function edgedemo(action, varargin)
% 子函數：
% InitializeEDGEDEMO - 	初始化圖像、控件、軸
% ComputeEdgeMap -     調用edge.m計算原始圖像的邊緣圖
% SelectMethod -         	選取邊緣檢測算法，并使相應的控件有效或無效
% LoadNewImage -        讀入選取的圖像
% UpdateThreshCtrl -      從編輯框中獲取門限值，并使【Apply】按鈕有效
% UpdateDirectionality -    根據彈出菜單中的內容顯示指示字符串
% Radio -                設置Radio Buttons中的值，并使得門限編輯框有效或無效
% UpdateLOGSize -       從編輯框中獲取LOG過濾器的大小
% UpdateLOGSigma -     從編輯框中獲取LOG過濾器的Sigma值 
% ActivateSPRControls -   打開Sobel, Prewitt, Roberts方法中用到的控件
% ActivateLOGControls -  打開LOG方法中用到的控件

if nargin<1,
   action='InitializeEDGEDEMO';
end;
feval(action,varargin{:});
%注意，這里沒有用前面推薦的程序結構。而是巧用feval函數來調用回調函數相應
%用戶的界面操作，這也是一種比較常用的程序結構，往往用在回調函數比較復雜
%的情況下。
return;

%%%  Sub-function - InitializeEDGEDEMO
function InitializeEDGEDEMO()

% 如果程序已經運行，將它放到前臺
h = findobj(allchild(0), 'tag', 'Edge Detection Demo');
			% 0代表根對象，在整個對象樹中處于最頂層
if ~isempty(h)
   figure(h(1))
   return
end

screenD = get(0, 'ScreenDepth');
if screenD>8
   grayres=256;
else
   grayres=128;
end

	%下面的代碼主要完成對界面對象的描述，包括大小、位置及其屬性
	%由于篇幅所限，這里只給出Figure的設置
EdgeDemoFig = figure( ...
   'Name','Edge Detection Demo', ...
   'NumberTitle','off', 'HandleVisibility', 'on', ...
   'tag', 'Edge Detection Demo', ...
   'Visible','off', 'Resize', 'off',...
   'BusyAction','Queue','Interruptible','off', ...
   'Color', [.8 .8 .8], ...
   'IntegerHandle', 'off', ...
   'DoubleBuffer', 'on', ...
   'Colormap', gray(grayres));

figpos = get(EdgeDemoFig, 'position');
% 調整Figure窗口的大小
figpos(3:4) = [560 420];
horizDecorations = 10;  % resize controls, etc.
vertDecorations = 45;   % title bar, etc.
screenSize = get(0,'ScreenSize');
if (screenSize(3) <= 1)
    % No display connected (apparently)
    screenSize(3:4) = [100000 100000]; % don't use Inf because of vms
end
if (((figpos(3) + horizDecorations) > screenSize(3)) | ...
            ((figpos(4) + vertDecorations) > screenSize(4)))
    % Screen size is too small for this demo!
    delete(EdgeDemoFig);
    error(['Screen resolution is too low ', ...
          '(or text fonts are too big) to run this demo']);
end
dx = screenSize(3) - figpos(1) - figpos(3) - horizDecorations;
dy = screenSize(4) - figpos(2) - figpos(4) - vertDecorations;
if (dx < 0)
    figpos(1) = max(5,figpos(1) + dx);
end
if (dy < 0)
    figpos(2) = max(5,figpos(2) + dy);
end
set(EdgeDemoFig, 'position', figpos);

rows = figpos(4); cols = figpos(3);
hs = (cols-512) / 3;        % Horizantal Spacing
bot = rows-2*hs-256;        % Bottom of the images

%====================================
% 接下來是控件和菜單的設置，省略
	……
%====================================

set(EdgeDemoFig, 'Userdata', hdl, 'Visible', 'on');
%初始化中創建的所有對象的句柄都放入hdl中，然后又將hdl放入圖形Figure
%的“Userdata”，由此實現了句柄的傳遞。這是一種很好的共享數據的方法。請讀者
%注意，
drawnow
LoadNewImage(EdgeDemoFig);
drawnow
set(EdgeDemoFig, 'HandleVisibility', 'Callback');
set([hdl.Apply hdl.Help hdl.Close] , 'Enable', 'on');
return

