I am using this piece of code to register the event and want to de-register Event after completing it's task but don't know how to do problem is that I am using local object for registering event..
code..
public void loadData()
{
//Here client is loacal object..
client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(AccessTokenDownloadCompleted);
}
void AccessTokenDownloadCompleted(object sender, DownloadStringCompletedEventArgs e)
{
}
If I understood you correctly, you want to remove your event handler after the download is completed. To remove an event handler, all you need to do is:
client.DownloadStringCompleted -= new DownloadStringCompletedEventHandler(AccessTokenDownloadCompleted);
Note the -= instead of +=.
Place this code where the download completes and you should be fine.
Maybe you can try this:
public void loadData()
{
//Here client is loacal object..
client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(AccessTokenDownloadCompleted);
}
void AccessTokenDownloadCompleted(object sender, DownloadStringCompletedEventArgs e)
{
Client client = sender as Client;
if(client != null)
client.DownloadStringCompleted -= new DownloadStringCompletedEventHandler(AccessTokenDownloadCompleted);
}
Related
I am developing a code that will allow me to send small amounts of data between my arduino mega and my windows 8.1 phone using a HC-05 bluetooth module.
Sending data from the phone to the arduino was pretty simple, but I am having a dire time attempting to read data that comes back from the arduino that I send on the serial port.
For testing purposes my code is simple, sending ascii charaters 'a' & 'b' to turn an LED on & off, this could not work any better, but I am having trouble trying to figure out how to correctly read the data that I send back to my phone.
I send a single arbitrary ascii character back to the phone but I cannot for the life of me figure out the correct way of reading this data from the bluetooth stream I have setup.
I have been trying for nearly two days, but everything I try ends up freezing my phone with no exceptions thrown? A lot of posts online send me to the Nokia dev site which is now inactive.
I have tried using the 'datareader' and the 'streamreader' classes to do this but it always freezes, does anyone know how to make this work? And why my streamreader keeps freezing my phone?
I have tried to annotate my code appropriatley (seen below). The problem occurs in the 'Tick' event handler at the bottom of the code.
(FYI: All capabilities have been added to the manifest files so this shouldn't be the problem).
Thank you.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Navigation;
using Microsoft.Phone.Controls;
using Microsoft.Phone.Shell;
using Bluetooth_SL.Resources;
using Windows.Networking;
using Windows.Networking.Proximity;
using Windows.Networking.Sockets;
using Windows.Devices.Bluetooth;
using System.IO;
using Microsoft.Xna.Framework;
using System.Windows.Threading;
using Windows.Storage.Streams; // <-- for the datareader class
namespace Bluetooth_SL // silverlight, does this matter?
{
public partial class MainPage : PhoneApplicationPage
{
DispatcherTimer Timer = new DispatcherTimer();
StreamSocket socket = new StreamSocket();
StreamWriter writer;
StreamReader reader;
public MainPage()
{
InitializeComponent();
Timer.Interval = TimeSpan.FromMilliseconds(1000); // dispatcher timer used to check for incoming data from arduino
Timer.Tick += Timer_Tick; // event handler for dispatcher timer
}
protected override void OnNavigatedFrom(NavigationEventArgs e) // frees up memory
{
socket.Dispose();
}
private void Connect_But_Tap(object sender, System.Windows.Input.GestureEventArgs e)
{
ConnectToBluetooth();
}
private async void ConnectToBluetooth() // sets up the connection // this works fine
{
// Configure PeerFinder to search for all paired devices.
PeerFinder.AlternateIdentities["Bluetooth:Paired"] = "";
var pairedDevices = await PeerFinder.FindAllPeersAsync();
if (pairedDevices.Count == 0)
{
Debug_Block.Text = "No paired devices were found.";
}
else
{
Debug_Block.Text = "Found";
PeerInformation selectedDevice = pairedDevices[0]; // pick the first paired device
try // 'try' used in the case the socket has already been connected
{
await socket.ConnectAsync(selectedDevice.HostName, "1");
writer = new StreamWriter(socket.OutputStream.AsStreamForWrite());
writer.AutoFlush = true;
reader = new StreamReader(socket.InputStream.AsStreamForRead());
Debug_Block.Text = "Connected";
}
catch (Exception x)
{
Debug_Block.Text = x.ToString();
}
}
}
private void SendButton_Tap(object sender, System.Windows.Input.GestureEventArgs e) // this works perfectly
{
try { writer.WriteLine("a"); } // attempts to write the ascii 'a' to the arduino which turns on the on-board LED
catch { Debug_Block.Text = "Failed to write"; }
}
private void SendButton_Off_Tap(object sender, System.Windows.Input.GestureEventArgs e) // this works perfectly
{
try { writer.WriteLine("b"); } // attempts to write the ascii 'b' to the arduino which turns off the on-board LED
catch { Debug_Block.Text = "Failed to write"; }
}
private void ReadButtonToggle_Tap(object sender, System.Windows.Input.GestureEventArgs e) // toggles the timer on and off
{
if(Timer.IsEnabled == true)
{
Timer.Stop();
Debug_Block.Text = "Timer Stopped";
}
else
{
Timer.Start();
Debug_Block.Text = "Timer Started";
}
}
void Timer_Tick(object sender, EventArgs e) // THIS IS THE PROBLEM
{
Debug_Block.Text = "Tick";
Debug_Block.Text = reader.ReadLine(); // <-- ALWAYS FREEZES HERE
Timer.Stop(); // This line is temporary for debugging
}
}
}
i have a problem with the info of a JSON in Windows Phone.
