dropdown list overlap with anchor view when changing the anchor view background to a transparent image

[jerrybi]

Hi, I set the background using a transparent png file, when pop up window showing,there is a redundant text appearing in the anchor view area,which has mixed to the anchor view text.if you lock phone screen and unlock again,the
redundant text will disappear,i don't know why this redundant text appear,nice spinner bug?list popup window bug?pop up window bug?the temporary solution is set a 300 miliseconds delay then invalidate the view.but still can see the redundant
text appear and disappear in a short time,it is not a perfect solution.
postDelayed(new Runnable() { @Override public void run() { invalidate(); } },300);
does anybody know the reason?

[jerrybi]

Here is the screenshot,please see the red arrow text,it is the redundant text.

[jerrybi]

By the way,this issue appears on Huawei P9(Android 8.0),my another phone Xiaomi 10(Android 10) doesn't have.i don't know if issue exists on other phones.