How can I code an on-screen keyboard within a GUI to be able to update an edit text box? Similar to a keyboard on a GPS system.

I want to be able to code three different text boxes and when on of them is clicked, then when the on-screen keyboard is pressed it will update the edit text to form a destination? If someone could help me construct the code for the two parts of my GUI, it would be much appreciated. The code below are the two parts I would like to code first.

function start_point_Callback(hObject, eventdata, handles)
% hObject    handle to start_point (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of start_point as text
%        str2double(get(hObject,'String')) returns contents of start_point as a double

% --- Executes during object creation, after setting all properties.
function start_point_CreateFcn(hObject, eventdata, handles)
% hObject    handle to start_point (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

% --- Executes on button press in A_pb.
function A_pb_Callback(hObject, eventdata, handles)
% hObject    handle to A_pb (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

Answer 1

[Sean de Wolski]

Here's how I would go about this:

function OnScreenKeyboard

      %Figure and edit box
      hFig = figure;
      hEdit = uicontrol('Style','edit',...
                  'Units','normalized',...
                  'Position',[0.2 0.8 0.6 0.1],...
                  'String','');

      %Letters        
      uicontrol('Style','pushbutton',...
            'Units','normalized',...
            'Position',[0.38 0.4 0.1 0.1],...
            'String','A',...
            'Callback',@(~,~)AddLetter('A'));        

      uicontrol('Style','pushbutton',...
            'Units','normalized',...
            'Position',[0.52 0.4 0.1 0.1],...
            'String','B',...
            'Callback',@(~,~)AddLetter('B'));        

      function AddLetter(letter)
          %Called when letter pressed

          %Add letter to string
          set(hEdit,'string',strcat(get(hEdit,'string'),letter));
          drawnow;

          %NOTE: Obviously, you'll need to add features here such as
          %backspace etc.

      end
  end

[Anthony Gonsalves]

How would I make a clear all, backspace and space button for this code?