add(project): initial commit

internal/utils/animation.go

@@ -0,0 +1,79 @@
+package utils
+
+import (
+	"math"
+	"time"
+
+	"gioui.org/layout"
+	"gioui.org/op"
+)
+
+type Animation struct {
+	start     float32
+	end       float32
+	current   float32
+	startTime time.Time
+	duration  time.Duration
+	active    bool
+	Easing    Easing
+}
+
+type Easing int
+
+const (
+	None Easing = iota
+	EasingIn
+	EasingOut
+	EasingOutSine
+	EasingInOutSine
+)
+
+func (a *Animation) Current() float32 {
+	return a.current
+}
+
+func applyEasing(easing Easing, t float32) float32 {
+	switch easing {
+	case EasingIn:
+		return t * t
+	case EasingOut:
+		return t * (2 - t)
+	case EasingOutSine:
+		return float32(math.Sin(float64(t) * math.Pi / 2))
+	case EasingInOutSine:
+		return float32(-0.5 * (math.Cos(math.Pi*float64(t)) - 1))
+	default:
+		return t
+	}
+}
+
+func (a *Animation) Start(start, end float32, duration time.Duration, easing Easing) {
+	a.start = start
+	a.end = end
+	a.current = start
+	a.startTime = time.Now()
+	a.duration = duration
+	a.Easing = easing
+	a.active = true
+}
+
+func (a *Animation) Update(gtx layout.Context) float32 {
+	if !a.active {
+		return a.current
+	}
+
+	elapsed := time.Since(a.startTime)
+
+	if elapsed >= a.duration {
+		a.current = a.end
+		a.active = false
+	} else {
+		progress := float32(elapsed) / float32(a.duration)
+		eased := applyEasing(a.Easing, progress)
+		a.current = a.start + (a.end-a.start)*eased
+	}
+
+	gtx.Execute(&op.InvalidateCmd{})
+
+	return a.current
+}