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Can you always Invoke instead of checking InvokeRequired?


By : Rach
Date : September 16 2020, 12:00 AM
Hope that helps One problematic situation is the case that you want to access controls on a form that doesn't yet have a handle. For example, if you call some initialization function on a created form to fill the form's controls before showing the form.
In this case, calling Invoke on the controls will throw an InvalidOperationException.
code :
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    public void Test()
    {
        Action a = () => { textBox1.Text = "A"; };
        textBox1.Invoke(a);
    }
}
Form1 form = new Form1();
form.Test();
form.ShowDialog();
public void Test()
{
    Action a = () => { textBox1.Text = "A"; };

    if (textBox1.InvokeRequired)
    {
        textBox1.Invoke(a);
    }
    else
    {
        a();
    }
}


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TPL vs. InvokeRequired/Invoke


By : user2316883
Date : March 29 2020, 07:55 AM
wish of those help This seems fairly subjective...
When you say "Since .NET 4.0", you are saying "as of April of this year" - .net has been around for 10 years now, and InvokeRequired/Invoke has been used for the last 9. Why would MS break all existing UI code for any reason? Even if a new way of calling to a thread existed, they could not simply modify the pattern without huge compatibility concerns.

How to process PropertyGrid changes with Invoke on InvokeRequired?


By : Eric Humberto
Date : March 29 2020, 07:55 AM
will be helpful for those in need Let's say you are binding your object to a PropertyGrid, whenever a Property of your object get changed, it should fire a PropertyChanged event in the GUI thread, in order for the PropertyGrid to update properly.
It is your duty to marshal a Property setter to GUI thread. If you can have a link to any Control, use that Control to invoke. Otherwise, a general solution is create a dummy control at the beginning and use it for invoking.
code :
public partial class ControlBase : UserControl
{
    /// <summary>
    /// Dummy control, use for invoking
    /// </summary>
    public static Control sDummyControl = null;

    /// <summary>
    /// Constructor
    /// </summary>
    public ControlBase()
    {
        InitializeComponent();

        if (sDummyControl == null)
        {
            sDummyControl = new Control();
            sDummyControl.Handle.ToString(); // Force create handle
        }
    }
}
    public event PropertyChangedEventHandler PropertyChanged;
    protected void RaisePropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        if (PropertyChanged == null)
        {
            return;
        }
        Control c = ControlBase.sDummyControl;
        if (c == null)
        {
            PropertyChanged(sender, e);
        }
        else
        {
            if (c.InvokeRequired)
            {
                c.BeginInvoke(new PropertyChangedEventHandler(RaisePropertyChanged), new object[] { sender, e });
            }
            else
            {
                PropertyChanged(sender, e);
            }
        }
    }
    public string Name
    {
        get { return _name; }
        set { _name = value; RaisePropertyChanged(this, new PropertyChangedEventArgs("Name")); }
    }

What does 'InvokeRequired' and 'Invoke' mean in .Net?


By : Vrobello
Date : March 29 2020, 07:55 AM
hop of those help? Me.InvokeRequired is checking to see if it's on the UI thread if not it equals True, Me.Invoke is asking for a delegate to handle communication between the diff threads.
As for your side note. I typically use an event to pass data - this event is still on the diff thread, but like above you can delegate the work.
code :
Public Sub UpdateGrid() 
    'why ask if I know it on a diff thread
    Me.Invoke(Sub() 'lambda sub
               DataGridView1.DataSource = dtResults 
               DataGridView1.Refresh() 
               btnRun.Text = "Run Query" 
               btnRun.ForeColor = Color.Black 
              End Sub)
End Sub

C# Questions regarding Invoke, Invokerequired & Multithreading


By : vsiatr
Date : March 29 2020, 07:55 AM
Hope this helps I have 2 forms running on different threads. Form2 will generate a string, send it back to form1 and update the richtextbox in form1. I got the code from my friend but I don't understand a part of it. , This part:
code :
SetTextCallback d = new SetTextCallback(SetText);
this.Invoke(d, new object[] { text });
if (this.f1_rtb_01.InvokeRequired)

Should I check InvokeRequired before Invoke()?


By : user2478237
Date : March 29 2020, 07:55 AM
hope this fix your issue According to Hans Passant in a comment the code for Invoke is intelligent enough to not "invoke" when being executed on the main thread. See source code (link supplied by Hans).
And here's a quote from that link:
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