Deactivate Screensaver/Power States while game is running

[Grendelus]

I've coded a simple dll in delphi in order to deactivate the screensaver when my game is running.
I can use the function _enableSSaver to activate it back when I am done, but in case of a ctrl+alt+del or a crash the screensaver won't go back to normal.
I've seen there are some tags initialization/finalization but I don't know how to use them. Is there a way to make it that the screensaver is always enabled when the dll is unloaded (freed)?

Here is my code:

[pascal]library screenhndl;

uses
Windows,
Messages,
SysUtils;

function _disableSSaver : pchar; stdcall;
begin
SystemParametersInfo(SPI_SETSCREENSAVEACTIVE,0,0,0 );
SystemParametersInfo(SPI_SETPOWEROFFACTIVE,0,0,0);
SystemParametersInfo(SPI_SETLOWPOWERACTIVE,0,0,0);
end;

function _enableSSaver : pchar; stdcall;
begin
SystemParametersInfo(SPI_SETSCREENSAVEACTIVE,1,0,0 );
SystemParametersInfo(SPI_SETPOWEROFFACTIVE,1,0,0);
SystemParametersInfo(SPI_SETLOWPOWERACTIVE,1,0,0);
end;


exports _disableSSaver;
exports _enableSSaver;
begin end.[/pascal]

[JSoftware]

I seem to recall reading somewhere that calling changeresolution with the flag cds_fullscreen will block screensavers and power options, eg. sleep, hibernate, etc.

[WILL]

Hey, not bad. Though I think a better solution may be to have the game 'kick' the system's input queue every so often instead.

What happens when you simply set and reset these values instead of 'permanently' setting them at the start and reseting them at the end of your game? Would that result in such a 'kick' as I'm referring to?

[Huehnerschaender]

I hope you test the settings before you use your DLL calls... Otherwise, the player will have the screensaver and those other stuff enabled after he played your game, even if it was disabled before

Greetings,
Dirk

[jasonf]

I hope you test the settings before you use your DLL calls... Otherwise, the player will have the screensaver and those other stuff enabled after he played your game, even if it was disabled before

..or the Screensaver will be disabled if the game crashes and doesn't clean up properly.

Probably be better to find a less destructive way of preventing the screensaver from kicking in.

[Grendelus]

I seem to recall reading somewhere that calling changeresolution with the flag cds_fullscreen will block screensavers and power options, eg. sleep, hibernate, etc.

You are talking about exclusive mode?

The fact is that with the [pascal]initialization[/pascal] and [pascal]finalization[/pascal] tags you can automatically unload a dll and its functions even when the game has been forced quit (ctrl+alt+del) or crashed.

But I don't know how to use them. Anyone that can apply it to the code above.

[JSoftware]

no actually I was talking about ChangeDisplaySettings

[czar]

procedure WMSysCommand(var Msg : TWMSysCommand); message WM_SYSCOMMAND;

[pascal]
// SWITCH OFF THE SCREENSAVER AND THE MONITOR POWER SAVER IF THEY TRY TO CUT IN
procedure TForm1.WMSysCommand(var Msg : TWMSysCommand);
begin
//catch the message and turn it off
if (Msg.CmdType = SC_MONITORPOWER) or (Msg.CmdType = SC_SCREENSAVE) then
begin
Msg.Result := -1;
end
else
inherited;///Otherwise do whatever is supposed to be done
end;
[/pascal]


That does the trick

[Clootie]

There is also another way:
[pascal]
type
EXECUTION_STATE = DWORD;
const
ES_SYSTEM_REQUIRED = DWORD($00000001);
ES_DISPLAY_REQUIRED = DWORD($00000002);
ES_USER_PRESENT = DWORD($00000004);
ES_CONTINUOUS = DWORD($80000000);

function SetThreadExecutionState(esFlags: EXECUTION_STATE): EXECUTION_STATE; stdcall; external kernel32;

......
SetThreadExecutionState(ES_DISPLAY_REQUIRED or ES_CONTINUOUS); // this will fix current state and disable screensaver[/pascal]

[Grendelus]

Will it be compatible with most versions of the Windows including Vista?