Re: INotifyPropertyChanged binding label problem during update in function - C# Discussion Boards

Re: INotifyPropertyChanged binding label problem during update in function

15-Jul-14 4:42

Hello I have a problem with update of binding of a label.
I have this simple class:

public partial class frTest : INotifyPropertyChanged
  {
    private string _message;
    public string Message
    {
      private set
      {
        _message = value;
        OnPropertyChanged("Message");
      }
      get
      {
        return _message;
      }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName = null)
    {
      PropertyChangedEventHandler handler = PropertyChanged;
      if (handler != null)
      {
        handler(this, new PropertyChangedEventArgs(propertyName));
      }
    }

    public frTest()
    {
      InitializeComponent();
      DataContext = this;
    }

    private void WindowLoaded(object sender, RoutedEventArgs e)
    {
      Message = "test";
      txtDevQty.Text = "1000";
      txtDevQty.TextAlignment = TextAlignment.Center;
      txtDevQty.IsEnabled = false;
    }

    private void BtnNextClick(object sender, RoutedEventArgs e)
    {
      for (int i = 0; i < 1000; i++)
      {
        Message = string.Format("Tested {0} of {1}", i, 1000);
        Thread.Sleep(10);
      }
    }
  }

I have in the xaml code a label with content binded to Message value

XML

<Label Name="lblHint" Content="{Binding Message}" HorizontalAlignment="Center" FontFamily="verdana" FontSize="11" FontWeight="Bold" Foreground="Black" Grid.ColumnSpan="2"></Label>

The problem is that when i launch the BtnNextClick function,i see the label updated only at the end of procedure,and what i would like is to see updated in every cycle the content of the label....
How can I do?
I think it's a problem between my form and the ui thread?

Thanks in advance

Best regards

Pete O'Hanlon15-Jul-14 5:18

Re: INotifyPropertyChanged binding label problem during update in function

15-Jul-14 5:18

The reason you're not seeing anything is because your Thread.Sleeps are locking the UI thread. If you want to see the labels, simply wrap the loop up like this:

Task.Factory.StartNew(() =>
{
  for (int i = 0; i < 1000; i++)
  {
    Message = string.Format("Tested {0} of {1}", i, 1000);
    Thread.Sleep(10);
  }
});

massisoda15-Jul-14 5:21

Re: INotifyPropertyChanged binding label problem during update in function

15-Jul-14 5:21

The sleep is necessary?

Pete O'Hanlon15-Jul-14 5:24

Re: INotifyPropertyChanged binding label problem during update in function

15-Jul-14 5:24

Only if you want to pause your thread long enough to actually see the update. If you remove it, you'll flood the UI with notifications.

massisoda16-Jul-14 1:48

Re: INotifyPropertyChanged binding label problem during update in function

16-Jul-14 1:48

I have tried but unfortunately using task don't solve my problem...
Because my code is a little bit different of what i wrote...

With this code the update of the label start only when all the iterations of the for (for (int j = 0; j < 10; j++)) are completed

public partial class frTest : INotifyPropertyChanged
  {
    private string _message;
    public string Message
    {
      private set
      {
        _message = value;
        OnPropertyChanged("Message");
      }
      get
      {
        return _message;
      }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName = null)
    {
      PropertyChangedEventHandler handler = PropertyChanged;
      if (handler != null)
      {
        handler(this, new PropertyChangedEventArgs(propertyName));
      }
    }

    public frTest()
    {
      InitializeComponent();
      DataContext = this;
    }

    private void WindowLoaded(object sender, RoutedEventArgs e)
    {
      Message = "test";
      txtDevQty.Text = "1000";
      txtDevQty.TextAlignment = TextAlignment.Center;
      txtDevQty.IsEnabled = false;
    }

    public void DoSomething()
    {
      var a = 0;

      for (int i = 0; i < 2000000; i++)
      {
        a++;
      }
    }    

    private void BtnNextClick(object sender, RoutedEventArgs e)
    {
        for (int j = 0; j < 10; j++)
        {
          DoSomething();

          Task.Factory.StartNew(() =>
          {

            try
            {
              for (int i = 0; i < 1000; i++)
              {
                Message = string.Format("Tested {0} of {1}", i, 1000);
                Thread.Sleep(10);
              }
            }
            catch (Exception ex)
            {

            }
          });
        }
    }
  }

Pete O'Hanlon16-Jul-14 1:53

Re: INotifyPropertyChanged binding label problem during update in function

16-Jul-14 1:53

And what else would you expect it to do? You aren't actually starting to update Message until you have completed the other loop. Just drop your outer loop into the task factory.

massisoda16-Jul-14 2:00

Re: INotifyPropertyChanged binding label problem during update in function

16-Jul-14 2:00

I cannot do it because in reality my DoSomething function do some work and start a thread that do some long operations.
For this reason i need to update the label for have a feedback of where is my routine arrived

Pete O'Hanlon16-Jul-14 2:22

ShowDialog doesn't make form modal

16-Jul-14 2:22

Look, I cannot read your mind about what you are trying to do. You cannot keep drip feeding things through. It's simple enough, you need to update your label text from a none UI thread, so you can simply spawn that off in its own TaskFactory. In your example, you aren't starting off the update of the label until you have completed DoSomething. Step away from the keyboard right now, and actually design the interactions you need rather than throwing things on here that don't actually match what you're trying to do.

