请参阅Android ？ProgressBar.setProgressDrawable只能一次的答案，重复如下：

See Android ProgressBar.setProgressDrawable only works once? for the answer, repeated below:

我发现的是，绘制不知道它的大小，当setprogressdrawable被调用。当最初设置，它不知道它的大小。这意味着有一个新的绘制设置为搜索栏，但绘制的大小为0，你不会看到任何东西。

What I found out is that the drawable doesn't know it's size when setprogressdrawable is called. When it is initially set up, it does know it's size. This means there is a new drawable set to the seekbar, but the size of the drawable is 0, you won't see anything.

解决的办法是先获取当前绘制的边界，然后设置新的绘制，最后再设定范围：

The solution is to first get the bounds of the current drawable, then set the new drawable and finally set the bounds again:

Rect bounds = mySeekBar.getProgressDrawable().getBounds();
mySeekBar.setProgressDrawable(newSeekBarBackground);
mySeekBar.getProgressDrawable().setBounds(bounds);