Getting GUI Slider updates while dragging

Is there a straightforward method to get updates on a slider's position while it is being dragged? The standard callback gets called only after the drag is complete and the button has been released.

I'm thinking of using the ButtonDownFcn to start a polling loop checking the slider's value. (Then how do I detect mouse up?)

[Matt Fig]

Why don't you describe in detail what you are hoping to accomplish with this information and we will see if there is a optimal way to get there?

[Sean de Wolski]

ButtonDownFcn is disabled over an enabled uicontrol

[Norton Allen]

Matt, what I'm trying to do is get a slider where the app updates while the slider is moving, for example the way a browser updates while you are moving the scroll bar.

Sean, I did discover that ButtonDownFcn is not the answer pretty quickly too!

Answer 1

[Sean de Wolski]

This can be done easily with addlistener

h = uicontrol('style','slider','callback',@(src,evt)disp(get(src,'value')));
addlistener(h,'Value','PreSet',@(~,~)disp('hi'));

[Norton Allen]

Yes, this sounds like what I am looking for. Thanks!

[Mohamad Roslan Mohd Roshdi]

Hi How to get the slider update value into variable?

[Stephen23]

Mohamad Roslan Mohd Roshdi also created a question here: http://www.mathworks.com/matlabcentral/answers/264979-continuous-slider-callback-how-to-get-value-from-addlistener

Answer 2

[AG]

The following worked for me. I get a 'live' scroll-bar update by calling this within another function:

slider_value = get(gcf.Children(j), 'Value');

...where j is the value of the UIcontrol corresponding to the scroll. You can find out which UIControl it is in the figure by putting a break in the code and using:

gcf.Children

This could also be ascertained in run-time using:

for j = 1:length(gcf.Children)
    get(gcf.Children(j), 'Tag')
end

which will return a char array with the Tag of each of the children which could then be compared using strcmp(), for example. I've done this using a GUI created with GUIDE.