I want to show if the app is running for the first time, and if not, don't show anything.
This is my function to show info on the JSON:
async void NavigationService_Navigated(object sender, NavigationEventArgs e)
{
if (e.IsNavigationInitiator
|| !e.IsNavigationInitiator && e.NavigationMode != NavigationMode.Back)
{
var navigationInfo = new
{
Mode = e.NavigationMode.ToString(),
From = this.BackStack.Any() ? this.BackStack.Last().Source.ToString() : string.Empty,
Current = e.Uri.ToString(),
};
var jsonData = Newtonsoft.Json.JsonConvert.SerializeObject(navigationInfo);
await this.currentApplication.Client.PageView(jsonData);
}
}
I want to add one more thing where is Mode, From and Current. I want to add IsFirstRun that give as True if it's the first time i open the app.
I've seen this for firstRun function, but i don't know how to put it in my code.
public static bool IsFirstRun()
{
if (!settings.Contains(FIRST_RUN_FLAG)) //First time running
{
settings.Add(FIRST_RUN_FLAG, false);
return true;
}
return false;
}
I need help... thanks!
It is pretty simple if you want to create a flag for First Run,
In App.xaml.cs
Look for a function named
// Code to execute when the application is launching (eg, from Start)
// This code will not execute when the application is reactivated
private void Application_Launching(object sender, LaunchingEventArgs e)
{
}
What we want to do is create a flag inside this function and only set it to true if it doesn't exist. Like so.
using System.IO.IsolatedStorage; // include this namespace in App.xaml.cs
// Code to execute when the application is launching (eg, from Start)
// This code will not execute when the application is reactivated
private void Application_Launching(object sender, LaunchingEventArgs e)
{
if (!IsolatedStorageSettings.ApplicationSettings.Contains("first_run"))
{
IsolatedStorageSettings.ApplicationSettings.Add("first_run", true);
}
else
{
// set the flag to flase
IsolatedStorageSettings.ApplicationSettings["first_run"] = false;
}
// save
IsolatedStorageSettings.ApplicationSettings.Save();
}
Now if you want to do something on first run all you have to do is check the settings again like so:
bool first_run = (bool) IsolatedStorageSettings.ApplicationSettings["first_run"];
For debugging cases you will probably want to remove the flag so it will hit first_run again by doing this
// remove the flag and save
IsolatedStorageSettings.ApplicationSettings.Remove("first_run");
IsolatedStorageSettings.ApplicationSettings.Save();
Im doing a cloud App(like Skydrive) in Windows Phone 8 , each time I navigate to a different folder I need to reload the FolderView.xaml page to display the content of this folder and I need to add the view to the back stack then I will be able to back to the previous path...
From now when I try to reload the FolderView from the FolderView.xaml.cs page, none event is called...
I don't understand why ? And if you have a solution you are welcome ...
private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)
{
if (App.ElementSelected != null)
{
BdeskElement FolderChoosen = new BdeskElement();
FolderChoosen = App.ElementSelected;
Gridentete.DataContext = FolderChoosen;
GetFiles(FolderChoosen);
}
}
private async void llsElements_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
LongListSelector llselement = null;
listElementCollection.Clear();
if (sender != null)
llselement =(LongListSelector)sender;
if(llselement.SelectedItem!=null)
{
BdeskElement bdelement=(BdeskElement)llselement.SelectedItem;
if (bdelement.TypeElement==BdeskElement.BdeskTypeElement.Folder)
{
App.DocLibSelected = null;
App.ElementSelected = bdelement;
// I navigate to the same view here but nothing happens
NavigationService.Navigate(new Uri("/Views/BDocs/FolderView.xaml", UriKind.RelativeOrAbsolute));
}
}
}
To navigate to the same page with a new instance, you must change the Uri. For example:
NavigationService.Navigate(new Uri(String.Format("/Views/BDocs/FolderView.xaml?id={0}", Guid.NewGuid().ToString()), UriKind.Relative));
You can discard that parameter if you don't want/use it.
