Drag Starting? Event

Requires: Base Development System

Type: Filter

Generated when you start a drag from a listbox control.

Use this event to signal when a drag and drop operation begins from a specific control. This event is generated only when LabVIEW begins a drag and drop operation on a listbox control. You can use the Start Drag method to begin a drag from other controls.

Example

Event Data Fields

Name

Description

Source

Source of the event. LabVIEW UI refers to any built-in user interface event.

0	LabVIEW UI

Type

Type of event that occurred, such as Mouse Down, Value Change, Timeout, and so on.

Time

Value of the millisecond timer when the event occurred.

CtlRef

Reference to the control on which the event occurred.

Coords

Coordinates of the location of the mouse click at the time the event occurs. Coordinates are relative to the drop target's owning pane origin, excluding clusters.

Button

Value that corresponds to which mouse button the user clicked. Left mouse button is 1, right mouse button is 2. Operating systems might assign higher numbers if you have a mouse with more than two buttons. For filter events, you can modify the data returned by this event data field.

Mods

Cluster of Booleans that contain platform-independent modifiers. LabVIEW returns all platform-dependent modifiers in the PlatMods event data field. For key events, this event returns a Boolean indicating if the event occurred on the numeric keypad. For mouse events, this event returns a Boolean indicating if the event was a double-click. For both events, a Boolean is returned if the platform-independent menu key, such as <Ctrl> on Windows or <Command> on macOS, was pressed when the event occurred. For filter events, you can modify the data returned by this event data field.

PlatMods

Cluster of Booleans that contain platform-dependent modifiers. Specifies if platform-dependent keys, such as <Ctrl>, <Shift>, <Alt>, <Command>, and <Option> were held down when the event was triggered. For filter events, you can modify the data returned by this event data field. A key can be both a Mod and PlatMod. For example, <Ctrl> is the platform-independent menu key on Windows, but you also can use it in platform-dependent programming.

Drag Data

Indicates the data provided during the drag and drop operation. For filter events, you can modify this field to provide your own custom data for the drag and drop operation. You cannot use the prefix LV_ on a user-defined data name, because it is reserved for LabVIEW data types. You can use the built-in LabVIEW data types and names.

LabVIEW Data Type	Description
LV_TEXT	String
LV_TREE_TAG	String
LV_TREE_ITEMS	Array of a cluster containing an array of strings, from left to right, in the item you are dragging, an integer representing the glyph index associated with the item from which you are dragging data, and an integer representing the indent level of the item from which you are dragging.
LV_LISTBOX	Cluster containing an array of strings from the row that you are dragging data and an integer representing the glyph index associated with the row from which you are dragging data.
LV_LISTBOX_ITEMS	Array of a cluster containing an array of strings, from left to right, in the item you are dragging and an integer representing the glyph index associated with the item from which you are dragging data.
LV_PATH	Path

Drag Mode

Specifies the operations that this control supports during the drag, such as copy or move, copy only, move only. If you select copy or move, pressing the <Ctrl> key copies the item. The operations you support control the values that the Results output of the Drag Ended and Drag Source Update events can provide.

For filter events, you can modify this field to change the drag mode when this event is generated.

Discard?

Allows you to prevent LabVIEW from processing the event, bypassing the behavior normally triggered by that event. The default is FALSE.

Example

Refer to the Drag and Drop - Passing Custom Drag Data VI in the labview\examples\Structures\Event Structure directory for an example of using the Drag Starting? event.

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