Terminal-based user interface toolkit
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package cview
import (
"fmt"
"strings"
"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://gitlab.com/tslocum/cview/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
// Visibility of the scroll bar.
scrollBarVisibility ScrollBarVisibility
// The scroll bar color.
scrollBarColor tcell.Color
// The background color for selected items.
selectedBackgroundColor tcell.Color
// If true, the selection is only shown when the list has focus.
selectedFocusOnly bool
// If true, the entire row is highlighted when selected.
highlightFullLine bool
// Whether or not navigating the list will wrap around.
wrapAround bool
// The number of list items skipped at the top before the first item is drawn.
offset int
// 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,
scrollBarVisibility: ScrollBarAuto,
mainTextColor: Styles.PrimaryTextColor,
secondaryTextColor: Styles.TertiaryTextColor,
shortcutColor: Styles.SecondaryTextColor,
selectedTextColor: Styles.PrimitiveBackgroundColor,
scrollBarColor: Styles.ScrollBarColor,
selectedBackgroundColor: Styles.PrimaryTextColor,
}
}
// SetCurrentItem sets the currently selected item by its index, starting at 0
// for the first item. If a negative index is provided, items are referred to
// from the back (-1 = last item, -2 = second-to-last item, and so on). Out of
// range indices are clamped to the beginning/end.
//
// Calling this function triggers a "changed" event if the selection changes.
func (l *List) SetCurrentItem(index int) *List {
if index < 0 {
index = len(l.items) + index
}
if index >= len(l.items) {
index = len(l.items) - 1
}
if index < 0 {
index = 0
}
if index != l.currentItem && l.changed != nil {
item := l.items[index]
l.changed(index, item.MainText, item.SecondaryText, item.Shortcut)
}
l.currentItem = index
return l
}
// GetCurrentItem returns the index of the currently selected list item,
// starting at 0 for the first item.
func (l *List) GetCurrentItem() int {
return l.currentItem
}
// RemoveItem removes the item with the given index (starting at 0) from the
// list. If a negative index is provided, items are referred to from the back
// (-1 = last item, -2 = second-to-last item, and so on). Out of range indices
// are clamped to the beginning/end, i.e. unless the list is empty, an item is
// always removed.
//
// The currently selected item is shifted accordingly. If it is the one that is
// removed, a "changed" event is fired.
func (l *List) RemoveItem(index int) *List {
if len(l.items) == 0 {
return l
}
// Adjust index.
if index < 0 {
index = len(l.items) + index
}
if index >= len(l.items) {
index = len(l.items) - 1
}
if index < 0 {
index = 0
}
// Remove item.
l.items = append(l.items[:index], l.items[index+1:]...)
// If there is nothing left, we're done.
if len(l.items) == 0 {
return l
}
// Shift current item.
previousCurrentItem := l.currentItem
if l.currentItem >= index {
l.currentItem--
}
// Fire "changed" event for removed items.
if previousCurrentItem == index && l.changed != nil {
item := l.items[l.currentItem]
l.changed(l.currentItem, item.MainText, item.SecondaryText, item.Shortcut)
}
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
}
// SetSelectedFocusOnly sets a flag which determines when the currently selected
// list item is highlighted. If set to true, selected items are only highlighted
// when the list has focus. If set to false, they are always highlighted.
func (l *List) SetSelectedFocusOnly(focusOnly bool) *List {
l.selectedFocusOnly = focusOnly
return l
}
// SetHighlightFullLine sets a flag which determines whether the colored
// background of selected items spans the entire width of the view. If set to
// true, the highlight spans the entire view. If set to false, only the text of
// the selected item from beginning to end is highlighted.
func (l *List) SetHighlightFullLine(highlight bool) *List {
l.highlightFullLine = highlight
return l
}
// ShowSecondaryText determines whether or not to show secondary item texts.
func (l *List) ShowSecondaryText(show bool) *List {
l.showSecondaryText = show
return l
}
// SetScrollBarVisibility specifies the display of the scroll bar.
