Question

I am working on a Silverlight for Windows Embedded project and running into a problem with my UI thread. Currently the application UI thread must continually update its display based on data stored in a shared memory file and then sleep for a specified number of milliseconds before updating the UI once again. So in essence the code is something like the following:

while(true){
    UpdateUI();    //gets data from shared memory and updates graphics
    Sleep(250);
}

However, as I am sure some of you know, it is not recommended to use Sleep() within the main Silverlight UI thread. Sure enough, my entire embedded system will crash after running for 20-30mins and I have identified the call to Sleep() as the issue.

What I need is an alternative method to update the UI, pause for some amount of time, and then update the UI again, repeating this process ad infinitum.

As far as I am aware, the embedded nature of the project does not allow me to use some of the obvious alternatives to Sleep() that would be a better solution in the UI thread (i.e. Join()).

Any suggestions would be greatly appreciated!

Answer 1

A timer is a far better route then a loop, especially a loop with a Sleep in the UI thread. A simple call to SetTimer or timeSetEvent is probably what you’re after.

int WinMain(...)
{
    // initialize xamls stuff

    // start a timer
    SetTimer(0, 0, 250, TimerProc);
    // *OR*
    timeSetEvent(250, 0, EventProc, NULL, TIME_PERIODIC | TIME_CALLBACK_FUNCTION);

    // call StartDialog or whatever to launch your UI
}

void CALLBACK TimerProc(HWND hwnd, UINT, UINT, DWORD dwTime)
{
    // this will get called every 250ms    
    UpdateUI();
}

void CALLBACK EventProc(UINT uID, UINT uMsg, DWORD dwUser, DWORD dw1, DWORD dw2)
{
    // this will get called every 250ms    
    UpdateUI();
}