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dropdown.go
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dropdown.go
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package tview
import (
"strings"
"github.com/gdamore/tcell/v2"
"github.com/rivo/uniseg"
)
// 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
// Whether or not this drop-down is disabled/read-only.
disabled bool
// The options from which the user can choose.
options []*dropDownOption
// Strings to be placed before and after each drop-down option.
optionPrefix, optionSuffix string
// The index of the currently selected option. Negative if no option is
// currently selected.
currentOption int
// Strings to be placed before and after the current option.
currentOptionPrefix, currentOptionSuffix string
// The text to be displayed when no option has yet been selected.
noSelection string
// 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 label area. A value of 0 means use the width of
// the label text.
labelWidth int
// 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)
// A callback function set by the Form class and called when the user leaves
// this form item.
finished func(tcell.Key)
// A callback function which is called when the user changes the drop-down's
// selection.
selected func(text string, index int)
dragging bool // Set to true when mouse dragging is in progress.
}
// NewDropDown returns a new drop-down.
func NewDropDown() *DropDown {
list := NewList()
list.ShowSecondaryText(false).
SetMainTextStyle(tcell.StyleDefault.Background(Styles.MoreContrastBackgroundColor).Foreground(Styles.PrimitiveBackgroundColor)).
SetSelectedStyle(tcell.StyleDefault.Background(Styles.PrimaryTextColor).Foreground(Styles.PrimitiveBackgroundColor)).
SetHighlightFullLine(true).
SetBackgroundColor(Styles.MoreContrastBackgroundColor)
d := &DropDown{
Box: NewBox(),
currentOption: -1,
list: list,
labelColor: Styles.SecondaryTextColor,
fieldBackgroundColor: Styles.ContrastBackgroundColor,
fieldTextColor: Styles.PrimaryTextColor,
prefixTextColor: Styles.ContrastSecondaryTextColor,
}
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. Calling
// this function will also trigger the "selected" callback (if there is one).
func (d *DropDown) SetCurrentOption(index int) *DropDown {
if index >= 0 && index < len(d.options) {
d.currentOption = index
d.list.SetCurrentItem(index)
if d.selected != nil {
d.selected(d.options[index].Text, index)
}
if d.options[index].Selected != nil {
d.options[index].Selected()
}
} else {
d.currentOption = -1
d.list.SetCurrentItem(0) // Set to 0 because -1 means "last item".
if d.selected != nil {
d.selected("", -1)
}
}
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
}
// SetTextOptions sets the text to be placed before and after each drop-down
// option (prefix/suffix), the text placed before and after the currently
// selected option (currentPrefix/currentSuffix) as well as the text to be
// displayed when no option is currently selected. Per default, all of these
// strings are empty.
func (d *DropDown) SetTextOptions(prefix, suffix, currentPrefix, currentSuffix, noSelection string) *DropDown {
d.currentOptionPrefix = currentPrefix
d.currentOptionSuffix = currentSuffix
d.noSelection = noSelection
d.optionPrefix = prefix
d.optionSuffix = suffix
for index := 0; index < d.list.GetItemCount(); index++ {
d.list.SetItemText(index, prefix+d.options[index].Text+suffix, "")
}
return d
}
// 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
}
// SetLabelWidth sets the screen width of the label. A value of 0 will cause the
// primitive to use the width of the label string.
func (d *DropDown) SetLabelWidth(width int) *DropDown {
d.labelWidth = width
return d
}
// 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
}
// SetListStyles sets the styles of the items in the drop-down list (unselected
// as well as selected items). Style attributes are currently ignored but may be
// used in the future.
func (d *DropDown) SetListStyles(unselected, selected tcell.Style) *DropDown {
d.list.SetMainTextStyle(unselected).SetSelectedStyle(selected)
_, bg, _ := unselected.Decompose()
d.list.SetBackgroundColor(bg)
return d
}
// SetFormAttributes sets attributes shared by all form items.
func (d *DropDown) SetFormAttributes(labelWidth int, labelColor, bgColor, fieldTextColor, fieldBgColor tcell.Color) FormItem {
d.labelWidth = labelWidth
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 := TaggedStringWidth(option.Text)
if width > fieldWidth {
fieldWidth = width
}
}
return fieldWidth
}
// GetFieldHeight returns this primitive's field height.
func (d *DropDown) GetFieldHeight() int {
return 1
}
// SetDisabled sets whether or not the item is disabled / read-only.
