前言

最近任务需求，特殊模式下任务管理界面 不能打开某个APK

任务分析

任务管理界面下单个task的onClick或者onTouch

首先找到Recents 源码 位于systemui 中

这里我们直接打开RecentsActivity.java 文件

在RecentsActivity 的oncreate中发现setContentView为recents资源文件

这里我们看到代码及注释，说明是一个自定义view – RecentsView

我们可以看到RecentsView是继承 FrameLayout的一个自定义View 

RecentsView 中 有三个view 一个TaskStackView 两个Textview

  public RecentsView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {         super(context, attrs, defStyleAttr, defStyleRes);         setWillNotDraw(false);          SystemServicesProxy ssp = Recents.getSystemServices();         mTransitionHelper = new RecentsTransitionHelper(getContext());         mDividerSize = ssp.getDockedDividerSize(context);         mTouchHandler = new RecentsViewTouchHandler(this);         mFlingAnimationUtils = new FlingAnimationUtils(context, 0.3f);         mScrimAlpha = Recents.getConfiguration().isGridEnabled                 ? GRID_LAYOUT_SCRIM_ALPHA : DEFAULT_SCRIM_ALPHA;         mBackgroundScrim = new ColorDrawable(                 Color.argb((int) (mScrimAlpha * 255), 0, 0, 0)).mutate();          LayoutInflater inflater = LayoutInflater.from(context);         if (RecentsDebugFlags.Static.EnableStackActionButton) {             mStackActionButton = (TextView) inflater.inflate(R.layout.recents_stack_action_button,                     this, false);             mStackActionButton.setOnClickListener(new View.OnClickListener() {                 @Override                 public void onClick(View v) {                     EventBus.getDefault().send(new DismissAllTaskViewsEvent());                 }             });             addView(mStackActionButton);         }         mEmptyView = (TextView) inflater.inflate(R.layout.recents_empty, this, false);         addView(mEmptyView);     }

mStackActionButton即全部清除按钮，mEmptyView 即当TaskStack(Task的集合) 数量为空时显示的TextView，因此我们平时见到的APP的任务管理应该是在TaskStackView中的

然后分析TaskStackView 发现 

TaskStackViewTouchHandler 这个应该是和Touch事件有关，因此我们进入 TaskStackViewTouchHandler中 

可以看到上面的注释  说明它是 处理TaskStackView 触摸事件的类

TaskStackViewTouchHandler 中有onInterceptTouchEvent和onTouchEvent 看到它都调用到了 handleTouchEvent

