MATLAB: calling GUI/GUIDE functions from outside

Question

When I try to invoke a subfunction in a GUI/GUIDE file (using a function handle which has been exposed as a global variable), a new axes is always created even if I set the axes to a specific axes in the GUIDE figure. Does anyone know why this is happening? GUIDE code is:

###############################################################
function varargout = demo(varargin)
  % Begin initialization code - DO NOT EDIT
  gui_Singleton = 1;
  gui_State = struct('gui_Name',       mfilename, ...
                     'gui_Singleton',  gui_Singleton, ...
                     'gui_OpeningFcn', @demo_OpeningFcn, ...
                     'gui_OutputFcn',  @demo_OutputFcn, ...
                     'gui_LayoutFcn',  [] , ...
                     'gui_Callback',   []);
  if nargin && ischar(varargin{1})
      gui_State.gui_Callback = str2func(varargin{1});
  end

  if nargout
      [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
  else
      gui_mainfcn(gui_State, varargin{:});
  end
  % End initialization code - DO NOT EDIT

function demo_OpeningFcn(hObject, eventdata, handles, varargin)
  handles.output = hObject;

  % Update handles structure
  guidata(hObject, handles);

  global myhandles updateFunction;
  myhandles = handles;
  updateFunction = @update;

function varargout = demo_OutputFcn(hObject, eventdata, handles) 
  varargout{1} = handles.output;

function pushbutton1_Callback(hObject, eventdata, handles)
  update();

function update()
  global myhandles;

  axes(myhandles.axes1);
  plot(1:2,1:2);

###########################################################################

And when I do (outside file above):

global updateFunction;
feval(updateFunction)

I always see the plot in a newly created figure window, not in the GUI figure. Why is this happening?

Answer 1

The first thing I would try is to replace the function update with the following:

function update
  global myhandles;
  plot(myhandles.axes1,1:2,1:2);

This will explicitly tell the PLOT function to plot into the given axes. If that doesn't work, try setting the axes 'NextPlot' property to 'add' (probably in demo_OpeningFcn):

set(myhandles.axes1,'NextPlot','add');