func (d *DropDown) SetDisabled(disabled bool) FormItem {
d.disabled = disabled
if d.finished != nil {
d.finished(-1)
}
return d
}
// 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(d.optionPrefix+text+d.optionSuffix, "", 0, nil)
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 _, text := range texts {
d.AddOption(text, nil)
}
d.selected = selected
return d
}
// GetOptionCount returns the number of options in the drop-down.
func (d *DropDown) GetOptionCount() int {
return len(d.options)
}
// RemoveOption removes the specified option from the drop-down. Panics if the
// index is out of range. If the currently selected option is removed, no option
// will be selected.
func (d *DropDown) RemoveOption(index int) *DropDown {
if index == d.currentOption {
d.currentOption = -1
}
d.options = append(d.options[:index], d.options[index+1:]...)
d.list.RemoveItem(index)
return d
}
// SetSelectedFunc sets a handler which is called when the user changes the
// drop-down's option. This handler will be called in addition and prior to
// an option's optional individual handler. The handler is provided with the
// selected option's text and index. If "no option" was selected, these values
// are an empty string and -1.
func (d *DropDown) SetSelectedFunc(handler func(text string, index int)) *DropDown {
d.selected = handler
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 sets a callback invoked when the user leaves this form item.
func (d *DropDown) SetFinishedFunc(handler func(key tcell.Key)) FormItem {
d.finished = handler
return d
}
// Draw draws this primitive onto the screen.
func (d *DropDown) Draw(screen tcell.Screen) {
d.Box.DrawForSubclass(screen, d)
// Prepare.
x, y, width, height := d.GetInnerRect()
rightLimit := x + width
if height < 1 || rightLimit <= x {
return
}
// Draw label.
if d.labelWidth > 0 {
labelWidth := d.labelWidth
if labelWidth > rightLimit-x {
labelWidth = rightLimit - x
}
Print(screen, d.label, x, y, labelWidth, AlignLeft, d.labelColor)
x += labelWidth
} else {
_, drawnWidth := Print(screen, d.label, x, y, rightLimit-x, AlignLeft, d.labelColor)
x += drawnWidth
}
// What's the longest option text?
maxWidth := 0
optionWrapWidth := TaggedStringWidth(d.optionPrefix + d.optionSuffix)
for _, option := range d.options {
strWidth := TaggedStringWidth(option.Text) + optionWrapWidth
if strWidth > maxWidth {
maxWidth = strWidth
}
}
// Draw selection area.
fieldWidth := d.fieldWidth
if fieldWidth == 0 {
fieldWidth = maxWidth
if d.currentOption < 0 {
noSelectionWidth := TaggedStringWidth(d.noSelection)
if noSelectionWidth > fieldWidth {
fieldWidth = noSelectionWidth
}
} else if d.currentOption < len(d.options) {
currentOptionWidth := TaggedStringWidth(d.currentOptionPrefix + d.options[d.currentOption].Text + d.currentOptionSuffix)
if currentOptionWidth > fieldWidth {
fieldWidth = currentOptionWidth
}
}
}
if rightLimit-x < fieldWidth {
fieldWidth = rightLimit - x
}
fieldStyle := tcell.StyleDefault.Background(d.fieldBackgroundColor)
if d.disabled {
fieldStyle = fieldStyle.Background(d.backgroundColor)
}
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.
currentOptionPrefixWidth := TaggedStringWidth(d.currentOptionPrefix)
prefixWidth := uniseg.StringWidth(d.prefix)
listItemText := d.options[d.list.GetCurrentItem()].Text
Print(screen, d.currentOptionPrefix, x, y, fieldWidth, AlignLeft, d.fieldTextColor)
Print(screen, d.prefix, x+currentOptionPrefixWidth, y, fieldWidth-currentOptionPrefixWidth, AlignLeft, d.prefixTextColor)
if len(d.prefix) < len(listItemText) {
Print(screen, listItemText[len(d.prefix):]+d.currentOptionSuffix, x+prefixWidth+currentOptionPrefixWidth, y, fieldWidth-prefixWidth-currentOptionPrefixWidth, AlignLeft, d.fieldTextColor)
}
} else {
color := d.fieldTextColor
text := d.noSelection
if d.currentOption >= 0 && d.currentOption < len(d.options) {
text = d.currentOptionPrefix + d.options[d.currentOption].Text + d.currentOptionSuffix
}
// Just show the current selection.