下面是整个handleTouchEvent的代码

 private boolean handleTouchEvent(MotionEvent ev) {         // Short circuit if we have no children         if (mSv.getTaskViews().size() == 0) {             return false;         }          final TaskStackLayoutAlgorithm layoutAlgorithm = mSv.mLayoutAlgorithm;         int action = ev.getAction();         switch (action & MotionEvent.ACTION_MASK) {             case MotionEvent.ACTION_DOWN: {                 // Stop the current scroll if it is still flinging                 mScroller.stopScroller();                 mScroller.stopBoundScrollAnimation();                 mScroller.resetDeltaScroll();                 cancelNonDismissTaskAnimations();                 mSv.cancelDeferredTaskViewLayoutAnimation();                  // Save the touch down info                 mDownX = (int) ev.getX();                 mDownY = (int) ev.getY();                 mLastY = mDownY;                 mDownScrollP = mScroller.getStackScroll();                 mActivePointerId = ev.getPointerId(0);                 mActiveTaskView = findViewAtPoint(mDownX, mDownY);     Log.e("zhuwww"," mActiveTaskView n");                 // Initialize the velocity tracker                 initOrResetVelocityTracker();                 mVelocityTracker.addMovement(ev);                 break;             }             case MotionEvent.ACTION_POINTER_DOWN: {                 final int index = ev.getActionIndex();                 mActivePointerId = ev.getPointerId(index);                 mDownX = (int) ev.getX(index);                 mDownY = (int) ev.getY(index);                 mLastY = mDownY;                 mDownScrollP = mScroller.getStackScroll();                 mScroller.resetDeltaScroll();                 mVelocityTracker.addMovement(ev);                 break;             }             case MotionEvent.ACTION_MOVE: {                 int activePointerIndex = ev.findPointerIndex(mActivePointerId);                 int y = (int) ev.getY(activePointerIndex);                 int x = (int) ev.getX(activePointerIndex);                 if (!mIsScrolling) {                     int yDiff = Math.abs(y - mDownY);                     int xDiff = Math.abs(x - mDownX);                     if (Math.abs(y - mDownY) > mScrollTouchSlop && yDiff > xDiff) {                         mIsScrolling = true;                         float stackScroll = mScroller.getStackScroll();                         List<TaskView> taskViews = mSv.getTaskViews();                         for (int i = taskViews.size() - 1; i >= 0; i--) {                             layoutAlgorithm.addUnfocusedTaskOverride(taskViews.get(i).getTask(),                                     stackScroll);                         }                         layoutAlgorithm.setFocusState(TaskStackLayoutAlgorithm.STATE_UNFOCUSED);                          // Disallow parents from intercepting touch events                         final ViewParent parent = mSv.getParent();                         if (parent != null) {                             parent.requestDisallowInterceptTouchEvent(true);                         }                          MetricsLogger.action(mSv.getContext(), MetricsEvent.OVERVIEW_SCROLL);                         mLastY = mDownY = y;                     }                 }                 if (mIsScrolling) {                     // If we just move linearly on the screen, then that would map to 1/arclength                     // of the curve, so just move the scroll proportional to that                     float deltaP = layoutAlgorithm.getDeltaPForY(mDownY, y);                      // Modulate the overscroll to prevent users from pulling the stack too far                     float minScrollP = layoutAlgorithm.mMinScrollP;                     float maxScrollP = layoutAlgorithm.mMaxScrollP;                     float curScrollP = mDownScrollP + deltaP;                     if (curScrollP < minScrollP || curScrollP > maxScrollP) {                         float clampedScrollP = Utilities.clamp(curScrollP, minScrollP, maxScrollP);                         float overscrollP = (curScrollP - clampedScrollP);                         float overscrollX = Math.abs(overscrollP) / MAX_OVERSCROLL;                         float interpX = OVERSCROLL_INTERP.getInterpolation(overscrollX);                         curScrollP = clampedScrollP + Math.signum(overscrollP) *                                 (interpX * MAX_OVERSCROLL);                     }                     mDownScrollP += mScroller.setDeltaStackScroll(mDownScrollP,                             curScrollP - mDownScrollP);                     mStackViewScrolledEvent.updateY(y - mLastY);                     EventBus.getDefault().send(mStackViewScrolledEvent);                 }                  mLastY = y;                 mVelocityTracker.addMovement(ev);                 break;             }             case MotionEvent.ACTION_POINTER_UP: {                 int pointerIndex = ev.getActionIndex();                 int pointerId = ev.getPointerId(pointerIndex);                 if (pointerId == mActivePointerId) {                     // Select a new active pointer id and reset the motion state                     final int newPointerIndex = (pointerIndex == 0) ? 1 : 0;                     mActivePointerId = ev.getPointerId(newPointerIndex);                     mDownX = (int) ev.getX(pointerIndex);                     mDownY = (int) ev.getY(pointerIndex);                     mLastY = mDownY;                     mDownScrollP = mScroller.getStackScroll();                 }                 mVelocityTracker.addMovement(ev);                 break;             }             case MotionEvent.ACTION_UP: {                 mVelocityTracker.addMovement(ev);                 mVelocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);                 int activePointerIndex = ev.findPointerIndex(mActivePointerId);                 int y = (int) ev.getY(activePointerIndex);                 int velocity = (int) mVelocityTracker.getYVelocity(mActivePointerId);                 if (mIsScrolling) {                     if (mScroller.isScrollOutOfBounds()) {                         mScroller.animateBoundScroll();                     } else if (Math.abs(velocity) > mMinimumVelocity) {                         float minY = mDownY + layoutAlgorithm.getYForDeltaP(mDownScrollP,                                 layoutAlgorithm.mMaxScrollP);                         float maxY = mDownY + layoutAlgorithm.getYForDeltaP(mDownScrollP,                                 layoutAlgorithm.mMinScrollP);                         mScroller.fling(mDownScrollP, mDownY, y, velocity, (int) minY, (int) maxY,                                 mOverscrollSize);                         mSv.invalidate();                     }                      // Reset the focused task after the user has scrolled, but we have no scrolling                     // in grid layout and therefore we don't want to reset the focus there.                     if (!mSv.mTouchExplorationEnabled && !mSv.useGridLayout()) {                         mSv.resetFocusedTask(mSv.getFocusedTask());                     }                 } else if (mActiveTaskView == null) {                     // This tap didn't start on a task.                     maybeHideRecentsFromBackgroundTap((int) ev.getX(), (int) ev.getY());                 }                  mActivePointerId = INACTIVE_POINTER_ID;                 mIsScrolling = false;                 recycleVelocityTracker();                 break;             }             case MotionEvent.ACTION_CANCEL: {                 mActivePointerId = INACTIVE_POINTER_ID;                 mIsScrolling = false;                 recycleVelocityTracker();                 break;             }         }         return mIsScrolling;     }

分析发现，在handleTouchEvent 中 当MotionEvent.ACTION_DOWN时 通过mActiveTaskView = findViewAtPoint(mDownX, mDownY);得到了一个TaskView 

findViewAtPoint实现

这里我们直接进入TaskView.java中查看 看到这里有实现点击事件的代码，这里我们加个Log打印，验证点击视图时是否经过这里

通过打印验证

的确是走的这个地方，那么我们这里可以看到主要是通过eventBus发送了一个 LaunchTaskEvent事件

 EventBus.getDefault().send(new LaunchTaskEvent(this, mTask, null, INVALID_STACK_ID,                 screenPinningRequested));

