120 lines
4.1 KiB
Go
120 lines
4.1 KiB
Go
package input
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import (
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"cmp"
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"fmt"
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"log/slog"
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"math"
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"github.com/egoist/mygo/ui"
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"git.zacharyzhang.com/ZacharyZhang-NY/MujicaUI/core"
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"git.zacharyzhang.com/ZacharyZhang-NY/MujicaUI/internal"
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"git.zacharyzhang.com/ZacharyZhang-NY/MujicaUI/theme"
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)
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// KnobOptions configure a Knob. Min and Max both zero mean 0 to 100.
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type KnobOptions struct {
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Min, Max float64
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// Step snaps the value; zero is continuous, moving 1% per arrow press.
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Step float64
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// Ticks draws that many evenly spaced marks around the dial; zero draws none.
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Ticks int
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// Size is the dial diameter; zero is 56.
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Size float32
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// Format writes the value under the dial; nil prints as many decimals as Min and Step need.
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Format func(float64) string
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Disabled bool
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// Label names the knob and shows above it.
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Label string
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}
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// knobSweep is the dial's travel, centered on twelve o'clock, in turns.
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const knobSweep = 0.75
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// knobDragPixels is how far a vertical drag travels the whole range.
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const knobDragPixels float32 = 160
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// Knob sets *value by dragging up and down, the arrows, Home and End; the dial shows the value and ticks.
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func Knob(c *ui.Context, value *float64, opts KnobOptions) core.ChoiceResult {
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if value == nil {
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panic("mujica: Knob needs a value")
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}
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if opts.Ticks < 0 || !(opts.Size >= 0) || math.IsInf(float64(opts.Size), 1) {
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panic(fmt.Sprintf("mujica: Knob Ticks %d or Size %v invalid", opts.Ticks, opts.Size))
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}
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g, _ := SliderSetup(opts.Min, opts.Max, opts.Step, nil, false, c)
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format := sliderFormat(opts.Format, g)
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size := cmp.Or(opts.Size, 56)
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k := core.Tokens(c)
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old := g.snap(*value)
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*value = old
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col := ui.Column(c).AlignItems(ui.Center).Gap(core.Density(c).Unit()).Disabled(opts.Disabled)
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disabled := col.IsDisabled()
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var s *ui.Element
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col.Children(func() {
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if opts.Label != "" {
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ui.Text(c, opts.Label).TextColor(k.Text).FontSize(core.FontSize(c, theme.CaptionSize))
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}
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var next float64
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var dragged bool
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s, next, dragged = SliderControl(c, old, g, g.lo, g.hi)
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want := ui.Local(s, "knob.want", func() float64 { return math.NaN() })
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if dragged {
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if math.IsNaN(*want) {
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*want = old
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}
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_, dy, _ := s.Dragged()
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*want = max(g.lo, min(g.hi, *want-float64(dy)*(g.hi-g.lo)/float64(knobDragPixels)))
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next = g.snap(*want)
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} else {
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*want = math.NaN()
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}
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if !disabled {
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*value = next
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}
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s.Size(size, size).FocusRing(false).Cursor(ui.CursorResizeNS).Label(cmp.Or(opts.Label, core.Msg(c, "knob.label")))
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hot := s.Hovered() || dragged
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v := *value
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s.Draw(func(p *ui.Painter, r ui.Rect) { knobPaint(p, r, k, g, v, opts.Ticks, hot, s.FocusVisible()) })
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ui.Text(c, format(*value)).TextColor(k.TextMuted).FontSize(core.FontSize(c, theme.CaptionSize)).FontFeatures("tnum")
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})
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changed := *value != old
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if changed {
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slog.Debug("mujica: knob changed", "label", opts.Label, "value", *value)
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}
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return core.NewChoiceResult(col, changed)
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}
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// knobPaint draws the track arc, the value arc, ticks and the diamond pointer.
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func knobPaint(p *ui.Painter, r ui.Rect, k theme.Tokens, g SliderGeom, v float64, ticks int, hot, focus bool) {
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cx, cy := internal.Snap(p, r.X+r.W/2), internal.Snap(p, r.Y+r.H/2)
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rad := r.W/2 - 6
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start := float32(-knobSweep / 2)
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frac := float32((v - g.lo) / (g.hi - g.lo))
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p.StrokePath(core.ProgressArc(p, cx, cy, rad, start, start+knobSweep), 3, k.Border)
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if frac > 0 {
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p.StrokePath(core.ProgressArc(p, cx, cy, rad, start, start+knobSweep*frac), 3, k.AccentText)
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}
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for i := range ticks {
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t := float64(start) + knobSweep*float64(i)/float64(max(ticks-1, 1))
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sin, cos := float32(math.Sin(2*math.Pi*t)), float32(math.Cos(2*math.Pi*t))
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p.Line(cx+sin*(rad+3), cy-cos*(rad+3), cx+sin*(rad+6), cy-cos*(rad+6), 1, k.TextMuted)
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}
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face := k.Surface
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if hot {
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face = k.SurfaceHover
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}
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var dial ui.Path
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dial.Circle(cx, cy, rad-6)
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p.FillPath(&dial, face)
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p.StrokePath(&dial, 1, k.ControlBorder)
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t := float64(start + knobSweep*frac)
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px := internal.Snap(p, cx+float32(math.Sin(2*math.Pi*t))*(rad-12))
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py := internal.Snap(p, cy-float32(math.Cos(2*math.Pi*t))*(rad-12))
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p.FillPath(internal.Diamond(px, py, 7), k.AccentText)
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if focus {
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internal.FocusRing(p, r, r.W/2, k.Focus)
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}
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}
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