class TreeView

Topic group Related topics

An expandable tree.

Syntax

[<oRef> =] new TreeView(<container> [,<name expC>])

<oRef>

A variable or property—typically of <container>—in which to store a reference to the newly created TreeView object.

The container—typically a Form object—to which you’re binding the TreeView object.

An optional name for the TreeView object. If not specified, the TreeView class will auto-generate a name for the object.

Properties

The following tables list the properties, events, and methods of interest in the TreeView class.

Property	Default	Description
allowDrop	false	Whether dragged objects can be dropped on the TreeView
allowEditLabels	true	Whether the text labels of the tree items are editable
allowEditTree	true	Whether items can be added or deleted from the tree
anchor	0 – None	How the TreeView object is anchored in its container (0=None, 1=Bottom, 2=Top, 3=Left, 4=Right, 5=Center, 6=Container)
baseClassName	TREEVIEW	Identifies the object as an instance of the TreeView class
checkBoxes	true	Whether each tree item has a checkbox
checkedImage		The image to display when a tree item is checked instead of a checked check box
className	(TREEVIEW)	Identifies the object as an instance of a custom class. When no custom class exists, defaults to baseClassName
colorNormal	WindowText /Window	The color of the text labels and background
disablePopup	false	Whether the tree view’s popup menu is disabled
firstChild		The first child tree item
firstVisibleChild		The first TreeItem that is visible in the TreeView area
hasButtons	true	Whether + and - icons are displayed for TreeItems that have children
hasLines	true	Whether lines are drawn between TreeItems
image		Default image displayed between checkbox and text label when a TreeItem does not have focus
imageScaleToFont	true	Whether TreeItem images automatically scale to match the text label font height
imageSize		The height of TreeItem images in pixels
indent		The horizontal indent, in pixels, for each level of TreeItems
linesAtRoot	true	Whether a line connects the TreeItems at the first level
selected		The currently selected TreeItem
selectedImage		Default image displayed between CheckBox and TextLabel when a TreeItem has focus
showSelAlways	true	Whether to highlight the selected item in the tree even when the TreeView does not have focus
toolTips	true	Whether to display TextLabels as tooltips if they are too long to display fully in the TreeView area as the mouse passes over them
trackSelect	true	Whether to highlight and underline TreeItems as the mouse passes over them
uncheckedImage		The image to display when a TreeItem is not checked instead of an empty check box
Event	Parameters	Description
canChange		Before selection moves to another TreeItem; return value determines if selection can leave current TreeItem
canEditLabel		When attempting to edit text label; return value determines whether editing is allowed
canExpand	<oItem>	When attempting to expand or collapse a TreeItem; return value determines whether expand/collapse occurs
onChange		After the selection moves to another TreeItem
onCheckBoxClick		After a checkbox in a TreeItem is clicked

onDragEnter	<left expN> <top expN> <type expC> <name expC>	When the mouse enters the TreeView display area during a Drag&Drop operation
onDragLeave		When the mouse leaves the TreeView display area without having dropped an object
onDragOver	<left expN> <top expN> <type expC> <name expC>	While the mouse drags an object over the TreeView display area during a Drag&Drop operation
onDrop	<left expN> <top expN> <type expC> <name expC>	When the mouse button is released over the TreeView display area during a Drag&Drop operation

onEditLabel	<text expC>	After the TextLabel in a TreeItem is edited; may optionally return a different label value to save
onExpand	<oItem>	After a TreeItem is expanded or collapsed
Method	Parameters	Description
count( )		Returns the total number of TreeItems in the tree
getItemByPos( )	<col expN> <row expN>	Returns an object reference to a TreeItem object located at a specified position
loadChildren( )	<filename expC>	Loads and instantiates child TreeItems from a text file
releaseAllChildren( )		Deletes all TreeItems in the tree
sortChildren( )		Sorts child TreeItems
streamChildren( )	<filename expC>	Streams child TreeItems out to a text file
visibleCount( )		Returns the number of TreeItems visible in the tree view area

The following table lists the common properties, events, and methods of the TreeView class:

Description

A TreeView displays a collapsible multi-level tree. There are four ways to create the tree:

Explicitly add items with code, like the code generated by the Form Designer.

Interactively through the TreeView’s runtime user interface (right-clicking or pressing certain keys).

Data-driven code that reads a table and dynamically creates the tree items.

Use the TreeView's loadChildren( ) method to add items previously saved to a text file using streamChildren( ).

The TreeView object acts as the root of the tree. It contains the first level of TreeItem objects, which can contain their own TreeItem objects, thus forming a tree.

Unlike the deeper levels of the tree, you cannot collapse the first level of a tree. Therefore, you may want to use only one item at the first level of the tree to make the entire tree collapsible.

Property		Event		Method
before borderStyle dragEffect enabled fontBold fontItalic fontName fontSize fontStrikeout fontUnderline form height helpFile helpId	hWnd id left mousePointer name pageno parent printable statusMessage systemTheme speedTip tabStop top visible width	onDesignOpen onDragBegin onGotFocus onHelp onLeftDblClick onLeftMouseDown onLeftMouseUp onLostFocus	onMiddleDblClick onMiddleMouseDown onMiddleMouseUp onMouseMove onOpen onRightDblClick onRightMouseDown onRightMouseUp	drag( ) move( ) release( ) setFocus( )