Method draw

axis.go:256–306

draw draws the axis along the lower edge of a draw.Canvas.

(c draw.Canvas)

// draw draws the axis along the lower edge of a draw.Canvas.
func (a horizontalAxis) draw(c draw.Canvas) {
	var (
		x vg.Length
		y = c.Min.Y
	)
	switch a.Label.Position {
	case draw.PosCenter:
		x = c.Center().X
	case draw.PosRight:
		x = c.Max.X
		x -= a.Label.TextStyle.Width(a.Label.Text) / 2
	}
	if a.Label.Text != "" {
		descent := a.Label.TextStyle.FontExtents().Descent
		c.FillText(a.Label.TextStyle, vg.Point{X: x, Y: y + descent}, a.Label.Text)
		y += a.Label.TextStyle.Height(a.Label.Text)
		y += a.Label.Padding
	}

	marks := a.Tick.Marker.Ticks(a.Min, a.Max)
	ticklabelheight := tickLabelHeight(a.Tick.Label, marks)
	descent := a.Tick.Label.FontExtents().Descent
	for _, t := range marks {
		x := c.X(a.Norm(t.Value))
		if !c.ContainsX(x) || t.IsMinor() {
			continue
		}
		c.FillText(a.Tick.Label, vg.Point{X: x, Y: y + ticklabelheight + descent}, t.Label)
	}

	if len(marks) > 0 {
		y += ticklabelheight
	} else {
		y += a.Width / 2
	}

	if len(marks) > 0 && a.drawTicks() {
		len := a.Tick.Length
		for _, t := range marks {
			x := c.X(a.Norm(t.Value))
			if !c.ContainsX(x) {
				continue
			}
			start := t.lengthOffset(len)
			c.StrokeLine2(a.Tick.LineStyle, x, y+start, x, y+len)
		}
		y += len
	}

	c.StrokeLine2(a.LineStyle, c.Min.X, y, c.Max.X, y)
}

// GlyphBoxes returns the GlyphBoxes for the tick labels.
func (a horizontalAxis) GlyphBoxes(p *Plot) []GlyphBox {