nt

treeview.go (26072B)

---

 package tview
 
 import (
 	"github.com/gdamore/tcell/v2"
 )
 
 // Tree navigation events.
 const (
 	treeNone int = iota
 	treeHome
 	treeEnd
 	treeMove
 	treeParent
 	treeChild
 	treeScroll // Move without changing the selection, even when off screen.
 )
 
 // TreeNode represents one node in a tree view.
 type TreeNode struct {
 	// The reference object.
 	reference interface{}
 
 	// This node's child nodes.
 	children []*TreeNode
 
 	// The item's text.
 	text string
 
 	// The text style.
 	textStyle tcell.Style
 
 	// The style of selected text.
 	selectedTextStyle tcell.Style
 
 	// Whether or not this node can be selected.
 	selectable bool
 
 	// Whether or not this node's children should be displayed.
 	expanded bool
 
 	// The additional horizontal indent of this node's text.
 	indent int
 
 	// An optional function which is called when the user selects this node.
 	selected func()
 
 	// The hierarchy level (0 for the root, 1 for its children, and so on). This
 	// is only up to date immediately after a call to process() (e.g. via
 	// Draw()).
 	level int
 
 	// Temporary member variables.
 	parent    *TreeNode // The parent node (nil for the root).
 	graphicsX int       // The x-coordinate of the left-most graphics rune.
 	textX     int       // The x-coordinate of the first rune of the text.
 }
 
 // NewTreeNode returns a new tree node.
 func NewTreeNode(text string) *TreeNode {
 	return &TreeNode{
 		text:              text,
 		textStyle:         tcell.StyleDefault.Foreground(Styles.PrimaryTextColor).Background(Styles.PrimitiveBackgroundColor),
 		selectedTextStyle: tcell.StyleDefault.Foreground(Styles.PrimitiveBackgroundColor).Background(Styles.PrimaryTextColor),
 		indent:            2,
 		expanded:          true,
 		selectable:        true,
 	}
 }
 
 // Walk traverses this node's subtree in depth-first, pre-order (NLR) order and
 // calls the provided callback function on each traversed node (which includes
 // this node) with the traversed node and its parent node (nil for this node).
 // The callback returns whether traversal should continue with the traversed
 // node's child nodes (true) or not recurse any deeper (false).
 func (n *TreeNode) Walk(callback func(node, parent *TreeNode) bool) *TreeNode {
 	n.parent = nil
 	nodes := []*TreeNode{n}
 	for len(nodes) > 0 {
 		// Pop the top node and process it.
 		node := nodes[len(nodes)-1]
 		nodes = nodes[:len(nodes)-1]
 		if !callback(node, node.parent) {
 			// Don't add any children.
 			continue
 		}
 
 		// Add children in reverse order.
 		for index := len(node.children) - 1; index >= 0; index-- {
 			node.children[index].parent = node
 			nodes = append(nodes, node.children[index])
 		}
 	}
 
 	return n
 }
 
 // SetReference allows you to store a reference of any type in this node. This
 // will allow you to establish a mapping between the TreeView hierarchy and your
 // internal tree structure.
 func (n *TreeNode) SetReference(reference interface{}) *TreeNode {
 	n.reference = reference
 	return n
 }
 
 // GetReference returns this node's reference object.
 func (n *TreeNode) GetReference() interface{} {
 	return n.reference
 }
 
 // SetChildren sets this node's child nodes.
 func (n *TreeNode) SetChildren(childNodes []*TreeNode) *TreeNode {
 	n.children = childNodes
 	return n
 }
 
 // GetText returns this node's text.
 func (n *TreeNode) GetText() string {
 	return n.text
 }
 
 // GetChildren returns this node's children.
 func (n *TreeNode) GetChildren() []*TreeNode {
 	return n.children
 }
 
 // ClearChildren removes all child nodes from this node.
 func (n *TreeNode) ClearChildren() *TreeNode {
 	n.children = nil
 	return n
 }
 
 // AddChild adds a new child node to this node.
 func (n *TreeNode) AddChild(node *TreeNode) *TreeNode {
 	n.children = append(n.children, node)
 	return n
 }
 
