Terminal-based user interface toolkit
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package cview
import (
// Button is labeled box that triggers an action when selected.
// See https://git.sr.ht/~tslocum/cview/wiki/Button for an example.
type Button struct {
// The text to be displayed before the input area.
label string
// The label color.
labelColor tcell.Color
// The label color when the button is in focus.
labelColorActivated tcell.Color
// The background color when the button is in focus.
backgroundColorActivated tcell.Color
// An optional function which is called when the button was selected.
selected func()
// An optional function which is called when the user leaves the button. A
// key is provided indicating which key was pressed to leave (tab or backtab).
blur func(tcell.Key)
// NewButton returns a new input field.
func NewButton(label string) *Button {
box := NewBox().SetBackgroundColor(Styles.ContrastBackgroundColor)
box.SetRect(0, 0, TaggedStringWidth(label)+4, 1)
return &Button{
Box: box,
label: label,
labelColor: Styles.PrimaryTextColor,
labelColorActivated: Styles.InverseTextColor,
backgroundColorActivated: Styles.PrimaryTextColor,
// SetLabel sets the button text.
func (b *Button) SetLabel(label string) *Button {
b.label = label
return b
// GetLabel returns the button text.
func (b *Button) GetLabel() string {
return b.label
// SetLabelColor sets the color of the button text.
func (b *Button) SetLabelColor(color tcell.Color) *Button {
b.labelColor = color
return b
// SetLabelColorActivated sets the color of the button text when the button is
// in focus.
func (b *Button) SetLabelColorActivated(color tcell.Color) *Button {
b.labelColorActivated = color
return b
// SetBackgroundColorActivated sets the background color of the button text when
// the button is in focus.
func (b *Button) SetBackgroundColorActivated(color tcell.Color) *Button {
b.backgroundColorActivated = color
return b
// SetSelectedFunc sets a handler which is called when the button was selected.
func (b *Button) SetSelectedFunc(handler func()) *Button {
b.selected = handler
return b
// SetBlurFunc sets a handler which is called when the user leaves the button.
// The callback function is provided with the key that was pressed, which is one
// of the following:
// - KeyEscape: Leaving the button with no specific direction.
// - KeyTab: Move to the next field.
// - KeyBacktab: Move to the previous field.
func (b *Button) SetBlurFunc(handler func(key tcell.Key)) *Button {
b.blur = handler
return b
// Draw draws this primitive onto the screen.
func (b *Button) Draw(screen tcell.Screen) {
// Draw the box.
borderColor := b.borderColor
backgroundColor := b.backgroundColor
if b.focus.HasFocus() {
b.backgroundColor = b.backgroundColorActivated
b.borderColor = b.labelColorActivated
defer func() {
b.borderColor = borderColor
b.backgroundColor = backgroundColor
// Draw label.
x, y, width, height := b.GetInnerRect()
if width > 0 && height > 0 {
y = y + height/2
labelColor := b.labelColor
if b.focus.HasFocus() {
labelColor = b.labelColorActivated
Print(screen, b.label, x, y, width, AlignCenter, labelColor)
// InputHandler returns the handler for this primitive.
func (b *Button) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) {
return b.WrapInputHandler(func(event *tcell.EventKey, setFocus func(p Primitive)) {
// Process key event.
switch key := event.Key(); key {
case tcell.KeyEnter: // Selected.
if b.selected != nil {
case tcell.KeyBacktab, tcell.KeyTab, tcell.KeyEscape: // Leave. No action.
if b.blur != nil {