100% CPU Utilization poll mouse 1

[griv]

Hi,

I have an app that has been crudely converted from DOS basic to Windows. Thh program polls for mouse input, while a user moves an item on the screen.

The program uses 100% of the CPU while this screen is displayed. If you open a file or select another area of the program the CPU drops to only a few percent. It seems to be in this area of the program that is using dos routines to poll for the mouse.

The program works fine even with 100% utilization. It can be minimized and other programs run OK as well. There is no obvious slowdown except for a certain screensaver that does not refresh as quickly when the program is running. I have dismissed this for the moment as it is just a sceensaver.

Is there an issue with a program that consumes a high number of clock cycles but all other program work fine? Is there a caveat emptor that I should be looking for?

I have searched the web and can't see anything specific. I have been asked by a few users why the cpu is so high but since everything runs fine, I am assuming that the Operating System is taking care of the time slicing.

Thanks for any advice.

 

[johnwm]

VB is basically event-driven, so you (generally) don't need to poll for the commonplace actions. Your form has a MouseMove event which is fired on a MouseMove. Try using the intrinsic events rather than polling

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[azrobert]

Do a kernel sleep in your loop and all will be good. about 100 milliseconds should do it.

 

[griv]

Bingo!

Thanks heaps for this azrobert. It has been driving me nuts for ages. I'm glad I ased the question.

Griv.

 

[griv]

Why does this work? Does it give the OS a chance to service other applications? It is great knowing the fix but I'd like to find out why.

Thanks.

 

[strongm]

It puts your application to sleep. Frankly, unless this is exactly what you want to do, I wouldn't advise it as a solution