Charts I: components 101-120

gauge.go

@@ -0,0 +1,154 @@
+package mujica
+
+import (
+	"fmt"
+	"math"
+
+	"github.com/egoist/mygo/ui"
+
+	"mujicaui/internal"
+	"mujicaui/theme"
+)
+
+// GaugeTone colors a Gauge segment; its label still names it.
+type GaugeTone int
+
+const (
+	GaugeNeutral GaugeTone = iota
+	GaugeGood
+	GaugeWarning
+	GaugeDanger
+)
+
+// GaugeSegment is a named dial range up to To.
+type GaugeSegment struct {
+	To    float64
+	Label string
+	Tone  GaugeTone
+}
+
+// GaugeOptions configure a Gauge; Frame.Height 0 means 200 DIPs.
+type GaugeOptions struct {
+	Frame    ChartFrame
+	Min, Max float64
+	// Segments split Min..Max ascending; the last ends at Max.
+	Segments []GaugeSegment
+	Unit     string
+	// Full draws a whole circle instead of a half.
+	Full   bool
+	Format func(v float64) string
+}
+
+// Gauge points a needle at value on named segments.
+func Gauge(c *ui.Context, value float64, opts GaugeOptions) ChartResult {
+	if !(opts.Max > opts.Min) || math.IsNaN(value) || value < opts.Min || value > opts.Max {
+		panic("mujica: Gauge needs Min < Max and a value between them")
+	}
+	prev := opts.Min
+	for i, s := range opts.Segments {
+		if s.To <= prev || s.Label == "" || i == len(opts.Segments)-1 && s.To != opts.Max {
+			panic("mujica: Gauge segments need labels and ascending ends finishing at Max")
+		}
+		prev = s.To
+	}
+	if opts.Frame.Height == 0 {
+		opts.Frame.Height = 200
+	}
+	ch := newChart(c, opts.Frame)
+	k := Tokens(c)
+	size := FontSize(c, theme.CaptionSize)
+	tone := func(t GaugeTone) ui.Color {
+		return map[GaugeTone]ui.Color{GaugeNeutral: internal.Palette(k)[5], GaugeGood: k.Success, GaugeWarning: k.Warning, GaugeDanger: k.Danger}[t]
+	}
+	val := func(v float64) string { return chartValue(c, v, opts.Format) }
+	seg := -1
+	for i, s := range opts.Segments {
+		if value <= s.To && seg < 0 {
+			seg = i
+		}
+	}
+	a0, a1 := -math.Pi/2, math.Pi/2
+	if opts.Full {
+		a0, a1 = -math.Pi, math.Pi
+	}
+	angle := func(v float64) float64 { return a0 + (a1-a0)*(v-opts.Min)/(opts.Max-opts.Min) }
+	geom := func(r ui.Rect) (cx, cy, rad float32) {
+		if opts.Full {
+			rad = min(r.W, r.H)/2 - 12
+			return r.X + r.W/2, r.Y + r.H/2, rad
+		}
+		rad = min(r.W/2-12, r.H-36)
+		return r.X + r.W/2, r.Y + 8 + rad, rad
+	}
+	reading := val(value) + " " + opts.Unit
+	if seg >= 0 {
+		reading += " · " + opts.Segments[seg].Label
+	}
+	spec := chartSpec{n: 1 + len(opts.Segments)}
+	spec.readout = func(i int) string {
+		if i == 0 {
+			return reading
+		}
+		s, from := opts.Segments[i-1], opts.Min
+		if i > 1 {
+			from = opts.Segments[i-2].To
+		}
+		return fmt.Sprintf("%s: %s–%s", s.Label, val(from), val(s.To))
+	}
+	spec.pick = func(r ui.Rect, x, y float32) int {
+		cx, cy, rad := geom(r)
+		d := float32(math.Hypot(float64(x-cx), float64(y-cy)))
+		if d < rad*0.45 {
+			return 0
+		}
+		if d > rad+6 {
+			return -1
+		}
+		a := math.Atan2(float64(x-cx), float64(cy-y))
+		from := a0
+		for i, s := range opts.Segments {
+			if a >= from && a <= angle(s.To) {
+				return i + 1
+			}
+			from = angle(s.To)
+		}
+		return -1
+	}
+	spec.draw = func(p *ui.Painter, r ui.Rect, active int) {
+		cx, cy, rad := geom(r)
+		from := a0
+		if len(opts.Segments) == 0 {
+			p.FillPath(internal.Sector(cx, cy, rad*0.78, rad, a0, a1), k.SurfaceHover)
+		}
+		for i, s := range opts.Segments {
+			to := angle(s.To)
+			grow := float32(0)
+			if active == i+1 {
+				grow = 4
+			}
+			p.FillPath(internal.Sector(cx, cy, rad*0.78-grow, rad+grow, from, to), tone(s.Tone))
+			p.StrokePath(internal.Sector(cx, cy, rad*0.78-grow, rad+grow, from, to), 1.5, k.Surface)
+			lx, ly := internal.Polar(cx, cy, rad+10, to)
+			if i < len(opts.Segments)-1 {
+				chartText(p, val(s.To), lx, ly, size, k.TextMuted, 0.5, 1)
+			}
+			from = to
+		}
+		nx, ny := internal.Polar(cx, cy, rad*0.9, angle(value))
+		var needle ui.Path
+		needle.MoveTo(cx, cy).LineTo(internal.Snap(p, nx), internal.Snap(p, ny))
+		w := float32(3)
+		if active == 0 {
+			w = 4.5
+		}
+		p.StrokePath(&needle, w, k.Text)
+		p.FillPath(internal.Diamond(cx, cy, 12), k.Text)
+		ty := cy + 34
+		chartText(p, val(value)+" "+opts.Unit, cx, ty, FontSize(c, theme.H3Size), k.Text, 0.5, 1)
+		if seg >= 0 {
+			chartText(p, opts.Segments[seg].Label, cx, ty+2, size, k.TextMuted, 0.5, 0)
+		}
+	}
+	res, _ := ch.build(spec)
+	return res
+}