Creating Graphical User Interfaces

The Contact Name Callback

The Contact Name text box displays the name of the address book entry. If you type in a new name and press enter, the callback performs these steps:

• If the name exists in the current address book, the corresponding phone number is displayed.
• If the name does not exist, a question dialog (questdlg) asks you if you want to create a new entry or cancel and return to the name previously displayed.
• If you create a new entry, you must save the MAT-file with the File -> Save menu.

Storing and Retrieving Data

This callback makes use of the handles structure to access the contents of the address book and to maintain an index pointer (handles.Index) that enables the callback to determine what name was displayed before it was changed by the user. The index pointer indicates what name is currently displayed. The address book and index pointer fields are added by the Check_And_Load function when the GUI is run.

If the user adds a new entry, the callback adds the new name to the address book and updates the index pointer to reflect the new value displayed. The updated address book and index pointer are again saved (guidata) in the handles structure.

Contact Name Callback

• function Contact_Name_Callback(hObject, eventdata, handles)
  % Get the strings in the Contact Name and Phone text box
  Current_Name = get(handles.Contact_Name,'string');
  Current_Phone = get(handles.Contact_Phone,'string');
  % If empty then return
  if isempty(Current_Name)
      return
  end
  % Get the current list of addresses from the handles structure
  Addresses = handles.Addresses;
  % Go through the list of contacts
  % Determine if the current name matches an existing name
  for i = 1:length(Addresses)
      if strcmp(Addresses(i).Name,Current_Name)
          set(handles.Contact_Name,'string',Addresses(i).Name)
          set(handles.Contact_Phone,'string',Addresses(i).Phone)
          handles.Index = i;
          guidata(hObject, handles)
          return
      end
  end
  % If it's a new name, ask to create a new entry
  Answer=questdlg('Do you want to create a new entry?', ...
      'Create New Entry', ...
      'Yes','Cancel','Yes');
  switch Answer
  case 'Yes'
      Addresses(end+1).Name = Current_Name; % Grow array by 1
      Addresses(end).Phone = Current_Phone; 
      index = length(Addresses);
      handles.Addresses = Addresses;
      handles.Index = index;
      guidata(hObject, handles)
      return       
  case 'Cancel'
      % Revert back to the original number
      
  set(handles.Contact_Name,'String',Addresses(handles.Index).Name
  )
      
  set(handles.Contact_Phone,'String',Addresses(handles.Index).Pho
  ne)
      return
  end
  

Loading an Address Book Into the Reader

The Contact Phone Number Callback