Method Plot

plotter/sankey.go:203–295

Plot implements the plot.Plotter interface.

(c draw.Canvas, plt *plot.Plot)

// Plot implements the plot.Plotter interface.
func (s *Sankey) Plot(c draw.Canvas, plt *plot.Plot) {
	trCat, trVal := plt.Transforms(&c)

	// sourceFlowPlaceholder and receptorFlowPlaceholder track
	// the current plotting location during
	// the plotting process.
	sourceFlowPlaceholder := make(map[*stock]float64, len(s.flows))
	receptorFlowPlaceholder := make(map[*stock]float64, len(s.flows))

	// Here we draw the flows.
	for _, f := range s.flows {
		startStock := s.stocks[f.SourceCategory][f.SourceLabel]
		endStock := s.stocks[f.ReceptorCategory][f.ReceptorLabel]
		catStart := trCat(float64(f.SourceCategory)) + s.StockBarWidth/2
		catEnd := trCat(float64(f.ReceptorCategory)) - s.StockBarWidth/2
		valStartLow := trVal(startStock.min + sourceFlowPlaceholder[startStock])
		valEndLow := trVal(endStock.min + receptorFlowPlaceholder[endStock])
		valStartHigh := trVal(startStock.min + sourceFlowPlaceholder[startStock] + f.Value)
		valEndHigh := trVal(endStock.min + receptorFlowPlaceholder[endStock] + f.Value)
		sourceFlowPlaceholder[startStock] += f.Value
		receptorFlowPlaceholder[endStock] += f.Value

		ptsLow := s.bezier(
			vg.Point{X: catStart, Y: valStartLow},
			vg.Point{X: catEnd, Y: valEndLow},
		)
		ptsHigh := s.bezier(
			vg.Point{X: catEnd, Y: valEndHigh},
			vg.Point{X: catStart, Y: valStartHigh},
		)

		color, lineStyle := s.FlowStyle(f.Group)

		// Here we fill the flow polygons.
		if color != nil {
			poly := c.ClipPolygonX(append(ptsLow, ptsHigh...))
			c.FillPolygon(color, poly)
		}

		// Here we draw the flow edges.
		outline := c.ClipLinesX(ptsLow)
		c.StrokeLines(lineStyle, outline...)
		outline = c.ClipLinesX(ptsHigh)
		c.StrokeLines(lineStyle, outline...)
	}

	// Here we draw the stocks.
	for _, stk := range s.stockList() {
		catLoc := trCat(float64(stk.category))
		if !c.ContainsX(catLoc) {
			continue
		}
		catMin, catMax := catLoc-s.StockBarWidth/2, catLoc+s.StockBarWidth/2
		valMin, valMax := trVal(stk.min), trVal(stk.max)

		label, textStyle, xOff, yOff, color, lineStyle := s.StockStyle(stk.label, stk.category)

		// Here we fill the stock bars.