**
* Change to the given scene, using the
* appropriate transition for this particular scene change
* (as specified to the TransitionManager, or the default
* if no such transition exists).
*
* @param scene The Scene to change to
*/
public void transitionTo(Scene scene) {
// Auto transition if there is no transition declared for the Scene, but there is
// a root or parent view
changeScene(scene, getTransition(scene));
}
/**
* Convenience method to simply change to the given scene using
* the default transition for TransitionManager.
*
* @param scene The Scene to change to
*/
public static void go(Scene scene) {
changeScene(scene, sDefaultTransition);
}
/**
* Convenience method to simply change to the given scene using
* the given transition.
*
* <p>Passing in <code>null</code> for the transition parameter will
* result in the scene changing without any transition running, and is
* equivalent to calling {@link Scene#exit()} on the scene root's
* current scene, followed by {@link Scene#enter()} on the scene
* specified by the <code>scene</code> parameter.</p>
*
* @param scene The Scene to change to
* @param transition The transition to use for this scene change. A
* value of null causes the scene change to happen with no transition.
*/
public static void go(Scene scene, Transition transition) {
changeScene(scene, transition);
}
/**
* Convenience method to animate, using the default transition,
* to a new scene defined by all changes within the given scene root between
* calling this method and the next rendering frame.
* Equivalent to calling {@link #beginDelayedTransition(ViewGroup, Transition)}
* with a value of <code>null</code> for the <code>transition</code> parameter.
*
* @param sceneRoot The root of the View hierarchy to run the transition on.
*/
public static void beginDelayedTransition(final ViewGroup sceneRoot) {
beginDelayedTransition(sceneRoot, null);
}
/**
* Convenience method to animate to a new scene defined by all changes within
* the given scene root between calling this method and the next rendering frame.
* Calling this method causes TransitionManager to capture current values in the
* scene root and then post a request to run a transition on the next frame.
* At that time, the new values in the scene root will be captured and changes
* will be animated. There is no need to create a Scene; it is implied by
* changes which take place between calling this method and the next frame when
* the transition begins.
*
* <p>Calling this method several times before the next frame (for example, if
* unrelated code also wants to make dynamic changes and run a transition on
* the same scene root), only the first call will trigger capturing values
* and exiting the current scene. Subsequent calls to the method with the
* same scene root during the same frame will be ignored.</p>
*
* <p>Passing in <code>null</code> for the transition parameter will
* cause the TransitionManager to use its default transition.</p>
*
* @param sceneRoot The root of the View hierarchy to run the transition on.
* @param transition The transition to use for this change. A
* value of null causes the TransitionManager to use the default transition.
*/
public static void beginDelayedTransition(final ViewGroup sceneRoot, Transition transition) {
if (!sPendingTransitions.contains(sceneRoot) && sceneRoot.isLaidOut()) {
if (Transition.DBG) {
Log.d(LOG_TAG, "beginDelayedTransition: root, transition = " +
sceneRoot + ", " + transition);
}
sPendingTransitions.add(sceneRoot);
if (transition == null) {
transition = sDefaultTransition;
}
final Transition transitionClone = transition.clone();
sceneChangeSetup(sceneRoot, transitionClone);
Scene.setCurrentScene(sceneRoot, null);
sceneChangeRunTransition(sceneRoot, transitionClone);
}
}
}
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