TreeCombo

Inheritance Hierarchy

Description

The TreeCombo component is used to display tree-like hierarchical structures, such as an object inheritance tree, in the form of drop-down lists.

Working with the Component

Select the component elements by clicking on the element icon or on the element itself, or pressing the SPACE key.

Double-clicking the column border automatically fits the left column. The column width is adjusted based on all elements that the node may contain (including expander, checkbox, icon, status icon, and node text).

NOTE. A drop-down list of elements can be resized by dragging its right, left or bottom border with the mouse. The minimum width of the drop-down list equals to the component width.

By default, information on the element selection is displayed in the component editor. To automatically update this information, use the AutoUpdateInfo property. To display user data in the component editor, change the Text base property.

Element Search

The following types of search are available in the expanded drop-down list:

On typing in first several characters of the element name the cursor moves to the first found element. This type of search is performed in cycles, and only by the elements in the expanded part of element tree hierarchy.
Using the search string, which opens on pressing F3 or CTRL+F. After entering part of the searched word and pressing the ENTER key or the button the search is executed. The search is executed in cycles by all the elements hierarchy.

If search has been successful, the cursor will focus on the found element. Selection state depends on value of the FindMode property. Depending on the selected multiple selection mode, the element is added to selection using the SPACE key, or by holding down the CTRL key.

The user can also search for elements with the collapsed component drop-down list. When the component is focused, entering a set of characters creates a list of elements, which names contain this set of characters:

Elements are selected using the previously noted method, depending on the value specified in the SelectionMode property. Closing this dialog box applies the selection to the component.

The user can search for one or several words based on segments in any mode. To do this, separate the search combinations with whitespace character. The word order in the names of search elements is ignored.

Data Sorting

Data sorting is available if the ShowColumnHeaders, Sorted and ColumnClick properties are set to True, and the SortType property has a value other than None.

In the form execution mode, click the header of the appropriate column to sort data by it. The data is sorted in the ascending direction. Double-clicking changes sorting direction. To sort data by multiple columns, click the headers of the required columns while holding down the CTRL key. The sorting order is as follows: the column, which header is clicked last, is sorted last.

Sorting can also be set up in the Sorting specialized dialog box:

This dialog box opens when selecting the appropriate item from the context menu called in the column header area.

NOTE. The context menu item is available if the ShowColumnHeaders and Sorted properties are set to True, and the SortType property has a value other than None.

Move the columns that are used to sort by to the selection list. The and buttons are used to change sorting direction by the selected column. The and the buttons are used to change the sorting order. Columns at the top of the list are sorted first.

In the Fore language, to apply sorting, set the Sorted property to True, and the SortType property must have a value other than None. The column, which data is sorted, is specified in the SortColumn property. Sorting direction is determined in the SortAscending property of the corresponding column.

The Sort and SortDefault methods can also be used to manage sorting.

