Store or retrieve UI data
data = guidata(object_handle)
data with the object specified by
object_handle is not a figure, then the object's
parent figure is used.
data can be any MATLAB® variable,
but is typically a structure, which enables you to add new fields
guidata can manage only one variable at any
time. Subsequent calls to
the previously stored
guidata to store and maintain
handles structure. In a GUIDE code file, do
not overwrite the
handles structure or your program
will no longer work. If you need to store other data, you can do so
by adding new fields to the
data = guidata(object_handle) returns
previously stored data, or an empty matrix if nothing is stored.
To change the data managed by
Get a copy of the data with the command
Make the desired changes to
Save the changed version of
guidata provides application developers
with a convenient interface to a figure's application data:
You do not need to create and maintain a hard-coded property name for the application data throughout your source code.
You can access the data from within a local function
callback routine using the component's handle (which is returned by
gcbo), without needing to find the figure's
If you are not using GUIDE,
particularly useful in conjunction with
which creates a structure containing the all of the components in
This example calls
guidata to save a structure
containing a figure's application data from within the initialization
section of the application code file. The first section shows how
to do this within a programmatic UI. The second section shows how
the code differs when you use GUIDE to create a template code file.
GUIDE provides a
handles structure as an argument
to all local function callbacks, so you do not need to call
obtain it. You do, however, need to call
save changes you make to the structure.
creates the structure into which your code places additional data.
It contains all handles used by the figure at the time it is called,
generating field names based on each object's
% Create figure figure_handle = figure('Toolbar','none'); % create structure of handles myhandles = guihandles(figure_handle); % Add some additional data as a new field called numberOfErrors myhandles.numberOfErrors = 0; % Save the structure guidata(figure_handle,myhandles)
You can recall the data from within a local callback function, modify it, and then replace the structure in the figure:
function My_Callback() % ... % Get the structure using guidata in the local function myhandles = guidata(gcbo); % Modify the value of your counter myhandles.numberOfErrors = myhandles.numberOfErrors + 1; % Save the change you made to the structure guidata(gcbo,myhandles)
If you use GUIDE, you do not need to call
create a structure. You can add your own data to the
For example, this code adds the field,
to the structure:
% --- Executes just before simple_gui_tab is made visible. function my_GUIDE_GUI_OpeningFcn(hObject, eventdata, handles, varargin) % This function has no output args, see OutputFcn. % hObject handle to figure % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % varargin command line arguments to simple_gui_tab (see VARARGIN) % ... % add some additional data as a new field called numberOfErrors handles.numberOfErrors = 0; % Save the change you made to the structure guidata(hObject,handles)
hObjectin place of
gcboto refer to the object whose callback is executing.
Suppose you needed to access the
in a push button callback. Your callback code now looks something
% --- Executes on button press in pushbutton1. function my_GUIDE_GUI_pushbutton1_Callback(hObject, eventdata, handles) % hObject handle to pushbutton1 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % ... % No need to call guidata to obtain a structure; % it is provided by GUIDE via the handles argument handles.numberOfErrors = handles.numberOfErrors + 1; % save the changes to the structure guidata(hObject,handles)