1 /*
2  * Copyright (C) 2014 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 com.android.systemui.recents.views;
18 
19 import android.animation.Animator;
20 import android.animation.ValueAnimator;
21 import android.content.Context;
22 import android.content.res.Resources;
23 import android.graphics.Path;
24 import android.graphics.Rect;
25 import android.util.ArrayMap;
26 import android.util.MutableBoolean;
27 import android.view.InputDevice;
28 import android.view.MotionEvent;
29 import android.view.VelocityTracker;
30 import android.view.View;
31 import android.view.ViewConfiguration;
32 import android.view.ViewDebug;
33 import android.view.ViewParent;
34 import android.view.animation.Interpolator;
35 
36 import com.android.internal.logging.MetricsLogger;
37 import com.android.internal.logging.MetricsProto.MetricsEvent;
38 import com.android.systemui.Interpolators;
39 import com.android.systemui.R;
40 import com.android.systemui.SwipeHelper;
41 import com.android.systemui.recents.Constants;
42 import com.android.systemui.recents.Recents;
43 import com.android.systemui.recents.events.EventBus;
44 import com.android.systemui.recents.events.activity.HideRecentsEvent;
45 import com.android.systemui.recents.events.ui.StackViewScrolledEvent;
46 import com.android.systemui.recents.events.ui.TaskViewDismissedEvent;
47 import com.android.systemui.recents.misc.FreePathInterpolator;
48 import com.android.systemui.recents.misc.SystemServicesProxy;
49 import com.android.systemui.recents.misc.Utilities;
50 import com.android.systemui.recents.model.Task;
51 import com.android.systemui.statusbar.FlingAnimationUtils;
52 
53 import java.util.ArrayList;
54 import java.util.List;
55 
56 /**
57  * Handles touch events for a TaskStackView.
58  */
59 class TaskStackViewTouchHandler implements SwipeHelper.Callback {
60 
61     private static final int INACTIVE_POINTER_ID = -1;
62     private static final float CHALLENGING_SWIPE_ESCAPE_VELOCITY = 800f; // dp/sec
63     // The min overscroll is the amount of task progress overscroll we want / the max overscroll
64     // curve value below
65     private static final float MAX_OVERSCROLL = 0.7f / 0.3f;
66     private static final Interpolator OVERSCROLL_INTERP;
67     static {
68         Path OVERSCROLL_PATH = new Path();
69         OVERSCROLL_PATH.moveTo(0, 0);
70         OVERSCROLL_PATH.cubicTo(0.2f, 0.175f, 0.25f, 0.3f, 1f, 0.3f);
71         OVERSCROLL_INTERP = new FreePathInterpolator(OVERSCROLL_PATH);
72     }
73 
74     Context mContext;
75     TaskStackView mSv;
76     TaskStackViewScroller mScroller;
77     VelocityTracker mVelocityTracker;
78     FlingAnimationUtils mFlingAnimUtils;
79     ValueAnimator mScrollFlingAnimator;
80 
81     @ViewDebug.ExportedProperty(category="recents")
82     boolean mIsScrolling;
83     float mDownScrollP;
84     int mDownX, mDownY;
85     int mLastY;
86     int mActivePointerId = INACTIVE_POINTER_ID;
87     int mOverscrollSize;
88     TaskView mActiveTaskView = null;
89 
90     int mMinimumVelocity;
91     int mMaximumVelocity;
92     // The scroll touch slop is used to calculate when we start scrolling
93     int mScrollTouchSlop;
94     // Used to calculate when a tap is outside a task view rectangle.
