Group multiple lines to one "object" and be able to "toggle" on or off

Hi, I have this functioj that draws a grid on an image

function drawGrid(RowSize,ColSize,IM,ax)

    % Rowsize=512
    % Colsize=256
    [height,width]=size(IM); 

    nRows=floor(height/RowSize);
    nCols=floor(width/ColSize);  
       hold(ax,"on");
       for i=1:nRows     %plot Col Lines          
            plot(ax,[1 width],[i*RowSize i*RowSize],'r','LineWidth',0.2) 
       end 
       
       for i=1:nCols   %Plot Row Lines
           XX=i*floor(width/nCols);         
           plot(ax,[XX XX],[1 height],'r','LineWidth',0.2)
       end    
        hold(ax,"off");
end

I want to be able to toggle the whole grid on or off once its drawn. So I was wondering

1: How to group all the lines to one object?

2: If I pass that "object" as an output, how can I toggle on or off.

Thanks

Jason

Answer 1

[Mathieu NOE]

hello

To group multiple lines into a single "object" in MATLAB, you can use a hggroup or hgtransform object.

here your code updated with hggroup

im = imread('your_image_here.jpg');
figure
imshow(im)
RowSize=40; % whatever number you want
ColSize=40; % whatever number you want 
group = drawGrid(RowSize,ColSize,im,gca);

% Toggle visibility of the group
set(group, 'Visible', 'off'); % Hide all lines in the group
% and
set(group, 'Visible', 'on');  % Show all lines in the group

%%%%%%%%%%%%

function group = drawGrid(RowSize,ColSize,IM,ax)
    % Rowsize=512
    % Colsize=256
    [height,width,p]=size(IM); 
    nRows=floor(height/RowSize);
    nCols=floor(width/ColSize);  
       hold(ax,"on");

   % Group the lines into a single object
    group = hggroup; % create group

       for i=1:nRows     %plot Col Lines          
            prow{i} = plot(ax,[1 width],[i*RowSize i*RowSize],'r','LineWidth',0.2) ;
            set(prow{i} , 'Parent', group);
       end 
       
       for i=1:nCols   %Plot Row Lines
           XX=i*floor(width/nCols);         
           pcol{i} = plot(ax,[XX XX],[1 height],'r','LineWidth',0.2);
           set(pcol{i} , 'Parent', group);
       end    
        hold(ax,"off");
end

[Jason]

Thats exactly what Im after - I hadn't heard of hggroup before. Thanks

[Mathieu NOE]

Tx

I also discovered that quite recently ! :)

Create Object Groups - MATLAB & Simulink

[Jason]

Actually, there something not quite right, On my axes "ax" I have an image

as soon as I equate the plot to something (like this)

prow{i} = plot(ax,[1 width],[i*RowSize i*RowSize],'r','LineWidth',0.2) ;

the lines are not plotted on my axes that I pass in i.e.ax, instead a new blank figure opens up.

But if i do this, it does plot on the image which is on axes ax.

plot(ax,[1 width],[i*RowSize i*RowSize],'r','LineWidth',0.2) ;

Why is that?

also would this be an alternative approach

h=findobj('Type','line')

[Mathieu NOE]

which matlab release are you working with ?

I tested my code with R2025a

could you share your code or a working example of your issue ?

[Jason]

Hi, Im using 2024b. Here is my code

function group=drawGrid(RowSize,ColSize,IM,ax)

    % IM is the image
    % ax is the uiaxes to display the lines on (which also has the image IM)
    
    [height,width]=size(IM); 
    nRows=floor(height/RowSize);
    nCols=floor(width/ColSize);
      
    hold(ax,"on");

    % Group the lines into a single object
    group = hggroup; % create group
    
       for i=1:nRows     %plot Col Lines          
            prow{i}=plot(ax,[1 width],[i*RowSize i*RowSize],'r','LineWidth',0.2);         
            set(prow{i} , 'Parent', group);
       end 
       
       for i=1:nCols   %Plot Row Lines
           XX=i*floor(width/nCols);         
           pcol{i}=plot(ax,[XX XX],[1 height],'r','LineWidth',0.2);
           set(pcol{i} , 'Parent', group);
       end    
        hold(ax,"off");
end

