1/* 2 * Copyright (C) 2011 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 17package android.support.v4.view; 18 19import android.os.Build; 20import android.view.View; 21import android.view.ViewGroup; 22import android.view.accessibility.AccessibilityEvent; 23 24/** 25 * Helper for accessing features in {@link ViewGroup} 26 * introduced after API level 4 in a backwards compatible fashion. 27 */ 28public class ViewGroupCompat { 29 30 /** 31 * This constant is a {@link #setLayoutMode(ViewGroup, int) layoutMode}. 32 * Clip bounds are the raw values of {@link android.view.View#getLeft() left}, 33 * {@link android.view.View#getTop() top}, 34 * {@link android.view.View#getRight() right} and {@link android.view.View#getBottom() bottom}. 35 */ 36 public static final int LAYOUT_MODE_CLIP_BOUNDS = 0; 37 38 /** 39 * This constant is a {@link #setLayoutMode(ViewGroup, int) layoutMode}. 40 * Optical bounds describe where a widget appears to be. They sit inside the clip 41 * bounds which need to cover a larger area to allow other effects, 42 * such as shadows and glows, to be drawn. 43 */ 44 public static final int LAYOUT_MODE_OPTICAL_BOUNDS = 1; 45 46 interface ViewGroupCompatImpl { 47 public boolean onRequestSendAccessibilityEvent(ViewGroup group, View child, 48 AccessibilityEvent event); 49 50 public void setMotionEventSplittingEnabled(ViewGroup group, boolean split); 51 public int getLayoutMode(ViewGroup group); 52 public void setLayoutMode(ViewGroup group, int mode); 53 public void setTransitionGroup(ViewGroup group, boolean isTransitionGroup); 54 public boolean isTransitionGroup(ViewGroup group); 55 } 56 57 static class ViewGroupCompatStubImpl implements ViewGroupCompatImpl { 58 public boolean onRequestSendAccessibilityEvent( 59 ViewGroup group, View child, AccessibilityEvent event) { 60 return true; 61 } 62 63 public void setMotionEventSplittingEnabled(ViewGroup group, boolean split) { 64 // no-op, didn't exist. 65 } 66 67 @Override 68 public int getLayoutMode(ViewGroup group) { 69 return LAYOUT_MODE_CLIP_BOUNDS; 70 } 71 72 @Override 73 public void setLayoutMode(ViewGroup group, int mode) { 74 // no-op, didn't exist. Views only support clip bounds. 75 } 76 77 @Override 78 public void setTransitionGroup(ViewGroup group, boolean isTransitionGroup) { 79 } 80 81 @Override 82 public boolean isTransitionGroup(ViewGroup group) { 83 return false; 84 } 85 } 86 87 static class ViewGroupCompatHCImpl extends ViewGroupCompatStubImpl { 88 @Override 89 public void setMotionEventSplittingEnabled(ViewGroup group, boolean split) { 90 ViewGroupCompatHC.setMotionEventSplittingEnabled(group, split); 91 } 92 } 93 94 static class ViewGroupCompatIcsImpl extends ViewGroupCompatHCImpl { 95 @Override 96 public boolean onRequestSendAccessibilityEvent( 97 ViewGroup group, View child, AccessibilityEvent event) { 98 return ViewGroupCompatIcs.onRequestSendAccessibilityEvent(group, child, event); 99 } 100 } 101 102 static class ViewGroupCompatJellybeanMR2Impl extends ViewGroupCompatIcsImpl { 103 @Override 104 public int getLayoutMode(ViewGroup group) { 105 return ViewGroupCompatJellybeanMR2.getLayoutMode(group); 106 } 107 108 @Override 109 public void setLayoutMode(ViewGroup group, int mode) { 110 ViewGroupCompatJellybeanMR2.setLayoutMode(group, mode); 111 } 112 } 113 114 static class ViewGroupCompatApi21Impl extends ViewGroupCompatJellybeanMR2Impl { 115 @Override 116 public void setTransitionGroup(ViewGroup group, boolean isTransitionGroup) { 117 ViewGroupCompatApi21.setTransitionGroup(group, isTransitionGroup); 118 } 119 120 @Override 121 public boolean isTransitionGroup(ViewGroup group) { 122 return ViewGroupCompatApi21.isTransitionGroup(group); 123 } 124 } 125 126 static final ViewGroupCompatImpl IMPL; 127 static { 128 final int version = Build.VERSION.SDK_INT; 129 if (version >= 21) { 130 IMPL = new ViewGroupCompatApi21Impl(); 131 } else if (version >= 18) { 132 IMPL = new ViewGroupCompatJellybeanMR2Impl(); 133 } else if (version >= 14) { 134 IMPL = new ViewGroupCompatIcsImpl(); 135 } else if (version >= 11) { 136 IMPL = new ViewGroupCompatHCImpl(); 137 } else { 138 IMPL = new ViewGroupCompatStubImpl(); 139 } 140 } 141 142 /* 143 * Hide the constructor. 