95     final int mWindowTouchSlop;
96 
97     private final StackViewScrolledEvent mStackViewScrolledEvent = new StackViewScrolledEvent();
98 
99     // The current and final set of task transforms, sized to match the list of tasks in the stack
100     private ArrayList<Task> mCurrentTasks = new ArrayList<>();
101     private ArrayList<TaskViewTransform> mCurrentTaskTransforms = new ArrayList<>();
102     private ArrayList<TaskViewTransform> mFinalTaskTransforms = new ArrayList<>();
103     private ArrayMap<View, Animator> mSwipeHelperAnimations = new ArrayMap<>();
104     private TaskViewTransform mTmpTransform = new TaskViewTransform();
105     private float mTargetStackScroll;
106 
107     SwipeHelper mSwipeHelper;
108     boolean mInterceptedBySwipeHelper;
109 
TaskStackViewTouchHandler(Context context, TaskStackView sv, TaskStackViewScroller scroller)110     public TaskStackViewTouchHandler(Context context, TaskStackView sv,
111             TaskStackViewScroller scroller) {
112         Resources res = context.getResources();
113         ViewConfiguration configuration = ViewConfiguration.get(context);
114         mContext = context;
115         mSv = sv;
116         mScroller = scroller;
117         mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
118         mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
119         mScrollTouchSlop = configuration.getScaledTouchSlop();
120         mWindowTouchSlop = configuration.getScaledWindowTouchSlop();
121         mFlingAnimUtils = new FlingAnimationUtils(context, 0.2f);
122         mOverscrollSize = res.getDimensionPixelSize(R.dimen.recents_fling_overscroll_distance);
123         mSwipeHelper = new SwipeHelper(SwipeHelper.X, this, context) {
124             @Override
125             protected float getSize(View v) {
126                 return getScaledDismissSize();
127             }
128 
129             @Override
130             protected void prepareDismissAnimation(View v, Animator anim) {
131                 mSwipeHelperAnimations.put(v, anim);
132             }
133 
134             @Override
135             protected void prepareSnapBackAnimation(View v, Animator anim) {
136                 anim.setInterpolator(Interpolators.FAST_OUT_SLOW_IN);
137                 mSwipeHelperAnimations.put(v, anim);
138             }
139 
140             @Override
141             protected float getUnscaledEscapeVelocity() {
142                 return CHALLENGING_SWIPE_ESCAPE_VELOCITY;
143             }
144 
145             @Override
146             protected long getMaxEscapeAnimDuration() {
147                 return 700;
148             }
149         };
150         mSwipeHelper.setDisableHardwareLayers(true);
151     }
152 
153     /** Velocity tracker helpers */
initOrResetVelocityTracker()154     void initOrResetVelocityTracker() {
155         if (mVelocityTracker == null) {
156             mVelocityTracker = VelocityTracker.obtain();
157         } else {
158             mVelocityTracker.clear();
159         }
160     }
recycleVelocityTracker()161     void recycleVelocityTracker() {
162         if (mVelocityTracker != null) {
163             mVelocityTracker.recycle();
164             mVelocityTracker = null;
165         }
166     }
167 
168     /** Touch preprocessing for handling below */
onInterceptTouchEvent(MotionEvent ev)169     public boolean onInterceptTouchEvent(MotionEvent ev) {
170         // Pass through to swipe helper if we are swiping
171         mInterceptedBySwipeHelper = mSwipeHelper.onInterceptTouchEvent(ev);
172         if (mInterceptedBySwipeHelper) {
173             return true;
174         }
175 
176         return handleTouchEvent(ev);
177     }
178 
179     /** Handles touch events once we have intercepted them */
onTouchEvent(MotionEvent ev)180     public boolean onTouchEvent(MotionEvent ev) {
181         // Pass through to swipe helper if we are swiping
182         if (mInterceptedBySwipeHelper && mSwipeHelper.onTouchEvent(ev)) {
183             return true;
184         }
185 
186         handleTouchEvent(ev);
187         return true;
188     }
189 
190     /**
191      * Finishes all scroll-fling and non-dismissing animations currently running.
