How to add OnComplete event to bitmap.SaveToFile('img.bmp');

Question

i want to halt my application when my bitmap is completely saved?

Answer 1

Unless you are calling that method in a separate thread I'm fairly certain that it will be completely saved at the point at which the method returns:

  bitmap.SaveToFile(..);
  // file is completely saved at this point

What is it that leads you to believe that it isn't completely saved at this point?

The only wrinkle might be that with "lazy writes" Windows itself might not yet have completed the business of physically writing the file to the disc, but as far as your application (or any other application) is concerned, that is irrelevant. If you attempt to access the file before Windows has completed committing it to disc that application will simply "block" until it can safely access the file, but you don't need to specifically handle this, it "just works".

Answer 2

If you want to halt your application cleanly there are several options:

1) Close the main form. When you close the main form, the application will close.

procedure TForm1.SaveAndClose(Filename:String);
begin
  Bitmap.SaveToFile(filename);
  Application.Mainform.Close;
end;

2) Call Application.Terminate. This shuts down your application abruptly, but does run any finalization code. It is normally invoked when the application receives a WM_Quit message or the main form closes.

procedure TForm1.SaveAndClose(Filename:String);
begin
  Bitmap.SaveToFile(filename);
  Application.Terminate;
end;

3) Post wm_Close to your application/main form. This has the added advantage that any other messages in queue for the application are processed. It is equivalent to pressing CTRL-F4 or pressing the "X" in the upper right on your main form. The only issue is that if the message queue is full then it may not ever reach the form (rare).

procedure TForm1.SaveAndClose(Filename:String);
begin
  Bitmap.SaveToFile(filename);
  postMessage(Application.MainForm,wm_close,0,0):
end;

4) Call Halt( ExitCode:Integer ). This is a bit more extreme and will terminate the application. Finalization code will still be run, but memory is not guaranteed to be freed. Optionally you can set an exit code that will be returned back to the calling application.

procedure TForm1.SaveAndClose(Filename:String);
begin
  Bitmap.SaveToFile(filename);
  Halt(0);
end;