I cannot seem to find a good solution for this issue online. I have a device that is running Windows Embedded Handheld 6.5. I run the solution located at below
C:\Program Files (x86)\Windows Mobile 6.5.3 DTK\Samples\PocketPC\CS\GPS
I deploy the code to my device, not an emulator, and the code breaks with a null reference exception at
Invoke(updateDataHandler);
The solution ive seen recommends changing this to below
BeginInvoke(updateDataHandler);
But now the code breaks at Main with NullRefreceException.
Application.Run(new Form1());
Has anyone found a solution for this?
Did you alter the code? updateDataHandler is initialized in Form_Load:
private void Form1_Load(object sender, System.EventArgs e)
{
updateDataHandler = new EventHandler(UpdateData);
so that object will not be NULL. But there are other annoyances with the code, especially the Samples.Location class. You may instead use http://www.hjgode.de/wp/2010/06/11/enhanced-gps-sample-update/ as a starting point and the older one: http://www.hjgode.de/wp/2009/05/12/enhanced-gps-sampe/
The main issue with the sample is that it does not use a callback (delegate) to update the UI. If an event handler is fired from a background thread, the handler can not directly update the UI. Here is what I always use to update the UI from a handler:
delegate void SetTextCallback(string text);
public void addLog(string text)
{
// InvokeRequired required compares the thread ID of the
// calling thread to the thread ID of the creating thread.
// If these threads are different, it returns true.
if (this.txtLog.InvokeRequired)
{
SetTextCallback d = new SetTextCallback(addLog);
this.Invoke(d, new object[] { text });
}
else
{
txtLog.Text += text + "\r\n";
}
}
Related
So i don't actually have a question because i've already solved it, but in case someone else runs into this issue it's always nice to have a neat solution.
And while there is a plentitude of "Can't create handler inside thread which has not called Looper.prepare()" - questions there is none tagged with xamarin. (so theirs is all java and i had 0 matches for "Can't create handler inside thread which has not called Looper.prepare() [xamarin]")
The issue is generated because You tried to do work on UI from other thread. If you want to change UI, Must call UI changes from UI thread.
Xamarin Android:
activity.RunOnUiThread(() =>
{
// Write your code here
});
Xamarin IOS:
nsObject.BeginInvokeOnMainThread(() =>
{
// Write your code here
});
Xamarin Forms:
Device.BeginInvokeOnMainThread(() =>
{
// Write your code here
});
public static class PageExtensions
{
public static Task<bool> DisplayAlertOnUi(this Page source, string title, string message, string accept, string cancel)
{
TaskCompletionSource<bool> doneSource = new TaskCompletionSource<bool>();
Device.BeginInvokeOnMainThread(async () =>
{
try
{
var result = await source.DisplayAlert(title, message, accept, cancel);
doneSource.SetResult(result);
}
catch (Exception ex)
{
doneSource.SetException(ex);
}
});
return doneSource.Task;
}
}
Finally i had a case for using TaskCompletionSource to solve an issue.
Very similar actually happend to me. Previous evening I was developing and testing my app. Next morning, from other computer I got the exception you described. I was remembered from a official Xamarin.Forms documentation that sometimes a bin and obj folder removal solves lot of issues.
I did exactly the same, removed my bin and obj folder from my shared Xamarin.Forms library and also from Xamarin.Android library.
The strange exception disappeared.
There is a way to fire the event ViewChanged (that was present in previous WP8) within an Windows Phone 8.1 app? I use Windows.UI.Xaml.Controls.Maps and I will manage the map when the view animation finishes.
You can try to use on of these events of the MapControl class:
ManipulationStarted: http://msdn.microsoft.com/en-us/library/hh702372.aspx
CenterChanged: http://msdn.microsoft.com/en-us/library/windows.ui.xaml.controls.maps.mapcontrol.centerchanged.aspx
ZoomLevelChanged: http://msdn.microsoft.com/en-us/library/windows.ui.xaml.controls.maps.mapcontrol.zoomlevelchanged.aspx
But the best event would be ManipulationCompleted: http://msdn.microsoft.com/en-us/library/windows.ui.xaml.uielement.manipulationcompleted.aspx
I've found that the LoadingStatusChanged event does what you want, provided you check the LoadingStatus first.
mapControl.LoadingStatusChanged += MapLoadingStatusChanged;
private void MapLoadingStatusChanged(MapControl sender, object args)
{
if (sender.LoadingStatus == MapLoadingStatus.Loaded)
{
// code here will only get hit when the map finishes drawing after a pan/zoom
}
}
I have searched numerous articles and tried several different ways of solving this issue.
Note that this process works fine in a Console app or a Windows app with the exact same code. So, there's nothing wrong with the logic. It's the way the Windows Service is processing these files that is somehow not letting subsequent files get through.
I tried reading a simple article to actually debug the service, but I don't have the "Attach To Process" selection under my Debug menu using Visual Studio 2010.
http://msdn.microsoft.com/en-us/library/7a50syb3(v=vs.100).aspx
I really need some help here, because my options have really run out.
Here is the simple scenario:
I have a FileSystemWatcher in the OnStart method that kicks off another method to process a file on my local machine. These are just simple txt files. When the first file is processed, everything is normal and I get the following in my Event log:
Data successfully inserted for file 20121212_AZM_Journey_MIS.txt
When I try and process subsequent files (exact same format, but a different name --- with the date), I get the following in my Event log:
The process cannot access the file 'C:\Projects\Data\VendingStats\20121213_AZM_Journey_MIS.txt' because it is being used by another process.
Note that the files are watched for in this same directory when created.