192      */
cancelNonDismissTaskAnimations()193     public void cancelNonDismissTaskAnimations() {
194         Utilities.cancelAnimationWithoutCallbacks(mScrollFlingAnimator);
195         if (!mSwipeHelperAnimations.isEmpty()) {
196             // For the non-dismissing tasks, freeze the position into the task overrides
197             List<TaskView> taskViews = mSv.getTaskViews();
198             for (int i = taskViews.size() - 1; i >= 0; i--) {
199                 TaskView tv = taskViews.get(i);
200 
201                 if (mSv.isIgnoredTask(tv.getTask())) {
202                     continue;
203                 }
204 
205                 tv.cancelTransformAnimation();
206                 mSv.getStackAlgorithm().addUnfocusedTaskOverride(tv, mTargetStackScroll);
207             }
208             mSv.getStackAlgorithm().setFocusState(TaskStackLayoutAlgorithm.STATE_UNFOCUSED);
209             // Update the scroll to the final scroll position from onBeginDrag()
210             mSv.getScroller().setStackScroll(mTargetStackScroll, null);
211 
212             mSwipeHelperAnimations.clear();
213         }
214         mActiveTaskView = null;
215     }
216 
handleTouchEvent(MotionEvent ev)217     private boolean handleTouchEvent(MotionEvent ev) {
218         // Short circuit if we have no children
219         if (mSv.getTaskViews().size() == 0) {
220             return false;
221         }
222 
223         final TaskStackLayoutAlgorithm layoutAlgorithm = mSv.mLayoutAlgorithm;
224         int action = ev.getAction();
225         switch (action & MotionEvent.ACTION_MASK) {
226             case MotionEvent.ACTION_DOWN: {
227                 // Stop the current scroll if it is still flinging
228                 mScroller.stopScroller();
229                 mScroller.stopBoundScrollAnimation();
230                 mScroller.resetDeltaScroll();
231                 cancelNonDismissTaskAnimations();
232                 mSv.cancelDeferredTaskViewLayoutAnimation();
233 
234                 // Save the touch down info
235                 mDownX = (int) ev.getX();
236                 mDownY = (int) ev.getY();
237                 mLastY = mDownY;
238                 mDownScrollP = mScroller.getStackScroll();
239                 mActivePointerId = ev.getPointerId(0);
240                 mActiveTaskView = findViewAtPoint(mDownX, mDownY);
241 
242                 // Initialize the velocity tracker
243                 initOrResetVelocityTracker();
244                 mVelocityTracker.addMovement(ev);
245                 break;
246             }
247             case MotionEvent.ACTION_POINTER_DOWN: {
248                 final int index = ev.getActionIndex();
249                 mActivePointerId = ev.getPointerId(index);
250                 mDownX = (int) ev.getX(index);
251                 mDownY = (int) ev.getY(index);
252                 mLastY = mDownY;
253                 mDownScrollP = mScroller.getStackScroll();
254                 mScroller.resetDeltaScroll();
255                 mVelocityTracker.addMovement(ev);
256                 break;
257             }
258             case MotionEvent.ACTION_MOVE: {
259                 int activePointerIndex = ev.findPointerIndex(mActivePointerId);
260                 int y = (int) ev.getY(activePointerIndex);
261                 int x = (int) ev.getX(activePointerIndex);
262                 if (!mIsScrolling) {
263                     int yDiff = Math.abs(y - mDownY);
264                     int xDiff = Math.abs(x - mDownX);
265                     if (Math.abs(y - mDownY) > mScrollTouchSlop && yDiff > xDiff) {
266                         mIsScrolling = true;
267                         float stackScroll = mScroller.getStackScroll();
268                         List<TaskView> taskViews = mSv.getTaskViews();
269                         for (int i = taskViews.size() - 1; i >= 0; i--) {
270                             layoutAlgorithm.addUnfocusedTaskOverride(taskViews.get(i).getTask(),
271                                     stackScroll);
272                         }
273                         layoutAlgorithm.setFocusState(TaskStackLayoutAlgorithm.STATE_UNFOCUSED);
274 
275                         // Disallow parents from intercepting touch events
276                         final ViewParent parent = mSv.getParent();
277                         if (parent != null) {
278                             parent.requestDisallowInterceptTouchEvent(true);
279                         }
280 
281                         MetricsLogger.action(mSv.getContext(), MetricsEvent.OVERVIEW_SCROLL);
282                     }
283                 }
284                 if (mIsScrolling) {
285                     // If we just move linearly on the screen, then that would map to 1/arclength
286                     // of the curve, so just move the scroll proportional to that
287                     float deltaP = layoutAlgorithm.getDeltaPForY(mDownY, y);
288 
289                     // Modulate the overscroll to prevent users from pulling the stack too far
