func (gc *GraphicContext) Scale(sx, sy float64) {
	gc.StackGraphicContext.Scale(sx, sy)
	gc.pdf.TransformScale(sx*100, sy*100, 0, 0)
}
func (gc *GraphicContext) Scale(sx, sy float64) {
	gc.StackGraphicContext.Scale(sx, sy)
	gc.pdf.TransformScale(sx*100, sy*100, 0, 0)
}
// Transformations
// Scale generally scales the following text, drawings and images.
// sx and sy are the scaling factors for width and height.
// This must be placed between gc.Save() and gc.Restore(), otherwise
// the pdf is invalid.