export_fig generates figure even after pressing cancel

following is the code i use to save the figure in required format, but it produces figure even after pressing cancel button. How do i suppress this execution?

function pushbuttonsaveplot_Callback(hObject, eventdata, handles)
% hObject    handle to pushbuttonsaveplot (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

[filename, pathname, filterindex]  = uiputfile({'*.jpg','JPEG image (*.jpg)';...
    '*.fig','MATLAB Figure (*.fig)';...
    '*.png','Portable Network Graphics file (*.png)';...
    '*.bmp','Bitmap file (*.bmp)';...
    '*.eps','EPS file (*.eps)';...
    '*.pdf','PDF (*.pdf)'}, 'Save Plot As', 'plot.jpg');
export_fig(filename, handles.Plot, '-m2');
end

Answer 1

[Walter Roberson]

Before calling export_fig,

if ~ischar(filename)
   return;  %user cancel
end