290                     float minScrollP = layoutAlgorithm.mMinScrollP;
291                     float maxScrollP = layoutAlgorithm.mMaxScrollP;
292                     float curScrollP = mDownScrollP + deltaP;
293                     if (curScrollP < minScrollP || curScrollP > maxScrollP) {
294                         float clampedScrollP = Utilities.clamp(curScrollP, minScrollP, maxScrollP);
295                         float overscrollP = (curScrollP - clampedScrollP);
296                         float overscrollX = Math.abs(overscrollP) / MAX_OVERSCROLL;
297                         float interpX = OVERSCROLL_INTERP.getInterpolation(overscrollX);
298                         curScrollP = clampedScrollP + Math.signum(overscrollP) *
299                                 (interpX * MAX_OVERSCROLL);
300                     }
301                     mDownScrollP += mScroller.setDeltaStackScroll(mDownScrollP,
302                             curScrollP - mDownScrollP);
303                     mStackViewScrolledEvent.updateY(y - mLastY);
304                     EventBus.getDefault().send(mStackViewScrolledEvent);
305                 }
306 
307                 mLastY = y;
308                 mVelocityTracker.addMovement(ev);
309                 break;
310             }
311             case MotionEvent.ACTION_POINTER_UP: {
312                 int pointerIndex = ev.getActionIndex();
313                 int pointerId = ev.getPointerId(pointerIndex);
314                 if (pointerId == mActivePointerId) {
315                     // Select a new active pointer id and reset the motion state
316                     final int newPointerIndex = (pointerIndex == 0) ? 1 : 0;
317                     mActivePointerId = ev.getPointerId(newPointerIndex);
318                     mDownX = (int) ev.getX(pointerIndex);
319                     mDownY = (int) ev.getY(pointerIndex);
320                     mLastY = mDownY;
321                     mDownScrollP = mScroller.getStackScroll();
322                 }
323                 mVelocityTracker.addMovement(ev);
324                 break;
325             }
326             case MotionEvent.ACTION_UP: {
327                 mVelocityTracker.addMovement(ev);
328                 mVelocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
329                 int activePointerIndex = ev.findPointerIndex(mActivePointerId);
330                 int y = (int) ev.getY(activePointerIndex);
331                 int velocity = (int) mVelocityTracker.getYVelocity(mActivePointerId);
332                 if (mIsScrolling) {
333                     if (mScroller.isScrollOutOfBounds()) {
334                         mScroller.animateBoundScroll();
335                     } else if (Math.abs(velocity) > mMinimumVelocity) {
336                         float minY = mDownY + layoutAlgorithm.getYForDeltaP(mDownScrollP,
337                                 layoutAlgorithm.mMaxScrollP);
338                         float maxY = mDownY + layoutAlgorithm.getYForDeltaP(mDownScrollP,
339                                 layoutAlgorithm.mMinScrollP);
340                         mScroller.fling(mDownScrollP, mDownY, y, velocity, (int) minY, (int) maxY,
341                                 mOverscrollSize);
342                         mSv.invalidate();
343                     }
344 
345                     // Reset the focused task after the user has scrolled
346                     if (!mSv.mTouchExplorationEnabled) {
347                         mSv.resetFocusedTask(mSv.getFocusedTask());
348                     }
349                 } else if (mActiveTaskView == null) {
350                     // This tap didn't start on a task.
351                     maybeHideRecentsFromBackgroundTap((int) ev.getX(), (int) ev.getY());
352                 }
353 
354                 mActivePointerId = INACTIVE_POINTER_ID;
355                 mIsScrolling = false;
356                 recycleVelocityTracker();
357                 break;
358             }
359             case MotionEvent.ACTION_CANCEL: {
360                 mActivePointerId = INACTIVE_POINTER_ID;
361                 mIsScrolling = false;
362                 recycleVelocityTracker();
363                 break;
364             }
365         }
366         return mIsScrolling;
367     }
368 
369     /** Hides recents if the up event at (x, y) is a tap on the background area. */
maybeHideRecentsFromBackgroundTap(int x, int y)370     void maybeHideRecentsFromBackgroundTap(int x, int y) {
371         // Ignore the up event if it's too far from its start position. The user might have been
372         // trying to scroll or swipe.
373         int dx = Math.abs(mDownX - x);
374         int dy = Math.abs(mDownY - y);
375         if (dx > mScrollTouchSlop || dy > mScrollTouchSlop) {
376             return;
377         }
378 
379         // Shift the tap position toward the center of the task stack and check to see if it would
380         // have hit a view. The user might have tried to tap on a task and missed slightly.
