/// <summary>
/// Gets called when the button to calculate Pi is pressed.
/// </summary>
/// <param name="sender">Sender</param>
async partial void HandleCalculatePi(UIButton sender)
{
// Toggle status.
if (this.IsCalculating)
{
this.IsCalculating = false;
btnCalculate.SetTitle("Start calculating", UIControlState.Normal);
// TODO: Cancel calculation if it is currently running.
this.cts.Cancel();
return;
}
this.IsCalculating = true;
btnCalculate.SetTitle("Stop calculating", UIControlState.Normal);
this.txtPi.Text = string.Empty;
// TODO: Reset cancellation token source.
this.cts = new CancellationTokenSource();
// Start a background task to request more time from the operating system.
// This has no negative side effect if called while the app is in the foreground.
nint finiteTaskId = UIApplication.SharedApplication.BeginBackgroundTask(this.HandleBackgroundTimeExpires);
// Now start calculating on a separate thread.
// TODO: Pass token to Pi calculation and to the Task.Run() call.
try
{
await Task.Run(() =>
PiHelper.CalcPi(pieceOfPi => this.UpdateUi(pieceOfPi), this.cts.Token), // pass to UpdateUi()
this.cts.Token); // pass to Task.Run()
}
catch (OperationCanceledException)
{
Console.WriteLine("Calculation canceled.");
this.IsCalculating = false;
}
// Also end the background task.
UIApplication.SharedApplication.EndBackgroundTask(finiteTaskId);
finiteTaskId = -1;
// Update the button's title.
btnCalculate.SetTitle("Start calculating", UIControlState.Normal);
}
/// <summary>
/// Gets called when the button to calculate Pi is pressed.
/// </summary>
/// <param name="sender">Sender</param>
async partial void HandleCalculatePi(UIButton sender)
{
// Toggle status.
if (this.IsCalculating)
{
this.IsCalculating = false;
btnCalculate.SetTitle("Start calculating", UIControlState.Normal);
this.cts.Cancel();
return;
}
this.IsCalculating = true;
btnCalculate.SetTitle("Stop calculating", UIControlState.Normal);
this.txtPi.Text = string.Empty;
this.cts = new CancellationTokenSource();
// Start a background task to request more time from the operating system.
// This has no negative side effect if called while the app is in the foreground.
nint finiteTaskId = UIApplication.SharedApplication.BeginBackgroundTask(this.HandleBackgroundTimeExpires);
Console.WriteLine("Started background task: " + finiteTaskId);
// Now start calculating on a separate thread. Note that the cancellation token is passed to the Task.Run() method:
// if the token is already cancelled, the task won't even start.
try
{
await Task.Run(() =>
PiHelper.CalcPi(pieceOfPi => this.UpdateUi(pieceOfPi), this.cts.Token),
this.cts.Token);
}
catch (OperationCanceledException)
{
Console.WriteLine("Calculation cancelled.");
this.IsCalculating = false;
}
// Also end the background task.
Console.WriteLine("Ending background task: " + finiteTaskId);
UIApplication.SharedApplication.EndBackgroundTask(finiteTaskId);
finiteTaskId = -1;
// Update the button's title.
btnCalculate.SetTitle("Start calculating", UIControlState.Normal);
}
public static void CalcPi(Action <string> piCallback, CancellationToken token = default(CancellationToken))
{
PiHelper.Process(1000000, piCallback, token);
}