How to retrieve data from the textboxes of a GUI created with GUIDE.

How to retrieve data from the textboxes of a GUI created with GUIDE.

I am having trouble understanding the process of taking entered values from textboxes so that the values may be used in a process, e.g. plotting.

I have created a simple GUI with three textboxes (Tags: edit1, edit2 and edit3)

I want to retrieve the values entered and plot a simple graph. I have read through the Matlab notes and help guides and think that I need to use guidata, handles and set, but I can’t seem to get my head around how these commands interact.

The code below is obviously repeated for each textbox:

function edit1_Callback(hObject, eventdata, handles)

%get value as a string from text box and convert to double
number1 = str2double(get(hObject,'string'));

%check that value is a number and display error if it is not
if isnan(number1) || ~isreal(number1)
  errordlg('Try Again','Try again','modal') 
    return
end

% --- Executes during object creation, after setting all properties.
function edit1_CreateFcn(hObject, eventdata, handles)

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

I ultimately want to plot a simple graph using something like:

x = [0 1 2]
y = [number1 number2 number3]
plot(x,y)

I obviously have a fundamental lack of knowledge on this subject so I would be very grateful if someone could take the time to give me a layman’s explanation of how this works or maybe point me in the right direction for some reading material.

Cheers

Steve

Answer 1

[Jan]

You can access the content of a textbox in any function that has access to the handles object. For instance if you want to access the content of the textbox tagged edit1 from a function called my_fun it would look something like:

 function my_fun( hObject, eventdata, handles )
   content_str = get( handles.edit1, 'String' )

Use guidata if you want to change the content of a handle. E.g. if you have a handle variable called my_var and you want to assign it a new value you would do

 function my_fun( hObject, eventdata, handles )
   handles.my_var = 5;
   guidata( hObject, handles );   % if you omit this line, the new value will not be set!

[StevieNewRoad]

This is very helpful, thanks.