DropDownListView.java revision 23087be7792c2d22173cf022a72d0648aa430ab5
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 19 20import com.android.internal.widget.AutoScrollHelper.AbsListViewAutoScroller; 21 22import android.animation.Animator; 23import android.animation.AnimatorListenerAdapter; 24import android.animation.ObjectAnimator; 25import android.content.Context; 26import android.graphics.drawable.Drawable; 27import android.util.IntProperty; 28import android.view.MotionEvent; 29import android.view.View; 30import android.view.animation.AccelerateDecelerateInterpolator; 31import android.widget.TextView; 32import android.widget.ListView; 33 34 35/** 36 * Wrapper class for a ListView. This wrapper can hijack the focus to 37 * make sure the list uses the appropriate drawables and states when 38 * displayed on screen within a drop down. The focus is never actually 39 * passed to the drop down in this mode; the list only looks focused. 40 * 41 * @hide 42 */ 43public class DropDownListView extends ListView { 44 /** Duration in milliseconds of the drag-to-open click animation. */ 45 private static final long CLICK_ANIM_DURATION = 150; 46 47 /** Target alpha value for drag-to-open click animation. */ 48 private static final int CLICK_ANIM_ALPHA = 0x80; 49 50 /** Wrapper around Drawable's <code>alpha</code> property. */ 51 private static final IntProperty<Drawable> DRAWABLE_ALPHA = 52 new IntProperty<Drawable>("alpha") { 53 @Override 54 public void setValue(Drawable object, int value) { 55 object.setAlpha(value); 56 } 57 58 @Override 59 public Integer get(Drawable object) { 60 return object.getAlpha(); 61 } 62 }; 63 64 /* 65 * WARNING: This is a workaround for a touch mode issue. 66 * 67 * Touch mode is propagated lazily to windows. This causes problems in 68 * the following scenario: 69 * - Type something in the AutoCompleteTextView and get some results 70 * - Move down with the d-pad to select an item in the list 71 * - Move up with the d-pad until the selection disappears 72 * - Type more text in the AutoCompleteTextView *using the soft keyboard* 73 * and get new results; you are now in touch mode 74 * - The selection comes back on the first item in the list, even though 75 * the list is supposed to be in touch mode 76 * 77 * Using the soft keyboard triggers the touch mode change but that change 78 * is propagated to our window only after the first list layout, therefore 79 * after the list attempts to resurrect the selection. 80 * 81 * The trick to work around this issue is to pretend the list is in touch 82 * mode when we know that the selection should not appear, that is when 83 * we know the user moved the selection away from the list. 84 * 85 * This boolean is set to true whenever we explicitly hide the list's 86 * selection and reset to false whenever we know the user moved the 87 * selection back to the list. 88 * 89 * When this boolean is true, isInTouchMode() returns true, otherwise it 90 * returns super.isInTouchMode(). 91 */ 92 private boolean mListSelectionHidden; 93 94 /** 95 * True if this wrapper should fake focus. 96 */ 97 private boolean mHijackFocus; 98 99 /** Whether to force drawing of the pressed state selector. */ 100 private boolean mDrawsInPressedState; 101 102 /** Current drag-to-open click animation, if any. */ 103 private Animator mClickAnimation; 104 105 /** Helper for drag-to-open auto scrolling. */ 106 private AbsListViewAutoScroller mScrollHelper; 107 108 /** 109 * Creates a new list view wrapper. 110 * 111 * @param context this view's context 112 */ 113 public DropDownListView(Context context, boolean hijackFocus) { 114 this(context, hijackFocus, com.android.internal.R.attr.dropDownListViewStyle); 115 } 116 117 /** 118 * Creates a new list view wrapper. 119 * 120 * @param context this view's context 121 */ 122 public DropDownListView(Context context, boolean hijackFocus, int defStyleAttr) { 123 super(context, null, defStyleAttr); 124 mHijackFocus = hijackFocus; 125 // TODO: Add an API to control this 126 setCacheColorHint(0); // Transparent, since the background drawable could be anything. 