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/*
* 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 com.android.internal.R;
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ObjectAnimator;
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
/**
* This transition tracks changes to the visibility of target views in the
* start and end scenes and fades views in or out when they become visible
* or non-visible. Visibility is determined by both the
* {@link View#setVisibility(int)} state of the view as well as whether it
* is parented in the current view hierarchy.
*
* The ability of this transition to fade out a particular view, and the
* way that that fading operation takes place, is based on
* the situation of the view in the view hierarchy. For example, if a view was
* simply removed from its parent, then the view will be added into a {@link
* android.view.ViewGroupOverlay} while fading. If a visible view is
* changed to be {@link View#GONE} or {@link View#INVISIBLE}, then the
* visibility will be changed to {@link View#VISIBLE} for the duration of
* the animation. However, if a view is in a hierarchy which is also altering
* its visibility, the situation can be more complicated. In general, if a
* view that is no longer in the hierarchy in the end scene still has a
* parent (so its parent hierarchy was removed, but it was not removed from
* its parent), then it will be left alone to avoid side-effects from
* improperly removing it from its parent. The only exception to this is if
* the previous {@link Scene} was
* {@link Scene#getSceneForLayout(android.view.ViewGroup, int, android.content.Context)
* created from a layout resource file}, then it is considered safe to un-parent
* the starting scene view in order to fade it out.
*
* A Fade transition can be described in a resource file by using the
* tag fade, along with the standard
* attributes of {@link android.R.styleable#Fade} and
* {@link android.R.styleable#Transition}.
*/
public class Fade extends Visibility {
private static boolean DBG = Transition.DBG && false;
private static final String LOG_TAG = "Fade";
/**
* Fading mode used in {@link #Fade(int)} to make the transition
* operate on targets that are appearing. Maybe be combined with
* {@link #OUT} to fade both in and out. Equivalent to
* {@link Visibility#MODE_IN}.
*/
public static final int IN = Visibility.MODE_IN;
/**
* Fading mode used in {@link #Fade(int)} to make the transition
* operate on targets that are disappearing. Maybe be combined with
* {@link #IN} to fade both in and out. Equivalent to
* {@link Visibility#MODE_OUT}.
*/
public static final int OUT = Visibility.MODE_OUT;
/**
* Constructs a Fade transition that will fade targets in and out.
*/
public Fade() {
}
/**
* Constructs a Fade transition that will fade targets in
* and/or out, according to the value of fadingMode.
*
* @param fadingMode The behavior of this transition, a combination of
* {@link #IN} and {@link #OUT}.
*/
public Fade(int fadingMode) {
setMode(fadingMode);
}
public Fade(Context context, AttributeSet attrs) {
super(context, attrs);
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.Fade);
int fadingMode = a.getInt(R.styleable.Fade_fadingMode, getMode());
setMode(fadingMode);
}
/**
* Utility method to handle creating and running the Animator.
*/
private Animator createAnimation(final View view, float startAlpha, final float endAlpha) {
if (startAlpha == endAlpha) {
return null;
}
view.setTransitionAlpha(startAlpha);
final ObjectAnimator anim = ObjectAnimator.ofFloat(view, "transitionAlpha", endAlpha);
if (DBG) {
Log.d(LOG_TAG, "Created animator " + anim);
}
final FadeAnimatorListener listener = new FadeAnimatorListener(view);
anim.addListener(listener);
anim.addPauseListener(listener);
addListener(new TransitionListenerAdapter() {
@Override
public void onTransitionEnd(Transition transition) {
view.setTransitionAlpha(1);
}
});
return anim;
}
@Override
public Animator onAppear(ViewGroup sceneRoot, View view,
TransitionValues startValues,
TransitionValues endValues) {
if (DBG) {
View startView = (startValues != null) ? startValues.view : null;
Log.d(LOG_TAG, "Fade.onAppear: startView, startVis, endView, endVis = " +
startView + ", " + view);
}
return createAnimation(view, 0, 1);
}
@Override
public Animator onDisappear(ViewGroup sceneRoot, final View view, TransitionValues startValues,
TransitionValues endValues) {
return createAnimation(view, 1, 0);
}
private static class FadeAnimatorListener extends AnimatorListenerAdapter {
private final View mView;
private float mPausedAlpha = -1;
private boolean mLayerTypeChanged = false;
public FadeAnimatorListener(View view) {
mView = view;
}
@Override
public void onAnimationStart(Animator animator) {
if (mView.hasOverlappingRendering() && mView.getLayerType() == View.LAYER_TYPE_NONE) {
mLayerTypeChanged = true;
mView.setLayerType(View.LAYER_TYPE_HARDWARE, null);
}
}
@Override
public void onAnimationEnd(Animator animator) {
mView.setTransitionAlpha(1);
if (mLayerTypeChanged) {
mView.setLayerType(View.LAYER_TYPE_NONE, null);
}
}
@Override
public void onAnimationPause(Animator animator) {
mPausedAlpha = mView.getTransitionAlpha();
mView.setTransitionAlpha(1);
}
@Override
public void onAnimationResume(Animator animator) {
mView.setTransitionAlpha(mPausedAlpha);
}
}
}