code: private void  viewportFill()
     {
        int    col;
        if (state.style.viewportFill instanceof SVG.Colour) {
           col = ((SVG.Colour) state.style.viewportFill).colour;
        } else if (state.style.viewportFill instanceof CurrentColor) {
           col = state.style.color.colour;
        } else {
           return;
        }
        if (state.style.viewportFillOpacity != null)
           col = colourWithOpacity(col, state.style.viewportFillOpacity);
  
        canvas.drawColor(col);
     }
docs: /*
  Viewport fill colour. A new feature in SVG 1.2.