Create a "listener" to a slider

I am creating a GUI in which I display a 3D image and navigate through it using a slider. I want to draw some points (using a "WindowButtonDownFcn" callback, i.e., I do not have any information about the position of the slider once I call the drawing function) over a certain slice using the mouse and that point should appear over all other slices and be editable as soon as the user uses the slider to switch between slices.

One possible solution that came to my mind is use "listeners", so whenever the user moves the slider, my drawing function is notified and the slider position is passed to it. . Following the MATLAB tutorial, I defined my classes so I can include the listener to my code, but it is not working. . How can I implement this functionality?

Thank you all in advance,

Answer 1

[Steven Lord]

Use the slider's Callback property to call the function that draws or updates the view.

[Gabriel]

I already do that. The point is: once I call the drawing function, I can't access the value of the slider so I can plot at the moment the user changes the slice using the slide bar. Only when the user hits "RETURN" and the control goes back to the main window (where the slider is placed).

Answer 2

[Walter Roberson]

The WindowButtonDownFcn can fetch the Value property of the slider as needed.

[Gabriel]

The point is: once I call the drawing function, I have no access to the slider value, since I changed the scope. I need a listener, so the program can activate the drawing function whenever the user changes the slider value.

[Steven Lord]

As long as your drawing function has access to the slider's handle, it most certainly can retrieve the slider's properties.

[Walter Roberson]

Right, you just need the handle. If you are using GUIDE and the slider was created as part of the .fig then the handle will be available in the handles structure. If you are not using GUIDE or you are creating the slider at run time then see

http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.28s.29.3F