55 Votes

Delphi/Lazarus: Delete selected items with DEL-key from ListView

Tip by Delphian | 2013-10-05 at 13:11

Having a TListView with some selected items in Delphi or Lazarus and pressing the "DEL" or "DELETE" key on the keyboard, first of all, nothing happens.

So, what can be do to implement this function of deleting the marked entries from our ListView? We have to add the following code to the OnKeyDown Event of the ListView:

procedure Tprog.ListView1KeyDown(Sender: TObject; var Key: Word; 
Shift: TShiftState);
var
  i: integer;
begin
  if key = $2E then begin
     ListView1.Items.BeginUpdate;
     for i := ListView1.Items.Count - 1 downto 0 do
       if ListView1.Items[i].Selected then ListView1.Items.Delete(i);
     ListView1.Items.EndUpdate;
  end;
end;

First, we have to look at which button has been pressed. If it is the delete button (this key has a value of $2E), we have to go through all entries currently marked (selected) in order to delete them one by one.

Here, it is important to go through the items in reverse order (downto loop). The reason is because otherwise, when deleting some entries at the beginning, the number of indices of the items actually in the ListView are no more matching our number of items in the loop.

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