Add WithSpringOptions to customize spring in NewModel

progress/progress.go

@@ -98,6 +98,13 @@ func WithWidth(w int) Option {
 	}
 }
 
+func WithSpringOptions(frequency, damping float64) Option {
+	return func(m *Model) {
+		m.SetSpringOptions(frequency, damping)
+		m.springCustomized = true
+	}
+}
+
 // FrameMsg indicates that an animation step should occur.
 type FrameMsg struct {
 	id  int
@@ -131,6 +138,7 @@ type Model struct {
 
 	// Members for animated transitons.
 	spring           harmonica.Spring
+	springCustomized bool
 	percent          float64
 	targetPercent    float64
 	velocity         float64
@@ -158,7 +166,9 @@ func NewModel(opts ...Option) Model {
 		ShowPercentage: true,
 		PercentFormat:  " %3.0f%%",
 	}
+	if !m.springCustomized {
 		m.SetSpringOptions(defaultFrequency, defaultDamping)
+	}
 
 	for _, opt := range opts {
 		opt(&m)