Terminal-based user interface toolkit
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package tview
import (
"github.com/gdamore/tcell"
)
// Button is labeled box that triggers an action when selected.
type Button struct {
*Box
// 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(tcell.ColorBlue)
return &Button{
Box: box,
label: label,
labelColor: tcell.ColorWhite,
labelColorActivated: tcell.ColorBlue,
backgroundColorActivated: tcell.ColorWhite,
}
}
// 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.
backgroundColor := b.backgroundColor
if b.focus.HasFocus() {
b.backgroundColor = b.backgroundColorActivated
}
b.Box.Draw(screen)
b.backgroundColor = backgroundColor
// Draw label.
x := b.x + b.width/2
y := b.y + b.height/2
width := b.width
if b.border {
width -= 2
}
labelColor := b.labelColor
if b.focus.HasFocus() {
labelColor = b.labelColorActivated
}
Print(screen, b.label, x, y, width, AlignCenter, labelColor)
if b.focus.HasFocus() {
screen.HideCursor()
}
}
// InputHandler returns the handler for this primitive.
func (b *Button) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) {
return func(event *tcell.EventKey, setFocus func(p Primitive)) {
// Process key event.
switch key := event.Key(); key {
case tcell.KeyEnter: // Selected.
if b.selected != nil {
b.selected()
}
case tcell.KeyBacktab, tcell.KeyTab, tcell.KeyEscape: // Leave. No action.
if b.blur != nil {
b.blur(key)
}
}
}
}