Initial draft of a spinner widget implementation based on a text entr…

…y widget and two buttons in a border layout

cmd/fyne_demo/screens/widget.go

@@ -77,7 +77,8 @@ func makeFormTab() fyne.Widget {
 	password := widget.NewPasswordEntry()
 	password.SetPlaceHolder("Password")
 	largeText := widget.NewMultiLineEntry()
-
+	age := widget.NewIntegralSpinner(0, 100, 1)
+	weight := widget.NewSpinner(0.0, 100.0, 0.25)
 	form := &widget.Form{
 		OnCancel: func() {
 			fmt.Println("Cancelled")
@@ -88,13 +89,16 @@ func makeFormTab() fyne.Widget {
 			fmt.Println("Email:", email.Text)
 			fmt.Println("Password:", password.Text)
 			fmt.Println("Message:", largeText.Text)
+			fmt.Println("Age:", age.GetValue())
+			fmt.Println("Weight:", weight.GetValue())
 		},
 	}
 	form.Append("Name", name)
 	form.Append("Email", email)
 	form.Append("Password", password)
 	form.Append("Message", largeText)
-
+	form.Append("Age", age)
+	form.Append("Weight", weight)
 	return form
 }
 

widget/spinner.go

@@ -0,0 +1,197 @@
+package widget
+
+import (
+	"fmt"
+	"image/color"
+	"math"
+	"strconv"
+
+	"fyne.io/fyne"
+	"fyne.io/fyne/layout"
+	"fyne.io/fyne/theme"
+)
+
+func sgn(a float64) float64 {
+	switch {
+	case a < 0:
+		return -1
+	case a > 0:
+		return +1
+	}
+	return 0
+}
+
+// extend entry to detect enter / and scrolling
+// and propergate to spinner widget
+type customEntry struct {
+	Entry
+	onEnter    func()
+	onScrolled func(s *fyne.ScrollEvent)
+}
+
+func newCustomEntry() *customEntry {
+	cutomEntry := &customEntry{}
+	cutomEntry.ExtendBaseWidget(cutomEntry)
+	return cutomEntry
+}
+
+func (e *customEntry) KeyDown(key *fyne.KeyEvent) {
+
+	if key.Name == fyne.KeyReturn {
+		if e.onEnter != nil {
+			e.onEnter()
+		}
+	} else {
+		e.Entry.KeyDown(key)
+	}
+}
+
+func (e *customEntry) Scrolled(s *fyne.ScrollEvent) {
+	if e.onScrolled != nil {
+		e.onScrolled(s)
+	}
+}
+
+type Spinner struct {
+	fyne.Container
+	value    float64
+	Min      float64
+	Max      float64
+	Step     float64
+	Fmt      string
+	startVal float64
+
+	buttonUp   *Button
+	buttonDown *Button
+	entry      *customEntry
+	integer    bool
+}
+
+func NewSpinner(min, max, step float64) *Spinner {
+	return newSpinnerImpl(min, max, step, false)
+}
+
+func NewIntegralSpinner(min, max, step int) *Spinner {
+	return newSpinnerImpl(float64(min), float64(max), float64(step), true)
+}
+
+func newSpinnerImpl(min, max, step float64, integer bool) *Spinner {
+	buttonUp := NewButtonWithIcon("", theme.MenuDropUpIcon(), func() {})
+	buttonDown := NewButtonWithIcon("", theme.MenuDropDownIcon(), func() {})
+	updown := NewHBox(buttonUp, buttonDown)
+
+	entry := newCustomEntry()
+	nip := &Spinner{
+		buttonUp:   buttonUp,
+		buttonDown: buttonDown,
+		entry:      entry,
+		Min:        min,
+		Max:        max,
+		value:      math.Min(math.Max(min, 1), max),
+		startVal:   math.Min(math.Max(min, 1), max),
+		Step:       1,
+		integer:    integer,
+	}
+	buttonDown.OnTapped = nip.onDown
+	buttonUp.OnTapped = nip.onUp
+	//entry.OnChanged = nip.onTextChanged
+	entry.onEnter = nip.onEnter
+	entry.onScrolled = nip.onScrolled
+	nip.Layout = layout.NewBorderLayout(nil, nil, nil, updown)
+	nip.AddObject(updown)
+	nip.AddObject(entry)
+	nip.updateVal()
+	return nip
+}
+
+func (spinner *Spinner) GetValue() float64 {
+	spinner.parseEntry()
+	return spinner.value
+}
+
+func (spinner *Spinner) SetValue(value float64) {
+	spinner.value = value
+	spinner.updateVal()
+}
+
+func (spinner *Spinner) onEnter() {
+	spinner.parseEntry()
+}
+func (spinner *Spinner) parseEntry() {
+	if f, err := strconv.ParseFloat(spinner.entry.Text, 64); err != nil {
+		spinner.value = spinner.startVal
+	} else {
+		spinner.value = math.Min(math.Max(spinner.Min, f), spinner.Max)
+	}
+	spinner.updateVal()
+}
+func (spinner *Spinner) onScrolled(e *fyne.ScrollEvent) {
+	if e.DeltaY != 0 {
+		spinner.value += spinner.Step * sgn(float64(e.DeltaY))
+		spinner.updateVal()
+	}
+}
+func (spinner *Spinner) onUp() {
+	spinner.parseEntry()
+	spinner.value += spinner.Step
+	spinner.updateVal()
+}
+func (spinner *Spinner) onDown() {
+	spinner.parseEntry()
+	spinner.value -= spinner.Step
+	spinner.updateVal()
+}
+func (spinner *Spinner) updateVal() {
+	spinner.value = math.Min(math.Max(spinner.Min, spinner.value), spinner.Max)
+	if spinner.integer {
+		spinner.value = math.Round(spinner.value)
+		spinner.entry.SetText(fmt.Sprintf("%d", int(spinner.value)))
+	} else if spinner.Fmt == "" {
+		spinner.entry.SetText(fmt.Sprintf("%.4f", spinner.value))
+	} else {
+		spinner.entry.SetText(fmt.Sprintf(spinner.Fmt, spinner.value))
+	}
+	if spinner.value <= spinner.Min {
+		spinner.buttonDown.Disable()
+	} else {
+		spinner.buttonDown.Enable()
+	}
+	if spinner.value >= spinner.Max {
+		spinner.buttonUp.Disable()
+	} else {
+		spinner.buttonUp.Enable()
+	}
+
+}
+
+func (spinner *Spinner) CreateRenderer() fyne.WidgetRenderer {
+	return &spinnerRenderer{
+		spinner: spinner,
+	}
+}
+
+type spinnerRenderer struct {
+	spinner *Spinner
+}
+
+func (renderer *spinnerRenderer) Layout(size fyne.Size) {
+	renderer.spinner.Layout.Layout(renderer.spinner.Objects, size)
+}
+func (renderer *spinnerRenderer) MinSize() fyne.Size {
+	return renderer.spinner.MinSize()
+}
+
+func (renderer *spinnerRenderer) Refresh() {
+	renderer.spinner.Refresh()
+}
+
+func (renderer *spinnerRenderer) BackgroundColor() color.Color {
+	return theme.BackgroundColor()
+}
+
+func (renderer *spinnerRenderer) Objects() []fyne.CanvasObject {
+	return renderer.spinner.Objects
+}
+
+func (renderer *spinnerRenderer) Destroy() {
+}