381         int shiftedX = x;
382         if (x > (mSv.getRight() - mSv.getLeft()) / 2) {
383             shiftedX -= mWindowTouchSlop;
384         } else {
385             shiftedX += mWindowTouchSlop;
386         }
387         if (findViewAtPoint(shiftedX, y) != null) {
388             return;
389         }
390 
391         // Disallow tapping above and below the stack to dismiss recents
392         if (x > mSv.mLayoutAlgorithm.mStackRect.left && x < mSv.mLayoutAlgorithm.mStackRect.right) {
393             return;
394         }
395 
396         // If tapping on the freeform workspace background, just launch the first freeform task
397         SystemServicesProxy ssp = Recents.getSystemServices();
398         if (ssp.hasFreeformWorkspaceSupport()) {
399             Rect freeformRect = mSv.mLayoutAlgorithm.mFreeformRect;
400             if (freeformRect.top <= y && y <= freeformRect.bottom) {
401                 if (mSv.launchFreeformTasks()) {
402                     // TODO: Animate Recents away as we launch the freeform tasks
403                     return;
404                 }
405             }
406         }
407 
408         // The user intentionally tapped on the background, which is like a tap on the "desktop".
409         // Hide recents and transition to the launcher.
410         EventBus.getDefault().send(new HideRecentsEvent(false, true));
411     }
412 
413     /** Handles generic motion events */
onGenericMotionEvent(MotionEvent ev)414     public boolean onGenericMotionEvent(MotionEvent ev) {
415         if ((ev.getSource() & InputDevice.SOURCE_CLASS_POINTER) ==
416                 InputDevice.SOURCE_CLASS_POINTER) {
417             int action = ev.getAction();
418             switch (action & MotionEvent.ACTION_MASK) {
419                 case MotionEvent.ACTION_SCROLL:
420                     // Find the front most task and scroll the next task to the front
421                     float vScroll = ev.getAxisValue(MotionEvent.AXIS_VSCROLL);
422                     if (vScroll > 0) {
423                         mSv.setRelativeFocusedTask(true, true /* stackTasksOnly */,
424                                 false /* animated */);
425                     } else {
426                         mSv.setRelativeFocusedTask(false, true /* stackTasksOnly */,
427                                 false /* animated */);
428                     }
429                     return true;
430             }
431         }
432         return false;
433     }
434 
435     /**** SwipeHelper Implementation ****/
436 
437     @Override
getChildAtPosition(MotionEvent ev)438     public View getChildAtPosition(MotionEvent ev) {
439         TaskView tv = findViewAtPoint((int) ev.getX(), (int) ev.getY());
440         if (tv != null && canChildBeDismissed(tv)) {
441             return tv;
442         }
443         return null;
444     }
445 
446     @Override
canChildBeDismissed(View v)447     public boolean canChildBeDismissed(View v) {
448         // Disallow dismissing an already dismissed task
449         TaskView tv = (TaskView) v;
450         Task task = tv.getTask();
451         return !mSwipeHelperAnimations.containsKey(v) &&
452                 (mSv.getStack().indexOfStackTask(task) != -1);
453     }
454 
455     /**
456      * Starts a manual drag that goes through the same swipe helper path.
457      */
onBeginManualDrag(TaskView v)458     public void onBeginManualDrag(TaskView v) {
459         mActiveTaskView = v;
460         mSwipeHelperAnimations.put(v, null);
461         onBeginDrag(v);
462     }
463 
464     @Override
onBeginDrag(View v)465     public void onBeginDrag(View v) {
466         TaskView tv = (TaskView) v;
467 
468         // Disable clipping with the stack while we are swiping
469         tv.setClipViewInStack(false);
470         // Disallow touch events from this task view
471         tv.setTouchEnabled(false);
472         // Disallow parents from intercepting touch events
473         final ViewParent parent = mSv.getParent();
474         if (parent != null) {
475             parent.requestDisallowInterceptTouchEvent(true);
476         }
477 
478         // Add this task to the set of tasks we are deleting
479         mSv.addIgnoreTask(tv.getTask());
480 
481         // Determine if we are animating the other tasks while dismissing this task
482         mCurrentTasks = new ArrayList<Task>(mSv.getStack().getStackTasks());
483         MutableBoolean isFrontMostTask = new MutableBoolean(false);
484         Task anchorTask = mSv.findAnchorTask(mCurrentTasks, isFrontMostTask);
485         TaskStackLayoutAlgorithm layoutAlgorithm = mSv.getStackAlgorithm();
486         TaskStackViewScroller stackScroller = mSv.getScroller();
487         if (anchorTask != null) {
488             // Get the current set of task transforms
489             mSv.getCurrentTaskTransforms(mCurrentTasks, mCurrentTaskTransforms);
490 
491             // Get the stack scroll of the task to anchor to (since we are removing something, the
492             // front most task will be our anchor task)
493             float prevAnchorTaskScroll = 0;
494             boolean pullStackForward = mCurrentTasks.size() > 0;
495             if (pullStackForward) {
