Terminal-based user interface toolkit
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package cview
import (
"sync"
"github.com/gdamore/tcell/v2"
)
// Button is labeled box that triggers an action when selected.
type Button struct {
*Box
// The text to be displayed before the input area.
label []byte
// The label color.
labelColor tcell.Color
// The label color when the button is in focus.
labelColorFocused tcell.Color
// The background color when the button is in focus.
backgroundColorFocused 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)
// An optional rune which is drawn after the label when the button is focused.
cursorRune rune
sync.RWMutex
}
// NewButton returns a new input field.
func NewButton(label string) *Button {
box := NewBox()
box.SetRect(0, 0, TaggedStringWidth(label)+4, 1)
box.SetBackgroundColor(Styles.MoreContrastBackgroundColor)
return &Button{
Box: box,
label: []byte(label),
labelColor: Styles.PrimaryTextColor,
labelColorFocused: Styles.PrimaryTextColor,
cursorRune: Styles.ButtonCursorRune,
backgroundColorFocused: Styles.ContrastBackgroundColor,
}
}
// SetLabel sets the button text.
func (b *Button) SetLabel(label string) {
b.Lock()
defer b.Unlock()
b.label = []byte(label)
}
// GetLabel returns the button text.
func (b *Button) GetLabel() string {
b.RLock()
defer b.RUnlock()
return string(b.label)
}
// SetLabelColor sets the color of the button text.
func (b *Button) SetLabelColor(color tcell.Color) {
b.Lock()
defer b.Unlock()
b.labelColor = color
}
// SetLabelColorFocused sets the color of the button text when the button is
// in focus.
func (b *Button) SetLabelColorFocused(color tcell.Color) {
b.Lock()
defer b.Unlock()
b.labelColorFocused = color
}
// SetCursorRune sets the rune to show within the button when it is focused.
func (b *Button) SetCursorRune(rune rune) {
b.Lock()
defer b.Unlock()
b.cursorRune = rune
}
// SetBackgroundColorFocused sets the background color of the button text when
// the button is in focus.
func (b *Button) SetBackgroundColorFocused(color tcell.Color) {
b.Lock()
defer b.Unlock()
b.backgroundColorFocused = color
}
// SetSelectedFunc sets a handler which is called when the button was selected.
func (b *Button) SetSelectedFunc(handler func()) {
b.Lock()
defer b.Unlock()
b.selected = handler
}
// 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)) {
b.Lock()
defer b.Unlock()
b.blur = handler
}
// Draw draws this primitive onto the screen.
func (b *Button) Draw(screen tcell.Screen) {
if !b.GetVisible() {
return
}
b.Lock()
defer b.Unlock()
// Draw the box.
borderColor := b.borderColor
backgroundColor := b.backgroundColor
if b.focus.HasFocus() {
b.backgroundColor = b.backgroundColorFocused
b.borderColor = b.labelColorFocused
defer func() {
b.borderColor = borderColor
}()
}
b.Unlock()
b.Box.Draw(screen)
b.Lock()
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.labelColorFocused
}
_, pw := Print(screen, b.label, x, y, width, AlignCenter, labelColor)
// Draw cursor.
if b.focus.HasFocus() && b.cursorRune != 0 {
cursorX := x + int(float64(width)/2+float64(pw)/2)
if cursorX > x+width-1 {
cursorX = x + width - 1
} else if cursorX < x+width {
cursorX++
}
Print(screen, []byte(string(b.cursorRune)), cursorX, y, width, AlignLeft, 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.
if HitShortcut(event, Keys.Select, Keys.Select2) {
if b.selected != nil {
b.selected()
}
} else if HitShortcut(event, Keys.Cancel, Keys.MovePreviousField, Keys.MoveNextField) {
if b.blur != nil {
b.blur(event.Key())
}
}
})
}
// MouseHandler returns the mouse handler for this primitive.
func (b *Button) MouseHandler() func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
return b.WrapMouseHandler(func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
if !b.InRect(event.Position()) {
return false, nil
}
// Process mouse event.
if action == MouseLeftClick {
setFocus(b)
if b.selected != nil {
b.selected()
}
consumed = true
}
return
})
}