Display Video Stream in App Designer

I am developing a simple app in App Designer and I have been struggling with including a video stream from a webcam.

I have come across the following post, but so far I have been unsuccessful in getting my app to work: https://uk.mathworks.com/matlabcentral/answers/357814-how-to-create-a-custom-preview-window-for-matlab-webcam

So far, what I am doing is including the following commands in my start-up function:

app.Camera = webcam;  %('USB2.0 PC CAMERA')
image(app.UIAxes2,zeros(size(snapshot(app.Camera)),'uint8'));

And the following lines relate to the activation of the video stream when a switch button is slid to Start:

% Value changed function: CameraStreamSwitch
function CameraStreamSwitchValueChanged(app, event)
   while strcmp(app.CameraStreamSwitch.Value,'Start')
       im = image(app.UIAxes_2,zeros(size(snapshot(app.Camera)),'uint8'));
       preview(app.Camera,im);
   end
end

Many thanks in advance for the help!

Answer 1

[Cris LaPierre]

You are close. Here's some sample code that works for me.

Add properties for the variables you create that you want to share

    properties (Access = private)
        Camera % webcam stream object
        himg % image object handle
    end

My startupFcn looks like this

value = app.CameraStreamSwitch.Value;
if strcmpi(value,'on')
    preview(app.Camera,app.himg)
end

I would also suggest adding a closing function so the webcam doesn't remain open once the app closes.

% Close request function: UIFigure
function UIFigureCloseRequest(app, event)
    delete(app)
    delete(app.Camera)
end

[Cris LaPierre]

The downside, I will admit, is that I can't find a way to close the preview without closing the app window. The function for this is closePreview.

[Pien Vinke]

Did you maybe find a solution for closing the preview of the camera?

[Cris LaPierre]

In the most recent version of MATLAB, closePreview no longer closes the app. Looking back, this seems to be the case since R2019b. What version of MATLAB are you using?