MATLAB: How to quickly refer to various object handles in the GUI

Question

Hello!

I am currently making a GUI in which you graphically select data from one plot and use it to produce an image.

I have 5 different pushbuttons which essentially do the same thing: allow for selection of a plotting range using ginput, display image over the corresponding data range (using imagesc) and update two edit text fields with the values obtained from ginput. However, I want each button to plot to a different set of axes (i.e. 5 different axes), and update different edit text fields.

Pushbutton handles are pbhTW1 … pbhTW5, and they each have a 'Tag' of '1' … '5' for reference. Axes for plotting the images are ahTW1 … ahTW5. There are two edit text fields accompanying each image, handles ethTW1a, ethTW1b … ethTW5a, ethTW5b.

I am currently achieving this using the following callback function, which is executed when each pushbutton is pressed:

function TWOut = TWPlot(hObject,~)
          X=ginput(2);
          if X(1)<X(2),
              WinStart=floor(X(1));
              WinStop=floor(X(2));
          else WinStart=floor(X(2));
              WinStop=floor(X(1));
          end
          TWOut=zeros(PixX*PixY,1);
          h=waitbar(0, ['Plotting from channel ' num2str(WinStart) ...
              ' to channel ' num2str(WinStop) '...']);
          steps=WinStop-WinStart;
          for i=WinStart:WinStop,
              fseek(fid,20+(i-1)*4,'bof');
              im=fread(fid,inf,'int32',(TCSPCChannels-1)*4);
              TWOut=TWOut+im;
              step=i-(WinStart-1);
              waitbar(step/steps)
          end
          close(h)
          TWOut=reshape(TWOut,PixY,PixX)';
          clear im
          Ref = get(hObject, 'Tag');
          if Ref == '1',
              set(fh,'CurrentAxes',ahTW1);
              imagesc(TWOut)
              set(ethTW1a,'String',num2str(WinStart));
              set(ethTW1b,'String',num2str(WinStop));
              TWOut1 = TWOut;
          elseif Ref == '2',
              set(fh,'CurrentAxes',ahTW2);
              imagesc(TWOut)
              set(ethTW2a, 'String', num2str(WinStart));
              set(ethTW2b, 'String', num2str(WinStop));
              TWOut2 = TWOut;
         elseif Ref == '3',
              set(fh,'CurrentAxes',ahTW3);
              imagesc(TWOut)
              set(ethTW3a, 'String', num2str(WinStart));
              set(ethTW3b, 'String', num2str(WinStop));
              TWOut3 = TWOut;
          elseif Ref == '4',
              set(fh,'CurrentAxes',ahTW4);
              imagesc(TWOut)
              set(ethTW4a, 'String', num2str(WinStart));
              set(ethTW4b, 'String', num2str(WinStop));
              TWOut4 = TWOut;
          elseif Ref == '5',
              set(fh,'CurrentAxes',ahTW5);
              imagesc(TWOut)
              set(ethTW5a, 'String', num2str(WinStart));
              set(ethTW5b, 'String', num2str(WinStop));
              TWOut5 = TWOut;
          end
      end

I would really like to tidy up all of the if statements at the end of the function. I was thinking that I could maybe use genvarname to have a condense these into a few lines, e.g.

      Ref = get(hObject, 'Tag');
      set(fh, 'CurrentAxes', genvarname(['ahTW' Ref]));
      imagesc(TWOut)
      set(genvarname(['ethTW' Ref 'a']), 'String', num2str(WinStart));
      set(genvarname(['ethTW' Ref 'b']), 'String', num2str(WinStop));
      genvarname(['TWOut' Ref]) = TWOut;

but from what I understand of genvarname this will not work as a variable name is not actually created using this function.

If anyone has any ideas on how I could achieve this, I would be really grateful . It's not the end of the world if it's not possible, as my current code does the job, but it would be a nice luxury and useful for future callback functions that I plan to use in my GUI.

Thank you very much!

Siân

Answer 1

Here is how I handle situations like these. I store all handles to a specific type in a structure with a fieldname corresponding to that type. This lets me index into the structure as needed, simplifying the code considerably. You could easily do a similar thing, even if you are using GUIDE. Just build the structure in the initialization code. Here is an example to show you what I mean:

function [] = GUI_mult_ax()
% Plot different plots according to slider location.
S.fh = figure('units','pixels',...
              'position',[300 300 860 300],...
              'menubar','none',...
              'name','GUI_mult_ax',...
              'numbertitle','off',...
              'resize','off');    
S.x = 0:.01:1;  % For plotting.         
S.ax(1) = axes('unit','pix',...
               'position',[20 80 260 210]);
S.ax(2) = axes('unit','pix',...
               'position',[300 80 260 210]); 
S.ax(3) = axes('unit','pix',...
               'position',[580 80 260 210]);     
plot(S.ax(1),S.x,S.x,'r');   
plot(S.ax(2),S.x,S.x.^2,'b');  
plot(S.ax(3),S.x,S.x.^3,'k'); 
set(S.ax,{'xtick','ytick'},{[],[]})
S.pb(1) = uicontrol('style','push',...
                    'unit','pix',...
                    'position',[20 10 260 30]);
S.pb(2) = uicontrol('style','push',...
                    'unit','pix',...
                    'position',[300 10 260 30]);
S.pb(3) = uicontrol('style','push',...
                    'unit','pix',...
                    'position',[580 10 260 30]);
set(S.pb,'String','Off','callback',{@sl_call,S})
function [] = sl_call(varargin)
% Callback for all pushbuttons.
% Note that I pass in the handle structure created above.  
% This could have been stored in GUIDATA or whatever.
[h,S] = varargin{[1,3]};  % calling handle and data structure.
N = find(S.pb==h);   % This lets us know which pb called.
if strcmp(get(S.ax(N),'visible'),'off')
    set(S.ax(N),'visible','On')
    set(S.pb(N),'string','Off')
else
    set(S.ax(N),'visible','Off')
    set(S.pb(N),'string','On')    
end