%%%
%%%  Sub-Function - ComputeEdgeMap
%%%

function ComputeEdgeMap(DemoFig)

if nargin<1
   callb = 1;    
   DemoFig = gcbf;
else 
   callb = 0;    
end

set(DemoFig,'Pointer','watch');
setstatus(DemoFig, 'Computing the edge map...');
hdl=get(DemoFig,'Userdata');
img = getimage(hdl.Image);

autothresh = get(hdl.RadioAutomatic, 'Value');

switch hdl.Method
case {'Sobel','Roberts','Prewitt'}
   if autothresh
      [edgemap,thresh]=edge(img,hdl.Method, dl.Directionality);
      setstatus(['The threshold is ' num2str(thresh) '.']);
   else
      edgemap = edge(img, ...
         hdl.Method, hdl.Threshold, hdl.Directionality);
      setstatus(DemoFig, '');
   end
case 'Laplacian of Gaussian'
   if autothresh
      [edgemap,thresh] = edge(img, 'log', [], hdl.LogSigma);
      setstatus(DemoFig, ['The threshold is ' num2str(thresh) '.']);
   else
      edgemap = edge(img, 'log', hdl.Threshold, hdl.LogSigma);
      setstatus(DemoFig, '');
   end
case 'Canny'
   if autothresh
      [edgemap,thresh] = edge(img, 'canny', [], hdl.LogSigma);
      setstatus(DemoFig, ['High threshold is ' num2str(thresh(2)) '.']);
   else
      [edgemap,thresh] = edge(img, 'canny', hdl.Threshold, hdl.LogSigma);
      setstatus(DemoFig, '');
   end
otherwise
   error('EDGEDEMO: Invalid edge detection method.');
end

set(hdl.Edge, 'CData', edgemap);
set(hdl.Apply, 'Enable', 'off');
set(DemoFig,'Pointer','arrow');
drawnow


%%%
%%%  Sub-Function - SelectMethod
%%%

function SelectMethod

DemoFig = gcbf;

hdl = get(DemoFig, 'userdata');
v = get(hdl.MethodPop,{'value','String'});
hdl.Method = deblank(v{2}(v{1},:));
switch hdl.Method
case {'Sobel','Prewitt'}
   ActivateSPRControls(DemoFig);
   set(hdl.sprDirPop, 'Enable', 'on');
case 'Laplacian of Gaussian'
   ActivateLOGControls(DemoFig);
   set(hdl.logSigmaCtrl, 'String', '2');
   hdl.LogSigma = 2;
case 'Canny'
   ActivateLOGControls(DemoFig);
   set(hdl.logSigmaCtrl, 'String', '1');
   hdl.LogSigma = 1;
case 'Roberts'
   ActivateSPRControls(DemoFig);
   set(hdl.sprDirPop, 'Enable', 'off', 'value', 1);
otherwise
   error('EDGEDEMO: invalid method specifier.');
end
   
set(hdl.Apply, 'Enable', 'on');
set(DemoFig, 'userdata', hdl);
% BlankOutEdgeMap(DemoFig);
setstatus(DemoFig, ['Press ''Apply'' to compute edges.']);


%%%
%%%  Sub-Function - LoadNewImage
%%%

function LoadNewImage(DemoFig)

if nargin<1
   callb = 1;    % We're in a callback
   DemoFig = gcbf;
else 
   callb = 0;    % We're in the initialization
end

set(DemoFig,'Pointer','watch');
			%由于圖像加載時間可能比較長，在加載前把鼠標的形狀改成沙漏形
hdl=get(DemoFig,'Userdata');
v = get(hdl.ImgPop,{'value','String'});
name = deblank(v{2}(v{1},:));
setstatus(DemoFig, ['Loading the ' name ' image...']);
drawnow

switch name
case 'Aluminum',
   alumgrns2 = [];                     % Parser hint
   load imdemos alumgrns2
%注意這里圖像是放在工作空間imdemos中，所以使用了load。否則，需要使用imread
%的函數。具體使用請參照前面的介紹
   img = alumgrns2;
case 'Blood',
   blood2 = [];                 
   load imdemos blood2
   img = blood2;
case 'Rice',
   rice3 = [];                    
   load imdemos rice3
   img = rice3;
case 'Saturn',
   saturn2 = [];              
   load imdemos saturn2
   img = saturn2; 
case 'Eight Bit',
   eight = [];       
   load imdemos eight
   img = eight; 
case 'Circuit',
   circuit4 = [];       
   load imdemos circuit4
   img = circuit4; 
case 'Vertigo',
   vertigo2 = [];       
   load imdemos vertigo2
   img = vertigo2; 
case 'Bone Marrow',
   bonemarr2 = [];       
   load imdemos bonemarr2
   img = bonemarr2; 
otherwise 
   error('EDGEDEMO: Unknown Image Option!');
end

set(hdl.Image, 'Cdata', img);
set(get(hdl.ImageAxes,'title'),'string',['Original ' name ' Image']);
set(DemoFig,'Pointer','arrow');
if callb
   set(hdl.Apply, 'Enable', 'on');
end
drawnow
if ~strcmp(hdl.Method, 'Laplacian of Gaussian')
   if get(hdl.RadioAutomatic, 'Value')==0
      Radio('auto',DemoFig);
   end
end
ComputeEdgeMap(DemoFig);
return;


