How to stop the timer by clicking the button twice in GUI, AND how can I return the number of the time I pause?

I write a countdown timer and want to stop it by click it twice and return the number on the screen when I stop it?

 function [] = timer_examp()
S.fh = figure('units','pixels',...
              'position',[500 500 200 100],...
              'menubar','none',...
              'name','Timer_examp',...
              'numbertitle','off',...
              'resize','off');
S.tx = uicontrol('style','text',...
                 'unit','pix',...
                 'position',[10 60 180 30],...
                 'fontsize',14,...
                 'string','60');  % the beggining time was in 60s   
S.tmr = timer('Name','Countdown',...
              'Period',1,...  % 1s update period.                
              'StartDelay',.01,... % update delay period is 0.01s
              'ExecutionMode','fixedSpacing',...
              'StopFcn',@deleter);   % Function def. below.
S.pb = uicontrol('style','push',...
                 'units','pix',...
                 'position',[10 10 180 40],...
                 'fontsize',14,...
                 'string','Start Countdown!',...
                 'callback',{@pb_call,S});
set(S.tmr,'TimerFcn',{@update_disp,S},'StartDelay',1);             
function [] = pb_call(varargin)
% Callback and delete from list box
S = varargin{3}
% word string checking
set(S.tmr,'TasksToExecute',str2double(get(S.tx,'string')))  
start(S.tmr);
function [] = update_disp(varargin)
S = varargin{3};
N = str2double(get(S.tx,'string'));
set(S.tx,'string',num2str(N-1));
function deleter(obj,edata)   %#ok   M-Lint doesn't know the callback fmt.
% Callback stopfcn.
wait(obj);
delete(obj);

Answer 1

[Geoff Hayes]

@Dongze - is there a reason why you want to stop the timer via a double-click of a button that says "Start Countdown"? Perhaps you can use a different button to pause/stop the timer. If though you really want to do this with a double-click, you could try the following

function [] = pb_call(varargin)

% not keen on using a persistent/static but...
persistent firstButtonPressTime

S = varargin{3};

if (strcmpi(S.tmr.Running,'on'))
    % if timer is running, then save the current time or compare against
    % the last saved time
    if isempty(firstButtonPressTime)
        firstButtonPressTime = now;
    else
        currentTime = now;
        % determine the delta in seconds
        xDeltaInSeconds = (currentTime - firstButtonPressTime) * 24 * 60 * 60;
        % stop timer if two consecutive button presses are less than 0.5
        % seconds apart
        if xDeltaInSeconds < 0.5
            firstButtonPressTime = [];
            stop(S.tmr);
        else
            firstButtonPressTime = currentTime;
        end
    end
else
    set(S.tmr,'TasksToExecute',str2double(get(S.tx,'string')))  
    start(S.tmr);
end