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.
//
// See https://github.com/rivo/tview/wiki/List for an example.
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 the user has navigated to a list
// item.
changed func(index int, mainText, secondaryText string, shortcut rune)
// 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)
// An optional function which is called when the user presses the Escape key.
done func()
}
// NewList returns a new form.
func NewList() *List {
return &List{
Box: NewBox(),
showSecondaryText: true,
mainTextColor: Styles.PrimaryTextColor,
secondaryTextColor: Styles.TertiaryTextColor,
shortcutColor: Styles.SecondaryTextColor,
selectedTextColor: Styles.PrimitiveBackgroundColor,
selectedBackgroundColor: Styles.PrimaryTextColor,
}
}
// SetCurrentItem sets the currently selected item by its index. This triggers
// a "changed" event.
func (l *List) SetCurrentItem(index int) *List {
l.currentItem = index
if l.currentItem < len(l.items) && l.changed != nil {
item := l.items[l.currentItem]
l.changed(l.currentItem, item.MainText, item.SecondaryText, item.Shortcut)
}
return l
}
// GetCurrentItem returns the index of the currently selected list item.
func (l *List) GetCurrentItem() int {
return l.currentItem
}
// 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
}
// SetChangedFunc sets the function which is called when the user navigates to
// 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.
//
// This function is also called when the first item is added or when
// SetCurrentItem() is called.
func (l *List) SetChangedFunc(handler func(int, string, string, rune)) *List {
l.changed = handler
return l
}
// SetSelectedFunc sets the function which is called when the user selects a
// list item by pressing Enter on the current selection. 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
}
// SetDoneFunc sets a function which is called when the user presses the Escape
// key.
func (l *List) SetDoneFunc(handler func()) *List {
l.done = 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,
})
if len(l.items) == 1 && l.changed != nil {
item := l.items[0]
l.changed(0, item.MainText, item.SecondaryText, item.Shortcut)
}
return l
}
// Clear removes all items from the list.
func (l *List) Clear() *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, y, width, height := l.GetInnerRect()
bottomLimit := y + height
// Do we show any shortcuts?
var showShortcuts bool
for _, item := range l.items {
if item.Shortcut != 0 {
showShortcuts = true
x += 4
width -= 4
break
}
}
// We want to keep the current selection in view. What is our offset?
var offset int
if l.showSecondaryText {
if l.currentItem >= height/2 {
offset = l.currentItem + 1 - (height / 2)
}
} else {
if l.currentItem >= height {
offset = l.currentItem + 1 - height
}
}
// Draw the list items.
for index, item := range l.items {
if index < offset {
continue
}
if y >= bottomLimit {
break
}
// Shortcuts.
if showShortcuts && item.Shortcut != 0 {
Print(screen, fmt.Sprintf("(%s)", string(item.Shortcut)), x-5, y, 4, AlignRight, l.shortcutColor)
}
// Main text.
Print(screen, item.MainText, x, y, width, AlignLeft, l.mainTextColor)
// Background color of selected text.
if index == l.currentItem {
textWidth := StringWidth(item.MainText)
for bx := 0; bx < textWidth && bx < width; bx++ {
m, c, style, _ := screen.GetContent(x+bx, y)
fg, _, _ := style.Decompose()
if fg == l.mainTextColor {
fg = l.selectedTextColor
}
style = style.Background(l.selectedBackgroundColor).Foreground(fg)
screen.SetContent(x+bx, y, m, c, style)
}
}
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 l.WrapInputHandler(func(event *tcell.EventKey, setFocus func(p Primitive)) {
previousItem := l.currentItem
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.KeyEscape:
if l.done != nil {
l.done()
}
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
}
if l.currentItem != previousItem && l.currentItem < len(l.items) && l.changed != nil {
item := l.items[l.currentItem]
l.changed(l.currentItem, item.MainText, item.SecondaryText, item.Shortcut)
}
})
}