 // RemoveChild removes a child node from this node. If the child node cannot be
 // found, nothing happens.
 func (n *TreeNode) RemoveChild(node *TreeNode) *TreeNode {
 	for index, child := range n.children {
 		if child == node {
 			n.children = append(n.children[:index], n.children[index+1:]...)
 			break
 		}
 	}
 	return n
 }
 
 // SetSelectable sets a flag indicating whether this node can be selected by
 // the user.
 func (n *TreeNode) SetSelectable(selectable bool) *TreeNode {
 	n.selectable = selectable
 	return n
 }
 
 // SetSelectedFunc sets a function which is called when the user selects this
 // node by hitting Enter when it is selected.
 func (n *TreeNode) SetSelectedFunc(handler func()) *TreeNode {
 	n.selected = handler
 	return n
 }
 
 // SetExpanded sets whether or not this node's child nodes should be displayed.
 func (n *TreeNode) SetExpanded(expanded bool) *TreeNode {
 	n.expanded = expanded
 	return n
 }
 
 // Expand makes the child nodes of this node appear.
 func (n *TreeNode) Expand() *TreeNode {
 	n.expanded = true
 	return n
 }
 
 // Collapse makes the child nodes of this node disappear.
 func (n *TreeNode) Collapse() *TreeNode {
 	n.expanded = false
 	return n
 }
 
 // ExpandAll expands this node and all descendent nodes.
 func (n *TreeNode) ExpandAll() *TreeNode {
 	n.Walk(func(node, parent *TreeNode) bool {
 		node.expanded = true
 		return true
 	})
 	return n
 }
 
 // CollapseAll collapses this node and all descendent nodes.
 func (n *TreeNode) CollapseAll() *TreeNode {
 	n.Walk(func(node, parent *TreeNode) bool {
 		node.expanded = false
 		return true
 	})
 	return n
 }
 
 // IsExpanded returns whether the child nodes of this node are visible.
 func (n *TreeNode) IsExpanded() bool {
 	return n.expanded
 }
 
 // SetText sets the node's text which is displayed.
 func (n *TreeNode) SetText(text string) *TreeNode {
 	n.text = text
 	return n
 }
 
 // GetColor returns the node's text color.
 func (n *TreeNode) GetColor() tcell.Color {
 	color, _, _ := n.textStyle.Decompose()
 	return color
 }
 
 // SetColor sets the node's text color. For compatibility reasons, this also
 // sets the background color of the selected text style. For more control over
 // styles, use [TreeNode.SetTextStyle] and [TreeNode.SetSelectedTextStyle].
 func (n *TreeNode) SetColor(color tcell.Color) *TreeNode {
 	n.textStyle = n.textStyle.Foreground(color)
 	n.selectedTextStyle = n.selectedTextStyle.Background(color)
 	return n
 }
 
 // SetTextStyle sets the text style for this node.
 func (n *TreeNode) SetTextStyle(style tcell.Style) *TreeNode {
 	n.textStyle = style
 	return n
 }
 
 // GetTextStyle returns the text style for this node.
 func (n *TreeNode) GetTextStyle() tcell.Style {
 	return n.textStyle
 }
 
 // SetSelectedTextStyle sets the text style for this node when it is selected.
 func (n *TreeNode) SetSelectedTextStyle(style tcell.Style) *TreeNode {
 	n.selectedTextStyle = style
 	return n
 }
 
 // GetSelectedTextStyle returns the text style for this node when it is
 // selected.
 func (n *TreeNode) GetSelectedTextStyle() tcell.Style {
 	return n.selectedTextStyle
 }
 
 // SetIndent sets an additional indentation for this node's text. A value of 0
 // keeps the text as far left as possible with a minimum of line graphics. Any
 // value greater than that moves the text to the right.
 func (n *TreeNode) SetIndent(indent int) *TreeNode {
 	n.indent = indent
 	return n
 }
 
 // GetLevel returns the node's level within the hierarchy, where 0 corresponds
 // to the root node, 1 corresponds to its children, and so on. This is only
 // guaranteed to be up to date immediately after the tree that contains this
 // node is drawn.
 func (n *TreeNode) GetLevel() int {
 	return n.level
 }
 
