有没有办法在编辑框中显示秒和毫秒？

Question

我正在尝试在 GUI/Matlab 中使用计时器编写倒计时代码。 GUI 是使用指南创建的。我的想法是有两个编辑框，其中一个框可以用 ss:ms 格式的时间填充（例如 50.200）。通过按下开始按钮，倒计时应显示在第二个编辑框中并被执行。 我目前的问题是，我只能在第二个编辑框中显示秒数而不是毫秒数。我尝试了 sprintf - 但我认为计时器的句柄“TasksToExecute”不接受小数点数字？！

有人可以帮忙吗？或者有人知道如何解决？

谢谢。

      function varargout = Countdown_test(varargin)
%     COUNTDOWN_TEST MATLAB code for Countdown_test.fig
%     COUNTDOWN_TEST, by itself, creates a new COUNTDOWN_TEST or raises the existing
%      singleton*.
%
%      H = COUNTDOWN_TEST returns the handle to a new COUNTDOWN_TEST or the handle to
%      the existing singleton*.
%
%      COUNTDOWN_TEST('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in COUNTDOWN_TEST.M with the given input arguments.
%
%      COUNTDOWN_TEST('Property','Value',...) creates a new COUNTDOWN_TEST or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before Countdown_test_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to Countdown_test_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help Countdown_test

% Last Modified by GUIDE v2.5 23-Jan-2017 14:47:18

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @Countdown_test_OpeningFcn, ...
                   'gui_OutputFcn',  @Countdown_test_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end

if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT


% --- Executes just before Countdown_test is made visible.
function Countdown_test_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 Countdown_test (see VARARGIN)

% Choose default command line output for Countdown_test
handles.output = hObject;

% Update handles structure
guidata(hObject, handles);

% UIWAIT makes Countdown_test wait for user response (see UIRESUME)
% uiwait(handles.Countdown_test);


countdown_timer = timer;
set(countdown_timer,'ExecutionMode','fixedrate');
set(countdown_timer,'Period',1.0);
set(countdown_timer,'TimerFcn',{@countdowntimercallback,handles});

% Store the timer in the GUI so it persists for the life of the GUI
setappdata(handles.Countdown_test, 'Countdown_timer', countdown_timer);


fileName = 'state.mat';

if exist(fileName)

    load(fileName)
    set(handles.ed_PS_Time,'String',state.PST);

    delete(fileName);
end



% --- Outputs from this function are returned to the command line.
function varargout = Countdown_test_OutputFcn(hObject, eventdata, handles) 
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure
varargout{1} = handles.output;



function ed_countdown_Callback(hObject, eventdata, handles)
% hObject    handle to ed_countdown (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 ed_countdown as text
%        str2double(get(hObject,'String')) returns contents of ed_countdown as a double


% --- Executes during object creation, after setting all properties.
function ed_countdown_CreateFcn(hObject, eventdata, handles)
% hObject    handle to ed_countdown (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

set(hObject,'String','');


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

countdown_timer = getappdata(handles.Countdown_test,'Countdown_timer');

anzahl=str2num(get(handles.ed_PS_Time,'String'));
sprintf('%0.3f',anzahl);
set(countdown_timer,'TasksToExecute',anzahl);

start(countdown_timer);

set(handles.ed_countdown, 'Enable','off');

durchlaeufe=get(countdown_timer,'TasksToExecute');
setappdata(handles.Countdown_test,'Durchlauf',durchlaeufe);



function countdowntimercallback(obj,~,handles)

countdown_timer = getappdata(handles.Countdown_test,'Countdown_timer');

durchlaeufe_aktuell=get(countdown_timer,'TasksExecuted');

durchlaeufe = getappdata(handles.Countdown_test,'Durchlauf');


Countdown = durchlaeufe - durchlaeufe_aktuell;
sprintf('%0.3f',Countdown);
set(handles.ed_countdown,'String',Countdown);

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

% handles.ed_PS_Time = str2num(get(handles.ed_PS_Time, 'String'));
% guidata(hObject,handles);
countdown_timer = getappdata(handles.Countdown_test,'Countdown_timer');
stop(countdown_timer);



function ed_PS_Time_Callback(hObject, eventdata, handles)
% hObject    handle to ed_PS_Time (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 ed_PS_Time as text
%        str2double(get(hObject,'String')) returns contents of ed_PS_Time as a double

