In my c# winforms application, while displaying the form I am loading the data in LoadDataAsync method, but before loading the data I want to start displaying the Splash Screen, which is not happening can someone guide me what I am doing wrong...or any ideas.
public partial class DepartmentListDetailView : BaseForm
{
private DepartmentDataScope _departmentDataScope;
private AppConfigDataScope _appConfigDataScope;
private DepartmentSearch _departmentSearch;
public DepartmentListDetailView() : base()
{
InitializeComponent();
Init();
}
private async void Init()
{
_departmentDataScope = new DepartmentDataScope();
_appConfigDataScope = new AppConfigDataScope();
_departmentSearch = new DepartmentSearch();
var res = await LoadDataAsync();
}
private async Task<bool> LoadDataAsync()
{
Ssm.ShowWaitForm(); // before loading the data, I want to display the spalsh screen
var result = await _departmentDataScope.FetchDataAsync();
BbiSearch.Enabled = true;
if (Ssm.IsSplashFormVisible)
{
this.Invoke((MethodInvoker) Ssm.CloseWaitForm);
}
return true;
}
}
Thanks
Show it before calling the async method like below code.
Ssm.ShowWaitForm();
var res = await LoadDataAsync();
if (Ssm.IsSplashFormVisible)
{
this.Invoke((MethodInvoker) Ssm.CloseWaitForm);
}
Related
So, first I have read a ton of threads on this particular problem and I still do not understand how to fix it. Basically, I am trying to communicate with a websocket and store the message received in an observable collection that is bound to a listview. I know that I am getting a response back properly from the socket, but when it tries to add it to the observable collection it gives me the following error:
The application called an interface that was marshalled for a different thread. (Exception from HRESULT: 0x8001010E (RPC_E_WRONG_THREAD))
I've read some information on "dispatch" as well as some other things, but I am just massively confused! Here is my code:
public ObservableCollection<string> messageList { get; set; }
private void MessageReceived(MessageWebSocket sender, MessageWebSocketMessageReceivedEventArgs args)
{
string read = "";
try
{
using (DataReader reader = args.GetDataReader())
{
reader.UnicodeEncoding = Windows.Storage.Streams.UnicodeEncoding.Utf8;
read = reader.ReadString(reader.UnconsumedBufferLength);
}
}
catch (Exception ex) // For debugging
{
WebErrorStatus status = WebSocketError.GetStatus(ex.GetBaseException().HResult);
// Add your specific error-handling code here.
}
if (read != "")
messageList.Add(read); // this is where I get the error
}
And this is the binding:
protected override async void OnNavigatedTo(NavigationEventArgs e)
{
//await Authenticate();
Gameboard.DataContext = Game.GameDetails.Singleton;
lstHighScores.ItemsSource = sendInfo.messageList;
}
How do I make the error go away while still binding to the observable collection for my listview?
This solved my issue:
Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
() =>
{
// Your UI update code goes here!
}
);
Correct way to get the CoreDispatcher in a Windows Store app
Try replacing
messageList.Add(read);
with
Dispatcher.Invoke((Action)(() => messageList.Add(read)));
If you're calling from outside your Window class, try:
Application.Current.Dispatcher.Invoke((Action)(() => messageList.Add(read)));
Slight modification for task based async methods but the code in here will not be awaited.
await Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
() =>
{
// Your UI update code goes here!
}
).AsTask();
This code WILL await, and will allow you to return a value:
private async static Task<string> GetPin()
{
var taskCompletionSource = new TaskCompletionSource<string>();
CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
async () =>
{
var pin = await UI.GetPin();
taskCompletionSource.SetResult(pin);
}
);
return await taskCompletionSource.Task;
}
And on Android:
private async Task<string> GetPin()
{
var taskCompletionSource = new TaskCompletionSource<string>();
RunOnUiThread(async () =>
{
var pin = await UI.GetPin();
taskCompletionSource.SetResult(pin);
});
return await taskCompletionSource.Task;
}
Maby this is not a "good" practice, but it works.. I leave a message from webSocket, to mainBody instance, where I have a timered reader...
