With the colors set, the text function emits your time string to the display window at the defined coordinates.
颜色设好后，text函数就会向将时间字符串发送到显示窗口已定义的坐标位置。
3
To our second example program just before the call to MainLoop, the program will print out the canvas coordinates to the console whenever we click the left mouse button over the canvas window.