根據SystemUI下的PanelView，他就是下拉通知欄和下拉快捷設定欄所繼承的父類，這裡面實現了下拉的動作監聽，即是對status bar最下面那根橫線的監聽，當對她進行OnTouch時間時，判斷下拉的狀態，當return true表示，OnTouch事件已經被消費了，不再分給別的元件使用；當return false表示，OnTouch事件未被消費，會分給別的元件使用，由於此處未對事件進行消費，則不會進行後續的操作（比如下拉之類的）

 protected void onFinishInflate() {

        super.onFinishInflate();
        mHandleView = findViewById(R.id.handle);

        loadDimens();

        if (DEBUG) logf("handle view: " + mHandleView);
        if (mHandleView != null) {
            mHandleView.setOnTouchListener(new View.OnTouchListener() {
                @Override
                public boolean onTouch(View v, MotionEvent event) {

// 20160720 by geo
                    float checkX = event.getX();
                    WindowManager wm = (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE);
                    int width = wm.getDefaultDisplay().getWidth();

                    hidequickstubischeck = SystemProperties.getBoolean("persist.sys.hidequickstub", false);
                    if (hidequickstubischeck && (checkX > width/2)) {
                        isClick = false;
                    }else {
                        isClick = true;
                    }
// 20160720 by geo

                    int pointerIndex = event.findPointerIndex(mTrackingPointer);
                    if (pointerIndex < 0) {
                        pointerIndex = 0;
                        mTrackingPointer = event.getPointerId(pointerIndex);
                    }
                    final float y = event.getY(pointerIndex);
                    final float rawDelta = event.getRawY() - event.getY();
                    final float rawY = y + rawDelta;
                    if (DEBUG) logf("handle.onTouch: a=%s p=[%d,%d] y=%.1f rawY=%.1f off=%.1f",
                            MotionEvent.actionToString(event.getAction()),
                            mTrackingPointer, pointerIndex,
                            y, rawY, mTouchOffset);
                    PanelView.this.getLocationOnScreen(mAbsPos);

                    switch (event.getActionMasked()) {
                        case MotionEvent.ACTION_DOWN:

  // 20160720 by geo                     
                        if (isClick) {
                             mTracking = true;
                            mHandleView.setPressed(true);
                            postInvalidate(); // catch the press state change
                            mInitialTouchY = y;
                            mVelocityTracker = FlingTracker.obtain();
                            trackMovement(event);
                            mTimeAnimator.cancel(); // end any outstanding animations
                            mBar.onTrackingStarted(PanelView.this);
                            mTouchOffset = (rawY - mAbsPos[1]) - mExpandedHeight;
                            if (mExpandedHeight == 0) {
                                mJustPeeked = true;
                                runPeekAnimation();
                            }
                            break;
                        }else{
                            return false;
 // 20160720 by geo                           
                        }

                        case MotionEvent.ACTION_POINTER_UP:
                            final int upPointer = event.getPointerId(event.getActionIndex());
                            if (mTrackingPointer == upPointer) {
                                // gesture is ongoing, find a new pointer to track
                                final int newIndex = event.getPointerId(0) != upPointer ? 0 : 1;
                                final float newY = event.getY(newIndex);
                                final float newRawY = newY + rawDelta;
                                mTrackingPointer = event.getPointerId(newIndex);
                                mTouchOffset = (newRawY - mAbsPos[1]) - mExpandedHeight;
                                mInitialTouchY = newY;
                            }
                            break;

                        case MotionEvent.ACTION_MOVE:
                            final float h = rawY - mAbsPos[1] - mTouchOffset;
                            if (h > mPeekHeight) {
                                if (mPeekAnimator != null && mPeekAnimator.isStarted()) {
                                    mPeekAnimator.cancel();
                                }
                                mJustPeeked = false;
                            }
                            if (!mJustPeeked) {

                           PanelView.this.setExpandedHeightInternal(h);
                               mBar.panelExpansionChanged(PanelView.this, mExpandedFraction);    
                          }

                            trackMovement(event);
                            break;

                        case MotionEvent.ACTION_UP:
                        case MotionEvent.ACTION_CANCEL:
                            mFinalTouchY = y;
                            mTracking = false;
                            mTrackingPointer = -1;
                            mHandleView.setPressed(false);
                            postInvalidate(); // catch the press state change
                            mBar.onTrackingStopped(PanelView.this);
                            trackMovement(event);

                            float vel = 0, yVel = 0, xVel = 0;
                            boolean negative = false;

                            if (mVelocityTracker != null) {
                                // the velocitytracker might be null if we got a bad input stream
                                mVelocityTracker.computeCurrentVelocity(1000);

                                yVel = mVelocityTracker.getYVelocity();
                                negative = yVel < 0;

                                xVel = mVelocityTracker.getXVelocity();
                                if (xVel < 0) {
                                    xVel = -xVel;
                                }
                                if (xVel > mFlingGestureMaxXVelocityPx) {
                                    xVel = mFlingGestureMaxXVelocityPx; // limit how much we care about the x axis
                                }

                                vel = (float)Math.hypot(yVel, xVel);
                                if (vel > mFlingGestureMaxOutputVelocityPx) {
                                    vel = mFlingGestureMaxOutputVelocityPx;
                                }

                                mVelocityTracker.recycle();
                                mVelocityTracker = null;
                            }

                            // if you've barely moved your finger, we treat the velocity as 0
                            // preventing spurious flings due to touch screen jitter
                            final float deltaY = Math.abs(mFinalTouchY - mInitialTouchY);
                            if (deltaY < mFlingGestureMinDistPx
                                    || vel < mFlingExpandMinVelocityPx
                                    ) {
                                vel = 0;
                            }

                            if (negative) {
                                vel = -vel;
                            }

                            if (DEBUG) logf("gesture: dy=%f vel=(%f,%f) vlinear=%f",
                                    deltaY,
                                    xVel, yVel,
                                    vel);

                            fling(vel, true);

                            break;
                    }

                        return true;
                }});
        }
    }