And this is how I call it

        clc;
        ax=app.UIAxes; ax2=app.UIAxes2;  cla(ax2,"reset"); CL=ax.CLim;      
       
        IM=getimage(ax);  [sy,sx]=size(IM);
        RemoveAnnotations(app,ax); RemoveAnnotations(app,ax2);
        xl=400; xr=10650;  yt=0; yb=0;   % For image crop         
      
        
        n=numel(app.imgArray);    % app.imgArray = my images
        data=[];
        
         for i=1:n      
                 % Get Image from ImageStack (already created)
                 app.ImSpinner.Value=i;     
                 data(i,1)=i;
                 IM=app.imgArray{i};   % This is where my images are!
                 [sy,sx]=size(IM);
                 
                 if i==1
                    cla(ax,"reset");
                    app.myimage=imagesc(ax, IM);  colormap(ax,'gray');  axis(ax,'image');  set(ax,'xtick',[]);  set(ax,'ytick',[]);                             
                 else    
                     % This is faster to view images by using CData
                     RemoveAnnotations(app,ax);
                     set(app.myimage, 'CData', IM);    % Update the image data using handle app.myimage (much faster)      
                 end  
                                                  

                 % Crop  Image & autoscale
                 rect=[xl, yb, xr-xl,sy-yt-yb];   %[x, y, width, height] 
                 hold(ax,'on') 
                 rectangle(ax,'Position',rect, 'EdgeColor','y','LineWidth',1);                     
                 IM=imcrop(IM,rect); cla(ax,"reset");
                 myImagesc(app, ax, IM);  cl=[0.15,0.15,0.2]; ax.Color=cl;   drawnow; 
                 [sy,sx]=size(IM);
                 % Create Block array    % make the y direction 512 pixels
                 ngridscol=floor(sx/512);
                 ngridsrow=floor(sy/512);
                 ReportMessage(app,[num2str(i),' # of Rows: ',num2str(ngridsrow)]);

                 % Perform BlockProc Measurements    
                 [blockFwhm,blockFwhm1,blockFwhm2]=IQBlockProc_FOV(app,ax,ax2,ngridsrow,ngridscol,IM,CL);
                 med=mean2(blockFwhm); mediandev=3*std2(blockFwhm);
                 data(i,2)=med; data(i,3)=mediandev;                 
         end   
         

where

            function RemoveAnnotations(app,ax)
            clc;
            h1 = findall(ax, 'type', 'line');
            h2 = findall(ax, 'type', 'text'); 
            h3 = findall(ax, 'type', 'rectangle');
            delete(findall(ax,'type', 'Marker')); %Delete  markers
            delete(findall(ax,'Type','images.roi.Line'));    
            h4 = findall(ax, 'type', 'ConstantLine');
            delete(h1); delete(h2); delete(h3); delete(h4);                 
              

and

            function [blockFwhm,blockFwhm1,blockFwhm2]=IQBlockProc_FOV(app,ax,ax2,ngridsrow,ngridscol,IM,CL)
            % % % ngridsrow=19;  % was 20
            % % % ngridscol=19;   % Number of blocks in each direction    ngridsrow=100;  ngridscol=1; 
            [sy,sx]=size(IM);
            RowSize=floor(sy/ngridsrow); ColSize=floor(sx/ngridscol);         
            app.myGrid=drawGrid(RowSize,ColSize,IM,ax);  
            blockSizeRow=RowSize; 
            blockSizeCol=ColSize;
            blockImages = splitImageIntoBlocks(IM, blockSizeRow, blockSizeCol);
            [nBlocksRow, nBlocksCol] = size(blockImages); 

