code: func (g *GeoM) Scale(x, y float64) {
  	a := (float64(g.a_1) + 1) * x
  	b := float64(g.b) * x
  	tx := float64(g.tx) * x
  	c := float64(g.c) * y
  	d := (float64(g.d_1) + 1) * y
  	ty := float64(g.ty) * y
  
  	g.a_1 = float32(a) - 1
  	g.b = float32(b)
  	g.c = float32(c)
  	g.d_1 = float32(d) - 1
  	g.tx = float32(tx)
  	g.ty = float32(ty)
  }
docs: // Scale scales the matrix by (x, y).