Example

Properties of the TreeCombo Component

	Property name	Brief description
	Align	The Align property determines behavior of the component when its parent component is resized.
	AllowDrag	The AllowDrag property determines whether an object can be dragged from the component.
	AllowDrop	The AllowDrop property determines whether the component can accept a dragged object.
	Anchors	The Anchors property returns settings that determine the percentage of the size change for the current component when the parent component is resized.
	AnimationType	The AnimationType property determines a type of animation to be used when component's combobox is expanded.
	AutoCheckParent	The AutoCheckParent property determines whether the parent nodes of the component automatically receive an indefinite state if not all of the child elements are selected.
	AutoUpdateInfo	The AutoUpdateInfo property determines whether information on selection is automatically refreshed in the component editor.
	BorderStyle	The BorderStyle property determines a component border style.
	Brush	The Brush property determines the brush that is used to fill component area.
	CancelOnEscape	The CancelOnEscape property determines whether selection is canceled, and the list is closed when the ESC key is pressed.
	Checkboxes	The Checkboxes property determines whether elements have checkboxes.
	ClientHeight	The ClientHeight property is used to receive or specify the height of the component’s client area.
	ClientWidth	The ClientWidth property is used to receive or specify the width of the component’s client area.
	CloseOnClick	The CloseOnClick property determines whether the list is automatically closed when one of the elements is selected with a mouse click.
	CloseOnEnter	The CloseOnEnter property determines whether the list is closed, and the selection is saved when the ENTER key is pressed.
	Color	The Color property determines a component background color.
	ColumnClick	The ColumnClick property determines whether column headers can be displayed as buttons.
	Columns	The Columns property returns the component columns collection.
	ComponentCount	The ComponentCount property returns the number of child components.
	Components	The Components property returns the child component.
	Cursor	The Cursor property determines the look of the cursor over the component.
	CustomMultiselectText	The CustomMultiselectText property determines whether a custom template is used to form component text on multiple selection.
	CustomMultiselectTextTemplate	The CustomMultiselectTextTemplate property determine the template, according to which component text will be formed on multiple selection.
	Data	The Data property is used to store any custom data.
	Dropped	The Dropped property returns the status of the drop-down list.
	DroppedListHeight	The DroppedListHeight property determines height of the component's drop-down list.
	DroppedListWidth	The DroppedListWidth property determines width of the component's drop-down list.
	DroppedPopupMenu	The DroppedPopupMenu property determines the context menu, which is opened in the area of the components's drop-down list.
	DropTargetNode	The DropTargetNode property determines the component node, over which the user is currently dragging another node.
	Enabled	The Enabled property determines whether the component is available for the user.
	EnableFindDialog	The EnableFindDialog property determines whether the standard element search dialog box opens on pressing CTRL+F or F3.
	FilterStyle	The FilterStyle property determines a mode of creating a tree of filtered elements.
	FindEditVisible	The FindEditVisible property determines whether a search field is displayed when the component drop-down list is expanded.
	FindMode	The FindMode property determines a mode of marking found elements.
	Focused	The Focused property returns True if the focus is set on the component.
	FocusedNode	The FocusedNode property determines the node, which is currently focused.
	Font	The Font property determines the set of characteristics describing the font that is used to display text.
	GridLines	The GridLines property determines whether a grid is displayed.
	HeaderMenu	The HeaderMenu property determines the context menu opened by clicking the component column header with the additional mouse button.
	Height	The Height property determines component height.
	HelpContext	The HelpContext property determines a unique index for the context help section for this component.
	HideSelection	The HideSelection property determines whether the selected component element remains selected when the focus moves to another component.
	HighlightTrack	The HighlightTrack property determines whether to highlight element on mouseover.
	Hint	The Hint property determines a component tooltip text.
	HotTrack	The HotTrack property determines whether the elements are underlined on mouseover.
	HotTrackAutoExpand	The HotTrackAutoExpand property determines whether the state of child elements tree is changed on clicking the selected element.
	Images	The Images property contains a list of images used for nodes rendering.
	InnerRoot	The InnerRoot property returns parameters of inner root node of the tree.
	Left	The Left property determines the coordinate of the left border of the component.
	Locked	The Locked property determines whether it is possible to change selection and edit component elements.
	Name	The Name property determines a component name.
	Nodes	The Nodes property returns the component elements collection.
	Parent	The Parent property determines a parent component.
	ParentColor	The ParentColor property determines whether the component inherits the color of the parent component.
	ParentFont	The ParentFont property determines whether the component uses the font of the parent component.
	ParentShowHint	The ParentShowHint property determines whether a tooltip is displayed.
	PopupMenu	The PopupMenu property determines the context menu opened by clicking the component with the additional mouse button.
	ReadOnly	The ReadOnly property determines whether elements are available for editing.
	RowSelect	The RowSelect property determines whether the whole row is highlighted when an element is selected.
	Scrolls	The Scrolls property returns parameters of component's scrollbars.
	Selected	The Selected property determines the last selected tree element.
	Selection	The Selection property returns the tree element selection.
	SelectionMode	The SelectionMode property determines a mode of selecting component elements.
	ShowButtons	The ShowButtons property determines whether expand/collapse child elements buttons are displayed.
	ShowColumnHeaders	The ShowColumnHeaders property determines whether column headers are displayed.
	ShowEditImage	The ShowEditImage property determines whether the icon element is displayed in the component editor.
	ShowHint	The ShowHint property enables and disables showing a component tooltip.
	ShowHints	The ShowHints property determines whether tooltips are displayed when the mouse cursor hovers over elements.
	ShowLines	The ShowLines property determines whether the line connecting a node with its children is displayed.
	ShowSystemHints	The ShowSystemHints property determines whether a system tooltip is displayed for different component elements.
	SortColumn	The SortColumn property determines index of the column, by which sorting is executed.
	Sorted	The Sorted property determines whether it is possible to execute sorting by the column specified in the SortColumn property.
	SortType	The SortType property determines a component sorting type.
	StateImages	The StateImages property determines a source of icons for the selected elements.
	TabOrder	The TabOrder property determines the component position in the tab order.
	TabStop	The TabStop property determines whether the component is focused when the TAB key is pressed.
	Tag	The Tag property is not used by the compiler. The user can change the value of the Tag property and use it as he wishes.
	Text	The Text property determines the row identifying a component for the user.
	Top	The Top property determines the coordinate of the top border of the component.
	Visible	The Visible property determines visibility of the component during execution.
	Width	The Width property determines component width.

Methods of the TreeCombo Component

	Method name	Brief description
	AdjustDroppedListWidth	The AdjustDroppedListWidth property adjusts width of the component's drop-down list.
	AdjustWidth	The AdjustWidth method is used to automatically fit a column based on its contents.
	BringToFront	The BringToFront method brings a component to front.
	ClientToScreen	The ClientToScreen method converts the coordinates of a point specified relative to the component coordinate system into screen coordinates.
	DoDragDrop	The DoDragDrop method enables to start dragging operation.
	DropDown	The DropDown method expands the drop-down list.
	GetImage	The GetImage method returns a graphic presentation of a component together with all child components.
	GetItemAt	The GetItemAt method checks if the node is in the specified point of component client area.
	HitTest	The HitTest method checks if element is in the specified point of component client area.
	RollUp	The RollUp method collapses the drop-down list.
	ScreenToClient	The ScreenToClient method converts screen coordinates of a point into coordinates specified relative to the component coordinate system.
	SendToBack	The SendToBack method sends a component to back.
	SetFocus	The SetFocus method sets focus to this component.
	Sort	The Sort method sorts by the values of the specified column.
	SortDefault	The SortDefault method executes sorting by the contents of the column, which index is specified in the SortColumn property.
	UpdateInfo	The UpdateInfo method updates data.