public class C_AUTHORIZATION
{
public Observer3.A_MainPage_cl parentPageInstance; //еще одни экземпляр родителя
public WebSocket x_Websocket;
private string payload = "";
private DateTime nowMoment = DateTime.Now;
public void GET_AUTHORIZED()
{
bitfinex_Websocket= new WebSocket("wss://*****.com/ws/2");
var apiKey = "";
var apiSecret = "";
DateTime nowMoment = DateTime.Now;
payload = "{}";
x_Websocket.Opened += new EventHandler(websocket_Opened);
x_Websocket.Closed += new EventHandler(websocket_Closed);
}
void websocket_Opened(object sender, EventArgs e)
{
x_Websocket.Send(payload);
parentPageInstance.F_messager(payload);
}
void websocket_Closed(object sender, EventArgs e)
{
parentPageInstance.F_messager("L106 websocket_Closed!");
GET_AUTHORIZED();
}
}
public sealed partial class A_MainPage_cl : Page
{
DispatcherTimer ChartsRedrawerTimer;
public bool HeartBeat = true;
private string Message;
public A_MainPage_cl()
{
this.InitializeComponent();
ChartsRedrawerTimer = new DispatcherTimer() { Interval = new TimeSpan(0, 0, 0, 0, 100) };
ChartsRedrawerTimer.Tick += Messager_Timer;
ChartsRedrawerTimer.Start();
}
private void Messager_Timer(object sender, object e)
{
if(Message !=null) //
{
F_WriteLine(Message);
Message = null; //
}
}
public void F_messager(string message) //
{
Message = message;
}
In Xamarin, I got around this by using:
Device.BeginInvokeOnMainThread(() => {
// code goes here
});
It's clear to me if I have a button that triggers an event, but in the case below, I want to pop up a dialog. The code below is a mess, I don't know how to do this right. I think async/await is part of this, but I'm not clear on this case.
class TaskObject : Form
{
public void MyFunc()
{
MyDialog d = new MyDialog(this);
d.ShowDialog(); // I don't want any other interaction except this dialog's controls
}
internal async Task<bool> LongFunction()
{
// ...
return true;
}
}
class MyDialog : Form
{
Task<bool> task;
public async MyDialog(TaskObject o)
{
task = new Task<bool>(o.LongFunction);
await task;
}
void when_LongFunction_does_something_interesting()
{
this.MyTextBox.Text = "Something interesting";
}
void when_task_completes()
{
this.CancelButton.Visible = false;
this.CloseButton.Visible = true;
}
}
There are two points here:
The constructor of your form cannot have the async modifier. As an alternative, you can use the Load event instead.
(Optional) You don't need to pass an instance of the "parent" form to the constructor, you can get it directly from the Owner property if you use ShowDialog(this) instead of ShowDialog().
Also, remember to dispose of any dialog form after you're done with it. Preferably, wrap the usage of it within a using block.
Here's how I would do it; In the TaskObject form:
internal async Task<bool> LongFunction()
{
// Do some magic.
// await ...
return true;
}
public void MyFunc()
{
using (MyDialog d = new MyDialog())
{
d.ShowDialog(this);
}
}
In the MyDialog form:
private async void MyDialog_Load(object sender, EventArgs e)
{
TaskObject owner = this.Owner as TaskObject;
await owner.LongFunction();
when_task_completes();
}
If you also want to track the progress of LongFunction, you can add a Progress<T> parameter to it and use it like this:
internal async Task<bool> LongFunction(IProgress<string> progress)
{
// Do some magic.
progress.Report("Something interesting");
// await ...
// More magic.
return true;
}
Then you can do something like this:
private async void MyDialog_Load(object sender, EventArgs e)
{
TaskObject owner = this.Owner as TaskObject;
var progress = new Progress<string>(s => when_LongFunction_does_something_interesting(s));
await owner.LongFunction(progress);
when_task_completes();
}
void when_LongFunction_does_something_interesting(string message)
{
this.MyTextBox.Text = message;
}
Note that I used Progress<string> as an example. Instead of string, you can use whatever type works best for your situation.
I am trying to consume an interface but I am having some difficulty here.
I am trying to set it to a xamrin list view in behind a content page
public class xxxApiClient : IApi
{
readonly string url = "http://localhost:81/ ";
readonly IHttpService httpService;
public xxxApiClient(IHttpService httpService)
{
this.httpService = httpService;
}
public Task<List<JobsList>> GetJobs() => httpService.Get<List<JobsList>>($"{url}JobsLists");
}
How ever I am not to sure how I cosume getjobs correclty I am trying the following
public partial class JobsPage : ContentPage ,xxxWC.Interface.IApi
{
public xxxWC.Interface.IApi api = new ful;
public JobsPage ()
{
InitializeComponent ();
}
private Task SetItemSource()
. {
. JobListing.ItemsSource = FuelAp
}
How do I use the get jobs correctly above in the method setItemSource?.