496                 prevAnchorTaskScroll = layoutAlgorithm.getStackScrollForTask(anchorTask);
497             }
498 
499             // Calculate where the views would be without the deleting tasks
500             mSv.updateLayoutAlgorithm(false /* boundScroll */);
501 
502             float newStackScroll = stackScroller.getStackScroll();
503             if (isFrontMostTask.value) {
504                 // Bound the stack scroll to pull tasks forward if necessary
505                 newStackScroll = stackScroller.getBoundedStackScroll(newStackScroll);
506             } else if (pullStackForward) {
507                 // Otherwise, offset the scroll by the movement of the anchor task
508                 float anchorTaskScroll =
509                         layoutAlgorithm.getStackScrollForTaskIgnoreOverrides(anchorTask);
510                 float stackScrollOffset = (anchorTaskScroll - prevAnchorTaskScroll);
511                 if (layoutAlgorithm.getFocusState() != TaskStackLayoutAlgorithm.STATE_FOCUSED) {
512                     // If we are focused, we don't want the front task to move, but otherwise, we
513                     // allow the back task to move up, and the front task to move back
514                     stackScrollOffset *= 0.75f;
515                 }
516                 newStackScroll = stackScroller.getBoundedStackScroll(stackScroller.getStackScroll()
517                         + stackScrollOffset);
518             }
519 
520             // Pick up the newly visible views, not including the deleting tasks
521             mSv.bindVisibleTaskViews(newStackScroll, true /* ignoreTaskOverrides */);
522 
523             // Get the final set of task transforms (with task removed)
524             mSv.getLayoutTaskTransforms(newStackScroll, TaskStackLayoutAlgorithm.STATE_UNFOCUSED,
525                     mCurrentTasks, true /* ignoreTaskOverrides */, mFinalTaskTransforms);
526 
527             // Set the target to scroll towards upon dismissal
528             mTargetStackScroll = newStackScroll;
529 
530             /*
531              * Post condition: All views that will be visible as a part of the gesture are retrieved
532              *                 and at their initial positions.  The stack is still at the current
533              *                 scroll, but the layout is updated without the task currently being
534              *                 dismissed.  The final layout is in the unfocused stack state, which
535              *                 will be applied when the current task is dismissed.
536              */
537         }
538     }
539 
540     @Override
updateSwipeProgress(View v, boolean dismissable, float swipeProgress)541     public boolean updateSwipeProgress(View v, boolean dismissable, float swipeProgress) {
542         // Only update the swipe progress for the surrounding tasks if the dismiss animation was not
543         // preempted from a call to cancelNonDismissTaskAnimations
544         if (mActiveTaskView == v || mSwipeHelperAnimations.containsKey(v)) {
545             updateTaskViewTransforms(
546                     Interpolators.FAST_OUT_SLOW_IN.getInterpolation(swipeProgress));
547         }
548         return true;
549     }
550 
551     /**
552      * Called after the {@link TaskView} is finished animating away.
553      */
554     @Override
onChildDismissed(View v)555     public void onChildDismissed(View v) {
556         TaskView tv = (TaskView) v;
557 
558         // Re-enable clipping with the stack (we will reuse this view)
559         tv.setClipViewInStack(true);
560         // Re-enable touch events from this task view
561         tv.setTouchEnabled(true);
562         // Remove the task view from the stack, ignoring the animation if we've started dragging
563         // again
564         EventBus.getDefault().send(new TaskViewDismissedEvent(tv.getTask(), tv,
565                 mSwipeHelperAnimations.containsKey(v)
566                     ? new AnimationProps(TaskStackView.DEFAULT_SYNC_STACK_DURATION,
567                         Interpolators.FAST_OUT_SLOW_IN)
568                     : null));
569         // Only update the final scroll and layout state (set in onBeginDrag()) if the dismiss
570         // animation was not preempted from a call to cancelNonDismissTaskAnimations
571         if (mSwipeHelperAnimations.containsKey(v)) {
572             // Update the scroll to the final scroll position
573             mSv.getScroller().setStackScroll(mTargetStackScroll, null);
574             // Update the focus state to the final focus state
575             mSv.getStackAlgorithm().setFocusState(TaskStackLayoutAlgorithm.STATE_UNFOCUSED);
576             mSv.getStackAlgorithm().clearUnfocusedTaskOverrides();
577             // Stop tracking this deletion animation
578             mSwipeHelperAnimations.remove(v);
579         }
580         // Keep track of deletions by keyboard
581         MetricsLogger.histogram(tv.getContext(), "overview_task_dismissed_source",
582                 Constants.Metrics.DismissSourceSwipeGesture);
583     }
584 
585     /**
586      * Called after the {@link TaskView} is finished animating back into the list.
