public static GeoStyle transparentFill(final int strokeColor, final int fillTransparency, final float width) {
        return GeoStyle.builder()
            .setStrokeColor(strokeColor)
            .setFillColor(Color.argb(fillTransparency, Color.red(strokeColor), Color.green(strokeColor), Color.blue(strokeColor)))
            .setStrokeWidth(width).build();
    }
creates a style where fill color is a transparent version of stroke color
main/src/main/java/cgeo/geocaching/models/geoitem/GeoStyle.java