CODEWITHSUNDEEP
user-interfacematlabcallbackglobal-variablesmatlab-guide
user665130
user665130

Reputation: 51

Variable shared by callbacks for a GUI built with Matlabs guide

Im kinda discovering GUI developement in Matlab and Im experimenting difficulties with some basic concepts. If anyone could help me I would be really greatful.

Im trying to build a GUI using matlab 'guide', and all I am ding is loading an image into an axes and I want to save it into some global variable that will be shared by all the callbacks in my GUI, this way i could process this image on other event handlers.

Im having trouble finding a way to do it, I tried to declare some variables as 'global' but it didn't worked. Can you please explain me how it works, or show a brief example. Thanks

Upvotes: 3

Views: 4583

Answers (1)

Adam Lewis
Adam Lewis

Reputation: 7257

Here is a working example (using GUIDE) that does what you're looking for in two different ways. Over all I prefer using the 'handles' method for 90% of my GUIs. The only time I will ever use a global is if I need to access the data outside of the GUI.

Please note that I have added the 'handles.img = 0' inside the opening function. As a disclaimer, there is no data validation from the browse. I have also only tested this with a .gif file and put no thought into the best way to display the image to the axes. Just quick and dirty :)

EDIT: When you copy and paste this data into an M-File. Be sure to name it picture_loader.m. Matlab has done some stupid things to me with the wrong file names :)

Hope this helps.

function varargout = picture_loader(varargin)
    % Begin initialization code - DO NOT EDIT
    gui_Singleton = 1;
    gui_State = struct('gui_Name',       mfilename, ...
                       'gui_Singleton',  gui_Singleton, ...
                       'gui_OpeningFcn', @picture_loader_OpeningFcn, ...
                       'gui_OutputFcn',  @picture_loader_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


% --- Executes just before picture_loader is made visible.
function picture_loader_OpeningFcn(hObject, eventdata, handles, varargin)
    handles.output = hObject;
    handles.img = 0;  % Add the img data to the handle
    guidata(hObject, handles);


% --- Outputs from this function are returned to the command line.
function varargout = picture_loader_OutputFcn(hObject, eventdata, handles) 
    varargout{1} = handles.output;


% --- Executes on button press in Browse.
function Browse_Callback(hObject, eventdata, handles)
    global img % Store the data global
    img_path = uigetfile('*.gif'); % browse for a file
    img = importdata(img_path); % Load the image data
    handles.img = img; % Store the img data in the handles struct 
    guidata(hObject, handles);  % Save handles so all call backs have the updated data

    % Plot the data in the axes1
    axes(handles.axes1) % Select axes1 to write to
    image(img.cdata) % Display the image
    colormap(img.colormap) % Apply proper colormap

% --- Executes on button press in load_global.
function load_global_Callback(hObject, eventdata, handles)
    global img
    if isstruct(img)
        axes(handles.axes1)  %Select the axes1 on the gui
        image(img.cdata)
        colormap(img.colormap)
    end

% --- Executes on button press in load_global_handle.
function load_handle_Callback(hObject, eventdata, handles)
    if isstruct(handles.img)
        axes(handles.axes1)  %Select the axes1 on the gui
        image(handles.img.cdata)
        colormap(handles.img.colormap)
    end

% --- Executes on button press in clear.
function clear_Callback(hObject, eventdata, handles)
    cla(handles.axes1)

Upvotes: 3

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