How to modify the handles structure (GUI) from an external function

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MRR
MRR 2013-3-8
回答： zakaria 2014-6-5
Hi,
I am developing a GUI. I can modify the handles structure (for example handles.variable1 = 2) within callbacks. However I am not able to do the same within an external function. E.g., this does not work:
function [matrix, indexVector] = myFunction(handles)
handles.variable1 = 1;
It is important to note that myFunction does not belong to the GUI callbacks, it is simply a function I have created in another m file. When I call it I can read the handles struture (actually im passing them as a parameter) but when I try to modify them the modification is not recorded.
Best,
-MRR

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Sean de Wolski
Sean de Wolski 2013-3-8
编辑：Sean de Wolski 2013-3-8
function [matrix, indexVector] = myFunction(handles)
handles.variable1 = 1;
guidata(handles.figure1,handles)
Where figure1 is the 'Tag' of the figure. You want to make sure that you assign the handles structure to the right place (i.e. the figure). hObject is dynamic, handles will always have the field for the figure.
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Jan
Jan 2013-3-20
编辑：Jan 2013-3-20
@MRR: Yes, of course, this is the expected behavior. Inside myFunction you update the handles struct and store it in the figure afterwards. Then after returned to Simulate_Callback, you use the local copy of handles with its value before calling myFunction() and overwrite the changes from inside this function. A suggestion for improvements:
function errorParameters = Simulate_Callback(hObject, eventdata, handles)
%some code here ...
handles = guidata(hObject); % Care for the newest version explicitly!
[output1, output2] = myFunction(hObject, handles);
handles = guidata(hObject); % Get the version updated in myFunction!
handles.variable1 = handles.variable1 + 1;
guidata(hObject, handles);
And inside myFunction(hObject, handles) I do:
handles.variable1 = 200; %or any other value
guidata(hObject, handles);
So Azzi's and Sean's answers hit the point already, but in your code there was a problem at another location, namely in the caller, which forgot to obtain the updated struct.
MRR
MRR 2013-3-20
@Jan Simon: Thank you, now it works. The key instruction that makes the handles structure to be updated is (and as you can see it wasnt used in any other previous solution in this post):
handles = guidata(hObject); % Get the version updated in myFunction!
But bear in mind that the other solutions (mine included) did not work, i.e., using guidata(hObject, handles) does not update the handles structure modified by myFunction, however it works for any callback function defined in the gui (i.e, those functions that are automatically associated with the pushbuttons, etc..), so Azzi's and Sean's answers, although hit the point, do not work. Of course, their and your feedback is very appreciated.
All in all, I would say the way GUIDE manages the handles structure is confusing.
Hope this discussion will help another "gui developers"
Best and thank you!
-MRR

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更多回答（3 个）

Azzi Abdelmalek
Azzi Abdelmalek 2013-3-8
Use
function [matrix, indexVector] = myFunction(hObject,handles)
handles.variable1 = 1;
guidata(hObject,handles)
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QiQin Zhan
QiQin Zhan 2013-3-8
zakaria
zakaria 2014-6-5
handles = guihandles(gcbo); % if not presents in the other external function

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