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