I have written a windows service that is supposed to run a chrome instance.
how ever on attaching the service to the process I am able to hit the breakpoint to Process.Start but it does not opens the chrome.
also I do not get any error.
can anyone help me here.
protected override void OnStart(string[] args)
{
var timer = new Timer(5000);
timer.Elapsed += TimerElapsed;
timer.Start();
}
void TimerElapsed(object sender, ElapsedEventArgs e)
{
try
{
var processes = Process.GetProcessesByName("Chrome");
var found = false;
foreach (var process in processes)
{
if (process.MainWindowTitle.StartsWith("title"))
{
found = true;
}
}
if (!found)
{
var process = Process.Start("Chrome", "http://localhost");
}
}
catch (Exception ex)
{
}
}
If I create a windows application for the same then it works fine.
due to session 0 isolation I guess this is not a good idea to proceed upon..
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I'm a new Xamarin developper and I'm trying to build an app with Xamarin.Forms. Everything works properly on the app but I noticed a strange behaviour : be it on device or with the emulator, when I turn the power off one time then on again, OnSleep() and OnResume() methods work just fine.
But the problem is, when I repeat the same operation a second time, the application freezes and to unlock it I have to either close the app and open it again or go to menu where you can select other apps working in background (I don't know how it's called) and return on the app. I checked with breakpoints and those two methods are called on the first and second time. I tried removing everything from those methods but the problem persists. Does anyone know why it behaves like that ? Thank you.
In my App.xaml.cs :
protected override void OnStart()
{
if (isLoggedIn())
{
MainPage = new NavigationPage(new MDPage());
GeneralViewModel general = new GeneralViewModel();
general.checkUser();
}
else
{
MainPage = new NavigationPage(new LoginPage());
}
}
protected override void OnSleep()
{
// Handle when your app sleeps
}
protected override void OnResume()
{
if (isLoggedIn()) //With a breakpoint, this is executed
{
MainPage.Navigation.PushAsync(new MDPage());
/*this is also executed but the second time,
*even if it is executed the application freezes*/
GeneralViewModel general = new GeneralViewModel();
general.checkUser();
}
else
{
MainPage = new NavigationPage(new LoginPage());
}
}
public bool isLoggedIn()
{
if (Settings.GeneralSettings != null && Settings.GeneralSettings != "")
{
return true;
}
else
{
return false;
}
}
The GeneralViewModel method I call (btw even without it the problem persists)
public void DoSomething()
{
ThreadPool.QueueUserWorkItem(o => checkUser());
}
public Task checkUser()
{
if (Settings.GeneralSettings != null && Settings.GeneralSettings != "")
{
DoSomething();
}
else
{
try
{
var data = Application.Current.MainPage;
Device.BeginInvokeOnMainThread(async () =>
{
await data.DisplayAlert("Information(s)", "Vous avez été déconnecté", "OK");
});
}
catch (Exception e)
{
Console.WriteLine("exception");
}
}
return default;
}
edit : I checked the console and it seems even though nothing appears on the screen, when I press a button on my frozen page the action the button should do happens but the screen doesn't change.
I'm currently trying to add some Bluetooth functionality to my app. I want to be able to change the Bluetooth Tethering on or off, as well as check its status.
I found the Java code on StackOverflow: How to check Bluetooth tethering status programmatically in Android
I have translated it into C#, but I don't seem to be able to get any result.
Regardless of the tethering setting, it always shows the toast with "Tethering:false", and the setBluetoothTethering doesn't change anything.
Any idea what I'm missing?
Here's my code:
[...]
try
{
Class classBluetoothPan = Class.ForName("android.bluetooth.BluetoothPan");
Method mBTPanConnect = classBluetoothPan.GetDeclaredMethod("connect", Class.FromType(typeof(BluetoothDevice)));
Constructor BTPanCtor = classBluetoothPan.GetDeclaredConstructor(Class.FromType(typeof(Context)), Class.FromType(typeof(IBluetoothProfileServiceListener)));
BTPanCtor.Accessible = true;
Java.Lang.Object BTSrvInstance = BTPanCtor.NewInstance(Activity, new BTPanServiceListener(Activity));
Method isTetheringOnMethod = classBluetoothPan.GetDeclaredMethod("isTetheringOn", null);
var isTetheringOn = isTetheringOnMethod.Invoke(BTSrvInstance);
Toast.MakeText(Activity, "Tethering:" + isTetheringOn, ToastLength.Short).Show();
Method setBluetoothTetheringMethod = classBluetoothPan.GetDeclaredMethod("setBluetoothTethering", new Class[1] { Class.FromType(typeof(bool)) });
setBluetoothTetheringMethod.Invoke(BTSrvInstance, true);
// tether = !tether;
}
catch (ClassNotFoundException e)
{
e.PrintStackTrace();
}
catch (Java.Lang.Exception e)
{
e.PrintStackTrace();
}
[...]
public class BTPanServiceListener : Java.Lang.Object, IBluetoothProfileServiceListener
{
private Activity _activity;
public BTPanServiceListener(Activity activity)
{
_activity = activity;
}
public void OnServiceConnected([GeneratedEnum] ProfileType profile, IBluetoothProfile proxy)
{
// throw new NotImplementedException();
}
public void OnServiceDisconnected([GeneratedEnum] ProfileType profile)
{
// throw new NotImplementedException();
}
}
I figured out how to enable Bluetooth tethering via setBluetoothTethering.
