%343.m
function demoft(varargin)
%DEMODF_FFT FFT display of an incoming analong input signal.
switch nargin
    case 0
        data = localInitAI;%Creat the annalog input.
        data = localInitFig(data);%creat the figure.
        hFig = data.handle.figure;
    case 1
        data = [];%initiallize variables.
        action = varargin{1};
        hFig = varargin{2};
        try
            data = get(hFig,'Userdata');
        end
        %Based on the action ,call the apropriate local function
        %create the figure.
           data = localInitFig(data);
           hFig = data.handle.figure;
        end
        %upfate the analog input object's userdata
        if isvalid(data.ai)
            set(data.ai,'Userdata',data);
        end
        %creat the object and get the first fft.
        function [data,errflag] = localInitAI(varargin)
        %initialize variables.
        errflag = 0;
        data = [];
        %either no input argumentd or all three -ADAPTORNAME,ID AND
        % CHANNELID.
        switch nargin
    case 0
        adaptor = 'winsound';   
        id = 0;
        chan = 1;
    otherwise
        laseterr('the ADAPTORNAME,ID and CHANID must be specified.');
        errflag = 1;
        return;
    end
    % object configration.
    % create an analog input object with one channel.
    ai = analoginput(adaptor,id);
    addchannel(ai,chan);
    %configure the anaog input object.
    set(ai,'SampleRate',44100);
    %configure the callback to updat the display.
    set(ai,'TimerAction',{'demoai_fft','fftshowdata'});
    set (ai,'TimerPeriod',0.1);
    %configure the analog input objest to trigger manually twise.
    set (ai,'SamplesPerTrigger',1024);
    set (ai,'TriggerRepeat',1);
    set (ai,'TriggerType','manual');
    %object execution.
    %start the analog input object .
    start (ai);
    trigger(ai);
    %obtain the available time and data.
    [d,time] = getdata(ai,ai.SamplesPerTrigger);
    %calcualte the fft
    Fs = get(ai,'SampleRate');
    blockSize = get(ai,'SamplesPerTrigger');
    [f,mag] = localDaqfft(d,Fs,blockSize);
    %create the data structure.
    data.ai = ai;
    data.getdata = [d time];
    data.daqfft = [f mag];
    data.handle = [];
    %set the object's userdata to data
    set (data.ai,'Userdata',data);
    %creat the display
    function data =localInitFig(data)
    %initiallize variables.
    btnColor = get(0,'DefaultUIControlBackgroundColor');
    %position the gui in the middle of the screen
    screenUnits=get(0,'Units');
    set(0,'Units','pixels');
    screenSize=get(0,'ScreenSize');
    set(0,'Units',screenUnits);
    figWidth=600;
    figHeight=360;
    figPos=[(screenSize(3)-figWidth)/2 (screenSize(4)-figHeight)/2 figWidth figHeight];
    %creat the figure window
hFig=figure(...
        'Color'            , btnColor        , ...
        'IntegerHandle'    , 'off'           ,...
        'DoubleBuffer'     , 'on'            ,...
        'DeleteFcn'        , 'demoai_fft(''close'',gcbf)' ,...
        'MenuBar'          , 'none'          ,...
        'HandleVisibility' , 'on'            ,...
        'Name'             , '模擬信號的頻譜監視'  ,...
        'Tag'              , '模擬信號的頻譜監視'  ,...
        'NumberTitle'      , 'off'          ,...
        'Units'            ,'pixels'        ,...
        'Position'         ,figPos          ,...
        'UserData'         ,[]              ,...
        'Colormap'         ,[]              ,...
        'Pointer'          ,'arrow'   ,...
        'Visible'          ,'on');
   % Create Data subplot.
   hAxes(1) = axes ( ...
       'Position'         ,[0.1300 0.5811 0.7750 0.3439],...
       'Parent'          , hFig ,...
       'XLim'            , [0 get(data.ai, 'SamplesPerTrigger')],...
