Terminal-based user interface toolkit
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package cview
import (
// Modal is a centered message window used to inform the user or prompt them
// for an immediate decision. It needs to have at least one button (added via
// AddButtons) or it will never disappear. You may change the title and
// appearance of the window by modifying the Frame returned by GetFrame. You
// may include additional elements within the window by modifying the Form
// returned by GetForm.
type Modal struct {
// The Frame embedded in the Modal.
frame *Frame
// The Form embedded in the Modal's Frame.
form *Form
// The message text (original, not word-wrapped).
text string
// The text color.
textColor tcell.Color
// The optional callback for when the user clicked one of the buttons. It
// receives the index of the clicked button and the button's label.
done func(buttonIndex int, buttonLabel string)
// NewModal returns a new centered message window.
func NewModal() *Modal {
m := &Modal{
Box: NewBox(),
textColor: Styles.PrimaryTextColor,
m.form = NewForm()
m.form.SetPadding(0, 0, 0, 0)
m.form.SetCancelFunc(func() {
if m.done != nil {
m.done(-1, "")
m.frame = NewFrame(m.form)
m.frame.SetBorders(0, 0, 1, 0, 0, 0)
m.frame.SetPadding(1, 1, 1, 1)
m.focus = m
return m
// SetBackgroundColor sets the color of the Modal Frame background.
func (m *Modal) SetBackgroundColor(color tcell.Color) {
defer m.Unlock()
// SetTextColor sets the color of the message text.
func (m *Modal) SetTextColor(color tcell.Color) {
defer m.Unlock()
m.textColor = color
// SetButtonBackgroundColor sets the background color of the buttons.
func (m *Modal) SetButtonBackgroundColor(color tcell.Color) {
defer m.Unlock()
// SetButtonTextColor sets the color of the button texts.
func (m *Modal) SetButtonTextColor(color tcell.Color) {
defer m.Unlock()
// SetDoneFunc sets a handler which is called when one of the buttons was
// pressed. It receives the index of the button as well as its label text. The
// handler is also called when the user presses the Escape key. The index will
// then be negative and the label text an empty string.
func (m *Modal) SetDoneFunc(handler func(buttonIndex int, buttonLabel string)) {
defer m.Unlock()
m.done = handler
// SetText sets the message text of the window. The text may contain line
// breaks. Note that words are wrapped, too, based on the final size of the
// window.
func (m *Modal) SetText(text string) {
defer m.Unlock()
m.text = text
// GetForm returns the Form embedded in the window. The returned Form may be
// modified to include additional elements (e.g. AddInputField, AddFormItem).
func (m *Modal) GetForm() *Form {
defer m.RUnlock()
return m.form
// GetFrame returns the Frame embedded in the window.
func (m *Modal) GetFrame() *Frame {
defer m.RUnlock()
return m.frame
// AddButtons adds buttons to the window. There must be at least one button and
// a "done" handler so the window can be closed again.
func (m *Modal) AddButtons(labels []string) {
defer m.Unlock()
for index, label := range labels {
func(i int, l string) {
m.form.AddButton(label, func() {
if m.done != nil {
m.done(i, l)
button := m.form.GetButton(m.form.GetButtonCount() - 1)
button.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
switch event.Key() {
case tcell.KeyDown, tcell.KeyRight:
return tcell.NewEventKey(tcell.KeyTab, 0, tcell.ModNone)
case tcell.KeyUp, tcell.KeyLeft:
return tcell.NewEventKey(tcell.KeyBacktab, 0, tcell.ModNone)
return event
}(index, label)
// ClearButtons removes all buttons from the window.
func (m *Modal) ClearButtons() {
defer m.Unlock()
// SetFocus shifts the focus to the button with the given index.
func (m *Modal) SetFocus(index int) {
defer m.Unlock()
// Focus is called when this primitive receives focus.
func (m *Modal) Focus(delegate func(p Primitive)) {
// HasFocus returns whether or not this primitive has focus.
func (m *Modal) HasFocus() bool {
return m.GetForm().HasFocus()
// Draw draws this primitive onto the screen.
func (m *Modal) Draw(screen tcell.Screen) {
if !m.GetVisible() {
formItemCount := m.form.GetFormItemCount()
defer m.Unlock()
// Calculate the width of this Modal.
buttonsWidth := 0
for _, button := range m.form.buttons {
buttonsWidth += TaggedTextWidth(button.label) + 4 + 2
buttonsWidth -= 2
screenWidth, screenHeight := screen.Size()
width := screenWidth / 3
if width < buttonsWidth {
width = buttonsWidth
// width is now without the box border.
// Reset the text and find out how wide it is.
lines := WordWrap(m.text, width)
for _, line := range lines {
m.frame.AddText(line, true, AlignCenter, m.textColor)
// Set the Modal's position and size.
height := len(lines) + (formItemCount * 2) + 6
width += 4
x := (screenWidth - width) / 2
y := (screenHeight - height) / 2
m.SetRect(x, y, width, height)
// Draw the frame.
m.frame.SetRect(x, y, width, height)
// MouseHandler returns the mouse handler for this primitive.
func (m *Modal) MouseHandler() func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
return m.WrapMouseHandler(func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
// Pass mouse events on to the form.
consumed, capture = m.form.MouseHandler()(action, event, setFocus)
if !consumed && action == MouseLeftClick && m.InRect(event.Position()) {
consumed = true