Card Trick with Matlab GUIs 

In this article we’re going to develop another computerized card trick using callback-functions in Matlab GUIs. I strongly suggest you read the first and second articles in this series, to know how to start and how to use the very important three instructions ‘get’, ‘set’ and ‘guidata’. 

On your command window type ‘guide’ (without the quotes). Choose the ‘Blank GUI’ option. You’ll see a menu on your left:

 
Drag-and-drop an ‘axes’ button, a ‘static text’ button and a ‘push button’ to your layout-area so that you get something similar to this figure:

To modify the properties of each element on your layout-area, you must double-click on each. You can modify properties such as size and position, font, font weight and allignment. 

Set these properties (you can experiment with others) and save your figure with the name ‘trick2.fig’:

 And now you should have something similar to this figure:

The editor will open with a prepared template, where you can edit the callback-functions for each element involved in the card trick.

For the opening function, you can complete it as follows (there are some comments included by Matlab, you just have to add the missing lines):

% --- Executes just before trick2 is made visible.
function trick2_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 trick2 (see VARARGIN) 

% Choose default command line output for trick2
handles.output = hObject;

clc
axes(handles.axes1);
bg = imread('trick2_001.jpg');
image(bg);
axis off; 

% Update handles structure
guidata(hObject, handles); 

% UIWAIT makes trick2 wait for user response (see UIRESUME)
% uiwait(handles.figure1); 

% --- Executes on button press in pushbutton1.
function 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)
str = {'I see it clearly... ';
       '';
       '';
       'I have made your card vanish!!'};
set(handles.text1,'String',str);
axes(handles.axes1);
bg = imread('trick2_002.jpg');
image(bg);
axis off; 

set(handles.pushbutton1,'Visible','off')

If you download the images and files that I’ve included, and you run the trick2.m file with Matlab, you’ll get this result:

 And after clicking the button, you get this figure:

 Done!