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tree.go
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tree.go
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package widgets
import (
"fmt"
"image"
"strings"
rw "github.com/mattn/go-runewidth"
. "github.com/s-westphal/termui/v3"
)
const treeIndent = " "
// TreeNode is a tree node.
type TreeNode struct {
Value fmt.Stringer
Expanded bool
Nodes []*TreeNode
// level stores the node level in the tree.
level int
}
// TreeWalkFn is a function used for walking a Tree.
// To interrupt the walking process function should return false.
type TreeWalkFn func(*TreeNode) bool
func (self *TreeNode) parseStyles(style Style) []Cell {
var sb strings.Builder
if len(self.Nodes) == 0 {
sb.WriteString(strings.Repeat(treeIndent, self.level+1))
} else {
sb.WriteString(strings.Repeat(treeIndent, self.level))
if self.Expanded {
sb.WriteRune(Theme.Tree.Expanded)
} else {
sb.WriteRune(Theme.Tree.Collapsed)
}
sb.WriteByte(' ')
}
sb.WriteString(self.Value.String())
return ParseStyles(sb.String(), style)
}
// Tree is a tree widget.
type Tree struct {
Block
TextStyle Style
SelectedRowStyle Style
WrapText bool
SelectedRow int
nodes []*TreeNode
// rows is flatten nodes for rendering.
rows []*TreeNode
topRow int
}
// NewTree creates a new Tree widget.
func NewTree() *Tree {
return &Tree{
Block: *NewBlock(),
TextStyle: Theme.Tree.Text,
SelectedRowStyle: Theme.Tree.Text,
WrapText: true,
}
}
func (self *Tree) SetNodes(nodes []*TreeNode) {
self.nodes = nodes
self.prepareNodes()
}
func (self *Tree) prepareNodes() {
self.rows = make([]*TreeNode, 0)
for _, node := range self.nodes {
self.prepareNode(node, 0)
}
}
func (self *Tree) prepareNode(node *TreeNode, level int) {
self.rows = append(self.rows, node)
node.level = level
if node.Expanded {
for _, n := range node.Nodes {
self.prepareNode(n, level+1)
}
}
}
func (self *Tree) Walk(fn TreeWalkFn) {
for _, n := range self.nodes {
if !self.walk(n, fn) {
break
}
}
}
func (self *Tree) walk(n *TreeNode, fn TreeWalkFn) bool {
if !fn(n) {
return false
}
for _, node := range n.Nodes {
if !self.walk(node, fn) {
return false
}
}
return true
}
func (self *Tree) Draw(buf *Buffer) {
self.Block.Draw(buf)
point := self.Inner.Min
// adjusts view into widget
if self.SelectedRow >= self.Inner.Dy()+self.topRow {
self.topRow = self.SelectedRow - self.Inner.Dy() + 1
} else if self.SelectedRow < self.topRow {
self.topRow = self.SelectedRow
}
// draw rows
for row := self.topRow; row < len(self.rows) && point.Y < self.Inner.Max.Y; row++ {
cells := self.rows[row].parseStyles(self.TextStyle)
if self.WrapText {
cells = WrapCells(cells, uint(self.Inner.Dx()))
}
for j := 0; j < len(cells) && point.Y < self.Inner.Max.Y; j++ {
style := cells[j].Style
if row == self.SelectedRow {
style = self.SelectedRowStyle
}
if point.X+1 == self.Inner.Max.X+1 && len(cells) > self.Inner.Dx() {
buf.SetCell(NewCell(ELLIPSES, style), point.Add(image.Pt(-1, 0)))
} else {
buf.SetCell(NewCell(cells[j].Rune, style), point)
point = point.Add(image.Pt(rw.RuneWidth(cells[j].Rune), 0))
}
}
point = image.Pt(self.Inner.Min.X, point.Y+1)
}
// draw UP_ARROW if needed
if self.topRow > 0 {
buf.SetCell(
NewCell(UP_ARROW, NewStyle(ColorWhite)),
image.Pt(self.Inner.Max.X-1, self.Inner.Min.Y),
)
}
// draw DOWN_ARROW if needed
if len(self.rows) > int(self.topRow)+self.Inner.Dy() {
buf.SetCell(
NewCell(DOWN_ARROW, NewStyle(ColorWhite)),
image.Pt(self.Inner.Max.X-1, self.Inner.Max.Y-1),
)
}
}
// ScrollAmount scrolls by amount given. If amount is < 0, then scroll up.
// There is no need to set self.topRow, as this will be set automatically when drawn,
// since if the selected item is off screen then the topRow variable will change accordingly.
func (self *Tree) ScrollAmount(amount int) {
if len(self.rows)-int(self.SelectedRow) <= amount {
self.SelectedRow = len(self.rows) - 1
} else if int(self.SelectedRow)+amount < 0 {
self.SelectedRow = 0
} else {
self.SelectedRow += amount
}
}
func (self *Tree) SelectedNode() *TreeNode {
if len(self.rows) == 0 {
return nil
}
return self.rows[self.SelectedRow]
}
func (self *Tree) ScrollUp() {
self.ScrollAmount(-1)
}
func (self *Tree) ScrollDown() {
self.ScrollAmount(1)
}
func (self *Tree) ScrollPageUp() {
// If an item is selected below top row, then go to the top row.
if self.SelectedRow > self.topRow {
self.SelectedRow = self.topRow
} else {
self.ScrollAmount(-self.Inner.Dy())
}
}
func (self *Tree) ScrollPageDown() {
self.ScrollAmount(self.Inner.Dy())
}
func (self *Tree) ScrollHalfPageUp() {
self.ScrollAmount(-int(FloorFloat64(float64(self.Inner.Dy()) / 2)))
}
func (self *Tree) ScrollHalfPageDown() {
self.ScrollAmount(int(FloorFloat64(float64(self.Inner.Dy()) / 2)))
}
func (self *Tree) ScrollTop() {
self.SelectedRow = 0
}
func (self *Tree) ScrollBottom() {
self.SelectedRow = len(self.rows) - 1
}
func (self *Tree) Collapse() {
self.rows[self.SelectedRow].Expanded = false
self.prepareNodes()
}
func (self *Tree) Expand() {
node := self.rows[self.SelectedRow]
if len(node.Nodes) > 0 {
self.rows[self.SelectedRow].Expanded = true
}
self.prepareNodes()
}
func (self *Tree) ToggleExpand() {
node := self.rows[self.SelectedRow]
if len(node.Nodes) > 0 {
node.Expanded = !node.Expanded
}
self.prepareNodes()
}
func (self *Tree) ExpandAll() {
self.Walk(func(n *TreeNode) bool {
if len(n.Nodes) > 0 {
n.Expanded = true
}
return true
})
self.prepareNodes()
}
func (self *Tree) CollapseAll() {
self.Walk(func(n *TreeNode) bool {
n.Expanded = false
return true
})
self.prepareNodes()
}