How to pause program execution until button press?

Question

I've got an algorithm. I'd like to pause it at some point and then continue once the user presses a button. How do I do that? I've browsed the documentation, and searched the internet, but no luck yet.

Here's a relevant code snip:

      if A[i]>A[i+1]
        then
          begin
            Zameni(i,i+1);
            done:=true;

            sleep(pauza);

            br:=br+1;
          end;

Right now, I use sleep (pauza is just a constant, means pause in Serbian). Ideally, I'd like to replace that line with a procedure which would sleep for the interval, or wait for a button press based on a configuration setting.

EDIT1: Ah yes, if it wasn't obvious - it's a graphics application, not console, so slapping a "readln" won't work (sadly).

Answer 1

That's not how you do event-driven programming. You should do the processing up to the pause point and end your function at that point. In a button press event handler you then do the remainder of the processing - this will only happen when the user presses the button. You can call the same code from an OnTimer event to continue the processing after a given peruiod.

Answer 2

I wouldn't recommend it as good application design, but if none of the other suggestions are suitable for you, you may prefer this.

Add a 'Paused: Boolean' field to your class/form, and a 'Continue' button.

When you start the operation, set Paused to False, and Continue.Enabled := False;

When your code reaches the section where you want to pause:

Paused := True;
Continue.Enabled := True;
while Paused do
begin
  sleep(100);
  Application.ProcessMessages;
end;

In your Continue buttons event handler:

procedure Form1.ContinueClick(Sender: TObject);
begin
  Paused := False;
  Continue.Enabled := False;
end;

As I said before, not pretty, but it should get the job done.