func (l *List) SetScrollBarVisibility(visibility ScrollBarVisibility) *List {
l.scrollBarVisibility = visibility
return l
}
// SetScrollBarColor sets the color of the scroll bar.
func (l *List) SetScrollBarColor(color tcell.Color) *List {
l.scrollBarColor = color
return l
}
// SetWrapAround sets the flag that determines whether navigating the list will
// wrap around. That is, navigating downwards on the last item will move the
// selection to the first item (similarly in the other direction). If set to
// false, the selection won't change when navigating downwards on the last item
// or navigating upwards on the first item.
func (l *List) SetWrapAround(wrapAround bool) *List {
l.wrapAround = wrapAround
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(index int, mainText string, secondaryText string, shortcut 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 calls InsertItem() with an index of -1.
func (l *List) AddItem(mainText, secondaryText string, shortcut rune, selected func()) *List {
l.InsertItem(-1, mainText, secondaryText, shortcut, selected)
return l
}
// InsertItem adds a new item to the list at the specified index. An index of 0
// will insert the item at the beginning, an index of 1 before the second item,
// and so on. An index of GetItemCount() or higher will insert the item at the
// end of the list. Negative indices are also allowed: An index of -1 will
// insert the item at the end of the list, an index of -2 before the last item,
// and so on. An index of -GetItemCount()-1 or lower will insert the item at the
// beginning.
//
// 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 callback is needed or if all events are handled
// through the selected callback set with SetSelectedFunc().
//
// The currently selected item will shift its position accordingly. If the list
// was previously empty, a "changed" event is fired because the new item becomes
// selected.
func (l *List) InsertItem(index int, mainText, secondaryText string, shortcut rune, selected func()) *List {
item := &listItem{
MainText: mainText,
SecondaryText: secondaryText,
Shortcut: shortcut,
Selected: selected,
}
// Shift index to range.
if index < 0 {
index = len(l.items) + index + 1
}
if index < 0 {
index = 0
} else if index > len(l.items) {
index = len(l.items)
}
// Shift current item.
if l.currentItem < len(l.items) && l.currentItem >= index {
l.currentItem++
}
// Insert item (make space for the new item, then shift and insert).
l.items = append(l.items, nil)
if index < len(l.items)-1 { // -1 because l.items has already grown by one item.
copy(l.items[index+1:], l.items[index:])
}
l.items[index] = item
// Fire a "change" event for the first item in the list.
if len(l.items) == 1 && l.changed != nil {
item := l.items[0]
l.changed(0, item.MainText, item.SecondaryText, item.Shortcut)
}
return l
}
// GetItemCount returns the number of items in the list.
func (l *List) GetItemCount() int {
return len(l.items)
}
// GetItemText returns an item's texts (main and secondary). Panics if the index
// is out of range.
func (l *List) GetItemText(index int) (main, secondary string) {
return l.items[index].MainText, l.items[index].SecondaryText
}
// SetItemText sets an item's main and secondary text. Panics if the index is
// out of range.
func (l *List) SetItemText(index int, main, secondary string) *List {
item := l.items[index]
item.MainText = main
item.SecondaryText = secondary
return l
}
// FindItems searches the main and secondary texts for the given strings and
// returns a list of item indices in which those strings are found. One of the
// two search strings may be empty, it will then be ignored. Indices are always
// returned in ascending order.
//
// If mustContainBoth is set to true, mainSearch must be contained in the main
// text AND secondarySearch must be contained in the secondary text. If it is
// false, only one of the two search strings must be contained.