 // TreeView displays tree structures. A tree consists of nodes (TreeNode
 // objects) where each node has zero or more child nodes and exactly one parent
 // node (except for the root node which has no parent node).
 //
 // The SetRoot() function is used to specify the root of the tree. Other nodes
 // are added locally to the root node or any of its descendents. See the
 // TreeNode documentation for details on node attributes. (You can use
 // SetReference() to store a reference to nodes of your own tree structure.)
 //
 // Nodes can be selected by calling SetCurrentNode(). The user can navigate the
 // selection or the tree by using the following keys:
 //
 //   - j, down arrow, right arrow: Move (the selection) down by one node.
 //   - k, up arrow, left arrow: Move (the selection) up by one node.
 //   - g, home: Move (the selection) to the top.
 //   - G, end: Move (the selection) to the bottom.
 //   - J: Move (the selection) up one level (if that node is selectable).
 //   - K: Move (the selection) to the last node one level down (if any).
 //   - Ctrl-F, page down: Move (the selection) down by one page.
 //   - Ctrl-B, page up: Move (the selection) up by one page.
 //
 // Selected nodes can trigger the "selected" callback when the user hits Enter.
 //
 // The root node corresponds to level 0, its children correspond to level 1,
 // their children to level 2, and so on. Per default, the first level that is
 // displayed is 0, i.e. the root node. You can call SetTopLevel() to hide
 // levels.
 //
 // If graphics are turned on (see SetGraphics()), lines indicate the tree's
 // hierarchy. Alternative (or additionally), you can set different prefixes
 // using SetPrefixes() for different levels, for example to display hierarchical
 // bullet point lists.
 //
 // See https://github.com/rivo/tview/wiki/TreeView for an example.
 type TreeView struct {
 	*Box
 
 	// The root node.
 	root *TreeNode
 
 	// The currently selected node or nil if no node is selected.
 	currentNode *TreeNode
 
 	// The last note that was selected or nil of there is no such node.
 	lastNode *TreeNode
 
 	// The movement to be performed during the call to Draw(), one of the
 	// constants defined above.
 	movement int
 
 	// The number of nodes to move down or up, when movement is treeMove,
 	// excluding non-selectable nodes for selection movement, including them for
 	// scrolling.
 	step int
 
 	// The top hierarchical level shown. (0 corresponds to the root level.)
 	topLevel int
 
 	// Strings drawn before the nodes, based on their level.
 	prefixes []string
 
 	// Vertical scroll offset.
 	offsetY int
 
 	// If set to true, all node texts will be aligned horizontally.
 	align bool
 
 	// If set to true, the tree structure is drawn using lines.
 	graphics bool
 
 	// The color of the lines.
 	graphicsColor tcell.Color
 
 	// An optional function which is called when the user has navigated to a new
 	// tree node.
 	changed func(node *TreeNode)
 
 	// An optional function which is called when a tree item was selected.
 	selected func(node *TreeNode)
 
 	// An optional function which is called when the user moves away from this
 	// primitive.
 	done func(key tcell.Key)
 
 	// The visible nodes, top-down, as set by process().
 	nodes []*TreeNode
 
 	// Temporarily set to true while we know that the tree has not changed and
 	// therefore does not need to be reprocessed.
 	stableNodes bool
 }
 
 // NewTreeView returns a new tree view.
 func NewTreeView() *TreeView {
 	return &TreeView{
 		Box:           NewBox(),
 		graphics:      true,
 		graphicsColor: Styles.GraphicsColor,
 	}
 }
 
 // SetRoot sets the root node of the tree.
 func (t *TreeView) SetRoot(root *TreeNode) *TreeView {
 	t.root = root
 	return t
 }
 
 // GetRoot returns the root node of the tree. If no such node was previously
 // set, nil is returned.
 func (t *TreeView) GetRoot() *TreeNode {
 	return t.root
 }
 
 // SetCurrentNode sets the currently selected node. Provide nil to clear all
 // selections. Selected nodes must be visible and selectable, or else the
 // selection will be changed to the top-most selectable and visible node.
 //
 // This function does NOT trigger the "changed" callback because the actual node
 // that will be selected is not known until the tree is drawn. Triggering the
 // "changed" callback is thus deferred until the next call to [TreeView.Draw].
 func (t *TreeView) SetCurrentNode(node *TreeNode) *TreeView {
 	t.currentNode = node
 	return t
 }
 
