Changing slider limit in gui

is there anyway i could get the slider to update the limit to the image count Ct?

It seems that the app.Slider.Limits only accepts numerical values - at the moment it is set at 2. How can in incorperate the .Count function into the slider limit so the limit automatically updates with the value of .Count should i decide to import another file with a different .Count value?

How can I add a listener function here also?

Imported imageSet code

    % Button pushed function: LoadImageButton
        function LoadImageButtonPushed(app, event)
            global Ct
            imgSetVector = imageSet(uigetdir(''),'recursive');
             Z = read(imgSetVector,1);
             Ct = imgSetVector.Count;
imshow(Z,'Parent',app.UIAxes)

Slider Code

     app.Slider = uislider(app.UIFigure);
            app.Slider.Limits = [1 2]; **
            app.Slider.MajorTicks = [];
            app.Slider.MajorTickLabels = {''};
            app.Slider.ValueChangedFcn = createCallbackFcn(app, @SliderValueChanged, true);
            app.Slider.MinorTicks = [];
            app.Slider.Position = [296 36 321 3];
            app.Slider.Value = 1;

Thanks!

Answer 1

[Ameer Hamza]

Try to set the slider limit after this line

Ct = imgSetVector.Count;
app.Slider.Limits(2) = Ct;

[Pranaya Kansakar]

Thanks for the reply!

I tried modifying the code as you mentioned:

 app.Slider = uislider(app.UIFigure);
            app.Slider.Limits(2) = Ct;
            app.Slider.MajorTicks = [];
            app.Slider.MajorTickLabels = {''};
            app.Slider.ValueChangedFcn = createCallbackFcn(app, @SliderValueChanged, true);
            app.Slider.MinorTicks = [];
            app.Slider.Position = [296 36 321 3];
            app.Slider.Value = 1;

However I got the error:

Unable to perform assignment because the left and right sides have a different number of elements.

[Ameer Hamza]

Not here. You need to assign it in LoadImageButtonPushed. So that the limits are changed when you push the button.

[Pranaya Kansakar]

Do i cut out the

app.Slider.Limits(2) = Ct;

from this section or revert back to the original code (shown in the first post)?

[Ameer Hamza]

Remain the slider code the same as in the question. Just try to change it in the callback.

[Pranaya Kansakar]

That's great - it worked!

Thanks!

Do you know if it's possible to create a listener function to the slider?

[Ameer Hamza]

The slider has value changed and value changing callbacks. You can use that to respond to change in slider value. In app-designer. right click the slider and in callback menu, create the type of callback you want.

[Pranaya Kansakar]

Hmm... the code that I edited appears to be a .m file as opposed to a .mlapp file.

How can I open the .m file in app deisgner?

Sorry i'm new to Matlab!

[Image Analyst]

Right. I don't think there's any need for a listener since you know every place where it might need updating.

[Pranaya Kansakar]

Thanks everyone for bearing with me.

I guess i'm trying to say is there any way of updating the slider value without lifting the mouse click?

I guess this issue is addressed in the following link (by creating a plot that automatically responds):

https://uk.mathworks.com/help/control/ug/build-app-with-interactive-plot-updates.html

However, this webpage demonstrates sliders using the "uicontrol" function instead of "app".

[Ameer Hamza]

The valueChanging callback for uislider does not require lifting the mouse button. Read here: https://www.mathworks.com/help/releases/R2020a/matlab/ref/uislider.html#buicpgg-1_sep_shared-ValueChangingFcn.

Why are you creating the app in a script? Isn't it easier to use the app-designer?

[Pranaya Kansakar]

I didn't realise that you could use the code in app-designer as well.

I've implemented it in app-designer and it works great!

Thanks!

I guess this was a trivial issue.

I attach my interpretation of the app if anyone else in the future stumbles across the same problem.

*it's laggy...