Class TreeViewAdvDragHighlightTracker

Represents the drag and drop UI helper class of TreeViewAdv.

Inheritance

System.Object

TreeViewAdvDragHighlightTracker

Implements

System.IDisposable

Inherited Members

System.Object.ToString()

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

Namespace: Syncfusion.Windows.Forms.Tools

Assembly: Syncfusion.Tools.Windows.dll

Syntax

public class TreeViewAdvDragHighlightTracker : IDisposable, ITreeNodeAdvPaintFilter

Remarks

Use this class (will be referred to as "tracker" below) only when you want to support dropping adjacent (above or below) to a node. Otherwise simply listen to the System.Windows.Forms.Control.DragOver and System.Windows.Forms.Control.DragDrop events and provide/use the . When used, this tracker will draw indicators above or below a node while dragging an item over the node. The tracker needs to be updated as shown below in the DragXXX events.

The usage semantics for the tracker is as follows:

1. Create an instance of this class and listen to the QueryAllowedPositionsForNode event.
2. In the TreeViewAdv's DragOver event update the highlighted node with a call to the SetHighlightNode(TreeNodeAdv, Point) method.
3. In the TreeViewAdv's DragLeave event clear the highlighted node with a call to the ClearHighlightNode() method.
4. In the QueryAllowedPositionsForNode event handler, specify whether a computed adjacent position should be allowed.
5. In the TreeViewAdv's DragDrop event get the highlighted node and the drop-position from the tracker and insert the new node(s) accordingly.

Examples

Please take a look at our sample in the ..\Essential Tools\Samples\Tree Package\TreeViewAdvDragDrop folder for more information.

Constructors

TreeViewAdvDragHighlightTracker(TreeViewAdv)

Initialize a new instance of the TreeViewAdvDragHighlightTracker class.

Declaration

public TreeViewAdvDragHighlightTracker(TreeViewAdv tree)

Parameters

Type	Name	Description
TreeViewAdv	tree	The TreeViewAdv instance where drag-and-drop will occur.

Properties

DropPosition

Gets the computed drop-position around the highlight node.

Declaration

public TreeViewDropPositions DropPosition { get; }

Property Value

Type	Description
TreeViewDropPositions

EdgeSensitivity

This property will soon be replaced by the and properties, please use them instead.

Declaration

[Obsolete("This property will soon be replaced by the EdgeSensitiviyOnTop and EdgeSensitiviyAtBottom properties, please use them instead.")]
public int EdgeSensitivity { get; set; }

Property Value

Type	Description
System.Int32	Default is zero.

EdgeSensitivityAtBottom

Gets or sets a height for the bottom edge of a node while dragging over.

Declaration

public int EdgeSensitivityAtBottom { get; set; }

Property Value

Type	Description
System.Int32	Default is -1.

Remarks

By default (when value is negative), the bottom 1/3 of the node will be considered the bottom edge. This value will be used when you allow dropping below a node using the AllowedPositions property. Set this to zero if you never want to drop below a node.

EdgeSensitivityOnTop

Gets or sets a height for the top edge of a node while dragging over.

Declaration

public int EdgeSensitivityOnTop { get; set; }

Property Value

Type	Description
System.Int32	Default is -1.

Remarks

By default (when value is negative), the top 1/3 of the node will be considered the top edge. This value will be used when you allow dropping before a node using the AllowedPositions property. Set this to zero if you never want to drop on top of a node.

HighlightNode

Gets the node over which the mouse is hovering for drop.

Declaration

public TreeNodeAdv HighlightNode { get; }

Property Value

Type	Description
TreeNodeAdv

WaitTimeBeforeExpand

Gets or sets the time interval after which a node will be expanded on mouse hover during drag and drop.

Declaration

public int WaitTimeBeforeExpand { get; set; }

Property Value

Type	Description
System.Int32	Time in milliseconds. Default is 750.

Remarks

If you do not want a node to expand on drag over, set this value to -1.

Methods

ClearHighlightNode()

Clears the current highlight node setting.

Declaration

public void ClearHighlightNode()

Remarks

Call this method from the TreeViewAdv's DragLeave and DragDrop(after you get the highlight information from the tracker class) events.

SetHighlightNode(TreeNodeAdv, Point)

Sets the node over which the mouse is currently hovering during drag-drop.

Declaration

public void SetHighlightNode(TreeNodeAdv highlightNode, Point ptInTree)

Parameters

Type	Name	Description
TreeNodeAdv	highlightNode	The new highlight node.
System.Drawing.Point	ptInTree	The point in tree where the mouse is in the tree view's client co-ordinates.

Remarks

Call this method from the TreeViewAdv's DragOver method.

Events

QueryAllowedPositionsForNode

Occurs before drawing a highlight indicator above or below a node.

Declaration

public event QueryAllowedPositionsEventHandler QueryAllowedPositionsForNode

Event Type

Type	Description
QueryAllowedPositionsEventHandler

Remarks

You can listen to this event and prevent drawing highlights for some specific nodes.

QueryDragInsertInfo

Occurs before drawing a DragInsert position.

Declaration

public event QueryDragInsertInfoEventHandler QueryDragInsertInfo

Event Type

Type	Description
QueryDragInsertInfoEventHandler

Remarks

You can listen to this event and change DragInsert highlight color.

Explicit Interface Implementations

IDisposable.Dispose()

Declaration

void IDisposable.Dispose()

Implements

System.IDisposable