 // GetCurrentNode returns the currently selected node or nil of no node is
 // currently selected.
 func (t *TreeView) GetCurrentNode() *TreeNode {
 	return t.currentNode
 }
 
 // GetPath returns all nodes located on the path from the root to the given
 // node, including the root and the node itself. If there is no root node, nil
 // is returned. If there are multiple paths to the node, a random one is chosen
 // and returned.
 func (t *TreeView) GetPath(node *TreeNode) []*TreeNode {
 	if t.root == nil {
 		return nil
 	}
 
 	var f func(current *TreeNode, path []*TreeNode) []*TreeNode
 	f = func(current *TreeNode, path []*TreeNode) []*TreeNode {
 		if current == node {
 			return path
 		}
 
 		for _, child := range current.children {
 			newPath := make([]*TreeNode, len(path), len(path)+1)
 			copy(newPath, path)
 			if p := f(child, append(newPath, child)); p != nil {
 				return p
 			}
 		}
 
 		return nil
 	}
 
 	return f(t.root, []*TreeNode{t.root})
 }
 
 // SetTopLevel sets the first tree level that is visible with 0 referring to the
 // root, 1 to the root's child nodes, and so on. Nodes above the top level are
 // not displayed.
 func (t *TreeView) SetTopLevel(topLevel int) *TreeView {
 	t.topLevel = topLevel
 	return t
 }
 
 // SetPrefixes defines the strings drawn before the nodes' texts. This is a
 // slice of strings where each element corresponds to a node's hierarchy level,
 // i.e. 0 for the root, 1 for the root's children, and so on (levels will
 // cycle).
 //
 // For example, to display a hierarchical list with bullet points:
 //
 //	treeView.SetGraphics(false).
 //	  SetPrefixes([]string{"* ", "- ", "x "})
 //
 // Deeper levels will cycle through the prefixes.
 func (t *TreeView) SetPrefixes(prefixes []string) *TreeView {
 	t.prefixes = prefixes
 	return t
 }
 
 // SetAlign controls the horizontal alignment of the node texts. If set to true,
 // all texts except that of top-level nodes will be placed in the same column.
 // If set to false, they will indent with the hierarchy.
 func (t *TreeView) SetAlign(align bool) *TreeView {
 	t.align = align
 	return t
 }
 
 // SetGraphics sets a flag which determines whether or not line graphics are
 // drawn to illustrate the tree's hierarchy.
 func (t *TreeView) SetGraphics(showGraphics bool) *TreeView {
 	t.graphics = showGraphics
 	return t
 }
 
 // SetGraphicsColor sets the colors of the lines used to draw the tree structure.
 func (t *TreeView) SetGraphicsColor(color tcell.Color) *TreeView {
 	t.graphicsColor = color
 	return t
 }
 
 // SetChangedFunc sets the function which is called when the currently selected
 // node changes, for example when the user navigates to a new tree node.
 func (t *TreeView) SetChangedFunc(handler func(node *TreeNode)) *TreeView {
 	t.changed = handler
 	return t
 }
 
 // SetSelectedFunc sets the function which is called when the user selects a
 // node by pressing Enter on the current selection.
 func (t *TreeView) SetSelectedFunc(handler func(node *TreeNode)) *TreeView {
 	t.selected = handler
 	return t
 }
 
 // GetSelectedFunc returns the function set with [TreeView.SetSelectedFunc]
 // or nil if no such function has been set.
 func (t *TreeView) GetSelectedFunc() func(node *TreeNode) {
 	return t.selected
 }
 
 // SetDoneFunc sets a handler which is called whenever the user presses the
 // Escape, Tab, or Backtab key.
 func (t *TreeView) SetDoneFunc(handler func(key tcell.Key)) *TreeView {
 	t.done = handler
 	return t
 }
 
 // GetScrollOffset returns the number of node rows that were skipped at the top
 // of the tree view. Note that when the user navigates the tree view, this value
 // is only updated after the tree view has been redrawn.
 func (t *TreeView) GetScrollOffset() int {
 	return t.offsetY
 }
 
 // GetRowCount returns the number of "visible" nodes. This includes nodes which
 // fall outside the tree view's box but notably does not include the children
 // of collapsed nodes. Note that this value is only up to date after the tree
 // view has been drawn.
 func (t *TreeView) GetRowCount() int {
 	return len(t.nodes)
 }
 