587      * onChildDismissed() calls.
588      */
589     @Override
onChildSnappedBack(View v, float targetLeft)590     public void onChildSnappedBack(View v, float targetLeft) {
591         TaskView tv = (TaskView) v;
592 
593         // Re-enable clipping with the stack
594         tv.setClipViewInStack(true);
595         // Re-enable touch events from this task view
596         tv.setTouchEnabled(true);
597 
598         // Stop tracking this deleting task, and update the layout to include this task again.  The
599         // stack scroll does not need to be reset, since the scroll has not actually changed in
600         // onBeginDrag().
601         mSv.removeIgnoreTask(tv.getTask());
602         mSv.updateLayoutAlgorithm(false /* boundScroll */);
603         mSv.relayoutTaskViews(AnimationProps.IMMEDIATE);
604         mSwipeHelperAnimations.remove(v);
605     }
606 
607     @Override
onDragCancelled(View v)608     public void onDragCancelled(View v) {
609         // Do nothing
610     }
611 
612     @Override
isAntiFalsingNeeded()613     public boolean isAntiFalsingNeeded() {
614         return false;
615     }
616 
617     @Override
getFalsingThresholdFactor()618     public float getFalsingThresholdFactor() {
619         return 0;
620     }
621 
622     /**
623      * Interpolates the non-deleting tasks to their final transforms from their current transforms.
624      */
updateTaskViewTransforms(float dismissFraction)625     private void updateTaskViewTransforms(float dismissFraction) {
626         List<TaskView> taskViews = mSv.getTaskViews();
627         int taskViewCount = taskViews.size();
628         for (int i = 0; i < taskViewCount; i++) {
629             TaskView tv = taskViews.get(i);
630             Task task = tv.getTask();
631 
632             if (mSv.isIgnoredTask(task)) {
633                 continue;
634             }
635 
636             int taskIndex = mCurrentTasks.indexOf(task);
637             TaskViewTransform fromTransform = mCurrentTaskTransforms.get(taskIndex);
638             TaskViewTransform toTransform = mFinalTaskTransforms.get(taskIndex);
639 
640             mTmpTransform.copyFrom(fromTransform);
641             // We only really need to interpolate the bounds, progress and translation
642             mTmpTransform.rect.set(Utilities.RECTF_EVALUATOR.evaluate(dismissFraction,
643                     fromTransform.rect, toTransform.rect));
644             mTmpTransform.dimAlpha = fromTransform.dimAlpha + (toTransform.dimAlpha -
645                     fromTransform.dimAlpha) * dismissFraction;
646             mTmpTransform.viewOutlineAlpha = fromTransform.viewOutlineAlpha +
647                     (toTransform.viewOutlineAlpha - fromTransform.viewOutlineAlpha) *
648                             dismissFraction;
649             mTmpTransform.translationZ = fromTransform.translationZ +
650                     (toTransform.translationZ - fromTransform.translationZ) * dismissFraction;
651 
652             mSv.updateTaskViewToTransform(tv, mTmpTransform, AnimationProps.IMMEDIATE);
653         }
654     }
655 
656     /** Returns the view at the specified coordinates */
findViewAtPoint(int x, int y)657     private TaskView findViewAtPoint(int x, int y) {
658         List<Task> tasks = mSv.getStack().getStackTasks();
659         int taskCount = tasks.size();
660         for (int i = taskCount - 1; i >= 0; i--) {
661             TaskView tv = mSv.getChildViewForTask(tasks.get(i));
662             if (tv != null && tv.getVisibility() == View.VISIBLE) {
663                 if (mSv.isTouchPointInView(x, y, tv)) {
664                     return tv;
665                 }
666             }
667         }
668         return null;
669     }
670 
671     /**
672      * Returns the scaled size used to calculate the dismiss fraction.
673      */
getScaledDismissSize()674     public float getScaledDismissSize() {
675         return 1.5f * Math.max(mSv.getWidth(), mSv.getHeight());
676     }
677 }
678