Method GlyphBoxes

axis.go:436–484

GlyphBoxes returns the GlyphBoxes for the tick labels

(p *Plot)

// GlyphBoxes returns the GlyphBoxes for the tick labels
func (a verticalAxis) GlyphBoxes(p *Plot) []GlyphBox {
	var (
		boxes []GlyphBox
		xoff  font.Length
	)

	if a.Label.Text != "" {
		yoff := a.Norm(p.Y.Max)
		switch a.Label.Position {
		case draw.PosCenter:
			yoff = a.Norm(0.5 * (p.Y.Max + p.Y.Min))
		case draw.PosTop:
			yoff -= a.Norm(0.5 * a.Label.TextStyle.Width(a.Label.Text).Points()) // FIXME(sbinet): want data coordinates
		}

		sty := a.Label.TextStyle
		sty.Rotation += math.Pi / 2

		xoff += a.Label.TextStyle.Height(a.Label.Text)
		descent := a.Label.TextStyle.FontExtents().Descent
		boxes = append(boxes, GlyphBox{
			Y:         yoff,
			Rectangle: sty.Rectangle(a.Label.Text).Add(vg.Point{X: xoff - descent}),
		})
		xoff += descent
		xoff += a.Label.Padding
	}

	marks := a.Tick.Marker.Ticks(a.Min, a.Max)
	if w := tickLabelWidth(a.Tick.Label, marks); len(marks) != 0 && w > 0 {
		xoff += w
	}

	var (
		ext  = a.Tick.Label.FontExtents()
		desc = ext.Height - ext.Ascent // descent + linegap
	)
	for _, t := range marks {
		if t.IsMinor() {
			continue
		}
		box := GlyphBox{
			Y:         a.Norm(t.Value),
			Rectangle: a.Tick.Label.Rectangle(t.Label).Add(vg.Point{X: xoff, Y: desc}),
		}
		boxes = append(boxes, box)
	}
	return boxes
}

// DefaultTicks is suitable for the Tick.Marker field of an Axis,
// it returns a reasonable default set of tick marks.