MATLAB: Does the callback for the edit box in the GUI execute twice in MATLAB 7.0.1 (R14SP1)

boxeditguiMATLABstring

When I change the value of the 'String' property in the edit box callback function, the callback is executed a second time when the edit box loses focus.

Best Answer

This is expected behavior. The callback event for an edit box is triggered by changing the String property and then changing the object focus.

To work around this issue, set a flag in the callback procedure that prevents the entire callback from being executed once the edit box loses focus.

For example:

function myedit_callback(hObject, eventdata, handles)
persistent myEditboxFlag
if isempty(myEdtiboxFlag)
    myEditboxFlag = true;
end
if myEditboxFlag
    %perform callback procedure
    set(hObject, 'String', 'A new string')
    myEditboxFlag = false;
else
    myEditboxFlag = false;
end

Related Solutions

MATLAB: In MATLAB 6.0 (R12) why does the callback of an edit uicontrol not fire when I change text in the field and then go to a menu and select an item on that menu

This bug has been fixed for Release 14 (R14). For previous releases, please read below for any possible workarounds:

This is the expected behavior for MATLAB under Windows. On UNIX systems, clicking on the menubar of the figure window causes the edit text callback to execute. However, on Windows systems, if an editable text box has focus, clicking on the menu bar does not cause the editable text callback routine to execute. This allows you to select text in an editable text box, and then choose copy/cut/paste routines from the menubar without executing the callback.

This behavior is consistent with the respective platform conventions. Clicking on other components or the background of the GUI executes the callback.

This issue has been forwarded to our documentation team to be clarified in future documentation.

If you would like for your editable text box's callback to execute when you click on a UIMENU, then you can use the following as a workaround:

% In the callback to the UIMENU, begin with the following lines of code: 
figure(gcbf);   % Changes the focus to the figure so that the editable text box loses focus 
drawnow;      % Forces the editable text box to update and fires the callback immediately 
% Subsequently, you can now access the editable text box's string: 
% This example assumes that the handle to the text box is stored in "handles.edit" 
get(handles.edit, 'string')  % returns the new string.

MATLAB: Can I execute a specific callback process when I lose the focus of edit text

The callback of the editable text box will be executed when

· the focus moves to another component from the edit text

· with edit text in focus, the enter key (Enter + Ctrl in case of multiple line input support) is entered

There is no callback function that operates only when the focus shifts, but as an alternative, you can use the way which identifying the last key entered in the Callback function. If it is not the "Enter" key, you can define that the focus has shifted.

The sample code below is an example.

In the editable text box Callback function, identify the last entered key using the Figure's CurrentCharacter property. This will change the processing of the callback when pressing the Enter key in the editable text box and moving the focus.

(edit_off_samp.m)
function edit_off_samp
h_figure = figure;
h_edit = uicontrol('Style','edit','Callback',@edit_callback); % create editbox
      function edit_callback(src,event)
      % define callback
          CK = get(h_figure, 'CurrentCharacter'); % get the last key entered
          if isequal(double(CK),13) % If it was "Enter" key
              disp('Pressed Enter Key')
          else
              disp('Focus off')
          end
      end
end

Best Answer

Related Solutions

MATLAB: In MATLAB 6.0 (R12) why does the callback of an edit uicontrol not fire when I change text in the field and then go to a menu and select an item on that menu

MATLAB: Can I execute a specific callback process when I lose the focus of edit text

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