 // Move moves the selection (if a node is currently selected) or scrolls the
 // tree view (if there is no selection), by the given offset (positive values to
 // move/scroll down, negative values to move/scroll up). For selection changes,
 // the offset refers to the number selectable, visible nodes. For scrolling, the
 // offset refers to the number of visible nodes.
 //
 // If the offset is 0, nothing happens.
 func (t *TreeView) Move(offset int) *TreeView {
 	if offset == 0 {
 		return t
 	}
 	t.movement = treeMove
 	t.step = offset
 	t.process(false)
 	return t
 }
 
 // process builds the visible tree, populates the "nodes" slice, and processes
 // pending movement actions. Set "drawingAfter" to true if you know that
 // [TreeView.Draw] will be called immediately after this function (to avoid
 // having [TreeView.Draw] call it again).
 func (t *TreeView) process(drawingAfter bool) {
 	t.stableNodes = drawingAfter
 	_, _, _, height := t.GetInnerRect()
 
 	// Determine visible nodes and their placement.
 	t.nodes = nil
 	if t.root == nil {
 		return
 	}
 	parentSelectedIndex, selectedIndex, topLevelGraphicsX := -1, -1, -1
 	var graphicsOffset, maxTextX int
 	if t.graphics {
 		graphicsOffset = 1
 	}
 	t.root.Walk(func(node, parent *TreeNode) bool {
 		// Set node attributes.
 		node.parent = parent
 		if parent == nil {
 			node.level = 0
 			node.graphicsX = 0
 			node.textX = 0
 		} else {
 			node.level = parent.level + 1
 			node.graphicsX = parent.textX
 			node.textX = node.graphicsX + graphicsOffset + node.indent
 		}
 		if !t.graphics && t.align {
 			// Without graphics, we align nodes on the first column.
 			node.textX = 0
 		}
 		if node.level == t.topLevel {
 			// No graphics for top level nodes.
 			node.graphicsX = 0
 			node.textX = 0
 		}
 
 		// Add the node to the list.
 		if node.level >= t.topLevel {
 			// This node will be visible.
 			if node.textX > maxTextX {
 				maxTextX = node.textX
 			}
 			if node == t.currentNode && node.selectable {
 				selectedIndex = len(t.nodes)
 
 				// Also find parent node.
 				for index := len(t.nodes) - 1; index >= 0; index-- {
 					if t.nodes[index] == parent && t.nodes[index].selectable {
 						parentSelectedIndex = index
 						break
 					}
 				}
 			}
 
 			// Maybe we want to skip this level.
 			if t.topLevel == node.level && (topLevelGraphicsX < 0 || node.graphicsX < topLevelGraphicsX) {
 				topLevelGraphicsX = node.graphicsX
 			}
 
 			t.nodes = append(t.nodes, node)
 		}
 
 		// Recurse if desired.
 		return node.expanded
 	})
 
 	// Post-process positions.
 	for _, node := range t.nodes {
 		// If text must align, we correct the positions.
 		if t.align && node.level > t.topLevel {
 			node.textX = maxTextX
 		}
 
 		// If we skipped levels, shift to the left.
 		if topLevelGraphicsX > 0 {
 			node.graphicsX -= topLevelGraphicsX
 			node.textX -= topLevelGraphicsX
 		}
 	}
 
 	// Process selection. (Also trigger events if necessary.)
 	if selectedIndex >= 0 {
 		// Move the selection.
 		switch t.movement {
 		case treeMove:
 			for t.step < 0 { // Going up.
 				index := selectedIndex
 				for index > 0 {
 					index--
 					if t.nodes[index].selectable {
 						selectedIndex = index
 						break
 					}
 				}
 				t.step++
 			}
 			for t.step > 0 { // Going down.
 				index := selectedIndex
 				for index < len(t.nodes)-1 {
 					index++
 					if t.nodes[index].selectable {
 						selectedIndex = index
 						break
 					}
 				}
 				t.step--
 			}
 		case treeParent:
 			if parentSelectedIndex >= 0 {
 				selectedIndex = parentSelectedIndex
 			}
 		case treeChild:
 			index := selectedIndex
 			for index < len(t.nodes)-1 {
 				index++
 				if t.nodes[index].selectable && t.nodes[index].parent == t.nodes[selectedIndex] {
 					selectedIndex = index
 				}
 			}
 		}
 		t.currentNode = t.nodes[selectedIndex]
 
