Add input components 066-085; gallery chrome on real components; deploy warms the edge

input/slider.go

@@ -0,0 +1,124 @@
+package input
+
+import (
+	"fmt"
+	"log/slog"
+	"math"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type SliderOptions struct {
+	// Min and Max are zero for 0 to 1.
+	Min, Max float64
+	// Width is the track in dots; zero means 96.
+	Width    int
+	Disabled bool
+}
+
+type SliderResult struct {
+	Element *ui.Element
+	Changed bool
+}
+
+// Slider sets *value by drag, arrows, Home and End.
+func Slider(c *ui.Context, text string, value *float64, o SliderOptions) SliderResult {
+	k := pixel.K(c)
+	lo, hi := bounds(o.Min, o.Max)
+	w := orDef("Slider Width", o.Width, 96)
+	shell, st, changed := slide(c, value, rail{lo: lo, hi: hi, label: text, disabled: o.Disabled})
+	shell.Size(k.D(w), k.D(12)).Draw(func(p *ui.Painter, r ui.Rect) {
+		g := k.Canvas(p, r)
+		x := knobAt(*value, lo, hi, g.W-6)
+		groove(g, x+3, 4)
+		g.Frame(x, 1, 6, 10, pixel.Raised, pixel.Face)
+		finish(g, st)
+	})
+	return report(shell, changed, "slider", text, *value)
+}
+
+// rail maps a slide's pointer and keys to a value.
+type rail struct {
+	lo, hi, step float64
+	vertical     bool
+	label        string
+	disabled     bool
+}
+
+// slide is a focusable track; pointer and keys set *v.
+func slide(c *ui.Context, v *float64, r rail) (*ui.Element, pixel.State, bool) {
+	shell, base, st := pixel.Shell(c, func() *ui.Element {
+		return ui.Box(c).Focusable().Role(ui.RoleSlider).Label(r.label).Description(fmtValue(*v)).Disabled(r.disabled)
+	})
+	old := *v
+	top := r.hi
+	if r.step > 0 {
+		top = r.lo + math.Floor((r.hi-r.lo)/r.step+1e-9)*r.step
+	}
+	set := func(x float64) {
+		if r.step > 0 {
+			x = r.lo + math.Round((x-r.lo)/r.step)*r.step
+		}
+		*v = max(r.lo, min(top, x))
+	}
+	if !r.disabled {
+		if _, _, held := base.Dragged(); held {
+			px, py, _ := base.PointerPosition()
+			b := base.Bounds()
+			frac := float64(px / max(1, b.W))
+			if r.vertical {
+				frac = 1 - float64(py/max(1, b.H))
+			}
+			set(r.lo + frac*(r.hi-r.lo))
+		}
+		step := r.step
+		if step == 0 {
+			step = (r.hi - r.lo) / 20
+		}
+		for _, kd := range []struct {
+			key ui.Key
+			to  func() float64
+		}{
+			{ui.KeyLeft, func() float64 { return *v - step }}, {ui.KeyDown, func() float64 { return *v - step }},
+			{ui.KeyRight, func() float64 { return *v + step }}, {ui.KeyUp, func() float64 { return *v + step }},
+			{ui.KeyHome, func() float64 { return r.lo }}, {ui.KeyEnd, func() float64 { return r.hi }},
+		} {
+			if base.Shortcut(0, kd.key) {
+				set(kd.to())
+			}
+		}
+	}
+	return shell, st, *v != old
+}
+
+// bounds are lo and hi; zeros mean 0 to 1.
+func bounds(lo, hi float64) (float64, float64) {
+	if lo == 0 && hi == 0 {
+		return 0, 1
+	}
+	if hi <= lo {
+		panic(fmt.Sprintf("input: range %v to %v is empty", lo, hi))
+	}
+	return lo, hi
+}
+
+// knobAt is the knob's offset for v along span dots.
+func knobAt(v, lo, hi float64, span int) int {
+	return int(math.Round((v - lo) / (hi - lo) * float64(span)))
+}
+
+// groove is the Well track, filled with Accent to x.
+func groove(g pixel.Canvas, x, y int) {
+	g.Frame(0, y, g.W, 4, pixel.Sunken, pixel.Well)
+	g.Rect(1, y+1, x-1, 2, pixel.Accent)
+}
+
+// report logs a change and wraps the result.
+func report(e *ui.Element, changed bool, kind, text string, v float64) SliderResult {
+	if changed {
+		slog.Debug("8bit: "+kind, "label", text, "value", v)
+	}
+	return SliderResult{Element: e, Changed: changed}
+}