Question

Basically I want an activity indicator that will show at a glance that there is an active calculation in progress on that tab. I’m looking for something very simple, like showing a gif on the tab, or showing a sequence of strings that change with a timer. I don’t want a complicated solution or a solution that requires new components.

I already have an implementation, but I’m having a problem with it that I’m asking for a more specific solution to here: How to show backslash in a japanese locale

In the case that there isn’t a solution to the other problem, or that there is a significantly better way to do this, I am asking the more general question. In any case, I’m sure that there will be others that could use a good way to do this.

Answer 1

Update :

The simplest way is probably this :

• Add an TImageList to your form.
• Add your animation images to the image list.
• Set the constant cMaxImageIndex to the last index of the animated list.
• Connect the ImageList to the TPageControl.
• Declare a function NextImageIndex.
• Activate the timer when appropriate.
• In the timer event, set the tabsheet ImageIndex property.

See code :

Const
  cMaxImageIndex = 5;

procedure TForm1.FormCreate(Sender: TObject);
begin
  FImageIndex := 0;
end;

function TForm1.NextImageIndex: Integer;
begin
  Inc(FImageIndex);
  if (FImageIndex > cMaxImageIndex) then FImageIndex:= 0;
  Result := FImageIndex;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  PageControl1.Pages[0].ImageIndex := NextImageIndex;
end;

Note : Before activating the timer, set FImageIndex to zero, and when work is done you might also have some logic to have a default image for the tab.