package tview import ( "strings" "maunium.net/go/tcell" runewidth "github.com/mattn/go-runewidth" ) // dropDownOption is one option that can be selected in a drop-down primitive. type dropDownOption struct { Text string // The text to be displayed in the drop-down. Selected func() // The (optional) callback for when this option was selected. } // DropDown implements a selection widget whose options become visible in a // drop-down list when activated. // // See https://github.com/rivo/tview/wiki/DropDown for an example. type DropDown struct { *Box // The options from which the user can choose. options []*dropDownOption // The index of the currently selected option. Negative if no option is // currently selected. currentOption int // Set to true if the options are visible and selectable. open bool // The runes typed so far to directly access one of the list items. prefix string // The list element for the options. list *List // The text to be displayed before the input area. label string // 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 color for prefixes. prefixTextColor tcell.Color // The screen width of the input area. A value of 0 means extend as much as // possible. fieldWidth int // An optional function which is called when the user indicated that they // are done selecting options. The key which was pressed is provided (tab, // shift-tab, or escape). done func(tcell.Key) } // NewDropDown returns a new drop-down. func NewDropDown() *DropDown { list := NewList().ShowSecondaryText(false) list.SetMainTextColor(Styles.PrimitiveBackgroundColor). SetSelectedTextColor(Styles.PrimitiveBackgroundColor). SetSelectedBackgroundColor(Styles.PrimaryTextColor). SetBackgroundColor(Styles.MoreContrastBackgroundColor) d := &DropDown{ Box: NewBox(), currentOption: -1, list: list, labelColor: Styles.SecondaryTextColor, fieldBackgroundColor: Styles.ContrastBackgroundColor, fieldTextColor: Styles.PrimaryTextColor, prefixTextColor: Styles.ContrastSecondaryTextColor, } d.focus = d return d } // SetCurrentOption sets the index of the currently selected option. This may // be a negative value to indicate that no option is currently selected. func (d *DropDown) SetCurrentOption(index int) *DropDown { d.currentOption = index d.list.SetCurrentItem(index) return d } // GetCurrentOption returns the index of the currently selected option as well // as its text. If no option was selected, -1 and an empty string is returned. func (d *DropDown) GetCurrentOption() (int, string) { var text string if d.currentOption >= 0 && d.currentOption < len(d.options) { text = d.options[d.currentOption].Text } return d.currentOption, text } // SetLabel sets the text to be displayed before the input area. func (d *DropDown) SetLabel(label string) *DropDown { d.label = label return d } // GetLabel returns the text to be displayed before the input area. func (d *DropDown) GetLabel() string { return d.label } // SetLabelColor sets the color of the label. func (d *DropDown) SetLabelColor(color tcell.Color) *DropDown { d.labelColor = color return d } // SetFieldBackgroundColor sets the background color of the options area. func (d *DropDown) SetFieldBackgroundColor(color tcell.Color) *DropDown { d.fieldBackgroundColor = color return d } // SetFieldTextColor sets the text color of the options area. func (d *DropDown) SetFieldTextColor(color tcell.Color) *DropDown { d.fieldTextColor = color return d } // SetPrefixTextColor sets the color of the prefix string. The prefix string is // shown when the user starts typing text, which directly selects the first // option that starts with the typed string. func (d *DropDown) SetPrefixTextColor(color tcell.Color) *DropDown { d.prefixTextColor = color return d } // SetFormAttributes sets attributes shared by all form items. func (d *DropDown) SetFormAttributes(label string, labelColor, bgColor, fieldTextColor, fieldBgColor tcell.Color) FormItem { d.label = label d.labelColor = labelColor d.backgroundColor = bgColor d.fieldTextColor = fieldTextColor d.fieldBackgroundColor = fieldBgColor return d } // SetFieldWidth sets the screen width of the options area. A value of 0 means // extend to as long as the longest option text. func (d *DropDown) SetFieldWidth(width int) *DropDown { d.fieldWidth = width return d } // GetFieldWidth returns this primitive's field screen width. func (d *DropDown) GetFieldWidth() int { if d.fieldWidth > 0 { return d.fieldWidth } fieldWidth := 0 for _, option := range d.options { width := StringWidth(option.Text) if width > fieldWidth { fieldWidth = width } } return fieldWidth } // AddOption adds a new selectable option to this drop-down. The "selected" // callback is called when this option was selected. It may be nil. func (d *DropDown) AddOption(text string, selected func()) *DropDown { d.options = append(d.options, &dropDownOption{Text: text, Selected: selected}) d.list.AddItem(text, "", 0, selected) return d } // SetOptions replaces all current options with the ones provided and installs // one callback function which is called when one of the options is selected. // It will