Print(screen, text, x, y, fieldWidth, AlignLeft, color)
}
// Draw options list.
if d.HasFocus() && d.open {
lx := x
ly := y + 1
lwidth := maxWidth
lheight := len(d.options)
swidth, sheight := screen.Size()
// We prefer to align the left sides of the list and the main widget, but
// if there is no space to the right, then shift the list to the left.
if lx+lwidth >= swidth {
lx = swidth - lwidth
if lx < 0 {
lx = 0
}
}
// We prefer to drop down but if there is no space, maybe drop up?
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)) {
if d.disabled {
return
}
// If the list has focus, let it process its own key events.
if d.list.HasFocus() {
if handler := d.list.InputHandler(); handler != nil {
handler(event, setFocus)
}
return
}
// 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)
d.evalPrefix()
}
d.openList(setFocus)
case tcell.KeyEscape, tcell.KeyTab, tcell.KeyBacktab:
if d.done != nil {
d.done(key)
}
if d.finished != nil {
d.finished(key)
}
}
})
}
// evalPrefix selects an item in the drop-down list based on the current prefix.
func (d *DropDown) evalPrefix() {
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])
}
}
// openList hands control over to the embedded List primitive.
func (d *DropDown) openList(setFocus func(Primitive)) {
d.open = true
optionBefore := d.currentOption
d.list.SetSelectedFunc(func(index int, mainText, secondaryText string, shortcut rune) {
if d.dragging {
return // If we're dragging the mouse, we don't want to trigger any events.
}
// An option was selected. Close the list again.
d.currentOption = index
d.closeList(setFocus)
// Trigger "selected" event.
currentOption := d.options[d.currentOption]
if d.selected != nil {
d.selected(currentOption.Text, d.currentOption)
}
if currentOption.Selected != nil {
currentOption.Selected()
}
}).SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
if event.Key() == tcell.KeyRune {
d.prefix += string(event.Rune())
d.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])
}
d.evalPrefix()
} else if event.Key() == tcell.KeyEscape {
d.currentOption = optionBefore
d.closeList(setFocus)
} else {
d.prefix = ""
}
return event
})
setFocus(d.list)
}
// closeList closes the embedded List element by hiding it and removing focus
// from it.
func (d *DropDown) closeList(setFocus func(Primitive)) {
d.open = false
if d.list.HasFocus() {
setFocus(d)
}
}
// IsOpen returns true if the drop-down list is currently open.
func (d *DropDown) IsOpen() bool {
return d.open
}
// Focus is called by the application when the primitive receives focus.
func (d *DropDown) Focus(delegate func(p Primitive)) {
// If we're part of a form and this item is disabled, there's nothing the
// user can do here so we're finished.
if d.finished != nil && d.disabled {
d.finished(-1)
return
}
if d.open {
delegate(d.list)
} else {
d.Box.Focus(delegate)
}
}
// HasFocus returns whether or not this primitive has focus.
func (d *DropDown) HasFocus() bool {
if d.open {
return d.list.HasFocus()
}
return d.Box.HasFocus()
}
// MouseHandler returns the mouse handler for this primitive.
func (d *DropDown) MouseHandler() func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
return d.WrapMouseHandler(func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
if d.disabled {
return false, nil
}
// Was the mouse event in the drop-down box itself (or on its label)?
x, y := event.Position()
rectX, rectY, rectWidth, _ := d.GetInnerRect()
inRect := y == rectY && x >= rectX && x < rectX+rectWidth
if !d.open && !inRect {
return d.InRect(x, y), nil // No, and it's not expanded either. Ignore.
}
// As long as the drop-down is open, we capture all mouse events.
if d.open {
capture = d
}
switch action {
case MouseLeftDown:
consumed = d.open || inRect
capture = d
if !d.open {
d.openList(setFocus)
d.dragging = true
} else if consumed, _ := d.list.MouseHandler()(MouseLeftClick, event, setFocus); !consumed {
d.closeList(setFocus) // Close drop-down if clicked outside of it.
}
case MouseMove:
if d.dragging {
// We pretend it's a left click so we can see the selection during
// dragging. Because we don't act upon it, it's not a problem.
d.list.MouseHandler()(MouseLeftClick, event, setFocus)
consumed = true
}
case MouseLeftUp:
if d.dragging {
d.dragging = false
d.list.MouseHandler()(MouseLeftClick, event, setFocus)
consumed = true
}
}
return
})
}