SynchronizationContext.Post to UI Method - update multiple labels

Question

In the following code snippet, How to update multiple labels? for example: Have several parameters in the update method instead of one parameter

 private void UIupdate(string name)
        {
            var timenow = DateTime.Now;
            if((DateTime.Now-dt).Milliseconds<=50)
                return;
            synchronizationcontext.Post(new SendOrPostCallback(o =>
            {
                
                lblFirstName.Text = "name" + (string)o;
                //lblLastName.Text = ?
                //lblZipCode.Text=?
            }),name );
            dt = timenow;
        }

then instead string post multiple strings(array/list) or some custom poco class — Selvin, Jul 08 '20 at 12:36
off-topic: why are you using `synchronizationcontext` instead normal async/await ? why the question has WCF tag? — Selvin, Jul 08 '20 at 12:37
what example ? instead `name` post `new string[] { name , something, somethingelse }` then cast `o` to `string[]` and read values from array and assign to right UI element — Selvin, Jul 08 '20 at 12:42
Can you change the above code snippet for multiple parameters and labels? I couldn't succeed, please help me — parvizblack, Jul 08 '20 at 21:58
You ask about UI. Which UI? Would you like a Xamarin answer? — H H, Jul 09 '20 at 05:22
How is this code being called? Why are you trying to prevent it running if it's been less than 50 milliseconds since the last time? Is this in a loop? — Enigmativity, Jul 13 '20 at 02:31

score 0 · Answer 1 · answered Jul 09 '20 at 05:16

You can simply use the method parameters inside the lambda. The parameters are captured in a closure, and are available to all inner functions of a method.

private SynchronizationContext _synchronizationContext;
private Stopwatch _stopwatch = Stopwatch.StartNew();
private TimeSpan _lastUpdateTimestamp;

private void UIUpdate(string firstName, string lastName)
{
    TimeSpan timestamp = _stopwatch.Elapsed;
    if (timestamp < _lastUpdateTimestamp.Add(TimeSpan.FromMilliseconds(50))) return;
    _lastUpdateTimestamp = timestamp;

    _synchronizationContext.Post(_ =>
    {
        lblFirstName.Text = firstName;
        lblLastName.Text = lastName;
    }, null);
}

I also fixed your time-measuring logic. The Milliseconds counts only the milliseconds of the current second (has a value between 0 and 999). You probably intended to use the TotalMilliseconds. But even then your measurements would be dependent to the stability of the system clock. The system time can be adjusted by either user actions or automated procedures, so it cannot be trusted for measuring intervals.

SynchronizationContext.Post to UI Method - update multiple labels

1 Answers1