Improved code for periodic Autofocus on scan for better cancellation and task handlilng (#1764)

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Federico Maccaroni 2022-02-10 15:03:02 -03:00 committed by GitHub
parent 9eed421c67
commit 92c40e2984
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@ -11,6 +11,9 @@ namespace Bit.App.Pages
{
private readonly Action<string> _callback;
private CancellationTokenSource _autofocusCts;
private Task _continuousAutofocusTask;
public ScanPage(Action<string> callback)
{
_callback = callback;
@ -27,7 +30,6 @@ namespace Bit.App.Pages
ToolbarItems.RemoveAt(0);
}
}
private CancellationTokenSource _autofocusCts;
protected override void OnAppearing()
{
@ -37,45 +39,42 @@ namespace Bit.App.Pages
// Fix for Autofocus, now it's done every 2 seconds so that the user does't have to do it
// https://github.com/Redth/ZXing.Net.Mobile/issues/414
_autofocusCts?.Cancel();
_autofocusCts = new CancellationTokenSource();
_autofocusCts = new CancellationTokenSource(TimeSpan.FromMinutes(3));
var autofocusCts = _autofocusCts;
Task.Run(async () =>
{
await Task.Delay(TimeSpan.FromMinutes(3), autofocusCts.Token);
autofocusCts.Cancel();
});
Device.StartTimer(TimeSpan.FromSeconds(2), () =>
_continuousAutofocusTask = Task.Run(async () =>
{
try
{
if (autofocusCts.IsCancellationRequested)
while (!autofocusCts.IsCancellationRequested)
{
await Task.Delay(TimeSpan.FromSeconds(2), autofocusCts.Token);
Device.BeginInvokeOnMainThread(() =>
{
if (!autofocusCts.IsCancellationRequested)
{
return false;
}
_zxing.AutoFocus();
return true;
}
catch (Exception ex)
{
// we don't need to display anything to the user because at the most they just lose autofocus
#if !FDROID
Crashes.TrackError(ex);
#endif
autofocusCts?.Cancel(); // we also cancel here to cancel the Task.Delay as well.
return false;
}
});
}
}
catch (TaskCanceledException) { }
catch (Exception ex)
{
#if !FDROID
Crashes.TrackError(ex);
#endif
}
}, autofocusCts.Token);
}
protected override void OnDisappearing()
protected override async void OnDisappearing()
{
_autofocusCts?.Cancel();
await _continuousAutofocusTask;
_zxing.IsScanning = false;
base.OnDisappearing();
}