%%%
%%%  Sub-function - UpdateThreshCtrl
%%%

function UpdateSprThresh()
DemoFig = gcbf;
hdl = get(DemoFig, 'UserData');
v = hdl.Threshold;
s = get(hdl.ThreshCtrl,'String');
vv = real(evalin('base',['[' s ']'],num2str(v)));
% Validate the threshold which was passed in
if isempty(vv) | ~isreal(vv) | vv(1)<0 
   vv = v;
   set(gcbo,'String',num2str(vv));
   return
end
vv = round(vv(1)*1000000)/1000000;
set(gcbo,'String',num2str(vv));
hdl.Threshold = vv;
set(hdl.Apply, 'Enable', 'on');
setstatus(DemoFig, 'Press ''Apply'' to compute edges.');
set(DemoFig, 'UserData', hdl);
return

%%%
%%%  Sub-function - UpdateDirectionality
%%%

function UpdateDirectionality()

DemoFig = gcbf;
hdl = get(DemoFig, 'UserData');
v = get(hdl.sprDirPop,{'value','String'});
dir = deblank(v{2}(v{1},:));
set(hdl.sprDirPop, 'userdata', dir);
hdl.Directionality = dir;
set(hdl.Apply, 'Enable', 'on');
setstatus(DemoFig, 'Press ''Apply'' to compute edges.');
set(DemoFig, 'UserData', hdl);
return


%%%
%%% Sub-function - Radio
%%%

unction Radio(control, DemoFig)

if nargin<2
   DemoFig = gcbf;
end
hdl = get(DemoFig, 'UserData');
if strcmp(control, 'auto')
   set(hdl.RadioAutomatic, 'Value', 1);
   set(hdl.RadioManual, 'Value', 0);
   set(hdl.ThreshCtrl, 'Enable', 'off');
   set(hdl.Apply, 'Enable', 'on');
   setstatus(DemoFig, 'Press ''Apply'' to compute edges.');
elseif strcmp(control, 'manual')
   set(hdl.RadioAutomatic, 'Value', 0);
   set(hdl.RadioManual, 'Value', 1);
   set(hdl.ThreshCtrl, 'Enable', 'on');
   set(hdl.Apply, 'Enable', 'on');
   setstatus(DemoFig, 'Press ''Apply'' to compute edges.');
end
return


%%%
%%% Sub-function - UpdateLOGSigma
%%%當用戶輸入SIGMA值后，一方面需要驗證取值的有效性，
%%%另一方面需要更新界面

function UpdateLOGSigma()
DemoFig = gcbf;
hdl = get(DemoFig, 'UserData');
v = hdl.LogSigma;
s = get(hdl.logSigmaCtrl,'String');
vv = real(evalin('base',s,num2str(v)));
if isempty(vv) | ~isreal(vv) | vv(1)<0      
% 驗證輸入的SIGMA值是否有效
   vv = v;
   set(hdl.logSigmaCtrl,'String',num2str(vv));
   return
end
vv = round(vv(1)*100)/100;
set(hdl.logSigmaCtrl,'String',num2str(vv));
hdl.LogSigma = vv;
set(hdl.Apply, 'Enable', 'on');
setstatus(DemoFig, 'Press ''Apply'' to compute edges.');
set(DemoFig, 'UserData', hdl);
return

%下面兩個子程序都是通過改變控件的可見屬性來完成界面的切換
%%%
%%% Sub-function - ActivateSPRControls
%%%該子程序激活SPR三種算法使用的公共控件

function ActivateSPRControls(DemoFig)
hdl = get(DemoFig, 'UserData');
set([hdl.sprDirPop hdl.sprDirLbl], 'Visible', 'on');
set([hdl.logSigmaCtrl hdl.logSigmaLbl], 'Visible', 'off');

%%%
%%%Sub-function – ActivateLOGControls
%%%該子程序激活LOG算法中使用的控件

function ActivateLOGControls(DemoFig)
hdl = get(DemoFig, 'UserData');
set([hdl.logSigmaCtrl hdl.logSigmaLbl],'Visible', 'on');
set([hdl.sprDirPop hdl.sprDirLbl], 'Visible', 'off');