144 */ 145 private ViewGroupCompat() { 146 147 } 148 149 /** 150 * Called when a child has requested sending an {@link AccessibilityEvent} and 151 * gives an opportunity to its parent to augment the event. 152 * <p> 153 * If an {@link AccessibilityDelegateCompat} has been specified via calling 154 * {@link ViewCompat#setAccessibilityDelegate(View, AccessibilityDelegateCompat)} its 155 * {@link AccessibilityDelegateCompat#onRequestSendAccessibilityEvent(ViewGroup, View, 156 * AccessibilityEvent)} is responsible for handling this call. 157 * </p> 158 * 159 * @param group The group whose method to invoke. 160 * @param child The child which requests sending the event. 161 * @param event The event to be sent. 162 * @return True if the event should be sent. 163 */ 164 public static boolean onRequestSendAccessibilityEvent(ViewGroup group, View child, 165 AccessibilityEvent event) { 166 return IMPL.onRequestSendAccessibilityEvent(group, child, event); 167 } 168 169 /** 170 * Enable or disable the splitting of MotionEvents to multiple children during touch event 171 * dispatch. This behavior is enabled by default for applications that target an 172 * SDK version of 11 (Honeycomb) or newer. On earlier platform versions this feature 173 * was not supported and this method is a no-op. 174 * 175 * <p>When this option is enabled MotionEvents may be split and dispatched to different child 176 * views depending on where each pointer initially went down. This allows for user interactions 177 * such as scrolling two panes of content independently, chording of buttons, and performing 178 * independent gestures on different pieces of content. 179 * 180 * @param group ViewGroup to modify 181 * @param split <code>true</code> to allow MotionEvents to be split and dispatched to multiple 182 * child views. <code>false</code> to only allow one child view to be the target of 183 * any MotionEvent received by this ViewGroup. 184 */ 185 public static void setMotionEventSplittingEnabled(ViewGroup group, boolean split) { 186 IMPL.setMotionEventSplittingEnabled(group, split); 187 } 188 189 /** 190 * Returns the basis of alignment during layout operations on this ViewGroup: 191 * either {@link #LAYOUT_MODE_CLIP_BOUNDS} or {@link #LAYOUT_MODE_OPTICAL_BOUNDS}. 192 * <p> 193 * If no layoutMode was explicitly set, either programmatically or in an XML resource, 194 * the method returns the layoutMode of the view's parent ViewGroup if such a parent exists, 195 * otherwise the method returns a default value of {@link #LAYOUT_MODE_CLIP_BOUNDS}. 196 * 197 * @return the layout mode to use during layout operations 198 * 199 * @see #setLayoutMode(ViewGroup, int) 200 */ 201 public static int getLayoutMode(ViewGroup group) { 202 return IMPL.getLayoutMode(group); 203 } 204 205 /** 206 * Sets the basis of alignment during the layout of this ViewGroup. 207 * Valid values are either {@link #LAYOUT_MODE_CLIP_BOUNDS} or 208 * {@link #LAYOUT_MODE_OPTICAL_BOUNDS}. 209 * 210 * @param mode the layout mode to use during layout operations 211 * 212 * @see #getLayoutMode(ViewGroup) 213 */ 214 public static void setLayoutMode(ViewGroup group, int mode) { 215 IMPL.setLayoutMode(group, mode); 216 } 217 218 /** 219 * Changes whether or not this ViewGroup should be treated as a single entity during 220 * Activity Transitions. 221 * @param isTransitionGroup Whether or not the ViewGroup should be treated as a unit 222 * in Activity transitions. If false, the ViewGroup won't transition, 223 * only its children. If true, the entire ViewGroup will transition 224 * together. 225 */ 226 public static void setTransitionGroup(ViewGroup group, boolean isTransitionGroup) { 227 IMPL.setTransitionGroup(group, isTransitionGroup); 228 } 229 230 /** 231 * Returns true if this ViewGroup should be considered as a single entity for removal 232 * when executing an Activity transition. If this is false, child elements will move 233 * individually during the transition. 234 */ 235 public static boolean isTransitionGroup(ViewGroup group) { 236 return IMPL.isTransitionGroup(group); 237 } 238} 239