The bit I am having hard time to understand is here.
How do I call the base GetJobs method I have already created in API Client.
Task<List<JobsList>> IApi.GetJobs()
{
throw new NotImplementedException();
}
private Task SetItemSource()
{
JobListings.ItemsSource =await GetJobs();
}
}
Edit 2
Ok based on suggestions below I updated My Code as such
IHttpService httpService;
xxxApiClient _api = newxxxApiClient(httpService);
public JobsPage ()
{
InitializeComponent ();
}
private Task SetItemSource()
{
JobListings.ItemsSource =await GetJobs();
}
But i get the below error
Severity Code Description Project File Line Suppression State
Error CS0236 A field initializer cannot reference the non-static
field, method, or property
'JobsPage.httpService' xxxCallManagmentAppMobile C:\Work\xxxCallAppDev\XamForms\xxxCallManagmentApp\xxxCallManagmentAppMobile\FuelCallManagmentAppMobile\Views\JobsPage.xaml.cs 17 Active
Can someone explain why
Edit 3
Ok i got a bit further but still having some issues. as the main method is not awaited how do I call set SetItemSource.
xxxApiClient _api ;
public JobsPage ()
{
InitializeComponent ()
SetItemSource();
}
private async Task SetItemSource()
{
JobListings.ItemsSource = await client.GetJobs();
}
Assuming that IApi has been mapped to xxxApiClient implementation
Try resolving the service using the DependencyService so that it is available to be used in the view
public partial class JobsPage : ContentPage {
public readonly IApi client;
public JobsPage () {
InitializeComponent ();
client = DependencyService.Get<IApi>();
}
private async Task SetItemSource() {
JobListing.ItemsSource = await client.GetJobs();
//...
}
}
As for calling the SetItemSource, it is async so should be awaited. That can't be done in the constructor.
Consider creating a event that can be raised and its handler used to await the desired behavior.
private event EventHandler loadingData = delegate { };
private async void onLoadingData(object sender, Eventargs args) {
JobListing.ItemsSource = await client.GetJobs();
}
Full code
public partial class JobsPage : ContentPage {
public readonly IApi client;
public JobsPage () {
InitializeComponent ();
//resolving client
client = DependencyService.Get<IApi>();
//subscribing to event
loadingData += onLoadingData;
//raising event
loadingData(this, EventArgs.Empty);
}
private async Task SetItemSource() {
JobListing.ItemsSource = await client.GetJobs();
//...
}
private event EventHandler loadingData = delegate { };
private async void onLoadingData(object sender, Eventargs args) {
JobListing.ItemsSource = await client.GetJobs();
}
}
Although a custom event was created, you could just as easily used on of the event/eventhandler of the view.
All of that code should actually live inside of a view model and then bound to the view in a binding context.
I make a method called Instance that allow me to have a single instance of the Settings window, like this:
public static async Task<Settings> Instance()
{
if (AppWindow == null)
{
AppWindow = new Settings();
AppWindow.Closing += async (x, y) =>
{
bool close = await AppWindow.CheckSettings();
y.cancel = (close) ? true : false;
AppWindow = null;
};
}
return AppWindow;
}
the CheckSettings have this structure:
private async Task<bool> CheckSettings()
{
//just as example
return true;
}
the method Instance() tell me that there is no await operator inside. Why happen this?
I need to ask also other questions:
Can this logic used inside a property instead of Instance method? How?
