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leyusha wrote:
How can make a second by second update (a timer that will always get exact count)or ; make the WM_TIMER message to have higher priority
forget it. Windows is not a Real-Time Operating System, that means that the kernel will always have priority upon the user events. this way, for an event to be treated, it will have to wait for the end of the event that is currently in treatment, or it will have to wait that the kernel finishes its task...
if you want this, sorry but, change your OS...
TOXCCT >>> GEII power
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leyusha wrote:
The OnTimer() function , which is called after a timer is created by SetTimer (),is processed when there is no other message to be processed. I wanted to make a second by second update to my program but it fails as when the user clicks very fast or if many messages are sent by the user or the program.
How can make a second by second update (a timer that will always get exact count)or ; make the WM_TIMER message to have higher priority
You didn't mention how exact the count needs to be, so I should mention that you aren't ever going to get milisecond accuracy. However, it's quite possible that you can display an update so that the user sees something new about every second.
Another issue it that paint messages have an even lower priority than timer messages. If your program has long periods in which no timer messages get through, then no paint messages will get through either. This can lead to things like message boxes not being displayed, leaving the user wondering why your program has stoped responding. Because of this, the best solution is probably just to make your message handling efficient enough that timer messages can get through in a reasonable amount of time.
That being said, you can effectively make higher priority timer messages by having a background thread wait on timer messages or a waitable timer object, and having the thread send a WM_COMMAND or a custom message that will have normal priority. If the background thread doesn't do anything else, you can safely raise the thread's priority to get a bit more accuracy.
Nathan Holt
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Nathan Holt at CCEI wrote:
You didn't mention how exact the count needs to be
was i the only one to see that he wanted a timeout of one second ( 1 s ) ?
TOXCCT >>> GEII power
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toxcct wrote:
was i the only one to see that he wanted a timeout of one second ( 1 s ) ?
Windows can usually syncronize things to within a second. Audio and video players wouldn't be possible if that wasn't the case. If the OP can accept updates a quarter of a second late, he can probably get what he wants. There are sometimes high load situations that can delay things further, but users can often just avoid running too many programs. It works with things like Windows Media Player.
Nathan Holt
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As the other reply states, you can't boost the priority of WM_TIMER. It isn't a real message in the
message queue, but is synthesised by windows.
But you can be cunning...
You can override CWinApp::Run and change the message loop to time out once a second, which is lot of
work.
Or...
Create a thread which does nothing much beyond:
DWORD MyTickingThread (LPVOID lpParameter)
{
HWND hWndNotify = (HWND) lpParameter;
while (g_CarryOnTicking)
{
::Sleep (1000);
PostMessage (hWnd, g_TickMessage, 0, 0);
}
return 0;
}
Of course, this is a very primitive example, but hopefully you get the idea.
You may want a more sophisticated (CreateEvent, etc) method of signalling to / from
the thread, and so on.
This still won't be exactly on the second, as windows is not a RTOS, but it will be
better WM_TIMER.
Iain.
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I have a similar problem with the applications that I need to write, and as I think someone previously has said Windows is not real time and you cannot perform tasks at precise times.
However if like me you are stuck with Windows the following might be of interest. I have found that I can get a close approximation by putting the time critical event in a seperate thread, keep it as small and as fast as possible and give it a high priority. My code takes samples from the RS232 port at 100ms intervals and is reasonably accurate.
I have added a check to ensure that if there is a large error in the timing the user is told and they can shut down some apps or get a faster machine!
Hope that helps, 
Ali
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 Hey guys thnks for the replies, i think i will go with the thread thing
Thanks a Lot but i was just wondering which os are real time systems ?
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Also, I have read in Game Development books to use QueryPerformanceCounter() and GetTickCount() because they're more accurate.
[insert witty comment here]
bdiamond 
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I developed a small project in vc++. What happens it runs perfectly in vc++ 6.0 environment,but didn't run properly outside it as i link it to the start menu.
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could you in brief detail the folder where you exe is located, and the files it needs (their location too). Explain also what you exactly do into the start menu...
thx
TOXCCT >>> GEII power
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ya hi toxcct.The exe is in the debug folder.when i put the .exe & .dat files in the windows start menu(Windows/startmenu/addressbook.exe).The program's exe not stores data properly as i wrote some times junk,sometimes overwrite the prev. data.It not stores the data perfectly as it stores under vc++ environment.help me.
My application is a simple address book app.. where records stores in the .dat file.
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See here.
"When I was born I was so surprised that I didn't talk for a year and a half." - Gracie Allen
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don't put your binary direclty into the start menu. let it in a folder (in program files for example), and just add in the start menu a shortcut (.lnk) to your .exe.
TOXCCT >>> GEII power
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Hi,
Need more information. Like error message you r getting etc.
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Hi Everybody,
Can any one tell me how to create a custom fonts in VC++. Is there any SDK to create our own custome fonts.
Thanks & Regards,
Promise
If you have faith in the cause and
the means and in God, the hot
Sun will be cool for you.
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What is the best way to arrange a ListCtrl to be re-drawn when the Window has been Minimised.
At present the CListCtrl is not on the dialog following a restore from a Minimised.
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Catch WM_SHOWWINDOW, and force a redraw of the control with RedrawWindow() when the window is restored.
~RaGE();
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I want to generate a message handler say COM_HANDLE which gets called, as soon as any character is received on COM1 port, from an external hardware. How can I make such an handler in VC++ ??? It will be great if I can get a code sample for doing it.
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Hello everybody,
I have a .swf file that contains a button(Flash).
I want to replace this button in my mfc app.
HOW?
Best wihes.
Thanks.
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 repost
TOXCCT >>> GEII power
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Hi all out there... i have a little problem with using DirectShow..
i got errors like the those shown below.. is there any1 who know how to debug it?
KNN error LNK2001: unresolved external symbol _CLSID_AudioCompressorCategory
KNN error LNK2001: unresolved external symbol _CLSID_FileWriter
KNN error LNK2001: unresolved external symbol _CLSID_FilterGraph
KNN error LNK2001: unresolved external symbol _CLSID_SystemDeviceEnum
KNN error LNK2001: unresolved external symbol _IID_IAMStreamConfig
KNN error LNK2001: unresolved external symbol _IID_IBaseFilter
KNN error LNK2001: unresolved external symbol _IID_ICreateDevEnum
KNN error LNK2001: unresolved external symbol _IID_IFileSinkFilter
KNN error LNK2001: unresolved external symbol _IID_IGraphBuilder
KNN error LNK2001: unresolved external symbol _IID_IMediaControl
KNN error LNK2001: unresolved external symbol _IID_IMediaEvent
The document from DirectShow says that Strmiids.lib are used to exports class identifiers (CLSIDs) and interface identifiers (IIDs). All DirectShow applications require this library. So i am wondering whether did i link this lib to my project. Is including <dshow.h> just enough? But y am i still having the same errors???
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yes,i did.
but there s nothing changed
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