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      */
EmptyViewController(ViewGroup mainLayout, View contentView, View emptyView)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      */
setEmpty(boolean isEmpty)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