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/*
* Copyright 2012 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 com.example.android.animationsdemo;
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.NavUtils;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
/**
* This sample demonstrates cross-fading between two overlapping views.
*
* <p>In this sample, the two overlapping views are a loading indicator and some text content. The
* active view is toggled by touching the toggle button in the action bar. In real-world
* applications, this toggle would occur as soon as content was available. Note that if content is
* immediately available, a loading spinner shouldn't be presented and there should be no
* animation.</p>
*/
public class CrossfadeActivity extends Activity {
/**
* The flag indicating whether content is loaded (text is shown) or not (loading spinner is
* shown).
*/
private boolean mContentLoaded;
/**
* The view (or view group) containing the content. This is one of two overlapping views.
*/
private View mContentView;
/**
* The view containing the loading indicator. This is the other of two overlapping views.
*/
private View mLoadingView;
/**
* The system "short" animation time duration, in milliseconds. This duration is ideal for
* subtle animations or animations that occur very frequently.
*/
private int mShortAnimationDuration;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_crossfade);
mContentView = findViewById(R.id.content);
mLoadingView = findViewById(R.id.loading_spinner);
// Initially hide the content view.
mContentView.setVisibility(View.GONE);
// Retrieve and cache the system's default "short" animation time.
mShortAnimationDuration = getResources().getInteger(android.R.integer.config_shortAnimTime);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
getMenuInflater().inflate(R.menu.activity_crossfade, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
// Navigate "up" the demo structure to the launchpad activity.
// See http://developer.android.com/design/patterns/navigation.html for more.
NavUtils.navigateUpTo(this, new Intent(this, MainActivity.class));
return true;
case R.id.action_toggle:
// Toggle whether content is loaded.
mContentLoaded = !mContentLoaded;
showContentOrLoadingIndicator(mContentLoaded);
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* Cross-fades between {@link #mContentView} and {@link #mLoadingView}.
*/
private void showContentOrLoadingIndicator(boolean contentLoaded) {
// Decide which view to hide and which to show.
final View showView = contentLoaded ? mContentView : mLoadingView;
final View hideView = contentLoaded ? mLoadingView : mContentView;
// Set the "show" view to 0% opacity but visible, so that it is visible
// (but fully transparent) during the animation.
showView.setAlpha(0f);
showView.setVisibility(View.VISIBLE);
// Animate the "show" view to 100% opacity, and clear any animation listener set on
// the view. Remember that listeners are not limited to the specific animation
// describes in the chained method calls. Listeners are set on the
// ViewPropertyAnimator object for the view, which persists across several
// animations.
showView.animate()
.alpha(1f)
.setDuration(mShortAnimationDuration)
.setListener(null);
// Animate the "hide" view to 0% opacity. After the animation ends, set its visibility
// to GONE as an optimization step (it won't participate in layout passes, etc.)
hideView.animate()
.alpha(0f)
.setDuration(mShortAnimationDuration)
.setListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
hideView.setVisibility(View.GONE);
}
});
}
}
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