GUI data Update

Hi guys,

I'm building a gui in matlab and have a question about the guidata update. I want to let the user change a value on a "Edit Text" control and this value changes the current plot function. I wait until the 'return' key is pressed and process the data. The problem is that the user has to hit the return key twice to change the value. I think the guidata is not updated. Does anyone has an advice? Gerd

 function txt_Faktor_KeyPressFcn(hObject, eventdata, handles)
% hObject    handle to txt_Faktor (see GCBO)
% eventdata  structure with the following fields (see UICONTROL)
%  Key: name of the key that was pressed, in lower case
%  Character: character interpretation of the key(s) that was pressed
%  Modifier: name(s) of the modifier key(s) (i.e., control, shift) pressed
% handles    structure with handles and user data (see GUIDATA)
if strcmp(eventdata.Key,'return')
    handles.Faktor = str2double(get(handles.txt_Faktor,'String'));
    % store variable
    guidata(hObject,handles);
    plotMainWindow(hObject, eventdata, handles);
end

Answer 1

[Walter Roberson]

Why are you doing things that way instead of just using a callback function on the edit uicontrol ?

Note by the way, that you should be taking precautions in case the user entered something other than a number.

[Gerd]

Hi Walter,

could you please explain what the difference is between the edit and keypressFcn callback ? I only want to change the plot if the 'return' key is pressed.

Your note is a good advice I will take the precausion for other than numerical data.

[Walter Roberson]

If you set

uicontrol('Style','edit', 'Callback', @txt_Faktor_Fcn)

then the callback will only be activated if "whenever you activate the uicontrol object (e.g., when you click on a push button or move a slider)" In the case of an edit callback, that occurs when you press return on the control, and does NOT occur if you type into the control but then click outside of the control.

[Gerd]

Thank you Walter,

the GUI works now fine. Thank you for the explanation.

Gerd