// Plot implements the plot.Plotter interface. func (b *BarChart) Plot(c draw.Canvas, plt *plot.Plot) { trCat, trVal := plt.Transforms(&c) if b.Horizontal { trCat, trVal = trVal, trCat } for i, ht := range b.Values { catVal := b.XMin + float64(i) catMin := trCat(float64(catVal)) if !b.Horizontal { if !c.ContainsX(catMin) { continue } } else { if !c.ContainsY(catMin) { continue } } catMin = catMin - b.Width/2 + b.Offset catMax := catMin + b.Width bottom := b.stackedOn.BarHeight(i) valMin := trVal(bottom) valMax := trVal(bottom + ht) var pts []draw.Point var poly []draw.Point if !b.Horizontal { pts = []draw.Point{ {catMin, valMin}, {catMin, valMax}, {catMax, valMax}, {catMax, valMin}, } poly = c.ClipPolygonY(pts) } else { pts = []draw.Point{ {valMin, catMin}, {valMin, catMax}, {valMax, catMax}, {valMax, catMin}, } poly = c.ClipPolygonX(pts) } c.FillPolygon(b.Color, poly) var outline [][]draw.Point if !b.Horizontal { pts = append(pts, draw.Point{X: catMin, Y: valMin}) outline = c.ClipLinesY(pts) } else { pts = append(pts, draw.Point{X: valMin, Y: catMin}) outline = c.ClipLinesX(pts) } c.StrokeLines(b.LineStyle, outline...) } }