127 } 128 129 @Override 130 protected boolean shouldShowSelector() { 131 View selectedView = getSelectedView(); 132 return selectedView != null && selectedView.isEnabled() || super.shouldShowSelector(); 133 } 134 135 @Override 136 public boolean onHoverEvent(MotionEvent ev) { 137 final int action = ev.getActionMasked(); 138 if (action == MotionEvent.ACTION_HOVER_ENTER 139 || action == MotionEvent.ACTION_HOVER_MOVE) { 140 final int position = pointToPosition((int) ev.getX(), (int) ev.getY()); 141 if (position != INVALID_POSITION && position != mSelectedPosition) { 142 final View hoveredItem = getChildAt(position - getFirstVisiblePosition()); 143 if (hoveredItem.isEnabled()) { 144 // Force a focus so that the proper selector state gets used when we update. 145 requestFocus(); 146 147 positionSelector(position, hoveredItem); 148 setSelectedPositionInt(position); 149 setNextSelectedPositionInt(position); 150 } 151 updateSelectorState(); 152 } 153 } else { 154 // Do not cancel the selected position if the selection is visible by other reasons. 155 if (!super.shouldShowSelector()) { 156 setSelectedPositionInt(INVALID_POSITION); 157 } 158 } 159 return super.onHoverEvent(ev); 160 } 161 162 @Override 163 public boolean onTouchEvent(MotionEvent event) { 164 final int x = (int) event.getX(); 165 final int y = (int) event.getY(); 166 final int position = pointToPosition(x, y); 167 if (position == INVALID_POSITION) { 168 return super.onTouchEvent(event); 169 } 170 171 if (position != mSelectedPosition) { 172 setSelectedPositionInt(position); 173 setNextSelectedPositionInt(position); 174 } 175 176 return super.onTouchEvent(event); 177 } 178 179 /** 180 * Handles forwarded events. 181 * 182 * @param activePointerId id of the pointer that activated forwarding 183 * @return whether the event was handled 184 */ 185 public boolean onForwardedEvent(MotionEvent event, int activePointerId) { 186 boolean handledEvent = true; 187 boolean clearPressedItem = false; 188 189 final int actionMasked = event.getActionMasked(); 190 switch (actionMasked) { 191 case MotionEvent.ACTION_CANCEL: 192 handledEvent = false; 193 break; 194 case MotionEvent.ACTION_UP: 195 handledEvent = false; 196 // $FALL-THROUGH$ 197 case MotionEvent.ACTION_MOVE: 198 final int activeIndex = event.findPointerIndex(activePointerId); 199 if (activeIndex < 0) { 200 handledEvent = false; 201 break; 202 } 203 204 final int x = (int) event.getX(activeIndex); 205 final int y = (int) event.getY(activeIndex); 206 final int position = pointToPosition(x, y); 207 if (position == INVALID_POSITION) { 208 clearPressedItem = true; 209 break; 210 } 211 212 final View child = getChildAt(position - getFirstVisiblePosition()); 213 setPressedItem(child, position, x, y); 214 handledEvent = true; 215 216 if (actionMasked == MotionEvent.ACTION_UP) { 217 clickPressedItem(child, position); 218 } 219 break; 220 } 221 222 // Failure to handle the event cancels forwarding. 223 if (!handledEvent || clearPressedItem) { 224 clearPressedItem(); 225 } 226 227 // Manage automatic scrolling. 228 if (handledEvent) { 229 if (mScrollHelper == null) { 230 mScrollHelper = new AbsListViewAutoScroller(this); 231 } 232 mScrollHelper.setEnabled(true); 233 mScrollHelper.onTouch(this, event); 234 } else if (mScrollHelper != null) { 235 mScrollHelper.setEnabled(false); 236 } 237 238 return handledEvent; 239 } 240 241 /** 242 * Sets whether the list selection is hidden, as part of a workaround for a touch mode issue 243 * (see the declaration for mListSelectionHidden). 