 		// Move selection into viewport.
 		if t.movement != treeScroll {
 			if selectedIndex-t.offsetY >= height {
 				t.offsetY = selectedIndex - height + 1
 			}
 			if selectedIndex < t.offsetY {
 				t.offsetY = selectedIndex
 			}
 			if t.movement != treeHome && t.movement != treeEnd {
 				// treeScroll, treeHome, and treeEnd are handled by Draw().
 				t.movement = treeNone
 				t.step = 0
 			}
 		}
 	} else {
 		// If selection is not visible or selectable, select the first candidate.
 		if t.currentNode != nil {
 			for index, node := range t.nodes {
 				if node.selectable {
 					selectedIndex = index
 					t.currentNode = node
 					break
 				}
 			}
 		}
 		if selectedIndex < 0 {
 			t.currentNode = nil
 		}
 	}
 
 	// Trigger "changed" callback.
 	if t.changed != nil && t.currentNode != nil && t.currentNode != t.lastNode {
 		t.changed(t.currentNode)
 	}
 	t.lastNode = t.currentNode
 }
 
 // Draw draws this primitive onto the screen.
 func (t *TreeView) Draw(screen tcell.Screen) {
 	t.Box.DrawForSubclass(screen, t)
 	if t.root == nil {
 		return
 	}
 	_, totalHeight := screen.Size()
 
 	if !t.stableNodes {
 		t.process(false)
 	} else {
 		t.stableNodes = false
 	}
 
 	// Scroll the tree, t.movement is treeNone after process() when there is a
 	// selection, except for treeScroll, treeHome, and treeEnd.
 	x, y, width, height := t.GetInnerRect()
 	switch t.movement {
 	case treeMove, treeScroll:
 		t.offsetY += t.step
 	case treeHome:
 		t.offsetY = 0
 	case treeEnd:
 		t.offsetY = len(t.nodes)
 	}
 	t.movement = treeNone
 
 	// Fix invalid offsets.
 	if t.offsetY >= len(t.nodes)-height {
 		t.offsetY = len(t.nodes) - height
 	}
 	if t.offsetY < 0 {
 		t.offsetY = 0
 	}
 
 	// Draw the tree.
 	posY := y
 	lineStyle := tcell.StyleDefault.Background(t.backgroundColor).Foreground(t.graphicsColor)
 	for index, node := range t.nodes {
 		// Skip invisible parts.
 		if posY >= y+height+1 || posY >= totalHeight {
 			break
 		}
 		if index < t.offsetY {
 			continue
 		}
 
 		// Draw the graphics.
 		if t.graphics {
 			// Draw ancestor branches.
 			ancestor := node.parent
 			for ancestor != nil && ancestor.parent != nil && ancestor.parent.level >= t.topLevel {
 				if ancestor.graphicsX >= width {
 					continue
 				}
 
 				// Draw a branch if this ancestor is not a last child.
 				if ancestor.parent.children[len(ancestor.parent.children)-1] != ancestor {
 					if posY-1 >= y && ancestor.textX > ancestor.graphicsX {
 						PrintJoinedSemigraphics(screen, x+ancestor.graphicsX, posY-1, Borders.Vertical, lineStyle)
 					}
 					if posY < y+height {
 						screen.SetContent(x+ancestor.graphicsX, posY, Borders.Vertical, nil, lineStyle)
 					}
 				}
 				ancestor = ancestor.parent
 			}
 
 			if node.textX > node.graphicsX && node.graphicsX < width {
 				// Connect to the node above.
 				if posY-1 >= y && t.nodes[index-1].graphicsX <= node.graphicsX && t.nodes[index-1].textX > node.graphicsX {
 					PrintJoinedSemigraphics(screen, x+node.graphicsX, posY-1, Borders.TopLeft, lineStyle)
 				}
 
 				// Join this node.
 				if posY < y+height {
 					screen.SetContent(x+node.graphicsX, posY, Borders.BottomLeft, nil, lineStyle)
 					for pos := node.graphicsX + 1; pos < node.textX && pos < width; pos++ {
 						screen.SetContent(x+pos, posY, Borders.Horizontal, nil, lineStyle)
 					}
 				}
 			}
 		}
 
