建立一个四箭头的球，当点击球时，就会触发事件，x,y值的增减取决于您点击球的位置-Height-directions trackball

This component creates a graphical ball with four-way arrows. If you click on the ball, an event is triggered with X and Y incremental values depending on where you click on the ball. The ball is eight-way sensitive and has three arrays of sensitivity with different increment values. A repetition timer with user-defined delays allows repetition until the mouse button is released