Method Plot

plot/plots/barchart.go:148–208

Plot implements the plot.Plotter interface.

(plt *plot.Plot)

// Plot implements the plot.Plotter interface.
func (b *BarChart) Plot(plt *plot.Plot) {
	pc := plt.Paint
	pc.FillStyle.Color = b.Color
	b.LineStyle.SetStroke(plt)

	nv := len(b.Values)
	b.XYs = make(plot.XYs, nv)
	b.PXYs = make(plot.XYs, nv)

	hw := 0.5 * b.Width
	ew := b.Width / 3
	for i, ht := range b.Values {
		cat := b.Offset + float32(i)*b.Stride
		var bottom, catVal, catMin, catMax, valMin, valMax float32
		var box math32.Box2
		if b.Horizontal {
			catVal = plt.PY(cat)
			catMin = plt.PY(cat - hw)
			catMax = plt.PY(cat + hw)
			bottom = b.StackedOn.BarHeight(i) // nil safe
			valMin = plt.PX(bottom)
			valMax = plt.PX(bottom + ht)
			b.XYs[i] = math32.Vec2(bottom+ht, cat)
			b.PXYs[i] = math32.Vec2(valMax, catVal)
			box.Min.Set(valMin, catMin)
			box.Max.Set(valMax, catMax)
		} else {
			catVal = plt.PX(cat)
			catMin = plt.PX(cat - hw)
			catMax = plt.PX(cat + hw)
			bottom = b.StackedOn.BarHeight(i) // nil safe
			valMin = plt.PY(bottom)
			valMax = plt.PY(bottom + ht)
			b.XYs[i] = math32.Vec2(cat, bottom+ht)
			b.PXYs[i] = math32.Vec2(catVal, valMax)
			box.Min.Set(catMin, valMin)
			box.Max.Set(catMax, valMax)
		}

		pc.DrawRectangle(box.Min.X, box.Min.Y, box.Size().X, box.Size().Y)
		pc.FillStrokeClear()

		if i < len(b.Errors) {
			errval := b.Errors[i]
			if b.Horizontal {
				eVal := plt.PX(bottom + ht + math32.Abs(errval))
				pc.MoveTo(valMax, catVal)
				pc.LineTo(eVal, catVal)
				pc.MoveTo(eVal, plt.PY(cat-ew))
				pc.LineTo(eVal, plt.PY(cat+ew))
			} else {
				eVal := plt.PY(bottom + ht + math32.Abs(errval))
				pc.MoveTo(catVal, valMax)
				pc.LineTo(catVal, eVal)
				pc.MoveTo(plt.PX(cat-ew), eVal)
				pc.LineTo(plt.PX(cat+ew), eVal)
			}
			pc.Stroke()