private int dp2px(int dp) {
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, getContext().getResources().getDisplayMetrics());
    }
Set the colors used in the progress animation from color resources.
The first color will also be the color of the bar that grows in response
to a user swipe gesture.

@param colors
library/src/main/java/com/baoyz/widget/MaterialDrawable.java