SetLineWidth ， How to change only the height of the line instead of its width

[FxStar]

SetLineWidth is proportionally scaled,

How to change only the height of the line instead of its width

For example, the image at the bottom

func TestAA(t *testing.T) {

    dc := gg.NewContext(1000, 1000)
    dc.SetRGB(1, 1, 1)
    dc.Clear()
    dc.SetRGB(0, 0, 0)
    w := 0.1
    for i := 100; i <= 900; i += 20 {
        x := float64(i)
        dc.DrawLine(x+50, 0, x-50, 1000)
        dc.SetLineWidth(w)

        dc.SetDash(2, 8, 8, 16)

        dc.Stroke()
        w += 0.2
    }
    dc.SavePNG("out11.png")
}