 		// Draw the prefix and the text.
 		if node.textX < width && posY < y+height {
 			// Prefix.
 			var prefixWidth int
 			if len(t.prefixes) > 0 {
 				_, _, prefixWidth = printWithStyle(screen, t.prefixes[(node.level-t.topLevel)%len(t.prefixes)], x+node.textX, posY, 0, width-node.textX, AlignLeft, node.textStyle, true)
 			}
 
 			// Text.
 			if node.textX+prefixWidth < width {
 				style := node.textStyle
 				if node == t.currentNode {
 					style = node.selectedTextStyle
 				}
 				printWithStyle(screen, node.text, x+node.textX+prefixWidth, posY, 0, width-node.textX-prefixWidth, AlignLeft, style, false)
 			}
 		}
 
 		// Advance.
 		posY++
 	}
 }
 
 // InputHandler returns the handler for this primitive.
 func (t *TreeView) InputHandler() func(event *tcell.EventKey, setFocus func(p Primitive)) {
 	return t.WrapInputHandler(func(event *tcell.EventKey, setFocus func(p Primitive)) {
 		selectNode := func() {
 			node := t.currentNode
 			if node != nil {
 				if t.selected != nil {
 					t.selected(node)
 				}
 				if node.selected != nil {
 					node.selected()
 				}
 			}
 		}
 
 		// Because the tree is flattened into a list only at drawing time, we also
 		// postpone the (selection) movement to drawing time.
 		switch key := event.Key(); key {
 		case tcell.KeyTab, tcell.KeyBacktab, tcell.KeyEscape:
 			if t.done != nil {
 				t.done(key)
 			}
 		case tcell.KeyDown, tcell.KeyRight:
 			t.movement = treeMove
 			t.step = 1
 		case tcell.KeyUp, tcell.KeyLeft:
 			t.movement = treeMove
 			t.step = -1
 		case tcell.KeyHome:
 			t.movement = treeHome
 		case tcell.KeyEnd:
 			t.movement = treeEnd
 		case tcell.KeyPgDn, tcell.KeyCtrlF:
 			_, _, _, height := t.GetInnerRect()
 			t.movement = treeMove
 			t.step = height
 		case tcell.KeyPgUp, tcell.KeyCtrlB:
 			_, _, _, height := t.GetInnerRect()
 			t.movement = treeMove
 			t.step = -height
 		case tcell.KeyRune:
 			switch event.Rune() {
 			case 'g':
 				t.movement = treeHome
 			case 'G':
 				t.movement = treeEnd
 			case 'j':
 				t.movement = treeMove
 				t.step = 1
 			case 'J':
 				t.movement = treeChild
 			case 'k':
 				t.movement = treeMove
 				t.step = -1
 			case 'K':
 				t.movement = treeParent
 			case ' ':
 				selectNode()
 			}
 		case tcell.KeyEnter:
 			selectNode()
 		}
 
 		t.process(true)
 	})
 }
 
 // MouseHandler returns the mouse handler for this primitive.
 func (t *TreeView) MouseHandler() func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
 	return t.WrapMouseHandler(func(action MouseAction, event *tcell.EventMouse, setFocus func(p Primitive)) (consumed bool, capture Primitive) {
 		x, y := event.Position()
 		if !t.InRect(x, y) {
 			return false, nil
 		}
 
 		switch action {
 		case MouseLeftDown:
 			setFocus(t)
 			consumed = true
 		case MouseLeftClick:
 			_, rectY, _, _ := t.GetInnerRect()
 			y += t.offsetY - rectY
 			if y >= 0 && y < len(t.nodes) {
 				node := t.nodes[y]
 				if node.selectable {
 					previousNode := t.currentNode
 					t.currentNode = node
 					if previousNode != node && t.changed != nil {
 						t.changed(node)
 					}
 					if t.selected != nil {
 						t.selected(node)
 					}
 					if node.selected != nil {
 						node.selected()
 					}
 				}
 			}
 			consumed = true
 		case MouseScrollUp:
 			t.movement = treeScroll
 			t.step = -1
 			consumed = true
 		case MouseScrollDown:
 			t.movement = treeScroll
 			t.step = 1
 			consumed = true
 		}
 
 		return
 	})
 }