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 17package android.widget; 18 19import android.os.SystemClock; 20import android.view.MotionEvent; 21import android.view.View; 22import android.view.ViewConfiguration; 23import android.view.ViewParent; 24 25import com.android.internal.view.menu.ShowableListMenu; 26 27/** 28 * Abstract class that forwards touch events to a {@link ShowableListMenu}. 29 * 30 * @hide 31 */ 32public abstract class ForwardingListener 33 implements View.OnTouchListener, View.OnAttachStateChangeListener { 34 35 /** Scaled touch slop, used for detecting movement outside bounds. */ 36 private final float mScaledTouchSlop; 37 38 /** Timeout before disallowing intercept on the source's parent. */ 39 private final int mTapTimeout; 40 41 /** Timeout before accepting a long-press to start forwarding. */ 42 private final int mLongPressTimeout; 43 44 /** Source view from which events are forwarded. */ 45 private final View mSrc; 46 47 /** Runnable used to prevent conflicts with scrolling parents. */ 48 private Runnable mDisallowIntercept; 49 50 /** Runnable used to trigger forwarding on long-press. */ 51 private Runnable mTriggerLongPress; 52 53 /** Whether this listener is currently forwarding touch events. */ 54 private boolean mForwarding; 55 56 /** The id of the first pointer down in the current event stream. */ 57 private int mActivePointerId; 58 59 public ForwardingListener(View src) { 60 mSrc = src; 61 mScaledTouchSlop = ViewConfiguration.get(src.getContext()).getScaledTouchSlop(); 62 mTapTimeout = ViewConfiguration.getTapTimeout(); 63 64 // Use a medium-press timeout. Halfway between tap and long-press. 65 mLongPressTimeout = (mTapTimeout + ViewConfiguration.getLongPressTimeout()) / 2; 66 67 src.addOnAttachStateChangeListener(this); 68 } 69 70 /** 71 * Returns the popup to which this listener is forwarding events. 72 * <p> 73 * Override this to return the correct popup. If the popup is displayed 74 * asynchronously, you may also need to override 75 * {@link #onForwardingStopped} to prevent premature cancellation of 76 * forwarding. 77 * 78 * @return the popup to which this listener is forwarding events 79 */ 80 public abstract ShowableListMenu getPopup(); 81 82 @Override 83 public boolean onTouch(View v, MotionEvent event) { 84 final boolean wasForwarding = mForwarding; 85 final boolean forwarding; 86 if (wasForwarding) { 87 forwarding = onTouchForwarded(event) || !onForwardingStopped(); 88 } else { 89 forwarding = onTouchObserved(event) && onForwardingStarted(); 90 91 if (forwarding) { 92 // Make sure we cancel any ongoing source event stream. 93 final long now = SystemClock.uptimeMillis(); 94 final MotionEvent e = MotionEvent.obtain(now, now, MotionEvent.ACTION_CANCEL, 95 0.0f, 0.0f, 0); 96 mSrc.onTouchEvent(e); 97 e.recycle(); 98 } 99 } 100 101 mForwarding = forwarding; 102 return forwarding || wasForwarding; 103 } 104 105 @Override 106 public void onViewAttachedToWindow(View v) { 107 } 108 109 @Override 110 public void onViewDetachedFromWindow(View v) { 111 mForwarding = false; 112 mActivePointerId = MotionEvent.INVALID_POINTER_ID; 113 114 if (mDisallowIntercept != null) { 115 mSrc.removeCallbacks(mDisallowIntercept); 116 } 117 } 118 119 /** 120 * Called when forwarding would like to start. 121 * <p> 122 * By default, this will show the popup returned by {@link #getPopup()}. 123 * It may be overridden to perform another action, like clicking the 124 * source view or preparing the popup before showing it. 125 * 126 * @return true to start forwarding, false otherwise 127 */ 128 protected boolean onForwardingStarted() { 129 final ShowableListMenu popup = getPopup(); 130 if (popup != null && !popup.isShowing()) { 131 popup.show(); 132 } 133 return true; 134 } 135 136 /** 137 * Called when forwarding would like to stop. 138 * <p> 139 * By default, this will dismiss the popup returned by 140 * {@link #getPopup()}. It may be overridden to perform some other 141 * action. 142 * 143 * @return true to stop forwarding, false otherwise 144 */ 145 protected boolean onForwardingStopped() { 146 final ShowableListMenu popup = getPopup(); 147 if (popup != null && popup.isShowing()) { 148 popup.dismiss(); 149 } 150 return true; 151 } 152 153 /** 154 * Observes motion events and determines when to start forwarding. 