Pausing an application in GUI

I'm trying to make easy GUI for Game of Life. The problem is I don't really know, how can I implement pausing by pressing a button. It works with a check-box, but I'd prefer Pause button instead.

function gameoflife_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 untitled (see VARARGIN)

set(gcf,'name','Conway''s Game Of Life');
% Choose default command line output for untitled
handles.output = hObject;
handles.iter_num = get(handles.iterations,'Value');
handles.iter_step = 1;
handles.size = get(handles.grid_size,'Value');
handles.vis_grid = zeros(30);
handles.vis_grid(rand(30)>0.5) = 1;
handles.paused=true;
% Update handles structure
guidata(hObject, handles);
plot_grid(handles);
% UIWAIT makes untitled wait for user response (see UIRESUME)
% uiwait(handles.figure1);
end

function startButton_Callback(hObject, eventdata, handles)
% hObject    handle to startButton (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
handles.paused = false;
start_app(handles);
end

function pause_Callback(hObject, eventdata, handles)
% hObject    handle to pause (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
handles.paused = ~handles.paused;

if handles.paused
    set(hObject, 'String', 'Resume');
else
    set(hObject, 'String', 'Pause');
end
guidata(hObject, handles);
end

function [] = start_app(handles)
    it = 0;
    while it < handles.iter_num
        if ~handles.paused
            handles.vis_grid = change_state(handles.vis_grid,neighbors(handles.vis_grid));
            plot_grid(handles);
            it = it + 1;
            pause(1)
        else
            waitfor(handles.paused)
        end
     end
end

It there a way to do it?

Answer 1

[Geoff Hayes]

Mykhaylo - rather than using a while loop to update the board, consider using a timer. Your start button would create the timer and start it and then your pause button could stop the timer or start it again depending upon the state of the timer. For example

 function startButton_Callback(hObject, eventdata, handles)

 % call function to start timer
 startTimer(hObject, handles);

 function pause_Callback(hObject, eventdata, handles)
 if strcmpi(get(hObject, 'String),'Resume')
     set(hObject, 'String', 'Pause');
     startTimer(hObject, handles);
 else
    set(hObject, 'String', 'Resume');
    stopTimer(hObject, handles);
 end

 function startTimer(hObject, handles)
 handles.timer = timer('Name','MyTimer',               ...
                       'Period',1,                    ... 
                       'StartDelay',0,                 ... 
                       'TasksToExecute',inf,           ... 
                       'ExecutionMode','fixedSpacing', ...
                       'TimerFcn',{@timerCallback,handles.figure1}); 
 guidata(hObject,handles);
 start(handles.timer);

 function stopTimer(hObject, handles)
 if isfield(handles,'timer') && ~isempty(handles.timer)
   stop(handles.timer);
   handles.timer = [];
   guidata(hObject,handles);
 end

The above code should allow you to start and stop a timer through the GUI buttons. Your timer callback would then have the code that updates the board

 function [] = timerCallback(~,~,guiHandle)
 if ~isempty(guiHandle)
    % get the handles
    handles = guihandles(guiHandle);
    handles.vis_grid = change_state(handles.vis_grid,neighbors(handles.vis_grid));
    plot_grid(handles);
    guidata(handles.figure1, handles);
 end

See https://www.mathworks.com/matlabcentral/answers/178682-collecting-a-variable-every-two-minutes for some reasoning behind the above code.