Charts I: components 101-120

funnel_chart.go

@@ -0,0 +1,85 @@
+package mujica
+
+import (
+	"fmt"
+	"math"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/internal"
+	"mujicaui/theme"
+)
+
+// FunnelChartOptions configure a FunnelChart.
+type FunnelChartOptions struct {
+	Frame  ChartFrame
+	Format func(v float64) string
+}
+
+// FunnelChart narrows by stage, labeled with conversion rates.
+func FunnelChart(c *ui.Context, stages []ChartSlice, opts FunnelChartOptions) ChartResult {
+	top := 0.0
+	for _, s := range stages {
+		if s.Label == "" || s.Value < 0 || math.IsNaN(s.Value) || math.IsInf(s.Value, 0) {
+			panic("mujica: FunnelChart stages need a label and a finite value ≥ 0")
+		}
+		top = max(top, s.Value)
+	}
+	ch := newChart(c, opts.Frame)
+	k := Tokens(c)
+	col := internal.Palette(k)[0]
+	size := FontSize(c, theme.CaptionSize)
+	n := len(stages)
+	if top == 0 {
+		n = 0
+	}
+	pct := func(a, b float64) string {
+		if b == 0 {
+			return "—"
+		}
+		return fmt.Sprintf("%.1f%%", 100*a/b)
+	}
+	rate := func(i int) string {
+		if i == 0 {
+			return pct(stages[0].Value, stages[0].Value)
+		}
+		return pct(stages[i].Value, stages[i-1].Value)
+	}
+	geom := func(r ui.Rect) (ui.Rect, internal.Band) {
+		plot := ui.Rect{X: r.X + 8, Y: r.Y + 4, W: r.W * 0.58, H: r.H - 8}
+		return plot, internal.Band{N: len(stages), R0: plot.Y, R1: plot.Y + plot.H, Pad: 0.08}
+	}
+	spec := chartSpec{n: n}
+	spec.readout = func(i int) string {
+		s := stages[i]
+		return fmt.Sprintf(msg(c, "funnel_chart.readout"), s.Label, chartValue(c, s.Value, opts.Format), rate(i), pct(s.Value, stages[0].Value))
+	}
+	spec.pick = func(r ui.Rect, x, y float32) int {
+		plot, band := geom(r)
+		if y < plot.Y || y >= plot.Y+plot.H || x < r.X || x > r.X+r.W {
+			return -1
+		}
+		return min(len(stages)-1, int((y-plot.Y)/band.Step()))
+	}
+	spec.draw = func(p *ui.Painter, r ui.Rect, active int) {
+		plot, band := geom(r)
+		cx := plot.X + plot.W/2
+		width := func(i int) float32 { return max(plot.W*float32(stages[min(i, len(stages)-1)].Value/top), 2) }
+		for i, s := range stages {
+			y0, y1 := band.Start(i), band.Start(i)+band.Width()
+			w0, w1 := width(i), width(i+1)
+			var shape ui.Path
+			shape.MoveTo(cx-w0/2, y0).LineTo(cx+w0/2, y0).LineTo(cx+w1/2, y1).LineTo(cx-w1/2, y1).Close()
+			p.FillPath(&shape, col)
+			if i == active {
+				p.StrokePath(&shape, 2, k.Text)
+			}
+			ly := (y0 + y1) / 2
+			lx := plot.X + plot.W + 16
+			chartText(p, s.Label+" · "+chartValue(c, s.Value, opts.Format), lx, ly, size, k.Text, 0, 1)
+			chartText(p, rate(i), lx, ly+2, size, k.TextMuted, 0, 0)
+		}
+	}
+	res, _ := ch.build(spec)
+	return res
+}