Mega Code Archive
Listbox items add is slow and flickers
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Adding a (larger) group of entries to a ListBox is very slow,
because after every "items.add" call the ListBox is repainted.
There are two ways to overcome this:
use the Windows message WM_SETREDRAW (see Win32.hlp for details).
The VCL provides two methods for this: BeginUpdate and EndUpdate.
I would assume that this is faster than method #2.
read the strings in a temporary TStringList object.
Maybe you already have such a list - in this case you should use your existing list.
Then use the Assign method to transfer the whole list.
Some sample code after a contribution from Bj?/a>:
// method #1
procedure TForm1.Button1Click(Sender: TObject);
var
i : integer;
begin
ListBox1.Items.BeginUpdate;
for i:=1 to maxitems do
ListBox1.Items.add(IntToStr(i));
ListBox1.Items.EndUpate;
end;
// method #2
procedure TForm1.Button2Click(Sender: TObject);
var
i : integer;
tmp: tstringlist;
begin
tmp:=TStringList.Create;
for i:=1 to maxitems do
tmp.add(inttostr(i));
ListBox1.Items.Assign(tmp);
tmp.Free;
end;
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