I want to add a progress bar but I don't know the correct way to do it.

[AfootDesert41]

Hello programmers! I am recently working on a college project where I have to develop a GUI app that simulates a very basic supermarket cashing system without Inventory database (basically you have to make up all the items you add) that will generate a on-screen sale invoice. The thing is that I want to add a "Printing, please wait..." window with a progress bar. I've tried implementing this by myself but I've failed to do it the way I want, I added a form wich there is a Ttimer (interval:=100) with a TprogressBar Below, this is the code I made for the progress bar to show, load, end and show the final form (and close the previous one) where the invoice is supposed show:

Code: Pascal  [Select][+][-]

1. procedure TVentanaImprimiendoFactura.Timer1Timer(Sender: TObject);
2. begin
3.   ProgressBar1.Position:=ProgressBar1.Position+5;
4.   If ProgressBar1.Position=100 then
5.   VentanaFactura.Show;
6.   VentanaImprimiendoFactura.Close;
7. end;
8.  

I dont exactly know how Ttimer works, but when I try to Debug a second time and so on, the Invoice form will show seconds after I start the debug, also the form wont close when I press the X (close window button), or it closes but it opens again, I want the last form to be able to be closed so I can generate Invoices for other costumers.

[wadman]

procedure TVentanaImprimiendoFactura.Timer1Timer(Sender: TObject);
begin
  ProgressBar1.Position:=ProgressBar1.Position+5;
  If ProgressBar1.Position>=100 then begin
    Timer1.Enabled := false;
    VentanaImprimiendoFactura.Close;
    VentanaFactura.Show;
  end;
end;


I would write something like this.

[lucamar]

Explanation

With the code written as it should the first error is easier to see:

Code: Pascal  [Select][+][-]

1. procedure TVentanaImprimiendoFactura.Timer1Timer(Sender: TObject);
2. begin
3.   ProgressBar1.Position:=ProgressBar1.Position+5;
4.   If ProgressBar1.Position=100 then
5.       VentanaFactura.Show;
6.   VentanaImprimiendoFactura.Close;
7. end;

The window closes with the first timer event. It should be:

Code: Pascal  [Select][+][-]

1. TVentanaImprimiendoFactura.Timer1Timer(Sender: TObject);
2. begin
3.   ProgressBar1.Position:=ProgressBar1.Position+5;
4.   If ProgressBar1.Position=100 then
5.   begin
6.       VentanaFactura.Show;
7.       VentanaImprimiendoFactura.Close;
8.   end;
9. end;

The second error is that you didn't stop the timer, so it kept ticking away and re-executing the handler. Which makes us note the third error: the comparison ProgressBar1.Position = 100 is too restrictive: it may happen just once ... or never! P.e. suppose you started by setting it to 1.

Taking all into account we end up with wadman's more correct code:

Code: Pascal  [Select][+][-]

1. procedure TVentanaImprimiendoFactura.Timer1Timer(Sender: TObject);
2. begin
3.   ProgressBar1.Position:=ProgressBar1.Position+5;
4.   If ProgressBar1.Position >= 100 then begin
5.     Timer1.Enabled := false;
6.     VentanaImprimiendoFactura.Close;
7.     VentanaFactura.Show;
8.   end;
9. end;

HTH!

[AfootDesert41]

Thank you so much for the replies!