// <snippet40>
// This event handler updates the ListView control when the
// PrimeNumberCalculator raises the ProgressChanged event.
//
// On fast computers, the PrimeNumberCalculator can raise many
// successive ProgressChanged events, so the user interface
// may be flooded with messages. To prevent the user interface
// from hanging, progress is only reported at intervals.
private void primeNumberCalculator1_ProgressChanged(
ProgressChangedEventArgs e)
{
if (this.progressCounter++ % this.progressInterval == 0)
{
Guid taskId = (Guid)e.UserState;
if (e is CalculatePrimeProgressChangedEventArgs)
{
CalculatePrimeProgressChangedEventArgs cppcea =
e as CalculatePrimeProgressChangedEventArgs;
this.UpdateListViewItem(
taskId,
cppcea.ProgressPercentage,
cppcea.LatestPrimeNumber);
}
else
{
this.UpdateListViewItem(
taskId,
e.ProgressPercentage);
}
}
else if (this.progressCounter > this.progressInterval)
{
this.progressCounter = 0;
}
}
// </snippet27>
// <snippet5>
// This method computes the list of prime numbers used by the
// IsPrime method.
private ArrayList BuildPrimeNumberList(
int numberToTest,
AsyncOperation asyncOp)
{
ProgressChangedEventArgs e = null;
ArrayList primes = new ArrayList();
int firstDivisor;
int n = 5;
// Add the first prime numbers.
primes.Add(2);
primes.Add(3);
// Do the work.
while (n < numberToTest &&
!TaskCanceled(asyncOp.UserSuppliedState))
{
if (IsPrime(primes, n, out firstDivisor))
{
// Report to the client that a prime was found.
e = new CalculatePrimeProgressChangedEventArgs(
n,
(int)((float)n / (float)numberToTest * 100),
asyncOp.UserSuppliedState);
asyncOp.Post(this.onProgressReportDelegate, e);
primes.Add(n);
// Yield the rest of this time slice.
Thread.Sleep(0);
}
// Skip even numbers.
n += 2;
}
return(primes);
}