//
// Set ignoreCase to true for case-insensitive search.
func (l *List) FindItems(mainSearch, secondarySearch string, mustContainBoth, ignoreCase bool) (indices []int) {
if mainSearch == "" && secondarySearch == "" {
return
}
if ignoreCase {
mainSearch = strings.ToLower(mainSearch)
secondarySearch = strings.ToLower(secondarySearch)
}
for index, item := range l.items {
mainText := item.MainText
secondaryText := item.SecondaryText
if ignoreCase {
mainText = strings.ToLower(mainText)
secondaryText = strings.ToLower(secondaryText)
}
// strings.Contains() always returns true for a "" search.
mainContained := strings.Contains(mainText, mainSearch)
secondaryContained := strings.Contains(secondaryText, secondarySearch)
if mustContainBoth && mainContained && secondaryContained ||
!mustContainBoth && (mainText != "" && mainContained || secondaryText != "" && secondaryContained) {
indices = append(indices, index)
}
}
return
}
// 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
screenWidth, _ := screen.Size()
scrollBarHeight := height
scrollBarX := x + (width - 1)
if scrollBarX > screenWidth-1 {
scrollBarX = screenWidth - 1
}
// Halve scroll bar height when drawing two lines per list item.
if l.showSecondaryText {
scrollBarHeight /= 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
}
}
// Adjust offset to keep the current selection in view.
if l.currentItem < l.offset {
l.offset = l.currentItem
} else if l.showSecondaryText {
if 2*(l.currentItem-l.offset) >= height-1 {
l.offset = (2*l.currentItem + 3 - height) / 2
}
} else {
if l.currentItem-l.offset >= height {
l.offset = l.currentItem + 1 - height
}
}
// Draw the list items.
for index, item := range l.items {
if index < l.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 && (!l.selectedFocusOnly || l.HasFocus()) {
textWidth := width
if !l.highlightFullLine {
if w := TaggedStringWidth(item.MainText); w < textWidth {
textWidth = w
}
}
for bx := 0; bx < textWidth; 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)
}
}
RenderScrollBar(screen, l.scrollBarVisibility, scrollBarX, y, scrollBarHeight, len(l.items), l.currentItem, index-l.offset, l.hasFocus, l.scrollBarColor)
y++
if y >= bottomLimit {
break
}
// Secondary text.
if l.showSecondaryText {
Print(screen, item.SecondaryText, x, y, width, AlignLeft, l.secondaryTextColor)
RenderScrollBar(screen, l.scrollBarVisibility, scrollBarX, y, scrollBarHeight, len(l.items), l.currentItem, index-l.offset, l.hasFocus, l.scrollBarColor)
y++
}
}
// Overdraw scroll bar when necessary.
for y < bottomLimit {
RenderScrollBar(screen, l.scrollBarVisibility, scrollBarX, y, scrollBarHeight, len(l.items), l.currentItem, bottomLimit-y, l.hasFocus, l.scrollBarColor)
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)) {
if event.Key() == tcell.KeyEscape {
if l.done != nil {
l.done()
}
return
} else if len(l.items) == 0 {
return
}
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:
if l.currentItem >= 0 && l.currentItem < len(l.items) {
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 {
if l.wrapAround {
l.currentItem = len(l.items) - 1
} else {
l.currentItem = 0
}
} else if l.currentItem >= len(l.items) {
if l.wrapAround {
l.currentItem = 0
} else {
l.currentItem = len(l.items) - 1
}
}
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)
}
})
}
// returns -1 if not found.
func (l *List) indexAtPoint(atX, atY int) int {
_, y, _, h := l.GetInnerRect()
if atY < y || atY >= y+h {
return -1
}
n := atY - y
if l.showSecondaryText {
n /= 2
}
if n >= len(l.items) {
return -1
}
return n
}
// MouseHandler returns the mouse handler for this primitive.
func (l *List) MouseHandler() func(event *EventMouse) {
return l.WrapMouseHandler(func(event *EventMouse) {
// Process mouse event.
if event.Action()&MouseClick != 0 {
atX, atY := event.Position()
index := l.indexAtPoint(atX, atY)
if index != -1 {
item := l.items[index]
if item.Selected != nil {
item.Selected()
}
if l.selected != nil {
l.selected(index, item.MainText, item.SecondaryText, item.Shortcut)
}
if index != l.currentItem && l.changed != nil {
l.changed(index, item.MainText, item.SecondaryText, item.Shortcut)
}
l.currentItem = index
}
}
})
}