I wrote an entire blog about this
You can find the final code here
I assume that isTetheringOn works in the same way
I'm working on WP7/8 application with barcode scanning. And have a problem with disposing camera. Camera initialize too long, and when camera is still initializing and I press back button, I've got a fatal error:
A first chance exception of type 'System.ObjectDisposedException'
occurred in Microsoft.Devices.Camera.ni.dll WinRT information: Fatal
error. Disposing capture device.
Could anybody helps me how to avoid this error?
my code:
protected override void OnNavigatedTo(NavigationEventArgs e)
{
InitializeAndGo();
base.OnNavigatedTo(e);
}
protected override void OnNavigatingFrom(System.Windows.Navigation.NavigatingCancelEventArgs e)
{
disposeCamera();
}
private void PhotoCameraOnInitialized(object sender, CameraOperationCompletedEventArgs cameraOperationCompletedEventArgs)
{
_width = Convert.ToInt32(_photoCamera.PreviewResolution.Width);
_height = Convert.ToInt32(_photoCamera.PreviewResolution.Height);
_luminance = new PhotoCameraLuminanceSource(_width, _height);
if (_photoCamera.IsFlashModeSupported(FlashMode.Auto))
{
_photoCamera.FlashMode = FlashMode.Off;
}
cameraInitialized = true;
Dispatcher.BeginInvoke(() =>
{
FlashCheckbox.IsEnabled = true;
if (_photoCamera.IsFlashModeSupported(FlashMode.Auto))
{
_photoCamera.FlashMode = FlashMode.Off;
}
});
_photoCamera.Focus();
}
private void InitializeAndGo()
{
stopScan = false;
_photoCamera = new PhotoCamera();
_photoCamera.Initialized += PhotoCameraOnInitialized;
_photoCamera.AutoFocusCompleted += PhotoCameraOnAutoFocusCompleted;
viewfinderBrush.SetSource(_photoCamera);
_previewTransform.Rotation = _photoCamera.Orientation;
_results = new ObservableCollection<Result>();
_barcodeReader = new BarcodeReader();
_barcodeReader.TryHarder = true;
_barcodeReader.AutoRotate = true;
_service = new MyMoviesDataService(ErrorDataService);
}
private void disposeCamera()
{
try
{
cameraInitialized = false;
StopScan();
_photoCamera.Initialized -= PhotoCameraOnInitialized;
_photoCamera.AutoFocusCompleted -= PhotoCameraOnAutoFocusCompleted;
_photoCamera.Dispose();
_photoCamera = null;
}
catch (Exception ex)
{
App.ShowErrorToast(ex.Message);
}
}
Don't use the camera until it's been successfully initialized (You can check this in the camera's Initialized event).
Also, wrap any usages of the camera in a
try
{
// camera code here
}
catch (ObjectDisposedException)
{
// re-initialize the camera?
}
to handle situations like suspension, which will dispose of the camera automatically.
As for the
An exception of type 'System.ObjectDisposedException' occurred in
Microsoft.Devices.Camera.ni.dll and wasn't handled before a
managed/native boundary WinRT information: Fatal error. Disposing
capture device.
This is something Microsoft needs to fix; I mean, how are you supposed to handle a native code exception if it isn't allowed to propagate to managed code?
Where is the exception coming from (which code line / block)?
I would for starter put a try...catch around InitializeAndGo() in the OnNavigatedTo event handler. And on the whole PhotoCameraOnInitialized event handler also.
Cheers,
My scenario is , When I navigate to a new page It takes some time to load the content. And for that duration of time, If I press back key it throws exception for some reason. So I want to stop the back key behaviour for that much duration and when content is fully loaded, user can press the back key and then navigate to previous page. I just want to be clear, Is it permitted in application certification requirement from microsoft so that my app could not get rejected. so please give answer.
You could do something like this:
bool flag = false;
// Assuming this is where you can handle executions during loading
loading()
{
flag = true;
}
// After loading is completed
loadComplete()
{
flag = false;
}
// Handle back button
protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
{
if (flag)
{
e.Cancel = true;
}
}
As long as you don't lock the user to never allow him to go back, it should pass the certification.
In xaml
<phone:PhoneApplicationPage
.....
BackKeyPress="PhoneApplicationPage_BackKeyPress">
In code
private void PhoneApplicationPage_BackKeyPress(object sender, System.ComponentModel.CancelEventArgs e)
{
e.Cancel = CouldStepBack();
}
private bool CouldStepBack()
{
// todo return true, when load comleted
// else return false
}
And if you need you also can clean stack of pages (optional)
protected override void OnNavigatedTo(NavigationEventArgs e)
{
if (NavigationService.CanGoBack)
{
while (NavigationService.RemoveBackEntry() != null)
{
NavigationService.RemoveBackEntry();
}
}
base.OnNavigatedTo(e);
}
Hope its help
This problem confuse me several days, when the code run to
await ApplicationData.Current.LocalFolder.GetFileAsync(udFileName);
The app was always jump to
UnhandledException += (sender, e) =>
{
if (global::System.Diagnostics.Debugger.IsAttached) global::System.Diagnostics.Debugger.Break();
};
The Exception e is：
{Windows.UI.Xaml.UnhandledExceptionEventArgs}
Exception {"Object reference not set to an instance of an object."}
System.Exception {System.NullReferenceException}
Message "System.NullReferenceException.......
Following is the function I invoked:
public async void RestoreUserDefaults()
{
string udFileName = "userdefaults.udef";
bool bExist = true;
{
try
{
await ApplicationData.Current.LocalFolder.GetFileAsync(udFileName);
}
catch (FileNotFoundException)
{
bExist = false;
}
}
}
I had add the file type to the package.appxmanifest.
anyone can help me, so many thanks.....