frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/stack/NotificationStackScrollLayout.java

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelView.java

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/PanelView.java

 

1. NotificationStackScrollLayout.java

 

2.NotificationPanelView.java

@Override    protected boolean onMiddleClicked() {        switch (mStatusBar.getBarState()) {            case StatusBarState.KEYGUARD:                if (!mDozingOnDown) {                    EventLogTags.writeSysuiLockscreenGesture(                            EventLogConstants.SYSUI_LOCKSCREEN_GESTURE_TAP_UNLOCK_HINT,                            0 /* lengthDp - N/A */, 0 /* velocityDp - N/A */);                    startUnlockHintAnimation();                }                return true;            case StatusBarState.SHADE_LOCKED:                if (!mQsExpanded) {                    mStatusBar.goToKeyguard();                }                return true;            case StatusBarState.SHADE:                // This gets called in the middle of the touch handling, where the state is still                // that we are tracking the panel. Collapse the panel after this is done.                //wtrom,zhaoxiaohui,20170221,for drop down menu                if(!isSupportWTRom){                    post(mPostCollapseRunnable);                }                return false;            default:                return true;        }    }

 

3.PanelView.java