fix getWidth() sometime return 0 bug

Author: gaopengfei

lib/src/main/java/io/feeeei/circleseekbar/CircleSeekBar.java

@@ -312,9 +312,9 @@ private void refershPosition() {
 
     private float calcXLocationInWheel(double angle, double cos) {
         if (angle < 180) {
-            return (float) (getWidth() / 2 + Math.sqrt(1 - cos * cos) * mUnreachedRadius);
+            return (float) (getMeasuredWidth() / 2 + Math.sqrt(1 - cos * cos) * mUnreachedRadius);
         } else {
-            return (float) (getWidth() / 2 - Math.sqrt(1 - cos * cos) * mUnreachedRadius);
+            return (float) (getMeasuredWidth() / 2 - Math.sqrt(1 - cos * cos) * mUnreachedRadius);
         }
     }