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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 1200 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 800 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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0
 
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
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LVL 5

Author Comment

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