% --- Executes during object creation, after setting all properties.
function ed_PS_Time_CreateFcn(hObject, eventdata, handles)
% hObject    handle to ed_PS_Time (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

set(hObject,'String','0');




% --- Executes when user attempts to close Countdown_test.
function Countdown_test_CloseRequestFcn(hObject, eventdata, handles)
% hObject    handle to Countdown_test (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hint: delete(hObject) closes the figure
saveState(handles)
delete(hObject);

function saveState(handles)

state.PST = get(handles.ed_PS_Time, 'String');

save('state.mat','state')
}

Answer 1

在倒数计时器的上下文中，TasksToExecute 本身并不是一个特别有用的值。您感兴趣的值是您的timer 对象的Period。

例如：

function honktimer
% Set up dummy GUI
h.mainfig = figure('MenuBar', 'none', 'ToolBar', 'None');
h.totaltimelbl = uicontrol('Style', 'text', 'Units', 'Normalized', ...
    'Position', [0.05, 0.80, 0.40, 0.05], 'String', 'Countdown Time (ss.ss)');
h.totaltimeeb = uicontrol('Style', 'edit', 'Units', 'Normalized', ... 
    'Position', [0.05, 0.70, 0.40, 0.10], 'String', '1.0');
h.periodlbl = uicontrol('Style', 'text', 'Units', 'Normalized', ...
    'Position', [0.55, 0.80, 0.40, 0.05], 'String', 'Update Rate (Hz)');
h.periodbox = uicontrol('Style', 'edit', 'Units', 'Normalized', ... 
    'Position', [0.55, 0.70, 0.40, 0.10], 'String', '10');
h.cdlbl = uicontrol('Style', 'text', 'Units', 'Normalized', ...
    'Position', [0.30, 0.55, 0.40, 0.05], 'String', 'Time Remaining (ss.SS)');
h.cdbox = uicontrol('Style', 'edit', 'Units', 'Normalized', ...
    'Position', [0.30, 0.45, 0.40, 0.10], 'String', '', 'Enable', 'inactive');
h.sb = uicontrol('Style', 'pushbutton', 'Units', 'Normalized', ...
    'Position', [0.30, 0.30, 0.40, 0.10], 'String', 'Start Timer');
h.sb.Callback = @(p,e)starttimer(h);  % Set callback here so h is fully populated
end

function starttimer(h)
% Set up the timer
UpdateRate = str2double(h.periodbox.String);  % Update rate, Hz
countdowntime = datetime(h.totaltimeeb.String, 'InputFormat', 'ss.SS');  % Convert countdown time to datetime object
nupdates = fix(countdowntime.Second*UpdateRate);  % Calculate number of timer iterations
countdown = timer('BusyMode', 'drop', 'ExecutionMode', 'fixedRate', ...
    'Period', 1/UpdateRate, 'StartDelay', 0, 'TasksToExecute', nupdates, ...
    'StartFcn', @(p,e)startcountdown(h), ...  % Execute on timer start
    'TimerFcn', @(p,e)updatecountdown(p, h) , ...  % Execute each timer update
    'StopFcn', @(p,e)endcountdown(h));  % Execute when timer ends

start(countdown);  % Start the timer!
end

function startcountdown(h)
h.cdbox.String = h.totaltimeeb.String;
end

function updatecountdown(timerobj, h)
currtime = datetime(h.cdbox.String, 'InputFormat', 'ss.SS');
tickduration = seconds(timerobj.Period);
newtime = currtime - tickduration;
h.cdbox.String = sprintf('%.2f', newtime.Second);
end

function endcountdown(h)
h.cdbox.String = 'Honk';
end

这为我们提供了一个基本的 GUI：

这里我们假设计时器每Period 秒执行一次（最小分辨率为0.001 秒），从倒计时框中当前显示的内容中减去Period 秒并更新字符串。对于更稳健的方法，我使用了datetime 和seconds 来确保时间完全按照所述表示，而不是假设倒计时字符串是十进制秒并使用str2double 或类似的。

您还可以采用将总时间存储为timer 对象的UserData 并根据目标时间Period 和TasksExecuted 属性计算每个TimerFcn 调用的时间的方法.

---

适用于编程计时器的常见警告。我们假设timer 对象的TimerFcn 或多或少地被按时调用。 timer 的文档在 ExecutionMode 属性的描述中详细介绍了执行。