Terminal-based user interface toolkit
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package tview
import (
"strings"
"github.com/gdamore/tcell"
)
// FormItem is the interface all form items must implement to be able to be
// included in a form.
type FormItem interface {
Primitive
// GetLabel returns the item's label text.
GetLabel() string
// SetFormAttributes sets a number of item attributes at once.
SetFormAttributes(label string, labelColor, bgColor, fieldTextColor, fieldBgColor tcell.Color) FormItem
// SetEnteredFunc sets the handler function for when the user finished
// entering data into the item. The handler may receive events for the
// Enter key (we're done), the Escape key (cancel input), the Tab key (move to
// next field), and the Backtab key (move to previous field).
SetFinishedFunc(handler func(key tcell.Key)) FormItem
}
// Form is a Box which contains multiple input fields, one per row.
type Form struct {
*Box
// The items of the form (one row per item).
items []FormItem
// The buttons of the form.
buttons []*Button
// The alignment of the buttons.
buttonsAlign int
// The number of empty rows between items.
itemPadding int
// The index of the item or button which has focus. (Items are counted first,
// buttons are counted last.)
focusedElement int
// The label color.
labelColor tcell.Color
// The background color of the input area.
fieldBackgroundColor tcell.Color
// The text color of the input area.
fieldTextColor tcell.Color
// The background color of the buttons.
buttonBackgroundColor tcell.Color
// The color of the button text.
buttonTextColor tcell.Color
// An optional function which is called when the user hits Escape.
cancel func()
}
// NewForm returns a new form.
func NewForm() *Form {
box := NewBox().SetBorderPadding(1, 1, 1, 1)
f := &Form{
Box: box,
itemPadding: 1,
labelColor: tcell.ColorYellow,
fieldBackgroundColor: tcell.ColorBlue,
fieldTextColor: tcell.ColorWhite,
buttonBackgroundColor: tcell.ColorBlue,
buttonTextColor: tcell.ColorWhite,
}
f.focus = f
return f
}
// SetItemPadding sets the number of empty rows between form items.
func (f *Form) SetItemPadding(padding int) *Form {
f.itemPadding = padding
return f
}
// SetLabelColor sets the color of the labels.
func (f *Form) SetLabelColor(color tcell.Color) *Form {
f.labelColor = color
return f
}
// SetFieldBackgroundColor sets the background color of the input areas.
func (f *Form) SetFieldBackgroundColor(color tcell.Color) *Form {
f.fieldBackgroundColor = color
return f
}
// SetFieldTextColor sets the text color of the input areas.
func (f *Form) SetFieldTextColor(color tcell.Color) *Form {
f.fieldTextColor = color
return f
}
// SetButtonsAlign sets how the buttons align horizontally, one of AlignLeft
// (the default), AlignCenter, and AlignRight.
func (f *Form) SetButtonsAlign(align int) *Form {
f.buttonsAlign = align
return f
}
// SetButtonBackgroundColor sets the background color of the buttons.
func (f *Form) SetButtonBackgroundColor(color tcell.Color) *Form {
f.buttonBackgroundColor = color
return f
}
// SetButtonTextColor sets the color of the button texts.
func (f *Form) SetButtonTextColor(color tcell.Color) *Form {
f.buttonTextColor = color
return f
}
// AddInputField adds an input field to the form. It has a label, an optional
// initial value, a field length (a value of 0 extends it as far as possible),
// and an optional accept function to validate the item's value (set to nil to
// accept any text).
func (f *Form) AddInputField(label, value string, fieldLength int, accept func(textToCheck string, lastChar rune) bool) *Form {
f.items = append(f.items, NewInputField().
SetLabel(label).
SetText(value).
SetFieldLength(fieldLength).
SetAcceptanceFunc(accept))
return f
}
// AddDropDown adds a drop-down element to the form. It has a label, options,
// and an (optional) callback function which is invoked when an option was
// selected.
func (f *Form) AddDropDown(label string, options []string, initialOption int, selected func(option string, optionIndex int)) *Form {
f.items = append(f.items, NewDropDown().
SetLabel(label).
SetCurrentOption(initialOption).
SetOptions(options, selected))
return f
}
// AddCheckbox adds a checkbox to the form. It has a label, an initial state,
// and an (optional) callback function which is invoked when the state of the
// checkbox was changed by the user.
func (f *Form) AddCheckbox(label string, checked bool, changed func(checked bool)) *Form {
f.items = append(f.items, NewCheckbox().
