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I am new to GUI programming for MATLAB, so my question relates to that.

Let's say that I create a GUI with GUIDE. In the creation function

MyGUI_OpeningFcn(hObject, eventdata, handles, varargin)

I call another function, 

SamplingRate_Callback(handles.SamplingRate, eventdata, handles)

defined as

function SamplingRate_Callback(hObject, eventdata, handles)

SamplingRate_Callback sets a few variables, 

handles.a = 1;
handles.b = 2;
handles.c = 3;

The handles structure updates correctly within the SamplingRate_Callback function. The problem I am having is that unless I change the function to 

function handles = SamplingRate_Callback(hObject, eventdata, handles),

I cannot return the data to the calling function, MyGUI_OpeningFcn. I have tried using guidata(gcf, handles) and guidata(hObject, handles), but neither works.

Would you be able to shed some light on this problem?

Also, I am not sure when to use guidata(gcf, handles) vs. guidata(hObject, handles).

Thanks for your help!

Rody Oldenhuis
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user1340654
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2 Answers2

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How do you call SamplingRate_Callback in your MyGUI_OpeningFcn function? It seems to me that you have not defined the return values, which would be values in this case.

The fix would be something like this:

function [handles] = SamplingRate_Callback(hObject, eventdata, handles)

And then you would call SamplingRate_Callback from MyGUI_OpeningFcn like this:

handles = SamplingRate_Callback(handles.SamplingRate, eventdata, handles);
nrz
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  • Hi nrz, thanks for your answer. Yes, that would work. I guess I don't understand why when SamplingRate_Callback is called directly by using its GUI element, you can simply save persistent handle values using guidata, but if you call the same function another way, guidata doesn't work. Does that make sense? Do you know why? – user1340654 Apr 19 '12 at 05:44
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Depending on what you mean by data, you can use getappdata and setappdata to save and load data to/from the object itself (I generally use the axes that the data will be plotted on).

Keegan Keplinger
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