滑块的移动调用名为fct的回调来改变显示的颜色条的长度，那个回调会调用ProgressBar的value函数来设置新的长度。

Moving the slider changes the length of the displayed color bar by invoking the callback named FCT, which calls the value function on the ProgressBars to set the new length.

youdao

滑块的移动调用名为fct的回调来改变显示的颜色条的长度，那个回调会调用ProgressBar的value函数来设置新的长度。

Moving the slider changes the length of the displayed color bar by invoking the callback named FCT, which calls the value function on the ProgressBars to set the new length.

youdao