How to Move ListBox Items with the Mouse

本是古典何须时尚 2021-11-29 11:34 195阅读 0赞

The TListBox Delphi component displays a collection of items in a scrollable list. Delphi makes it easy to program [dragging and dropping][] into your applications.

Here's how to allow a user to rearrange (change item's position) the items of a ListBox using drag and drop:

1.  Drop a TListBox (named *ListBox1*) on a form
2.  Add several strings using the Items property
3.  Set ListBox1's DragMode to dmAutomatic (in Form's OnCreate or using Object Inspector at design-time).
4.  Handle LisBox-es MouseDown, DragOver and DragDrop events

> **var** *// form level*  
> StartingPoint : TPoint;  
>   
> **implementation**  
>   
> ...  
>   
> **procedure** TForm1.FormCreate(Sender: TObject) ;  
> **begin**  
> ListBox1.DragMode := dmAutomatic;  
> **end**;  
>   
> **procedure** TForm1.ListBox1DragDrop(Sender, Source: TObject; X, Y: Integer) ;  
> **var**  
> DropPosition, StartPosition: Integer;  
> DropPoint: TPoint;  
> **begin**  
> DropPoint.X := X;  
> DropPoint.Y := Y;  
> **with** Source **as** TListBox **do**  
> **begin**  
> StartPosition := ItemAtPos(StartingPoint,True) ;  
> DropPosition := ItemAtPos(DropPoint,True) ;  
>   
> Items.Move(StartPosition, DropPosition) ;  
> **end**;  
> **end**;  
>   
> **procedure** TForm1.ListBox1DragOver(Sender, Source: TObject; X, Y: Integer; State: TDragState; **var** Accept: Boolean) ;  
> **begin**  
> Accept := Source = ListBox1;  
> **end**;  
>   
> **procedure** TForm1.ListBox1MouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer) ;  
> **begin**  
> StartingPoint.X := X;  
> StartingPoint.Y := Y;  
> **end**;

How to Move ListBox Items with the Mouse

转载于:https://www.cnblogs.com/tecsoon/archive/2009/06/04/1496286.html

[dragging and dropping]: http://delphi.about.com/od/vclusing/a/dragdrop.htm