int getNextForegroundColor() {
        final int[] colors = mForegroundColor;
        final Paint fPaint = mForegroundPaint;
        if (colors.length > 1) {
            int index = mForegroundColorIndex + 1;
            if (index >= colors.length)
                index = 0;

            fPaint.setColor(colors[index]);
            mForegroundColorIndex = index;
        } else {
            fPaint.setColor(colors[0]);
        }
        return fPaint.getColor();
    }
A drawable to draw loading
The loading draw a Circle
caprice/ui/src/main/java/net/qiujuer/genius/ui/drawable/LoadingDrawable.java