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      1 /*
      2  * Copyright (C) 2015 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 com.android.deskclock.widget;
     18 
     19 import android.transition.Fade;
     20 import android.transition.Transition;
     21 import android.transition.TransitionManager;
     22 import android.transition.TransitionSet;
     23 import android.view.View;
     24 import android.view.ViewGroup;
     25 
     26 import com.android.deskclock.Utils;
     27 
     28 /**
     29  * Controller that displays empty view and handles animation appropriately.
     30  */
     31 public final class EmptyViewController {
     32 
     33     private static final int ANIMATION_DURATION = 300;
     34     private static final boolean USE_TRANSITION_FRAMEWORK = Utils.isLOrLater();
     35 
     36     private final Transition mEmptyViewTransition;
     37     private final ViewGroup mMainLayout;
     38     private final View mContentView;
     39     private final View mEmptyView;
     40     private boolean mIsEmpty;
     41 
     42     /**
     43      * Constructor of the controller.
     44      *
     45      * @param contentView  The view that should be displayed when empty view is hidden.
     46      * @param emptyView The view that should be displayed when main view is empty.
     47      */
     48     public EmptyViewController(ViewGroup mainLayout, View contentView, View emptyView) {
     49         mMainLayout = mainLayout;
     50         mContentView = contentView;
     51         mEmptyView = emptyView;
     52         if (USE_TRANSITION_FRAMEWORK) {
     53             mEmptyViewTransition = new TransitionSet()
     54                     .setOrdering(TransitionSet.ORDERING_SEQUENTIAL)
     55                     .addTarget(contentView)
     56                     .addTarget(emptyView)
     57                     .addTransition(new Fade(Fade.OUT))
     58                     .addTransition(new Fade(Fade.IN))
     59                     .setDuration(ANIMATION_DURATION);
     60         } else {
     61             mEmptyViewTransition = null;
     62         }
     63     }
     64 
     65     /**
     66      * Sets the state for the controller. If it's empty, it will display the empty view.
     67      *
     68      * @param isEmpty Whether or not the controller should transition into empty state.
     69      */
     70     public void setEmpty(boolean isEmpty) {
     71         if (mIsEmpty == isEmpty) {
     72             return;
     73         }
     74         mIsEmpty = isEmpty;
     75         // State changed, perform transition.
     76         if (USE_TRANSITION_FRAMEWORK) {
     77             TransitionManager.beginDelayedTransition(mMainLayout, mEmptyViewTransition);
     78         }
     79         mEmptyView.setVisibility(mIsEmpty ? View.VISIBLE : View.GONE);
     80         mContentView.setVisibility(mIsEmpty ? View.GONE : View.VISIBLE);
     81     }
     82 }
     83