Don Guy15-Jul-14 4:34

Don Guy

15-Jul-14 4:34

Hello there,

I have a C# application and with in a thread am popping open another form using the ShowDialog() function. For some reason the form is not displayed as MODAL. I tried passing "this" and obviously that causes a problem as it cannot be used within a thread.

The main C# application is a MDI and has multiple forms embedded in it.

How can i make this form MODAL?

Thanks!

Re: ShowDialog doesn't make form modal

Eddy Vluggen15-Jul-14 5:28

Eddy Vluggen

15-Jul-14 5:28

Don Guy wrote:
I tried passing "this" and obviously that causes a problem as it cannot be used within a thread.

The dialog should be created (and would then be owned) by the main-thread. You could pass the entire mainform to the thread as an argument, and when the dialog needs be shown, use the mainform to invoke[^] the code on the mainthread.

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

To create reports

stokkee15-Jul-14 2:19

stokkee

15-Jul-14 2:19

Hi. I`m starting programmer in C #. I have a task to automate OpenOffice. I need to create reports OO Calc on fly. Anyone can help me?

Win 7 x32, VS2010 C#

Re: To create reports

Simon_Whale15-Jul-14 3:22

Simon_Whale

15-Jul-14 3:22

You haven't given much to go on really. So I would suggest that you have a read of this TblProc: OpenOffice Calc and Excel[^]

Every day, thousands of innocent plants are killed by vegetarians.

Help end the violence EAT BACON

Re: To create reports

deenn22-Jul-14 2:26

deenn

22-Jul-14 2:26

You need to include some component (COM, LibOpeOffice).
From my expirience I can't advise you COM for OpenOpeffice automation. I'm using LibOpenOffice. Look here http://4k.com.ua/products/others/libopenoffice

reading magnetic card stripe

Jassim Rahma15-Jul-14 1:22

Jassim Rahma

15-Jul-14 1:22

Hi,

I would like to ask about the magnetic strips on the cards?

How can I read the data?

is it just a raw data just like the bard code and I have to split it? or it's encrypted and needs special way to read?

Technology News @ www.JassimRahma.com

OriginalGriff15-Jul-14 1:31

OriginalGriff

15-Jul-14 1:31

Depends on the card, depends on the reader.

What are you trying to do?

Those who fail to learn history are doomed to repeat it. --- George Santayana (December 16, 1863 – September 26, 1952)
Those who fail to clear history are doomed to explain it. --- OriginalGriff (February 24, 1959 – ∞)

Jassim Rahma15-Jul-14 1:35

Jassim Rahma

15-Jul-14 1:35

I am trying to do a loyalty card. I don't have anything yet

I will purchase zebra printer with its encoder but I want to develop the application which will read the magnetic stripe and do the required task accordingly.

Technology News @ www.JassimRahma.com

OriginalGriff15-Jul-14 1:38

OriginalGriff

15-Jul-14 1:38

Then talk to the manufacturers and see what they can provide!
They may do several versions...

Jassim Rahma15-Jul-14 1:39

Jassim Rahma

15-Jul-14 1:39

you mean there is no standard way of storing the data on magnetic stripes?!

Technology News @ www.JassimRahma.com

Pete O'Hanlon15-Jul-14 1:49

15-Jul-14 1:49

It's not the data side you need to worry about, it's the API for the reader. You aren't actually be reading the card, the reader does - what you need to do is interpret the output from the reader.

Re: C# , Websocket -HTTPS

Gerry Schmitz15-Jul-14 9:18

Gerry Schmitz

15-Jul-14 9:18

One interfaces with the "card reader"; which could be a USB device; which is opened and read (when armed) as a file stream.

The card's strip would contain some fields and "tracks" of data at particular offsets in the card reader "file".

You need to extract the required fields (using offsets and lengths), wrap them as strings in a "transaction", and typically send them to a "payment processor" (or whatever) via a web service.

The data is encrypted; the client does not decrypt it; it is sent "as is" (with say a $ amount) to the credit card data processor who decrypts the credit data; verifies it; approves the transaction; or declines it; by sending a web service response back to the client.

C# , Websocket -HTTPS

sgeorge10615-Jul-14 0:49

sgeorge106

15-Jul-14 0:49

HI,
 I am facing an issue , from my client side (HTTPS browser) I am trying to connect a HttpTaskAsyncHandler in the project
  
 Eg:
var webSockets = new  WebSocket("wss://xxx.com//Racer.HTML5/WSHandlerCall));
if (webSockets != null) {
webSockets.onopen = function () {
alert('Connection open');
}
 
webconfig:
  <system.webServer>
    <handlers>
      <add name="WebSocketHandler" verb="*" path="WSHandlerCall" type="Racer.HTML5.WebSocketHandler,Racer.HTML5" resourceType="Unspecified" />
    </handlers>
  </system.webServer>
  <appSettings>
       <add key ="wsURL" value="/Racer.HTML5/WSHandlerCall"/>



 1.The sockets send a request. 
 2. OnOpen Listener is triggered but not called the handler.
  
 Plz Help !!

modified 15-Jul-14 14:42pm.

Pete O'Hanlon15-Jul-14 1:45