Solved

Win32 Timers

Posted on 1998-10-20
4
2,089 Views
Last Modified: 2009-12-04
I am programming a DirectX game in Delphi 2.0, and I want to have a timer fire off messages about 50 times a second so I can update the display and game variables. I tried the TTimer component that comes with Delphi, but the display kept "shaking" and I don't like this. Is it possible that I can utilize the timers in the Windows API? If so, how can I do this? Say I want Form1.OnUpdate to recieve the messages. How can I specify this in the Win32 SetTimer() function?
0
Comment
Question by:mmarvi
  • 2
4 Comments
 
LVL 8

Expert Comment

by:Answers2000
ID: 1343526
The WinAPI SetTimer functions uses a low precision clock.  Tick 18.2 per sec.  Too slow
0
 
LVL 4

Expert Comment

by:BoRiS
ID: 1343527
mmarvi

Here is how the SetTimer API is called in delphi...

SetTimer(Form1.Handle, WM_TIMER, 50, nil);

Later
BoRiS


0
 
LVL 5

Accepted Solution

by:
inter earned 70 total points
ID: 1343528
Here is the implementation part of correctly setting a high resolution multimedia timer, note that you can not acquire higher than your system reports, I think the code is self explanatory, anyway just ask if you stuck -I have already test the code-
regards, igor

implementation

uses
  mmsystem;

const
  TARGET_RESOLUTION = 1;         // 1-millisecond target resolution
var
  wTimerRes : UINT; //this is a global variable where we read the min timer period
  wTimerID : UINT; //id of our timer if succesfull

function Min(x,y : integer):integer;
begin
  Result := y;
  if x<y then Result := x;
end;

function Max(x,y : integer):integer;
begin
  Result := y;
  if x>y then Result := x;
end;

//obtain timer capabilities
function CheckTimerCaps:boolean;
var
 tc : TTIMECAPS;
begin
  if (timeGetDevCaps(@tc, sizeof(TTIMECAPS)) <> TIMERR_NOERROR) then
    Result := false
  else
  begin
    wTimerRes := min(max(tc.wPeriodMin, TARGET_RESOLUTION), tc.wPeriodMax);
    timeBeginPeriod(wTimerRes);
    Result := true;
  end;
end;

//this is the core called by windows
procedure TimerCallback(TimerID , msg : UINT;
      dwUser, dw1, dw2 : DWORD); stdcall;
begin
  //************ DO WHAT YOU WANT HERE **************************
end;

// setup timer event and callback
// returns false if failed
// just give the number of miliseconds you want
function SetTimerCallback(msInterval : UINT):boolean;  // event interval
begin
    wTimerID := timeSetEvent(
        msInterval,                    // delay
        wTimerRes,                     // resolution (global variable)
        TimerCallback,               // callback function
        0,                  // user data
        TIME_PERIODIC );                // single timer event

    Result := wTimerID <> 0;
end;

procedure DestroyTimer;
begin
  if(wTimerID <> 0) then// is timer event pending?
  begin
     timeKillEvent(wTimerID);  // cancel the event
     wTimerID := 0;
  end;
end;


// TRY TO START TIMER with 10 msec
procedure TForm1.Button1Click(Sender: TObject);
begin
  if CheckTimerCaps then
    if SetTimerCallback(10) then
    begin
      ShowMessage('Timer Succesful : '+IntToStr(wTimerRes));
    end;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  DestroyTimer;
end;

//DELETE TIMER
procedure TForm1.Button2Click(Sender: TObject);
begin
  DestroyTimer;
end;

end.  //unit
0
 
LVL 5

Expert Comment

by:inter
ID: 1343529
It generates periodic event as you want, but I missed a wrong comment there (I have addaped it before msdn)
regards, igor
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A lot of questions regard threads in Delphi.   One of the more specific questions is how to show progress of the thread.   Updating a progressbar from inside a thread is a mistake. A solution to this would be to send a synchronized message to the…
Objective: - This article will help user in how to convert their numeric value become words. How to use 1. You can copy this code in your Unit as function 2. than you can perform your function by type this code The Code   (CODE) The Im…
Need to grow your business through quality cloud solutions? With everything required to build a cloud platform and solution, you may feel like the distance between you and the cloud is quite long. Help is here. Spend some time learning about the Con…
A company’s greatest vulnerability is their email. CEO fraud, ransomware and spear phishing attacks are the no1 threat to a company’s security. Cybercrime is responsible for the largest loss of money to companies today with losses projected to r…

914 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

19 Experts available now in Live!

Get 1:1 Help Now