For example, a selector file like this:
`<?xml version="1.0" encoding="utf-8"?>
`
pass it into the method : **editor.setBackgroundResource(R.drawable.post_et_selector)**
cause crash:
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.graphics.Bitmap.compress(android.graphics.Bitmap$CompressFormat, int, java.io.OutputStream)' on a null object reference
at jp.wasabeef.richeditor.Utils.toBase64(Utils.java:36)
at jp.wasabeef.richeditor.RichEditor.setBackgroundResource(RichEditor.java:226)
For example, a selector file like this: `<?xml version="1.0" encoding="utf-8"?>