protected int makePressColor(){
		int r = (this.backgroundColor >> 16) & 0xFF;
		int g = (this.backgroundColor >> 8) & 0xFF;
		int b = (this.backgroundColor >> 0) & 0xFF;
		return Color.argb(128,r, g, b);		
	}
Make a dark color to ripple effect
@return
MaterialDesignLibrary/MaterialDesign/src/main/java/com/gc/materialdesign/views/ProgressBarDeterminate.java