final ImageView iv_key = (ImageView) findViewById(R.id.key);
final ImageView iv_unlock = (ImageView) findViewById(R.id.unlock);
iv_key.setOnTouchListener(new OnTouchListener() {
int Y, lastY;
int lastL, lastT, lastR, lastB;

@Override
public boolean onTouch(View view, MotionEvent event) {

switch (event.getAction()) {

    case MotionEvent.ACTION_DOWN:
    lastY = (int) event.getRawY();
    Y = lastY;
    lastL = view.getLeft();
    lastT = view.getTop();
    lastR = view.getRight();
    lastB = view.getBottom();
    break;

    case MotionEvent.ACTION_MOVE:
     LockScreenActivity.viewPager.
                    requestDisallowInterceptTouchEvent(true);

    int distanceY = (int) event.getRawY() - lastY;

    int l = view.getLeft();
    int r = view.getRight();
    int t = view.getTop() + distanceY;
    int b = view.getBottom() + distanceY;

    //假如向下滑,碰到unlock图标,unlock变色
if(distanceY > 0 && iv_unlock.getTop() < (view.getBottom()-10)){                        

iv_unlock.setImageResource(R.drawable.unlock_shape_bg_pressed);
}
// 画出移动中的控件
view.layout(l, t, r, b);                
lastY = (int) event.getRawY();                  
break;