Is possible close the window without implement a Task<bool>
UPDATE
based on the helpful answer and comments on this great community I have edited the method as this (now is a property):
public static Settings Instance
{
get
{
if (AppWindow == null)
{
AppWindow = new Settings();
AppWindow.Closing += async (x, y) =>
{
bool close = await AppWindow.CheckSettings();
y.Cancel = close;
//AppWindow.Close();
//AppWindow = null;
};
}
return AppWindow;
}
}
the problem is that the Cancel does not await the CheckSettings()
Set the Cancel property to true before you call your async method:
public static Settings Instance
{
get
{
if (AppWindow == null)
{
AppWindow = new Settings();
//attach the event handler
AppWindow.Closing += AppWindow_Closing;
}
return AppWindow;
}
}
private static async void AppWindow_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
e.Cancel = true;
//call the async method
bool close = await AppWindow.CheckSettings();
if (close)
{
AppWindow win = (AppWindow)sender;
//detach the event handler
AppWindow.Closing -= AppWindow_Closing;
//...and close the window immediately
win.Close();
AppWindow = null;
}
}
So, first I have read a ton of threads on this particular problem and I still do not understand how to fix it. Basically, I am trying to communicate with a websocket and store the message received in an observable collection that is bound to a listview. I know that I am getting a response back properly from the socket, but when it tries to add it to the observable collection it gives me the following error:
The application called an interface that was marshalled for a different thread. (Exception from HRESULT: 0x8001010E (RPC_E_WRONG_THREAD))
I've read some information on "dispatch" as well as some other things, but I am just massively confused! Here is my code:
public ObservableCollection<string> messageList { get; set; }
private void MessageReceived(MessageWebSocket sender, MessageWebSocketMessageReceivedEventArgs args)
{
string read = "";
try
{
using (DataReader reader = args.GetDataReader())
{
reader.UnicodeEncoding = Windows.Storage.Streams.UnicodeEncoding.Utf8;
read = reader.ReadString(reader.UnconsumedBufferLength);
}
}
catch (Exception ex) // For debugging
{
WebErrorStatus status = WebSocketError.GetStatus(ex.GetBaseException().HResult);
// Add your specific error-handling code here.
}
if (read != "")
messageList.Add(read); // this is where I get the error
}
And this is the binding:
protected override async void OnNavigatedTo(NavigationEventArgs e)
{
//await Authenticate();
Gameboard.DataContext = Game.GameDetails.Singleton;
lstHighScores.ItemsSource = sendInfo.messageList;
}
How do I make the error go away while still binding to the observable collection for my listview?
This solved my issue:
Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
() =>
{
// Your UI update code goes here!
}
);
Correct way to get the CoreDispatcher in a Windows Store app
Try replacing
messageList.Add(read);
with
Dispatcher.Invoke((Action)(() => messageList.Add(read)));
If you're calling from outside your Window class, try:
Application.Current.Dispatcher.Invoke((Action)(() => messageList.Add(read)));
Slight modification for task based async methods but the code in here will not be awaited.
await Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
() =>
{
// Your UI update code goes here!
}
).AsTask();
This code WILL await, and will allow you to return a value:
private async static Task<string> GetPin()
{
var taskCompletionSource = new TaskCompletionSource<string>();
CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
async () =>
{
var pin = await UI.GetPin();
taskCompletionSource.SetResult(pin);
}
);
return await taskCompletionSource.Task;
}
And on Android:
private async Task<string> GetPin()
{
var taskCompletionSource = new TaskCompletionSource<string>();
RunOnUiThread(async () =>
{
var pin = await UI.GetPin();
taskCompletionSource.SetResult(pin);
});
return await taskCompletionSource.Task;
}
Maby this is not a "good" practice, but it works.. I leave a message from webSocket, to mainBody instance, where I have a timered reader...
public class C_AUTHORIZATION
{
public Observer3.A_MainPage_cl parentPageInstance; //еще одни экземпляр родителя
public WebSocket x_Websocket;
private string payload = "";
private DateTime nowMoment = DateTime.Now;
public void GET_AUTHORIZED()
{
bitfinex_Websocket= new WebSocket("wss://*****.com/ws/2");
var apiKey = "";
var apiSecret = "";
DateTime nowMoment = DateTime.Now;
payload = "{}";
x_Websocket.Opened += new EventHandler(websocket_Opened);
x_Websocket.Closed += new EventHandler(websocket_Closed);
}
void websocket_Opened(object sender, EventArgs e)
{
x_Websocket.Send(payload);
parentPageInstance.F_messager(payload);
}
void websocket_Closed(object sender, EventArgs e)
{
parentPageInstance.F_messager("L106 websocket_Closed!");
GET_AUTHORIZED();
}
}
public sealed partial class A_MainPage_cl : Page
{
DispatcherTimer ChartsRedrawerTimer;
public bool HeartBeat = true;
private string Message;
public A_MainPage_cl()
{
this.InitializeComponent();
ChartsRedrawerTimer = new DispatcherTimer() { Interval = new TimeSpan(0, 0, 0, 0, 100) };
ChartsRedrawerTimer.Tick += Messager_Timer;
ChartsRedrawerTimer.Start();
}
private void Messager_Timer(object sender, object e)
{
if(Message !=null) //
{
F_WriteLine(Message);
Message = null; //
}
}
public void F_messager(string message) //
{
Message = message;
}
In Xamarin, I got around this by using:
Device.BeginInvokeOnMainThread(() => {
// code goes here
});