Terminal-based user interface toolkit
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package tview
import (
"fmt"
"github.com/gdamore/tcell"
)
// listItem represents one item in a List.
type listItem struct {
MainText string // The main text of the list item.
SecondaryText string // A secondary text to be shown underneath the main text.
Shortcut rune // The key to select the list item directly, 0 if there is no shortcut.
Selected func() // The optional function which is called when the item is selected.
}
// List displays rows of items, each of which can be selected.
type List struct {
*Box
// The items of the list.
items []*listItem
// The index of the currently selected item.
currentItem int
// Whether or not to show the secondary item texts.
showSecondaryText bool
// The item main text color.
mainTextColor tcell.Color
// The item secondary text color.
secondaryTextColor tcell.Color
// The item shortcut text color.
shortcutColor tcell.Color
// The text color for selected items.
selectedTextColor tcell.Color
// The background color for selected items.
selectedBackgroundColor tcell.Color
// An optional function which is called when a list item was selected. This
// function will be called even if the list item defines its own callback.
selected func(index int, mainText, secondaryText string, shortcut rune)
}
// NewList returns a new form.
func NewList() *List {
return &List{
Box: NewBox(),
showSecondaryText: true,
mainTextColor: tcell.ColorWhite,
secondaryTextColor: tcell.ColorGreen,
shortcutColor: tcell.ColorYellow,
selectedTextColor: tcell.ColorBlack,
selectedBackgroundColor: tcell.ColorWhite,
}
}
// SetCurrentItem sets the currently selected item by its index.
func (l *List) SetCurrentItem(index int) *List {
l.currentItem = index
return l
}
// SetMainTextColor sets the color of the items' main text.
func (l *List) SetMainTextColor(color tcell.Color) *List {
l.mainTextColor = color
return l
}
// SetSecondaryTextColor sets the color of the items' secondary text.
func (l *List) SetSecondaryTextColor(color tcell.Color) *List {
l.secondaryTextColor = color
return l
}
// SetShortcutColor sets the color of the items' shortcut.
func (l *List) SetShortcutColor(color tcell.Color) *List {
l.shortcutColor = color
return l
}
// SetSelectedTextColor sets the text color of selected items.
func (l *List) SetSelectedTextColor(color tcell.Color) *List {
l.selectedTextColor = color
return l
}
// SetSelectedBackgroundColor sets the background color of selected items.
func (l *List) SetSelectedBackgroundColor(color tcell.Color) *List {
l.selectedBackgroundColor = color
return l
}
// ShowSecondaryText determines whether or not to show secondary item texts.
func (l *List) ShowSecondaryText(show bool) *List {
l.showSecondaryText = show
return l
}
// SetSelectedFunc sets the function which is called when the user selects a
// list item. The function receives the item's index in the list of items
// (starting with 0), its main text, secondary text, and its shortcut rune.
func (l *List) SetSelectedFunc(handler func(int, string, string, rune)) *List {
l.selected = handler
return l
}
// AddItem adds a new item to the list. An item has a main text which will be
// highlighted when selected. It also has a secondary text which is shown
// underneath the main text (if it is set to visible) but which may remain
// empty.
//
// The shortcut is a key binding. If the specified rune is entered, the item
// is selected immediately. Set to 0 for no binding.
//
// The "selected" callback will be invoked when the user selects the item. You
// may provide nil if no such item is needed or if all events are handled
// through the selected callback set with SetSelectedFunc().
func (l *List) AddItem(mainText, secondaryText string, shortcut rune, selected func()) *List {
l.items = append(l.items, &listItem{
MainText: mainText,
SecondaryText: secondaryText,
Shortcut: shortcut,
Selected: selected,
})
return l
}
// ClearItems removes all items from the list.
func (l *List) ClearItems() *List {
l.items = nil
l.currentItem = 0
return l
}
// Draw draws this primitive onto the screen.
func (l *List) Draw(screen tcell.Screen) {
l.Box.Draw(screen)
// Determine the dimensions.
x := l.x
y := l.y
width := l.width
bottomLimit := l.y + l.height
if l.border {
x++
y++
width -= 2
bottomLimit -= 2
}
// Do we show any shortcuts?
var showShortcuts bool
for _, item := range l.items {
if item.Shortcut != 0 {
showShortcuts = true
x += 4
width -= 4
break
}
}
// Draw the list items.
for index, item := range l.items {
if y >= bottomLimit {
break
}
// Shortcuts.
if showShortcuts && item.Shortcut != 0 {
Print(screen, fmt.Sprintf("(%s)", string(item.Shortcut)), x-2, y, width+4, AlignRight, l.shortcutColor)
}
// Main text.
color := l.mainTextColor
if l.focus.HasFocus() && index == l.currentItem {
textLength := len([]rune(item.MainText))
style := tcell.StyleDefault.Background(l.selectedBackgroundColor)
for bx := 0; bx < textLength && bx < width; bx++ {
screen.SetContent(x+bx, y, ' ', nil, style)
}
color = l.selectedTextColor
}
Print(screen, item.MainText, x, y, width, AlignLeft, color)
y++
if y >= bottomLimit {
break
}
// Secondary text.
if l.showSecondaryText {
Print(screen, item.SecondaryText, x, y, width, AlignLeft, l.secondaryTextColor)
y++
}
}
}
// InputHandler returns the handler for this primitive.
func (l *List) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) {
return func(event *tcell.EventKey, setFocus func(p Primitive)) {
switch key := event.Key(); key {
case tcell.KeyTab, tcell.KeyDown, tcell.KeyRight:
l.currentItem++
case tcell.KeyBacktab, tcell.KeyUp, tcell.KeyLeft:
l.currentItem--
case tcell.KeyHome:
l.currentItem = 0
case tcell.KeyEnd:
l.currentItem = len(l.items) - 1
case tcell.KeyPgDn:
l.currentItem += 5
case tcell.KeyPgUp:
l.currentItem -= 5
case tcell.KeyEnter:
item := l.items[l.currentItem]
if item.Selected != nil {
item.Selected()
}
if l.selected != nil {
l.selected(l.currentItem, item.MainText, item.SecondaryText, item.Shortcut)
}
case tcell.KeyRune:
ch := event.Rune()
if ch != ' ' {
// It's not a space bar. Is it a shortcut?
var found bool
for index, item := range l.items {
if item.Shortcut == ch {
// We have a shortcut.
found = true
l.currentItem = index
break
}
}
if !found {
break
}
}
item := l.items[l.currentItem]
if item.Selected != nil {
item.Selected()
}
if l.selected != nil {
l.selected(l.currentItem, item.MainText, item.SecondaryText, item.Shortcut)
}
}
if l.currentItem < 0 {
l.currentItem = len(l.items) - 1
} else if l.currentItem >= len(l.items) {
l.currentItem = 0
}
}
}