244 * @param listSelectionHidden 245 */ 246 public void setListSelectionHidden(boolean listSelectionHidden) { 247 this.mListSelectionHidden = listSelectionHidden; 248 } 249 250 /** 251 * Starts an alpha animation on the selector. When the animation ends, 252 * the list performs a click on the item. 253 */ 254 private void clickPressedItem(final View child, final int position) { 255 final long id = getItemIdAtPosition(position); 256 final Animator anim = ObjectAnimator.ofInt( 257 mSelector, DRAWABLE_ALPHA, 0xFF, CLICK_ANIM_ALPHA, 0xFF); 258 anim.setDuration(CLICK_ANIM_DURATION); 259 anim.setInterpolator(new AccelerateDecelerateInterpolator()); 260 anim.addListener(new AnimatorListenerAdapter() { 261 @Override 262 public void onAnimationEnd(Animator animation) { 263 performItemClick(child, position, id); 264 } 265 }); 266 anim.start(); 267 268 if (mClickAnimation != null) { 269 mClickAnimation.cancel(); 270 } 271 mClickAnimation = anim; 272 } 273 274 private void clearPressedItem() { 275 mDrawsInPressedState = false; 276 setPressed(false); 277 updateSelectorState(); 278 279 final View motionView = getChildAt(mMotionPosition - mFirstPosition); 280 if (motionView != null) { 281 motionView.setPressed(false); 282 } 283 284 if (mClickAnimation != null) { 285 mClickAnimation.cancel(); 286 mClickAnimation = null; 287 } 288 } 289 290 private void setPressedItem(View child, int position, float x, float y) { 291 mDrawsInPressedState = true; 292 293 // Ordering is essential. First, update the container's pressed state. 294 drawableHotspotChanged(x, y); 295 if (!isPressed()) { 296 setPressed(true); 297 } 298 299 // Next, run layout if we need to stabilize child positions. 300 if (mDataChanged) { 301 layoutChildren(); 302 } 303 304 // Manage the pressed view based on motion position. This allows us to 305 // play nicely with actual touch and scroll events. 306 final View motionView = getChildAt(mMotionPosition - mFirstPosition); 307 if (motionView != null && motionView != child && motionView.isPressed()) { 308 motionView.setPressed(false); 309 } 310 mMotionPosition = position; 311 312 // Offset for child coordinates. 313 final float childX = x - child.getLeft(); 314 final float childY = y - child.getTop(); 315 child.drawableHotspotChanged(childX, childY); 316 if (!child.isPressed()) { 317 child.setPressed(true); 318 } 319 320 // Ensure that keyboard focus starts from the last touched position. 321 setSelectedPositionInt(position); 322 positionSelectorLikeTouch(position, child, x, y); 323 324 // Refresh the drawable state to reflect the new pressed state, 325 // which will also update the selector state. 326 refreshDrawableState(); 327 328 if (mClickAnimation != null) { 329 mClickAnimation.cancel(); 330 mClickAnimation = null; 331 } 332 } 333 334 @Override 335 boolean touchModeDrawsInPressedState() { 336 return mDrawsInPressedState || super.touchModeDrawsInPressedState(); 337 } 338 339 /** 340 * Avoids jarring scrolling effect by ensuring that list elements 341 * made of a text view fit on a single line. 342 * 343 * @param position the item index in the list to get a view for 344 * @return the view for the specified item 345 */ 346 @Override 347 View obtainView(int position, boolean[] isScrap) { 348 View view = super.obtainView(position, isScrap); 349 350 if (view instanceof TextView) { 351 ((TextView) view).setHorizontallyScrolling(true); 352 } 353 354 return view; 355 } 356 357 @Override 358 public boolean isInTouchMode() { 359 // WARNING: Please read the comment where mListSelectionHidden is declared 360 return (mHijackFocus && mListSelectionHidden) || super.isInTouchMode(); 361 } 362 363 /** 364 * Returns the focus state in the drop down. 365 * 366 * @return true always if hijacking focus 367 */ 368 @Override 369 public boolean hasWindowFocus() { 370 return mHijackFocus || super.hasWindowFocus(); 371 } 372 373 /** 374 * Returns the focus state in the drop down. 375 * 376 * @return true always if hijacking focus 377 */ 378 @Override 379 public boolean isFocused() { 380 return mHijackFocus || super.isFocused(); 381 } 382 383 /** 384 * Returns the focus state in the drop down. 385 * 386 * @return true always if hijacking focus 387 */ 388 @Override 389 public boolean hasFocus() { 390 return mHijackFocus || super.hasFocus(); 391 } 392}