Here is my code in my Windows Service. Can someone please let me know how I can solve this issue? Note that e.FullPath evaluates to "C:\Projects\Data\VendingStats" on my local machine.
public partial class VendingStatsService : ServiceBase
{
public VendingStatsService()
{
InitializeComponent();
}
protected override void OnStart(string[] args)
{
FileSystemWatcher Watcher = new FileSystemWatcher(#"C:\Projects\Data\VendingStats");
Watcher.EnableRaisingEvents = true;
Watcher.Created += new FileSystemEventHandler(**Watcher_Created**);
Watcher.Filter = "*.txt";
Watcher.IncludeSubdirectories = false;
}
private void Watcher_Created(object sender, FileSystemEventArgs e)
{
try
{
using (TextReader tr = new StreamReader(e.FullPath))
{
// code here to insert data from file into a DB
}
Dispose();
}
catch (Exception ex)
{
EventLog.WriteEntry("VendorStats", "Error in the Main:" + "\r\n\r\n" + ex.Message + "\r\n\r\n" + ex.InnerException);
return;
}
}
public void Dispose()
{
GC.Collect();
}
I think the title or the question is clear enough. I saw something about the EventSink, but I found it difficult to use. Any hint?
The Visio Primary Interop Assembly exposes these events as C# events therefore you can simply hook the event with a delegate.
See this simple example:
namespace VisioEventsExample
{
using System;
using Microsoft.Office.Interop.Visio;
class Program
{
public static void Main(string[] args)
{
Application app = new Application();
Document doc = app.Documents.Add("");
Page page = doc.Pages[1];
// Setup event handles for the events you are intrested in.
// Shape deleted is easy.
page.BeforeShapeDelete +=
new EPage_BeforeShapeDeleteEventHandler(onBeforeShapeDelete);
// To find out if a shape has moved hook the cell changed event
// and then check to see if PinX or PinY changed.
page.CellChanged +=
new EPage_CellChangedEventHandler(onCellChanged);
// In C# 4 for you can simply do this:
//
// page.BeforeShapeDelete += onBeforeShapeDelete;
// page.CellChanged += onCellChanged;
// Now wait for the events.
Console.WriteLine("Wait for events. Press any key to stop.");
Console.ReadKey();
}
// This will be called when a shape sheet cell for a
// shape on the page is changed. To know if the shape
// was moved see of the pin was changed. This will
// fire twice if the shape is moved horizontally and
// vertically.
private static void onCellChanged(Cell cell)
{
if (cell.Name == "PinX" || cell.Name == "PinY")
{
Console.WriteLine(
string.Format("Shape {0} moved", cell.Shape.Name));
}
}
// This will be called when a shape is deleted from the page.
private static void onBeforeShapeDelete(Shape shape)
{
Console.WriteLine(string.Format("Shape deleted {0}", shape.Name));
}
}
}
If you haven't already downloaded the Visio SDK you should do so. Recent versions of the SDK it contains many useful examples include one called "Shape Add\Delete Event". If you have the 2010 version can browse the examples by going to Start Menu\Programs\Microsoft Office 2010 Developer Resources\Microsoft Visio 2010 SDK\Microsoft Visio Code Samples Library.
I believe that you have to implement EvenSink to get access to "ShapesDeleted", i.e.
(short)Microsoft.Office.Interop.Visio.VisEventCodes.visEvtCodeShapeDelete
the code above will help you if you are looking for the event "BeforeShapeDelete" not the "after"ShapeDelete ;)
I'm trying to recognize speech with Windows 7 but it always recognizes a speech as a command or just says "What was that?".
How I can get all speeches?
CODE:
SpeechRecognizer _speechRecognizer;
public Window1()
{
InitializeComponent();
// set up the recognizer
_speechRecognizer = new SpeechRecognizer();
_speechRecognizer.Enabled = false;
_speechRecognizer.SpeechRecognized +=
new EventHandler<SpeechRecognizedEventArgs>(_speechRecognizer_SpeechRecognized); }
Perhaps you want to use the .net System.Speech namespace instead of SAPI? There is a very good article that was published a few years ago at http://msdn.microsoft.com/en-us/magazine/cc163663.aspx. It is probably the best introductory article I’ve found so far. It is a little out of date, but very helfpul. (The AppendResultKeyValue method was dropped after the beta.)
Are you trying to use a shared recognizer? That may be why you are seeing commands. Do you have a specific task for recognition? In that case, you would be better served with a task specific grammar and an inproc recognizer.
If you need to handle any words, use the DictationGrammar that comes with System.Speech. See http://msdn.microsoft.com/en-us/library/system.speech.recognition.dictationgrammar%28VS.85%29.aspx
For fun, I whipped together the simplest .NET windows forms app to use a dictation grammar that I could think of. I created a form. Dropped a button on it and made the button big. Added a reference to System.Speech and the line:
using System.Speech.Recognition;
Then I added the following event handler to button1:
private void button1_Click(object sender, EventArgs e)
{
SpeechRecognitionEngine recognizer = new SpeechRecognitionEngine();
Grammar dictationGrammar = new DictationGrammar();
recognizer.LoadGrammar(dictationGrammar);
try
{
button1.Text = "Speak Now";
recognizer.SetInputToDefaultAudioDevice();
RecognitionResult result = recognizer.Recognize();
button1.Text = result.Text;
}
catch (InvalidOperationException exception)
{
button1.Text = String.Format("Could not recognize input from default aduio device. Is a microphone or sound card available?\r\n{0} - {1}.", exception.Source, exception.Message);
}
finally
{
recognizer.UnloadAllGrammars();
}
}