56 lines
1.5 KiB
Go
56 lines
1.5 KiB
Go
package input
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import (
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"math"
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"github.com/egoist/mygo/ui"
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"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
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)
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type KnobOptions struct {
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// Min and Max are zero for 0 to 1.
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Min, Max float64
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// Step snaps the value; zero means none.
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Step float64
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Disabled bool
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}
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type KnobResult = SliderResult
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type knobKey struct{}
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// Knob turns through 16 angles by vertical drag or arrows.
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func Knob(c *ui.Context, text string, value *float64, o KnobOptions) KnobResult {
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k := pixel.K(c)
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lo, hi := bounds(o.Min, o.Max)
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r := rail{lo: lo, hi: hi, step: o.Step}
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shell, base, st := pixel.Shell(c, func() *ui.Element {
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return ui.Box(c).Focusable().Role(ui.RoleSlider).Label(text).Description(fmtValue(*value)).Disabled(o.Disabled)
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})
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old, set := *value, r.snap(value)
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// raw is the unrounded value a drag carries.
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raw := ui.Local(base, knobKey{}, func() float64 { return *value })
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if !o.Disabled {
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if _, dy, held := base.Dragged(); held {
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*raw = max(lo, min(hi, *raw-float64(dy/k.Dot())*(hi-lo)/64))
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set(*raw)
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} else {
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*raw = *value
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}
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r.keys(base, value, set)
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}
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shell.Size(k.D(24), k.D(24)).Draw(func(p *ui.Painter, rc ui.Rect) {
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g := k.Canvas(p, rc)
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g.Disc(12, 12, 11, pixel.Edge)
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g.Disc(12, 12, 10, pixel.Shade)
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g.Disc(11, 11, 9, pixel.Face)
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a := (-135 + 18*math.Round((*value-lo)/(hi-lo)*15)) * math.Pi / 180
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x, y := 12+int(math.Round(7*math.Sin(a))), 12-int(math.Round(7*math.Cos(a)))
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g.Line(12, 12, x, y, pixel.Accent)
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g.Dot(x, y, pixel.Ink)
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finish(g, st)
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})
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return report(shell, *value != old, "knob", text, *value)
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}
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