SetLabel(label).
SetChecked(checked).
SetChangedFunc(changed))
return f
}
// AddButton adds a new button to the form. The "selected" function is called
// when the user selects this button. It may be nil.
func (f *Form) AddButton(label string, selected func()) *Form {
f.buttons = append(f.buttons, NewButton(label).SetSelectedFunc(selected))
return f
}
// SetCancelFunc sets a handler which is called when the user hits the Escape
// key.
func (f *Form) SetCancelFunc(callback func()) *Form {
f.cancel = callback
return f
}
// Draw draws this primitive onto the screen.
func (f *Form) Draw(screen tcell.Screen) {
f.Box.Draw(screen)
// Determine the dimensions.
x, y, width, height := f.GetInnerRect()
bottomLimit := y + height
rightLimit := x + width
// Find the longest label.
var labelLength int
for _, item := range f.items {
label := strings.TrimSpace(item.GetLabel())
if len([]rune(label)) > labelLength {
labelLength = len([]rune(label))
}
}
labelLength++ // Add one space.
// Set up and draw the input fields.
for _, item := range f.items {
if y >= bottomLimit {
return // Stop here.
}
label := strings.TrimSpace(item.GetLabel())
item.SetFormAttributes(
label+strings.Repeat(" ", labelLength-len([]rune(label))),
f.labelColor,
f.backgroundColor,
f.fieldTextColor,
f.fieldBackgroundColor,
).SetRect(x, y, width, 1)
if item.GetFocusable().HasFocus() {
defer item.Draw(screen)
} else {
item.Draw(screen)
}
y += 1 + f.itemPadding
}
// How wide are the buttons?
buttonWidths := make([]int, len(f.buttons))
buttonsWidth := 0
for index, button := range f.buttons {
width := len([]rune(button.GetLabel())) + 4
buttonWidths[index] = width
buttonsWidth += width + 2
}
buttonsWidth -= 2
// Where do we place them?
if x+buttonsWidth < rightLimit {
if f.buttonsAlign == AlignRight {
x = rightLimit - buttonsWidth
} else if f.buttonsAlign == AlignCenter {
x = (x + rightLimit - buttonsWidth) / 2
}
}
// Draw them.
if f.itemPadding == 0 {
y++
}
if y >= bottomLimit {
return // Stop here.
}
for index, button := range f.buttons {
space := rightLimit - x
if space < 1 {
break // No space for this button anymore.
}
buttonWidth := buttonWidths[index]
if buttonWidth > space {
buttonWidth = space
}
button.SetLabelColor(f.buttonTextColor).
SetLabelColorActivated(f.buttonBackgroundColor).
SetBackgroundColorActivated(f.buttonTextColor).
SetBackgroundColor(f.buttonBackgroundColor).
SetRect(x, y, buttonWidth, 1)
button.Draw(screen)
x += buttonWidth + 2
}
}
// Focus is called by the application when the primitive receives focus.
func (f *Form) Focus(delegate func(p Primitive)) {
if len(f.items)+len(f.buttons) == 0 {
return
}
// Hand on the focus to one of our child elements.
if f.focusedElement < 0 || f.focusedElement >= len(f.items)+len(f.buttons) {
f.focusedElement = 0
}
handler := func(key tcell.Key) {
switch key {
case tcell.KeyTab, tcell.KeyEnter:
f.focusedElement++
f.Focus(delegate)
case tcell.KeyBacktab:
f.focusedElement--
if f.focusedElement < 0 {
f.focusedElement = len(f.items) + len(f.buttons) - 1
}
f.Focus(delegate)
case tcell.KeyEscape:
if f.cancel != nil {
f.cancel()
} else {
f.focusedElement = 0
f.Focus(delegate)
}
}
}
if f.focusedElement < len(f.items) {
// We're selecting an item.
item := f.items[f.focusedElement]
item.SetFinishedFunc(handler)
delegate(item)
} else {
// We're selecting a button.
button := f.buttons[f.focusedElement-len(f.items)]
button.SetBlurFunc(handler)
delegate(button)
}
}
// HasFocus returns whether or not this primitive has focus.
func (f *Form) HasFocus() bool {
for _, item := range f.items {
if item.GetFocusable().HasFocus() {
return true
}
}
for _, button := range f.buttons {
if button.focus.HasFocus() {
return true
}
}
return false
}