LaunchTaskEvent源码

因此我们直接在recents中搜索哪个地方的方法用到了LaunchTaskEvent

这里看到只在TaskStackView和RecentsView中有使用到LaunchTaskEvent，其余的都是eventBus发送事件，所以我们就不用管了

然后下面看TaskStackView中的实现，很明显不是的，因此我们可以先确定是在RecentsView中的方法中

如下图所示，这个我们看它用的方法，通过mTransitionHelper去launchTaskFromRecents。这里从字面意思应该不难看出，地方已经找对了 launchTaskFromRecents即从recents中运行一个task。

然后我们在launchTaskFromRecents方法中发现有一个startTaskActivity方法

 public void launchTaskFromRecents(final TaskStack stack, @Nullable final Task task,             final TaskStackView stackView, final TaskView taskView,             final boolean screenPinningRequested, final int destinationStack) {          final ActivityOptions.OnAnimationStartedListener animStartedListener;         final AppTransitionAnimationSpecsFuture transitionFuture;         if (taskView != null) {              // Fetch window rect here already in order not to be blocked on lock contention in WM             // when the future calls it.             final Rect windowRect = Recents.getSystemServices().getWindowRect();             transitionFuture = getAppTransitionFuture(                     () -> composeAnimationSpecs(task, stackView, destinationStack, windowRect));             animStartedListener = () -> {                 // If we are launching into another task, cancel the previous task's                 // window transition                 EventBus.getDefault().send(new CancelEnterRecentsWindowAnimationEvent(task));                 EventBus.getDefault().send(new ExitRecentsWindowFirstAnimationFrameEvent());                 stackView.cancelAllTaskViewAnimations();                  if (screenPinningRequested) {                     // Request screen pinning after the animation runs                     mStartScreenPinningRunnable.taskId = task.key.id;                     mHandler.postDelayed(mStartScreenPinningRunnable, 350);                 }             };         } else {             // This is only the case if the task is not on screen (scrolled offscreen for example)             transitionFuture = null;             animStartedListener = () -> {                 // If we are launching into another task, cancel the previous task's                 // window transition                 EventBus.getDefault().send(new CancelEnterRecentsWindowAnimationEvent(task));                 EventBus.getDefault().send(new ExitRecentsWindowFirstAnimationFrameEvent());                 stackView.cancelAllTaskViewAnimations();             };         }          final ActivityOptions opts = ActivityOptions.makeMultiThumbFutureAspectScaleAnimation(mContext,                 mHandler, transitionFuture != null ? transitionFuture.future : null,                 animStartedListener, true /* scaleUp */);         if (taskView == null) {             // If there is no task view, then we do not need to worry about animating out occluding             // task views, and we can launch immediately             startTaskActivity(stack, task, taskView, opts, transitionFuture, destinationStack);         } else {             LaunchTaskStartedEvent launchStartedEvent = new LaunchTaskStartedEvent(taskView,                     screenPinningRequested);             if (task.group != null && !task.group.isFrontMostTask(task)) {                 launchStartedEvent.addPostAnimationCallback(new Runnable() {                     @Override                     public void run() {                         startTaskActivity(stack, task, taskView, opts, transitionFuture,                                 destinationStack);                     }                 });                 EventBus.getDefault().send(launchStartedEvent);             } else {                 EventBus.getDefault().send(launchStartedEvent);                 startTaskActivity(stack, task, taskView, opts, transitionFuture, destinationStack);             }         }         Recents.getSystemServices().sendCloseSystemWindows(                 StatusBar.SYSTEM_DIALOG_REASON_HOME_KEY);     }

关键代码  ssp.startActivityFromRecents 从Recents 中启动activity

  private void startTaskActivity(TaskStack stack, Task task, @Nullable TaskView taskView,             ActivityOptions opts, AppTransitionAnimationSpecsFuture transitionFuture,             int destinationStack) {         SystemServicesProxy ssp = Recents.getSystemServices();         ssp.startActivityFromRecents(mContext, task.key, task.title, opts, destinationStack,                 succeeded -> {             if (succeeded) {                 // Keep track of the index of the task launch                 int taskIndexFromFront = 0;                 int taskIndex = stack.indexOfStackTask(task);                 if (taskIndex > -1) {                     taskIndexFromFront = stack.getTaskCount() - taskIndex - 1;                 }                 EventBus.getDefault().send(new LaunchTaskSucceededEvent(taskIndexFromFront));             } else {                 // Dismiss the task if we fail to launch it                 if (taskView != null) {                     taskView.dismissTask();                 }                  // Keep track of failed launches                 EventBus.getDefault().send(new LaunchTaskFailedEvent());             }         });         if (transitionFuture != null) {             mHandler.post(transitionFuture::precacheSpecs);         }     }

至此，已经找到了任务管理中启动task的地方，我们这里只需要在RecentsView.java的onBusEvent方法中拦截即可

比如任务管理中不能打开相册

全文结束，欢迎