Event order - Error in the Wiki?

[simone]

The following wiki: http://wiki.freepascal.org/Event_order

states that typical event order for forms is:

OnCreate => OnShow => OnActivate => OnPaint => OnResize => OnPaint => ...

I do some experiments and It seems to me that the real sequence is:

OnCreate => OnResize => OnShow => OnActivate => OnPaint  => OnResize => OnPaint => ...

Is my result correct? Thanks in advance.

[Thaddy]

This is platform dependent. And between the create and the actual paint you should not make assumptions that affect display. Hence "typically". Under normal circumstances that is the case, but event messages, specifically "posted" can be ignored or processed out of order by the OS.
So in your case take some precautions if you use onresize: don't make assumptions regarding input/output and size. Anything else should be safe.

[zeljko]

The following wiki: http://wiki.freepascal.org/Event_order

states that typical event order for forms is:

OnCreate => OnShow => OnActivate => OnPaint => OnResize => OnPaint => ...

I do some experiments and It seems to me that the real sequence is:

OnCreate => OnResize => OnShow => OnActivate => OnPaint  => OnResize => OnPaint => ...

Is my result correct? Thanks in advance.

Lazarus version ? Operating system ? Widgetset ? 32 or 64bit ?

[simone]

I thought this behavior was platform independent... I apologize... I did my experiments with Windows 8.1, Lazarus 1.6.4 32bit, win32 widgetset.

In debugging my application I had some doubt, so I write the following simple test program to understand what happens behind the scenes (before compiling I disabled checkbox for win32 gui application, to see output in console):

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     procedure FormActivate(Sender: TObject);
16.     procedure FormCreate(Sender: TObject);
17.     procedure FormPaint(Sender: TObject);
18.     procedure FormResize(Sender: TObject);
19.     procedure FormShow(Sender: TObject);
20.   private
21.     { private declarations }
22.   public
23.     { public declarations }
24.   end;
25.  
26. var
27.   Form1: TForm1;
28.  
29. implementation
30.  
31. {$R *.lfm}
32.  
33. { TForm1 }
34.  
35. procedure TForm1.FormActivate(Sender: TObject);
36. begin
37.   Writeln('FormActivate');
38. end;
39.  
40. procedure TForm1.FormCreate(Sender: TObject);
41. begin
42.   Writeln('FormCreate');
43. end;
44.  
45. procedure TForm1.FormPaint(Sender: TObject);
46. begin
47.   Writeln('FormPaint');
48. end;
49.  
50. procedure TForm1.FormResize(Sender: TObject);
51. begin
52.   Writeln('FormResize');
53. end;
54.  
55. procedure TForm1.FormShow(Sender: TObject);
56. begin
57.   Writeln('FormShow');
58. end;
59.  
60. end.