155 * 156 * @param srcEvent motion event in source view coordinates 157 * @return true to start forwarding motion events, false otherwise 158 */ 159 private boolean onTouchObserved(MotionEvent srcEvent) { 160 final View src = mSrc; 161 if (!src.isEnabled()) { 162 return false; 163 } 164 165 final int actionMasked = srcEvent.getActionMasked(); 166 switch (actionMasked) { 167 case MotionEvent.ACTION_DOWN: 168 mActivePointerId = srcEvent.getPointerId(0); 169 170 if (mDisallowIntercept == null) { 171 mDisallowIntercept = new DisallowIntercept(); 172 } 173 src.postDelayed(mDisallowIntercept, mTapTimeout); 174 175 if (mTriggerLongPress == null) { 176 mTriggerLongPress = new TriggerLongPress(); 177 } 178 src.postDelayed(mTriggerLongPress, mLongPressTimeout); 179 break; 180 case MotionEvent.ACTION_MOVE: 181 final int activePointerIndex = srcEvent.findPointerIndex(mActivePointerId); 182 if (activePointerIndex >= 0) { 183 final float x = srcEvent.getX(activePointerIndex); 184 final float y = srcEvent.getY(activePointerIndex); 185 186 // Has the pointer moved outside of the view? 187 if (!src.pointInView(x, y, mScaledTouchSlop)) { 188 clearCallbacks(); 189 190 // Don't let the parent intercept our events. 191 src.getParent().requestDisallowInterceptTouchEvent(true); 192 return true; 193 } 194 } 195 break; 196 case MotionEvent.ACTION_CANCEL: 197 case MotionEvent.ACTION_UP: 198 clearCallbacks(); 199 break; 200 } 201 202 return false; 203 } 204 205 private void clearCallbacks() { 206 if (mTriggerLongPress != null) { 207 mSrc.removeCallbacks(mTriggerLongPress); 208 } 209 210 if (mDisallowIntercept != null) { 211 mSrc.removeCallbacks(mDisallowIntercept); 212 } 213 } 214 215 private void onLongPress() { 216 clearCallbacks(); 217 218 final View src = mSrc; 219 if (!src.isEnabled() || src.isLongClickable()) { 220 // Ignore long-press if the view is disabled or has its own 221 // handler. 222 return; 223 } 224 225 if (!onForwardingStarted()) { 226 return; 227 } 228 229 // Don't let the parent intercept our events. 230 src.getParent().requestDisallowInterceptTouchEvent(true); 231 232 // Make sure we cancel any ongoing source event stream. 233 final long now = SystemClock.uptimeMillis(); 234 final MotionEvent e = MotionEvent.obtain(now, now, MotionEvent.ACTION_CANCEL, 0, 0, 0); 235 src.onTouchEvent(e); 236 e.recycle(); 237 238 mForwarding = true; 239 } 240 241 /** 242 * Handles forwarded motion events and determines when to stop 243 * forwarding. 244 * 245 * @param srcEvent motion event in source view coordinates 246 * @return true to continue forwarding motion events, false to cancel 247 */ 248 private boolean onTouchForwarded(MotionEvent srcEvent) { 249 final View src = mSrc; 250 final ShowableListMenu popup = getPopup(); 251 if (popup == null || !popup.isShowing()) { 252 return false; 253 } 254 255 final DropDownListView dst = (DropDownListView) popup.getListView(); 256 if (dst == null || !dst.isShown()) { 257 return false; 258 } 259 260 // Convert event to destination-local coordinates. 261 final MotionEvent dstEvent = MotionEvent.obtainNoHistory(srcEvent); 262 src.toGlobalMotionEvent(dstEvent); 263 dst.toLocalMotionEvent(dstEvent); 264 265 // Forward converted event to destination view, then recycle it. 266 final boolean handled = dst.onForwardedEvent(dstEvent, mActivePointerId); 267 dstEvent.recycle(); 268 269 // Always cancel forwarding when the touch stream ends. 270 final int action = srcEvent.getActionMasked(); 271 final boolean keepForwarding = action != MotionEvent.ACTION_UP 272 && action != MotionEvent.ACTION_CANCEL; 273 274 return handled && keepForwarding; 275 } 276 277 private class DisallowIntercept implements Runnable { 278 @Override 279 public void run() { 280 final ViewParent parent = mSrc.getParent(); 281 parent.requestDisallowInterceptTouchEvent(true); 282 } 283 } 284 285 private class TriggerLongPress implements Runnable { 286 @Override 287 public void run() { 288 onLongPress(); 289 } 290 } 291}