Add input components 086-105; park focus off disabled controls

input/slotpicker.go

@@ -0,0 +1,102 @@
+package input
+
+import (
+	"fmt"
+	"log/slog"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type SlotPickerOptions struct {
+	Disabled bool
+}
+
+type SlotPickerResult struct {
+	Element *ui.Element
+	Changed bool
+}
+
+type reelKey struct{}
+
+// reel holds a drag's and the wheel's leftover DIPs.
+type reel struct {
+	drag, wheel float32
+	changed     bool
+}
+
+// SlotPicker spins a looping reel; the centered option is chosen.
+func SlotPicker(c *ui.Context, text string, value *int, options []string, o SlotPickerOptions) SlotPickerResult {
+	k := pixel.K(c)
+	n := len(options)
+	if *value < 0 || *value >= n {
+		panic(fmt.Sprintf("input: SlotPicker value %d outside %d options", *value, n))
+	}
+	shell, base, st := pixel.Shell(c, func() *ui.Element {
+		return ui.Box(c).Focusable().Role(ui.RoleSlider).Label(text).Description(options[*value]).Disabled(o.Disabled)
+	})
+	s := ui.Local(base, reelKey{}, func() reel { return reel{} })
+	spin := func(d int) {
+		*value = ((*value+d)%n + n) % n
+		s.changed = true
+	}
+	row := k.D(pixel.LineHeight)
+	base.HandleInput(func(ev ui.InputEvent) bool {
+		if ev.Kind != ui.InputScroll || o.Disabled {
+			return false
+		}
+		s.wheel += ev.DY
+		turn(&s.wheel, row, spin)
+		return true
+	})
+	if base.Shortcut(0, ui.KeyDown) {
+		spin(1)
+	}
+	if base.Shortcut(0, ui.KeyUp) {
+		spin(-1)
+	}
+	if _, dy, held := base.Dragged(); held && !o.Disabled {
+		s.drag += dy
+		turn(&s.drag, row, func(d int) { spin(-d) })
+	} else {
+		s.drag = 0
+	}
+	res := SlotPickerResult{Element: shell, Changed: s.changed}
+	s.changed = false
+	if res.Changed {
+		slog.Debug("8bit: slot picker", "label", text, "value", options[*value])
+	}
+	off := int(s.drag / k.Dot())
+	shell.Size(k.D(widest(options)+28), k.D(3*pixel.LineHeight+4)).Draw(func(p *ui.Painter, r ui.Rect) {
+		g := k.Canvas(p, r)
+		g.Frame(0, 0, g.W, g.H, pixel.Sunken, pixel.Well)
+		g.Clip(2, 2, g.W-4, g.H-4, func() {
+			for i := -2; i <= 2; i++ {
+				ink := pixel.Faint
+				if i == 0 {
+					ink = pixel.Ink
+				}
+				opt := options[((*value+i)%n+n)%n]
+				g.Text((g.W-pixel.Measure(opt))/2, 2+pixel.LineHeight*(1+i)+off, opt, ink, 1)
+			}
+		})
+		g.Veil(2, 2, g.W-4, 6, pixel.Shade, 4)
+		g.Veil(2, g.H-8, g.W-4, 6, pixel.Shade, 4)
+		mid := 2 + pixel.LineHeight + (pixel.LineHeight-tinyRight.H)/2
+		g.Sprite(3, mid, tinyRight, 0, pixel.Accent, 1)
+		g.Sprite(g.W-6, mid, tinyLeft, 0, pixel.Accent, 1)
+		finish(g, st)
+	})
+	return res
+}
+
+// turn spends whole rows of *left on step.
+func turn(left *float32, row float32, step func(int)) {
+	for ; *left >= row; *left -= row {
+		step(1)
+	}
+	for ; *left <= -row; *left += row {
+		step(-1)
+	}
+}