       'YLim'            ,[-0.5 0.5]);
   %Plot the data.
   hLine(1) = plot(data.getdata(:,1));
   set(hAxes(1),'XLim',[0 get(data.ai, 'SamplesPerTrigger')]);
   %Label the plot.
   xlabel('采樣');
   ylabel('輸入信號幅度(v)');
   title('輸入模擬信號');
   %Create the FFT subplot.
   hAxes(2) = axes(...
       'Position'       , [0.1300 0.1100 0.7750 0.3439],...
       'Parent'         ,hFig,...
       'XLim'           , [0 max(data.daqfft(:,1))]...
       );
   % Plot the data.
   hLine(2) = plot(data.daqfft(:,1),data.daqfft(:,2));
   set(hAxes(2), 'XLim' , [0 max(data.daqfft(:,1))]);
   %Label the plot.
   xlabel('頻率(Hz)');
   ylabel('幅度(dB)');
   title('監測到的頻譜');
   %Create a start/stop pushbutton.
   htoggle = uicontrol(...
       'Parent'        ,   hFig,...
       'Style'         ,   'pushbutton',...
       'Units'         ,   'normalized',...
       'Position'      ,  [0.0150 0.0111 0.1 0.0556],...
       'Value'         ,  1,...
       'String'        ,   'Stop',...
       'Callback'      ,  'demoai_fft(''stop'',gcbf);');
   hmenu(1) = uimenu('Parent',hFig,'Label','File');
   hmenu(2)= uimenu(hmenu(1),'Label','Close demoai_fft',...
       'Callback', 'demoai_fft(''close'',gcbf)');
   hmenu(3) = uimenu ('Parent', hFig,'Label','Help');
   hmenu(4) = uimenu (hmenu(3),'Label','Data Acquisition Toolbox',...
       'Callback','helpwin(''daq'')');
   hmenu(5)=uimenu(hmenu(3),'Label', 'demoai_fft',...
       'Callback','helpwin(''demoai_fft'')');       
%store the handles in the data matrix
data.handle.figure=hFig;
data.handle.axes=hAxes;
data.handle.line=hLine;
data.handle.toggle=htoggle;
data.state=0;
% set the axes handlevixibility to off.
set(hAxes,'HandleVisibility','off');
%store the data matrix and display figure.
set(hFig,'Visible','on','UserData',data,'HandleVisibility','off');
%close the figure window.
function localClose(data)
% stop the device if it is running and delete the object.
if isvalid(data.ai)
if strcmp(get(data.ai,'Running'),'on')
	stop(data.ai);
 end
 delete(data.ai);
end
% close the figure window.
delete(data.handle.figure);
% stop or start the device.
function data =localStop(data)
%based on the state either stop or start.
if data.state ==0
	stop(data.ai); %stop the device.
	set(data.handle.toggle,'string','start');
	data.state =1; % store the new state.
else
	start(date.ai); % store the device.
	set(data.handle.toggle,'string','stop');
	data.state =0; % store the new state.
end
%計算數據的FFT
function [f,mag] = localDaqfft(data,Fs,blockSize)
% calculate the fft of the data.
xFFT = fft(data);
xfft = abs(xFFT);
% Avoid taking the log of 0.
index =find(xfft == 0);
xfft(index) = 1e-17; 
mag = 20*log10(xfft);
mag = mag(1:blockSize/2);
f = (0:length(mag)-1)*Fs/blockSize;
f = f(:);
function localfftShowData(obj,event)
% get the handles.
data = obj.UserData;
hFig = data.handle.figure;
hAxes = data.handle.axes;
hLine = data.handle.line;
% execute a peekdata.
x = peekdata(obj,obj.SamplesPerTrigger);
% 計算FFt
Fs = obj.SampleRate;
blockSize = obj.SamplesPerTrigger;
[f,mag] = localDaqfft(x,Fs,blockSize);
%更新曲線
set(hLine(1),'YData',x(:,1));
set(hLine(2),'XData',f(:,1),'YData',mag(:,1));
drawnow;