DropDownListView.java revision 00aa5103e2f71ad3f29f53168e37ef7da8ca03f2
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 boolean shouldShowSelector() { 131 return isHovered() || super.shouldShowSelector(); 132 } 133 134 @Override 135 public boolean onHoverEvent(MotionEvent ev) { 136 // Allow the super class to handle hover state management first. 137 final boolean handled = super.onHoverEvent(ev); 138 139 final int action = ev.getActionMasked(); 140 if (action == MotionEvent.ACTION_HOVER_ENTER 141 || action == MotionEvent.ACTION_HOVER_MOVE) { 142 final int position = pointToPosition((int) ev.getX(), (int) ev.getY()); 143 if (position != INVALID_POSITION && position != mSelectedPosition) { 144 final View hoveredItem = getChildAt(position - getFirstVisiblePosition()); 145 if (hoveredItem.isEnabled()) { 146 // Force a focus so that the proper selector state gets used when we update. 147 requestFocus(); 148 149 positionSelector(position, hoveredItem); 150 setSelectedPositionInt(position); 151 setNextSelectedPositionInt(position); 152 } 153 updateSelectorState(); 154 } 155 } else { 156 // Do not cancel the selected position if the selection is visible by other reasons. 157 if (!super.shouldShowSelector()) { 158 setSelectedPositionInt(INVALID_POSITION); 159 setNextSelectedPositionInt(INVALID_POSITION); 160 } 161 } 162 163 return handled; 164 } 165 166 /** 167 * Handles forwarded events. 168 * 169 * @param activePointerId id of the pointer that activated forwarding 170 * @return whether the event was handled 171 */ 172 public boolean onForwardedEvent(MotionEvent event, int activePointerId) { 173 boolean handledEvent = true; 174 boolean clearPressedItem = false; 175 176 final int actionMasked = event.getActionMasked(); 177 switch (actionMasked) { 178 case MotionEvent.ACTION_CANCEL: 179 handledEvent = false; 180 break; 181 case MotionEvent.ACTION_UP: 182 handledEvent = false; 183 // $FALL-THROUGH$ 184 case MotionEvent.ACTION_MOVE: 185 final int activeIndex = event.findPointerIndex(activePointerId); 186 if (activeIndex < 0) { 187 handledEvent = false; 188 break; 189 } 190 191 final int x = (int) event.getX(activeIndex); 192 final int y = (int) event.getY(activeIndex); 193 final int position = pointToPosition(x, y); 194 if (position == INVALID_POSITION) { 195 clearPressedItem = true; 196 break; 197 } 198 199 final View child = getChildAt(position - getFirstVisiblePosition()); 200 setPressedItem(child, position, x, y); 201 handledEvent = true; 202 203 if (actionMasked == MotionEvent.ACTION_UP) { 204 clickPressedItem(child, position); 205 } 206 break; 207 } 208 209 // Failure to handle the event cancels forwarding. 210 if (!handledEvent || clearPressedItem) { 211 clearPressedItem(); 212 } 213 214 // Manage automatic scrolling. 215 if (handledEvent) { 216 if (mScrollHelper == null) { 217 mScrollHelper = new AbsListViewAutoScroller(this); 218 } 219 mScrollHelper.setEnabled(true); 220 mScrollHelper.onTouch(this, event); 221 } else if (mScrollHelper != null) { 222 mScrollHelper.setEnabled(false); 223 } 224 225 return handledEvent; 226 } 227 228 /** 229 * Sets whether the list selection is hidden, as part of a workaround for a touch mode issue 230 * (see the declaration for mListSelectionHidden). 