CODEWITHSUNDEEP
wpf
Mujadid Mughal
Mujadid Mughal

Reputation: 2663

Text Input very slow in WPF Application

I have a simple WPF application in which I open a webcam and set it to 30 Frames per second, like this:

 webcam = new WebCamCapture();
 webcam.FrameNumber = ((ulong)(0ul));
 webcam.TimeToCapture_milliseconds = FrameNumber;
 webcam.ImageCaptured += new WebCamCapture.WebCamEventHandler(webcam_ImageCaptured);

This application shows the camera preview in an ImageControl (30 frames per second).

Below the Image box, I've a TextBox

<TextBox Name="txtMsg" HorizontalAlignment="Left" Width="214" Height="22" Margin="0,260,0,0" TextWrapping="Wrap" VerticalAlignment="Top"></TextBox>

Now when I try to type in the textbox, it takes seconds to reply. Sometimes I press keys several times, but get no response. If I delay the camera capture event (e.g. 1 frame per second) it works fine.

My question is how can I have the UI updated frequently, but get a fast response in TextBox at the same time.

Thanks.

Upvotes: 0

Views: 221

Answers (1)

Dominic Jonas
Dominic Jonas

Reputation: 5025

The webcam object is running in the UI Thread. Here is an example, how you can start it in a separate Thread. Be careful, because the ImageCaptured event is fired in a background Thread, so you have to call a Dispatcher.

private void _StartWebCam()
{
    ThreadStart webCamThreadStart = () =>
    {
        webcam = new WebCamCapture();
        webcam.FrameNumber = ((ulong)(0ul));
        webcam.TimeToCapture_milliseconds = FrameNumber;
        webcam.ImageCaptured += new WebCamCapture.WebCamEventHandler(webcam_ImageCaptured);
    };
    Thread threadnameThread = new Thread(webCamThreadStart) { IsBackground = true };
    threadnameThread.Start();
}

private void webcam_ImageCaptured(object sender, EventArgs eventArgs)
{
    System.Windows.Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Normal, new Action(() =>
    {
        //Set you captured Image to your ImageControl
    }));
}

Upvotes: 1

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