[Overview][Constants][Types][Classes][Procedures and functions][Variables][Index] Reference for unit 'Controls' (#lcl)

TDragImageList

[Properties (by Name)] [Methods (by Name)] [Events (by Name)]

A list of Images used in dragging.

Declaration

Source position: controls.pp line 339

type TDragImageList = class(TCustomImageList) end;

protected

  class procedure WSRegisterClass; override;

  procedure Initialize; override;

  

Initialize - sets up the list

public

  function BeginDrag();

  

Start dragging an image; returns True if successful.

  function DragLock();

  

Show drag image during drag operation.

  function DragMove();

  

Show the image at a new location.

  procedure DragUnlock;

  

Hide the drag image.

  function EndDrag;

  

Finish dragging of the image, restore the old cursor shape.

  function GetHotSpot; override;

  

Returns the offset from the drawing position to the image origin.

  procedure HideDragImage;

  

Hide the dragged image without unlocking the window.

  function SetDragImage();

  

Set index of dragged image and hotspot.

  procedure ShowDragImage;

  

Display the drag image.

  property DragCursor: TCursor; [rw]

  

The cursor shape to use while dragging.

  property DragHotspot: TPoint; [rw]

  

The position of the image HotSpot, i.e. the offset to the mouse position while dragging.

  property Dragging: Boolean; [r]

  

True if dragging in progress.

Inheritance

TDragImageList

  

A list of Images used in dragging.

|

TCustomImageList

  

Base class for TImageList (not the same as a TBitmap collection)

|

TLCLReferenceComponent

  

Base class for all components having an associated widget.

|

TLCLComponent

  

The base class for LCL components associated with widgets.

|

TComponent

?

TObject

Description

A drag image is shown when a DragImageList is supplied at all, and when no accepting target is under the mouse, or the source control style includes csDisplayDragImage, or AlwaysShowDragImage is set in the DragObject.

In drag-dock operations typically no drag image is shown, since the DockRect frame already gives all required visual feedback.

This is a vague idea of the usage of this class:

SetDragImage selects an image from the list, and defines the hotspot within this image.
  (the hotspot typically is the offset of the mouse position to the origin of the dragged control)

BeginDrag starts dragging, the image is shown at the starting location.

DragMove moves the image.

EndDrag stops dragging, the image is removed from the screen.
The latest version of this document can be found at lazarus-ccr.sourceforge.net.