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Drag Up or Down Position of a Listview Entry

Posted on 2009-05-14
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Last Modified: 2012-05-07
Hi I'd like to be able to move a listview item up and down the listview. is there anyway of doing this with a mouse or button?

for example, to rearrange the items in an order of choice.
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Question by:eNarc
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10 Comments
 
LVL 12

Accepted Solution

by:
Hypo earned 300 total points
ID: 24386537
Hi,
I don't know if there is any way to alter the index of a ListItem, at least It doesn't seem to at first glance, and maybe that's because the ListView is tightly connected to the WinAPI. Anyway, If you can handle that the ListItems will be destroyed and then recreated when moved, then you could move the items with drag n drop. See the example below, it shows you how you can move the items by deleting and recreating the items.

regards
Hypo.
unit Unit1;
 

interface
 

uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, ComCtrls;
 

type

  TForm1 = class(TForm)

    procedure ListViewDragOver(Sender, Source: TObject; X, Y: Integer; State: TDragState; var Accept: Boolean);

    procedure ListViewDragDrop(Sender, Source: TObject; X, Y: Integer);

    procedure FormCreate(Sender: TObject);

  private

    { Private declarations }

  public

    { Public declarations }

  end;
 

var

  Form1: TForm1;
 

implementation
 

{$R *.dfm}
 

procedure TForm1.FormCreate(Sender: TObject);

var i : Integer;

    aListView : TListView;
 

begin

  // ListViewA

  aListView := TListView.Create(Self);

  aListView.Parent := Self;

  aListView.BoundsRect := Rect(10, 10, 200, 300);

  aListView.ViewStyle := vsReport;

  aListView.DragMode := dmAutomatic;

  aListView.OnDragOver := ListViewDragOver;

  aListView.OnDragDrop := ListViewDragDrop;

  aListView.MultiSelect := True;

  for i := 0 to 5 do

    aListView.Items.Add.Caption := 'ListViewA '+IntToStr(Random(100));

  With aListView.Columns.Add do begin

    Width := 100;

    Caption := 'Items';

  end;
 

  // ListViewB

  aListView := TListView.Create(Self);

  aListView.Parent := Self;

  aListView.BoundsRect := Rect(210, 10, 420, 300);

  aListView.ViewStyle := vsReport;

  aListView.DragMode := dmAutomatic;

  aListView.OnDragOver := ListViewDragOver;

  aListView.OnDragDrop := ListViewDragDrop;

  aListView.MultiSelect := True;

  for i := 0 to 5 do

    aListView.Items.Add.Caption := 'ListViewA '+IntToStr(Random(100));

  With aListView.Columns.Add do begin

    Width := 100;

    Caption := 'Items';

  end;

end;
 

procedure TForm1.ListViewDragOver(Sender, Source: TObject; X, Y: Integer; State: TDragState; var Accept: Boolean);

begin

  Accept := (Sender is TListView) and (Source is TListView);

end;
 

procedure TForm1.ListViewDragDrop(Sender, Source: TObject; X, Y: Integer);

var i : Integer;

    aItem : TListItem;

    aTarget : TListView;

    aSource : TListView;

    aSelected : TList;

begin

  aSelected := TList.Create;

  try

    aTarget := Sender as TListView;

    aSource := Source as TListView;
 

    aTarget.Items.BeginUpdate;

    aSource.Items.BeginUpdate;

    // Extract what items are selected...

    for i := 0 to aSource.Items.Count-1 do

      if aSource.Items[i].Selected then

        aSelected.Add(aSource.Items[i]);

    // Get what position item we will above at...

    aItem := aTarget.GetItemAt(X, Y);
 

    // Move items to new listview...

    if Assigned(aItem) then begin

      for i := 0 to aSelected.Count-1 do

        aTarget.Items.Insert(aItem.Index).Assign(aSelected[i]);

    end else begin

      for i := 0 to aSelected.Count-1 do

        aTarget.Items.Add.Assign(aSelected[i]);

    end;

    // Remove source items...

    for i := 0 to aSelected.Count-1 do

      TObject(aSelected[i]).Free;
 

    aItem := aTarget.GetItemAt(X, Y);

    if Assigned(aItem) then

      aItem.Focused := True;

  finally

    aSource.Items.EndUpdate;

    aTarget.Items.EndUpdate;

    aSelected.Free;

  end;

end;
 

end.

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LVL 1

Assisted Solution

by:KillerCode
KillerCode earned 200 total points
ID: 24388599
maybe this will help



function MoveListViewItem(ListView: TListView; ItemFrom, ItemTo: Word): Boolean;

var

  Source, Target: TListItem;

begin

  listview.Items.BeginUpdate;

  try

    Source := ListView.Items[ItemFrom];

    Target := ListView.Items.Insert(ItemTo);

    Target.Assign(Source);

    Target.Selected := True;

    Source.Free;

    Result := True;

  finally

    ListView.Items.EndUpdate;

  end;

end;
 

//Move Down

 if ListView1.Selected <> nil then

  MoveListViewItem(ListView1, ListViewIP1.Selected.Index, ListView1.Selected.Index + 2);
 

//Move Up

 if ListView1.Selected <> nil then

  MoveListViewItem(ListView1, ListView1.Selected.Index, ListView1.Selected.Index -1);

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LVL 5

Author Comment

by:eNarc
ID: 24388661
wow not only does your code drag it also able to drag it into another listview :D thankyou thankyou thankyou :D

I searched "ListViewDragDrop" on google and found this

http://delphi.about.com/od/vclusing/a/arrangelistview.htm

and I thought it would be relevant to add this for future :D
0
 
LVL 5

Author Comment

by:eNarc
ID: 24388797
oh no, I need an admin to fix this I made a mistake when finalizing.
0
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LVL 5

Author Comment

by:eNarc
ID: 24389223
how does one use that code KillerCode? were do I put it?
0
 
LVL 1

Expert Comment

by:KillerCode
ID: 24389275
u can add it to 2 Buttons next to the listview, or in a PopUpMenu, ill see what i can do with ur other topic now
0
 
LVL 1

Expert Comment

by:KillerCode
ID: 24389357
or thats another thing??
if i didnt get what u mean explain me more plz
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LVL 12

Expert Comment

by:Hypo
ID: 24389651
Ohh, ok... but you got it to work at least?
/Hypo
0
 
LVL 5

Author Comment

by:eNarc
ID: 24399807
thanks coolleomod :D


Hypo: hell yea it works :D it was awesome your code its does exactly what I ask :D being able to move the items from 1 listview to the other is wow! I totally can use that in other apps too :D thankyou thankyou thankyou

KillerCode: your code works too, and is great, I love functions they do make everything easier, almost everything I've coded has a function makes everything a complete package :D

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