draw2dpdf/gc.go
func (gc *GraphicContext) SetStrokeColor(c color.Color) {
	gc.StackGraphicContext.SetStrokeColor(c)
	gc.pdf.SetDrawColor(rgb(c))
}
func (gc *GraphicContext) SetStrokeColor(c color.Color) {
	gc.StackGraphicContext.SetStrokeColor(c)
	gc.pdf.SetDrawColor(rgb(c))
}
// overwrite StackGraphicContext methods
// SetStrokeColor sets the stroke color