be called with the option's text and its index into the options // slice. The "selected" parameter may be nil. func (d *DropDown) SetOptions(texts []string, selected func(text string, index int)) *DropDown { d.list.Clear() d.options = nil for index, text := range texts { func(t string, i int) { d.AddOption(text, func() { if selected != nil { selected(t, i) } }) }(text, index) } return d } // SetDoneFunc sets a handler which is called when the user is done selecting // options. The callback function is provided with the key that was pressed, // which is one of the following: // // - KeyEscape: Abort selection. // - KeyTab: Move to the next field. // - KeyBacktab: Move to the previous field. func (d *DropDown) SetDoneFunc(handler func(key tcell.Key)) *DropDown { d.done = handler return d } // SetFinishedFunc calls SetDoneFunc(). func (d *DropDown) SetFinishedFunc(handler func(key tcell.Key)) FormItem { return d.SetDoneFunc(handler) } // Draw draws this primitive onto the screen. func (d *DropDown) Draw(screen tcell.Screen) { d.Box.Draw(screen) // Prepare. x, y, width, height := d.GetInnerRect() rightLimit := x + width if height < 1 || rightLimit <= x { return } // Draw label. _, drawnWidth := Print(screen, d.label, x, y, rightLimit-x, AlignLeft, d.labelColor) x += drawnWidth // What's the longest option text? maxWidth := 0 for _, option := range d.options { strWidth := StringWidth(option.Text) if strWidth > maxWidth { maxWidth = strWidth } } // Draw selection area. fieldWidth := d.fieldWidth if fieldWidth == 0 { fieldWidth = maxWidth } if rightLimit-x < fieldWidth { fieldWidth = rightLimit - x } fieldStyle := tcell.StyleDefault.Background(d.fieldBackgroundColor) if d.GetFocusable().HasFocus() && !d.open { fieldStyle = fieldStyle.Background(d.fieldTextColor) } for index := 0; index < fieldWidth; index++ { screen.SetContent(x+index, y, ' ', nil, fieldStyle) } // Draw selected text. if d.open && len(d.prefix) > 0 { // Show the prefix. Print(screen, d.prefix, x, y, fieldWidth, AlignLeft, d.prefixTextColor) prefixWidth := runewidth.StringWidth(d.prefix) listItemText := d.options[d.list.GetCurrentItem()].Text if prefixWidth < fieldWidth && len(d.prefix) < len(listItemText) { Print(screen, listItemText[len(d.prefix):], x+prefixWidth, y, fieldWidth-prefixWidth, AlignLeft, d.fieldTextColor) } } else { if d.currentOption >= 0 && d.currentOption < len(d.options) { color := d.fieldTextColor // Just show the current selection. if d.GetFocusable().HasFocus() && !d.open { color = d.fieldBackgroundColor } Print(screen, d.options[d.currentOption].Text, x, y, fieldWidth, AlignLeft, color) } } // Draw options list. if d.HasFocus() && d.open { // We prefer to drop down but if there is no space, maybe drop up? lx := x ly := y + 1 lwidth := maxWidth lheight := len(d.options) _, sheight := screen.Size() if ly+lheight >= sheight && ly-2 > lheight-ly { ly = y - lheight if ly < 0 { ly = 0 } } if ly+lheight >= sheight { lheight = sheight - ly } d.list.SetRect(lx, ly, lwidth, lheight) d.list.Draw(screen) } } // InputHandler returns the handler for this primitive. func (d *DropDown) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) { return d.WrapInputHandler(func(event *tcell.EventKey, setFocus func(p Primitive)) { // A helper function which selects an item in the drop-down list based on // the current prefix. evalPrefix := func() { if len(d.prefix) > 0 { for index, option := range d.options { if strings.HasPrefix(strings.ToLower(option.Text), d.prefix) { d.list.SetCurrentItem(index) return } } // Prefix does not match any item. Remove last rune. r := []rune(d.prefix) d.prefix = string(r[:len(r)-1]) } } // Process key event. switch key := event.Key(); key { case tcell.KeyEnter, tcell.KeyRune, tcell.KeyDown: d.prefix = "" // If the first key was a letter already, it becomes part of the prefix. if r := event.Rune(); key == tcell.KeyRune && r != ' ' { d.prefix += string(r) evalPrefix() } // Hand control over to the list. d.open = true d.list.SetSelectedFunc(func(index int, mainText, secondaryText string, shortcut rune) { // An option was selected. Close the list again. d.open = false setFocus(d) d.currentOption = index // Trigger "selected" event. if d.options[d.currentOption].Selected != nil { d.options[d.currentOption].Selected() } }).SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey { if event.Key() == tcell.KeyRune { d.prefix += string(event.Rune()) evalPrefix() } else if event.Key() == tcell.KeyBackspace || event.Key() == tcell.KeyBackspace2 { if len(d.prefix) > 0 { r := []rune(d.prefix) d.prefix = string(r[:len(r)-1]) } evalPrefix() } else { d.prefix = "" } return event }) setFocus(d.list) case tcell.KeyEscape, tcell.KeyTab, tcell.KeyBacktab: if d.done != nil { d.done(key) } } }) } // Focus is called by the application when the primitive receives focus. func (d *DropDown) Focus(delegate func(p Primitive)) { d.Box.Focus(delegate) if d.open { delegate(d.list) } } // HasFocus returns whether or not this primitive has focus. func (d *DropDown) HasFocus() bool { if d.open { return d.list.HasFocus() } return d.hasFocus }