      
            % setup waitbar for info:
            hwait = waitbar(0, 'Please wait... ','Position',[10 50 300 50],'Name','Working on Block...','CreateCancelBtn','setappdata(gcbf,''canceling'',1)');   %left, bottom, width, height
           
            
            l=nBlocksRow*nBlocksCol;
            indx=1; ct=0;            
            xoff=floor(blockSizeCol/2);
            yoff=floor(blockSizeRow/2);
            blockFwhm = zeros(nBlocksRow, nBlocksCol);    % Holder for variable 1
            blockFwhm1 = zeros(nBlocksRow, nBlocksCol);   % Holder for variable 2
            blockFwhm2 = zeros(nBlocksRow, nBlocksCol);   % Holder for variable 3   
            data=[]; 

            midblockCol=round(nBlocksCol/2)+1;
           
            for blockIdxRow = 1 : nBlocksRow
                  % Check for clicked Cancel button
                if getappdata(hwait,'canceling')
                    break
                end
                for blockIdxCol = 1 : nBlocksCol
                    if (blockIdxCol~=1) &&(blockIdxCol~=midblockCol) &&(blockIdxCol~=nBlocksCol)  %Just get ends and central regions
                       indx=indx+1; ct=ct+1;
                        continue
                    end    
                    waitbar(indx/l,hwait,[num2str(indx),'/',num2str(l)]);
                    indx=indx+1; ct=ct+1;
                    drawnow;            
                    blockImage = double(blockImages{blockIdxRow, blockIdxCol}); 
                    blockImage=blockImage-min(blockImage(:));     % Background subtract

                    try
                        % Make measurements on BlockImage             
                         sd=std2(blockImage);                         
                         FM = std2(blockImage)^2/mean2(blockImage);
                         Bren=fmeasure(blockImage,'BREN',[]);  % Focus metric
                         [~,ImQS]=IQCalc(app,blockImage,0);    % another focus metric
      
                    catch
                                blockFwhm(blockIdxRow, blockIdxCol) = NaN;  
                                blockFwhm1(blockIdxRow, blockIdxCol) = NaN;  
                                blockFwhm2(blockIdxRow, blockIdxCol) = NaN;  
                
                           continue;
                    end
             
                           
                    if ct==1
                        cla(ax2,"reset");
                        app.myimage=imagesc(ax2,blockImage);  %image creation  
                        colormap(ax2,'gray');  axis(ax2,'image'); set(ax2,'xtick',[]);  set(ax2,'ytick',[]); 
                        ax2.CLim=CL;
                    else
                          RemoveAnnotations(app,ax2);
                          set(app.myimage, 'CData', blockImage);    % Update the image data using handle app.myimage (much faster)
                    end                     

            
                    blockFwhm(blockIdxRow, blockIdxCol) = ImQS;  
                    blockFwhm1(blockIdxRow, blockIdxCol) = sd;   %FM;  
                    blockFwhm2(blockIdxRow, blockIdxCol) =Bren;        %fwhmBlockY; 
 
                    % Show current Block location analysed on raw image        
                     xx=blockSizeCol*blockIdxCol-xoff;
                     yy=blockSizeRow*blockIdxRow-yoff;
                     hold(ax,"on"); 
                     plot(ax,xx,yy,'c.','MarkerSize',20);  drawnow;
                end
            end
            delete(hwait);
            % Remove all columns with zeros
            blockFwhm = blockFwhm(:,any(blockFwhm,1)); blockFwhm1 = blockFwhm1(:,any(blockFwhm1,1)); blockFwhm2 = blockFwhm2(:,any(blockFwhm2,1));
          

[Mathieu NOE]

hmm, it's going to be difficult for me to help you

app's are not really my area of expertise and I probably will not be able to reproduce & run your test environment on my side

what is the error message you get ?

[Jason]

Ok thsnks for your help and introducing me to hggrouo.

I think i have an easier way, but have run into another issue, so i will post a new question.

[Mathieu NOE]

ok good luck !!