1 /*
2  * Copyright (C) 2006 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 android.widget;
18 
19 import android.content.Context;
20 import android.util.AttributeSet;
21 import android.view.View;
22 import android.view.ViewGroup;
23 
24 /**
25  * {@link ViewAnimator} that switches between two views, and has a factory
26  * from which these views are created.  You can either use the factory to
27  * create the views, or add them yourself.  A ViewSwitcher can only have two
28  * child views, of which only one is shown at a time.
29  */
30 public class ViewSwitcher extends ViewAnimator {
31     /**
32      * The factory used to create the two children.
33      */
34     ViewFactory mFactory;
35 
36     /**
37      * Creates a new empty ViewSwitcher.
38      *
39      * @param context the application's environment
40      */
ViewSwitcher(Context context)41     public ViewSwitcher(Context context) {
42         super(context);
43     }
44 
45     /**
46      * Creates a new empty ViewSwitcher for the given context and with the
47      * specified set attributes.
48      *
49      * @param context the application environment
50      * @param attrs a collection of attributes
51      */
ViewSwitcher(Context context, AttributeSet attrs)52     public ViewSwitcher(Context context, AttributeSet attrs) {
53         super(context, attrs);
54     }
55 
56     /**
57      * {@inheritDoc}
58      *
59      * @throws IllegalStateException if this switcher already contains two children
60      */
61     @Override
addView(View child, int index, ViewGroup.LayoutParams params)62     public void addView(View child, int index, ViewGroup.LayoutParams params) {
63         if (getChildCount() >= 2) {
64             throw new IllegalStateException("Can't add more than 2 views to a ViewSwitcher");
65         }
66         super.addView(child, index, params);
67     }
68 
69     @Override
getAccessibilityClassName()70     public CharSequence getAccessibilityClassName() {
71         return ViewSwitcher.class.getName();
72     }
73 
74     /**
75      * Returns the next view to be displayed.
76      *
77      * @return the view that will be displayed after the next views flip.
78      */
getNextView()79     public View getNextView() {
80         int which = mWhichChild == 0 ? 1 : 0;
81         return getChildAt(which);
82     }
83 
obtainView()84     private View obtainView() {
85         View child = mFactory.makeView();
86         LayoutParams lp = (LayoutParams) child.getLayoutParams();
87         if (lp == null) {
88             lp = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
89         }
90         addView(child, lp);
91         return child;
92     }
93 
94     /**
95      * Sets the factory used to create the two views between which the
96      * ViewSwitcher will flip. Instead of using a factory, you can call
97      * {@link #addView(android.view.View, int, android.view.ViewGroup.LayoutParams)}
98      * twice.
99      *
100      * @param factory the view factory used to generate the switcher's content
101      */
setFactory(ViewFactory factory)102     public void setFactory(ViewFactory factory) {
103         mFactory = factory;
104         obtainView();
105         obtainView();
106     }
107 
108     /**
109      * Reset the ViewSwitcher to hide all of the existing views and to make it
110      * think that the first time animation has not yet played.
111      */
reset()112     public void reset() {
113         mFirstTime = true;
114         View v;
115         v = getChildAt(0);
116         if (v != null) {
117             v.setVisibility(View.GONE);
118         }
119         v = getChildAt(1);
120         if (v != null) {
121             v.setVisibility(View.GONE);
122         }
123     }
124 
125     /**
126      * Creates views in a ViewSwitcher.
127      */
128     public interface ViewFactory {
129         /**
130          * Creates a new {@link android.view.View} to be added in a
131          * {@link android.widget.ViewSwitcher}.
132          *
133          * @return a {@link android.view.View}
134          */
makeView()135         View makeView();
136     }
137 }
138 
139