How to continuously change the plotted data according to the value obtained from a "uislider" component?

The following code should change the y-value of the plotted horizontal line according to the value obtained from the "uislider" component continuously. But the obtained values seem to be incorrect and lagging behind the position of the slider.

f = uifigure('Position',[10 10 500 800]);
a = uiaxes('Parent',f,'Position',[10 10 480 700]);
s = uislider('Parent',f,'Position',[10 760 400 10]);
p = plot(a,[0 4],[4 4]);
s.ValueChangingFcn = @updatePlot;

function updatePlot(src,event)
         src.Parent.Children(2).Children.YData(:) = src.Value;
end

Answer 1

[MathWorks Support Team]

The issue is resolved by modifying the callback function as follows:

function updatePlot(src,event)
    src.Parent.Children(2).Children.YData(:) = event.Value;
end

According the the documentation for "uislider", in order to monitor the continuously changing value of the slider, the callback should use the "Value" property of the "event" argument, and not of the "source" argument. For an example and more details on creating response to a moving slider, please refer to the following documentation link:

https://www.mathworks.com/help/matlab/ref/uislider.html#buicpyj-1