Author: Arp Dev

How to apply a time out to prevent user inactivity.

Answer:

Here a sample code that will allow you to close an application if the user is 
getting asleep while working / if he go afk for too long. 
This can be useful for program like MIRC where they use such Time-Out value. Some 
online games work like that also to prevent user to take server bandwitch, also 
coming to my mind are screensaver application or CPU cooler program. 

First declare a global constant called MaxTimeOutDelay. Affect it to some integer 
value that will represent the maximum number of seconds where your program is 
allowed to record user inactivity before taking action. 

Second, declare a variable called TimeElapsed as integer. This will keep track of 
the time elapsed since user last activity recorded. 

Third put a timer on the form. 

On the FormCreate event set the TimeElapsed to 0. 

Now declare a simple Procedure that will Reset the TimeElapsed. 

It should look like: 

1   procedure TForm1.ResetTimeElapsed;
2   begin
3     TimeElapsed := 0;
4   end;


Two event can resume in a sufficient manner the gloabl user activity. 

OnKeyDown Event 
OnMouseMove 

When the user do something the TimeElapsed is reset so for the two event the code 
will look like this. 
5   
6   procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
7     Shift: TShiftState);
8   begin
9     ResetTimeElapsed;
10  end;
11  
12  procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
13    Y: Integer);
14  begin
15    ResetTimeElapsed;
16  end;


Here the last bit of code. On timer event the TimeElapsed is incremented. In short, 
the Timer Transfer a value to the TimeElapsed variable every second (If you default 
value for timer wasn't changed). 
Than it's just a simple check to see if the TimeElapsed have reached the 
MaxTimeOutValue. 

17  procedure TForm1.Timer1Timer(Sender: TObject);
18  begin
19    Inc(TimeElapsed);
20    if TimeElapsed = MaxTimeOutValue then
21    begin
22      Timer1.Enabled := False;
23      Close;
24    end;
25  end;


This program close the application. But actually it's a lot more useful to associate the TimeOut to a more useful routine. For example you can make the computer sleep when the user didn't do anything for 15 minute, make it run in the system tray to save power/pcu usage.