func (m *Marker) draw(gc *gg.Context, trans *transformer) {
gc.ClearPath()
gc.SetLineJoin(gg.LineJoinRound)
gc.SetLineWidth(1.0)
radius := 0.5 * m.Size
x, y := trans.ll2p(m.Position)
gc.DrawArc(x, y-m.Size, radius, (90.0+60.0)*math.Pi/180.0, (360.0+90.0-60.0)*math.Pi/180.0)
gc.LineTo(x, y)
gc.ClosePath()
gc.SetColor(m.Color)
gc.FillPreserve()
gc.SetRGB(0, 0, 0)
gc.Stroke()
if m.Label != "" {
if Luminance(m.Color) >= 0.5 {
gc.SetColor(color.RGBA{0x00, 0x00, 0x00, 0xff})
} else {
gc.SetColor(color.RGBA{0xff, 0xff, 0xff, 0xff})
}
gc.DrawStringAnchored(m.Label, x, y-m.Size, 0.5, 0.5)
}
}