I have a valid URL for a remote JPEG which I'm trying to load in the background. But I find I never get control back after invoking the BitmapImage() constructor. My question is, should this approach work, or should I pitch it all, load up BcpAsync project from NuGet and start working with WebClient asynch methods?
A sample URL for which it fails is
http://image.weather.com/images/maps/current/garden_june_720x486.jpg
It is valid. .UpdateAsync() references it from AppViewModel.Instance, it's not explicitly referenced here.
Here's the background agent:
protected override async void OnInvoke(ScheduledTask task)
{
AppViewModel.LoadData();
await AppViewModel.Instance.RemoteImageProxy.UpdateAsync();
AppViewModel.Instance.ImageUrl = AppViewModel.Instance.RemoteImageProxy.LocalFileUri;
AppViewModel.Instance.UpdateCount++;
PinnedTile.Update();
}
AppViewModel.SaveData();
#if DEBUG
ScheduledActionService.LaunchForTest(task.Name, TimeSpan.FromSeconds(AppViewModel.Instance.BgAgentInterval));
#endif
NotifyComplete();
}
Here's the invoked method:
public Task<double> UpdateAsync() {
LastCheckedTime = DateTime.UtcNow;
CompletionTask = new TaskCompletionSource<double>();
// Not usually called on UI thread, not worth optimizing for that case here.
Deployment.Current.Dispatcher.BeginInvoke(() => { //todo determine whether System.Windows.Deployment.Dispatcher can be called from main app, or just bgAgent.
HelperImageControl = new Image();
HelperImageControl.Loaded += im_Loaded;
HelperImageControl.ImageFailed += im_ImageFailed;
HelperImageControl.ImageOpened += im_ImageOpened;
// breakpoint here
HelperImageControl.Source = new BitmapImage(SourceUri);
// stepping over the function, control does not return here. Nor are any of the above events fired.
});
return CompletionTask.Task; // this will be completed in one of the subsequent control events...
}
You need to call CompletionTask.SetResult(); to return control back to the caller method.
This works (I'm returning 100 in case of successful download because you set the task to return double).
TaskCompletionSource<double> CompletionTask;
public Task<double> UpdateAsync()
{
CompletionTask = new TaskCompletionSource<double>();
Deployment.Current.Dispatcher.BeginInvoke(() =>
{
var HelperImageControl = new Image();
var bmp = new BitmapImage();
bmp.ImageOpened += bmp_ImageOpened;
bmp.ImageFailed += bmp_ImageFailed;
bmp.CreateOptions = BitmapCreateOptions.None;
bmp.UriSource = new Uri("http://image.weather.com/images/maps/current/garden_june_720x486.jpg", UriKind.Absolute);
HelperImageControl.Source = bmp;
});
return CompletionTask.Task;
}
void bmp_ImageFailed(object sender, ExceptionRoutedEventArgs e)
{
CompletionTask.SetException(e.ErrorException);
}
void bmp_ImageOpened(object sender, RoutedEventArgs e)
{
CompletionTask.SetResult(100);
}
I'm developing app which connects to service and consume some JSON data. Consuming works great (JSON.net rocks) but I wonder where I should catch exception error annd show simple MessageBox? Tried in few places but still my app is closing. Or maybe I should do it based on json response which contain error tag? I think that normal error handling could be easier, but have blank spot in my mind now..
Code is below:
private void LoginLoginButton_Click(object sender, System.EventArgs e)
{
((ApplicationBarIconButton)ApplicationBar.Buttons[0]).IsEnabled = false;
ProgressOverlay.Show();
GenerateLoginString();
var w = new SharpGIS.GZipWebClient();
Observable.FromEvent<DownloadStringCompletedEventArgs>(w, "DownloadStringCompleted")
.Subscribe(r =>
{
var settings = IsolatedStorageSettings.ApplicationSettings;
var deserializedRootObject = JsonConvert.DeserializeObject<RootObject>(r.EventArgs.Result);
UserSettings us = new UserSettings()
{
first_name = deserializedRootObject.user.first_name,
last_name = deserializedRootObject.user.last_name,
user_id = deserializedRootObject.user_id,
};
settings.Add("UserSettings", us);
settings.Save();
});
w.DownloadStringAsync(new Uri(UserUri));
w.DownloadStringCompleted += new DownloadStringCompletedEventHandler(w_DownloadStringCompleted);
}
void w_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
NavigationService.Navigate(new Uri("/MainPage.xaml", UriKind.Relative));
}
If you mean you want to catch an exception which occurs in your web client call then it should be in the Error property of DownloadStringCompletedEventArgs.
void w_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if(e.Error != null)
{
MessageBox.Show("An error occurred!");
}
else
{
NavigationService.Navigate(new Uri("/MainPage.xaml", UriKind.Relative));
}
}
Solved!
I used try and catch in this case. Works perfect :)