MATLAB: R2010b event ContinuousValueChange is not supported by a slider

addlistenercontinuousvaluechangeerroreventMATLABr2010br2013a

I use R2013a and I tried to do Matlab GUI using GUIDE. I have a slider and a textbox. The textbox is to diplaying continuous value change of slider. So i added listener to do it.

 function bp_gui2_3_OpeningFcn(hObject, eventdata, handles, varargin)
 handles.sliderListener1 = addlistener(handles.filtr_slider,'ContinuousValueChange', ...
                                      @(hObject, event) filtr_sliderContValCallback(...
                                        hObject, eventdata, handles));
 set(handles.filtr_text, 'String', '15');
 handles.output = hObject;
 guidata(hObject, handles);

Then i created callback

 function filtr_sliderContValCallback(hObject, eventdata, handles)
 set(handles.filtr_text, 'String', num2str(round(get(handles.filtr_slider, 'Value'))));

It works fine, but when I try to use R2010b causes to return the following error: The specified event is not supported by the object

Any ideas to resolve problem with event 'ContinuousValueChange' using R2010b ? Thanks !

Best Answer

I also faced this challenge in 2010b, and solved it for multiple sliders. You can see the working code here, in the Mfile "cubehelix_view", which was written in 2010b:

http://www.mathworks.com/matlabcentral/fileexchange/43700-cubehelix-colormaps--beautiful--distinct--versatile-

The core of it sets a listener like this:

addlistener(h, 'Value', 'PostSet', @callbackfun);

The method I used uses some advice gleaned from various sources:

http://www.mathworks.com/help/matlab/matlab_oop/listening-for-changes-to-property-values.html

http://de.mathworks.com/matlabcentral/answers/141054-matlab-slider-pass-value-to-event-handler

http://undocumentedmatlab.com/blog/continuous-slider-callback

Related Solutions

MATLAB: Add listener in slider CreateFcn

addlistener(hObject, 'ContinuousValueChange', @(hObject, eventdata) slider1_Callback(hObject, eventdata, handles))

But be careful: it is the value of handles as of the time of the call to addlistener that will be "captured" and passed in to the slider1_Callback. Any changes you might make to handles after that call will not be reflected.

For this reason I recommend passing the figure number of the GUI instead, and then in the callback routine, using guidata() on the GUI figure to pull out the current version of the handles structure.

Exception: if you are using only a single figure (including the GUI) then I would not bother to pass handles and instead in the callback would use

handles = guidata(hObject);

to pull out the current handles structure. You can do this as long as the callback object is part of the GUI figure; if the callback object is part of some other figure then you need to know the GUI figure number (or at least the tag of something known to be part of the GUI figure.)

MATLAB: Fix Values of a slider in GUI to be multiple of two

vittorio - you can try discretizing the slider values as at https://www.mathworks.com/matlabcentral/answers/153278-discretizing-matlab-slider-gui. If you know how many values or steps you want in your slider, you could do in the OpeningFcn

 function yourGuiName_OpeningFcn(hObject, eventdata, handles, varargin)
 handles.output = hObject;
 % add a continuous value change listener
 if ~isfield(handles,'hListener')
    handles.hListener = ...
        addlistener(handles.slider1,'ContinuousValueChange',@respondToContSlideCallback);
 end
 % set the slider range and step size
 numSteps = 13;
 set(handles.slider1, 'Min', 1);
 set(handles.slider1, 'Max', numSteps);
 set(handles.slider1, 'Value', 1);
 set(handles.slider1, 'SliderStep', [1/(numSteps-1) , 1/(numSteps-1) ]);
 % save the current/last slider value
 handles.lastSliderVal = get(handles.slider1,'Value');
 % Update handles structure
 guidata(hObject, handles);

In the slider callback, you would then multiply your slider value by two

 function respondToContSlideCallback(hObject, eventdata)
 % first we need the handles structure which we can get from hObject
 handles = guidata(hObject);
 % get the slider value and convert it to the nearest integer that is less
 % than this value
 newVal = floor(get(hObject,'Value'));
 % set the slider value to this integer which will be in the set {1,2,3,...,12,13}
 set(hObject,'Value',newVal);
 % now only do something in response to the slider movement if the 
 % new value is different from the last slider value
 if newVal ~= handles.lastSliderVal
     % it is different, so we have moved up or down from the previous integer
     % save the new value
     handles.lastSliderVal = newVal;
     guidata(hObject,handles);
    % calculate the new number of points
    numPoints = 2 * get(hObject, 'Value');
 end

Best Answer

Related Solutions

MATLAB: Add listener in slider CreateFcn

MATLAB: Fix Values of a slider in GUI to be multiple of two

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