Android 9.0 的 recent 键/事件的拦截

在5.0之前的版本中，我们可以在phoneWindowManager里监听key_code_F12键来获取recent键的点击事件，但在如今版本中已经不能这样做了，recent键被单独拿了出来，我们可以在

/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarFragment.java

中的onRecentsClick(View v) 方法中监听到

    private void onRecentsClick(View v) {
    if (LatencyTracker.isEnabled(getContext())) {
        LatencyTracker.getInstance(getContext()).onActionStart(
                LatencyTracker.ACTION_TOGGLE_RECENTS);
    }
    mStatusBar.awakenDreams();
    mCommandQueue.toggleRecentApps();
}

也可以在

SystemUI/src/com/android/systemui/recents/RecentsImpl.java

中的 startRecentsActivity(ActivityOptions opts, final AppTransitionAnimationSpecsFuture future) 方法中做监听

private void startRecentsActivity(ActivityOptions opts,
        final AppTransitionAnimationSpecsFuture future) {
    Intent intent = new Intent();
    intent.setClassName(RECENTS_PACKAGE, RECENTS_ACTIVITY);
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK
            | Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS
            | Intent.FLAG_ACTIVITY_TASK_ON_HOME);
    HidePipMenuEvent hideMenuEvent = new HidePipMenuEvent();
    hideMenuEvent.addPostAnimationCallback(() -> {
        Recents.getSystemServices().startActivityAsUserAsync(intent, opts);
        EventBus.getDefault().send(new RecentsActivityStartingEvent());
        if (future != null) {
            future.composeSpecsSynchronous();
        }
    });
    EventBus.getDefault().send(hideMenuEvent);

    // Once we have launched the activity, reset the dummy stack view tasks so we don't hold
    // onto references to the same tasks consumed by the activity
    mDummyStackView.setTasks(mEmptyTaskStack, false /* notifyStackChanges */);
}

有些手机厂商开发了手势模式，和系统原生走的是完全不同的方法
我们可以在

SystemUI/src/com/android/systemui/statusbar/phone/QuickStepController.java

中的startQuickStep(MotionEvent event)方法中监听到

    private void startQuickStep(MotionEvent event) {
    mQuickStepStarted = true;
    event.transform(mTransformGlobalMatrix);
    try {
        mOverviewEventSender.getProxy().onQuickStep(event);
        if (DEBUG_OVERVIEW_PROXY) {
            Log.d(TAG_OPS, "Quick Step Start");
        }
    } catch (RemoteException e) {
        Log.e(TAG, "Failed to send quick step started.", e);
    } finally {
        event.transform(mTransformLocalMatrix);
    }
    mOverviewEventSender.notifyQuickStepStarted();
    mHandler.removeCallbacksAndMessages(null);

    if (mHitTarget != null) {
        mHitTarget.abortCurrentGesture();
    }

    if (mQuickScrubActive) {
        animateEnd();
    }
}

在手势模式中对home键还做了左右滑动事件的监听，我们同样可以在该类的 startQuickScrub() 中监听到

    private void startQuickScrub() {
    if (!mQuickScrubActive) {
        mQuickScrubActive = true;
        mLightTrackColor = mContext.getColor(R.color.quick_step_track_background_light);
        mDarkTrackColor = mContext.getColor(R.color.quick_step_track_background_dark);

        ObjectAnimator trackAnimator = ObjectAnimator.ofPropertyValuesHolder(this,
                PropertyValuesHolder.ofFloat(mTrackAlphaProperty, 1f),
                PropertyValuesHolder.ofFloat(mTrackScaleProperty, 1f));
        trackAnimator.setInterpolator(ALPHA_IN);
        trackAnimator.setDuration(ANIM_IN_DURATION_MS);
        ObjectAnimator navBarAnimator = ObjectAnimator.ofFloat(this, mNavBarAlphaProperty, 0f);
        navBarAnimator.setInterpolator(ALPHA_OUT);
        navBarAnimator.setDuration(ANIM_OUT_DURATION_MS);
        mTrackAnimator = new AnimatorSet();
        mTrackAnimator.playTogether(trackAnimator, navBarAnimator);
        mTrackAnimator.start();

        try {
            mOverviewEventSender.getProxy().onQuickScrubStart();
            if (DEBUG_OVERVIEW_PROXY) {
                Log.d(TAG_OPS, "Quick Scrub Start");
            }
        } catch (RemoteException e) {
            Log.e(TAG, "Failed to send start of quick scrub.", e);
        }
        mOverviewEventSender.notifyQuickScrubStarted();

        if (mHitTarget != null) {
            mHitTarget.abortCurrentGesture();
        }
    }
}