Events of the TreeCombo Component

	Event name	Brief description
	OnAdded	The OnAdded event occurs when a new element is added.
	OnBeginDrag	The OnBeginDrag event occurs for a component when the user starts to drag an object from the component.
	OnBeginFilter	The OnBeginFilter event occurs at the start of filtering of component elements list.
	OnBeginSearch	The OnBeginSearch event occurs when elements are started to be searched in the component.
	OnChecked	The OnChecked event occurs when the element checkbox is selected.
	OnChecking	The OnChecking event occurs when the element checkbox is selected.
	OnClick	The OnClick event occurs if the user clicks the component area.
	OnCollapsed	The OnCollapsed event occurs after collapsing the hierarchy of the tree node children.
	OnCollapsing	The OnCollapsing event occurs before collapsing the hierarchy of tree node children.
	OnColumnClick	The OnColumnClick event occurs on mouse click on the component column header.
	OnCompareItems	The OnCompareItems event occurs during comparison of two elements during custom element sorting.
	OnDblClick	The OnDblClick event occurs if the user double-clicks the component area.
	OnDeleting	The OnDeleting event occurs when the element is deleted.
	OnDragDrop	The OnDragDrop event occurs for the component if the user drops a dragged object over it.
	OnDragEnter	The OnDragEnter event occurs when a dragged object crosses the borders of this component.
	OnDragLeave	The OnDragLeave event occurs when a dragged object leaves the borders of this component.
	OnDragOver	The OnDragOver event occurs for the component when the user drags an object over it.
	OnDropDown	The OnDropDown event occurs on expanding the component list.
	OnEdited	The OnEdited event occurs on exiting the mode of editing the contents of the component current record field.
	OnEditing	The OnEditing event occurs when switching to the mode of editing the field contents of the current component record.
	OnEnter	The OnEnter event occurs when the component receives focus.
	OnExit	The OnExit event occurs when the component loses focus.
	OnExpanded	The OnExpanded event occurs after expanding the hierarchy of tree node children.
	OnExpanding	The OnExpanding event occurs directly before expanding the tree node children hierarchy.
	OnFilter	The OnFilter event occurs after the components list is filtered.
	OnFocusedChanged	The OnFocusedChanged event occurs when the focus is moved to another component element.
	OnFocusedChanging	The OnFocusedChanged event occurs before the focus is moved to another component node.
	OnGetHint	The OnGetHint event occurs when a tooltip is displayed over the element, over which the mouse cursor is hovered.
	OnGetNodeImage	The OnGetNodeImage event occurs on determining an image near the tree element.
	OnGetNodeStateImage	The OnGetNodeStateImage event occurs on determining the state images near the tree element.
	OnHover	The OnHover event occurs when the mouse cursor hovers over the element and this component element is underlined.
	OnHScroll	The OnHScroll event occurs when horizontal scrollbar slider changes its position.
	OnKeyDown	The OnKeyDown event occurs if the component is focused and a keyboard key is pressed.
	OnKeyPress	The OnKeyPress event occurs if the component is focused when the user presses a character key.
	OnKeyPreview	The OnKeyPreview event occurs prior to each event related to key pressing.
	OnKeyUp	The OnKeyUp event occurs if the component is focused and the user releases any button previously pressed.
	OnMouseDown	The OnMouseDown event occurs if the pointer is in component's area and a mouse key is pressed.
	OnMouseEnter	The OnMouseEnter event occurs when mouse cursor enters the component area.
	OnMouseHover	The OnMouseHover event occurs when mouse cursor is held in the component area.
	OnMouseLeave	The OnMouseLeave event occurs when mouse cursor leaves the component area.
	OnMouseMove	The OnMouseMove event occurs on moving the cursor over component.
	OnMouseUp	The OnMouseUp event occurs on releasing mouse button when the cursor is in component area.
	OnMouseWheel	The OnMouseWheel event occurs if the component is focused when the mouse wheel is rotated.
	OnRollUp	The OnRollUp event occurs when the component list is collapsed.
	OnSearch	The OnSearch event occurs after the element search in the component is finished.
	OnSelected	The OnSelected event occurs after selecting a node.
	OnSelecting	The OnSelecting event occurs before selecting a node.
	OnSelectionChanged	The OnSelectionChanged event occurs when the component element selection is changed.
	OnUnselected	The OnUnselected event occurs after deselecting a node.
	OnUnselecting	The OnUnselecting event occurs before deselecting an element.
	OnVScroll	The OnVScroll event occurs when vertical scrollbar slider changes its position.