231 * @param listSelectionHidden 232 */ 233 public void setListSelectionHidden(boolean listSelectionHidden) { 234 this.mListSelectionHidden = listSelectionHidden; 235 } 236 237 /** 238 * Starts an alpha animation on the selector. When the animation ends, 239 * the list performs a click on the item. 240 */ 241 private void clickPressedItem(final View child, final int position) { 242 final long id = getItemIdAtPosition(position); 243 final Animator anim = ObjectAnimator.ofInt( 244 mSelector, DRAWABLE_ALPHA, 0xFF, CLICK_ANIM_ALPHA, 0xFF); 245 anim.setDuration(CLICK_ANIM_DURATION); 246 anim.setInterpolator(new AccelerateDecelerateInterpolator()); 247 anim.addListener(new AnimatorListenerAdapter() { 248 @Override 249 public void onAnimationEnd(Animator animation) { 250 performItemClick(child, position, id); 251 } 252 }); 253 anim.start(); 254 255 if (mClickAnimation != null) { 256 mClickAnimation.cancel(); 257 } 258 mClickAnimation = anim; 259 } 260 261 private void clearPressedItem() { 262 mDrawsInPressedState = false; 263 setPressed(false); 264 updateSelectorState(); 265 266 final View motionView = getChildAt(mMotionPosition - mFirstPosition); 267 if (motionView != null) { 268 motionView.setPressed(false); 269 } 270 271 if (mClickAnimation != null) { 272 mClickAnimation.cancel(); 273 mClickAnimation = null; 274 } 275 } 276 277 private void setPressedItem(View child, int position, float x, float y) { 278 mDrawsInPressedState = true; 279 280 // Ordering is essential. First, update the container's pressed state. 281 drawableHotspotChanged(x, y); 282 if (!isPressed()) { 283 setPressed(true); 284 } 285 286 // Next, run layout if we need to stabilize child positions. 287 if (mDataChanged) { 288 layoutChildren(); 289 } 290 291 // Manage the pressed view based on motion position. This allows us to 292 // play nicely with actual touch and scroll events. 293 final View motionView = getChildAt(mMotionPosition - mFirstPosition); 294 if (motionView != null && motionView != child && motionView.isPressed()) { 295 motionView.setPressed(false); 296 } 297 mMotionPosition = position; 298 299 // Offset for child coordinates. 300 final float childX = x - child.getLeft(); 301 final float childY = y - child.getTop(); 302 child.drawableHotspotChanged(childX, childY); 303 if (!child.isPressed()) { 304 child.setPressed(true); 305 } 306 307 // Ensure that keyboard focus starts from the last touched position. 308 setSelectedPositionInt(position); 309 positionSelectorLikeTouch(position, child, x, y); 310 311 // Refresh the drawable state to reflect the new pressed state, 312 // which will also update the selector state. 313 refreshDrawableState(); 314 315 if (mClickAnimation != null) { 316 mClickAnimation.cancel(); 317 mClickAnimation = null; 318 } 319 } 320 321 @Override 322 boolean touchModeDrawsInPressedState() { 323 return mDrawsInPressedState || super.touchModeDrawsInPressedState(); 324 } 325 326 /** 327 * Avoids jarring scrolling effect by ensuring that list elements 328 * made of a text view fit on a single line. 329 * 330 * @param position the item index in the list to get a view for 331 * @return the view for the specified item 332 */ 333 @Override 334 View obtainView(int position, boolean[] isScrap) { 335 View view = super.obtainView(position, isScrap); 336 337 if (view instanceof TextView) { 338 ((TextView) view).setHorizontallyScrolling(true); 339 } 340 341 return view; 342 } 343 344 @Override 345 public boolean isInTouchMode() { 346 // WARNING: Please read the comment where mListSelectionHidden is declared 347 return (mHijackFocus && mListSelectionHidden) || super.isInTouchMode(); 348 } 349 350 /** 351 * Returns the focus state in the drop down. 352 * 353 * @return true always if hijacking focus 354 */ 355 @Override 356 public boolean hasWindowFocus() { 357 return mHijackFocus || super.hasWindowFocus(); 358 } 359 360 /** 361 * Returns the focus state in the drop down. 362 * 363 * @return true always if hijacking focus 364 */ 365 @Override 366 public boolean isFocused() { 367 return mHijackFocus || super.isFocused(); 368 } 369 370 /** 371 * Returns the focus state in the drop down. 372 * 373 * @return true always if hijacking focus 374 */ 375 @Override 376 public boolean hasFocus() { 377 return mHijackFocus || super.hasFocus(); 378 } 379}