How to delete the dotted plot on top of the Image in UIAxes

Hello,

I have plotted a rectangle lines(dots) in UIaxes on top of the image using the selected co-ordinate.

Each time i clicked a button, I am selecting a new coordinates and plotting new rectangle area.

I want to delete the old rectangle on the image. Image should be still present on the UIaxes.

below is the following code i have used to draw the rectangle area on the image in UIaxes

%% Image is already uploded to UIaxes
 %% deleting previously selected area
                  hold(app.UIAxesImage,'on');
                  h=findobj('Color','r');
                  delete(h);
                  hold(app.UIAxesImage,'off');
                   
               %% Obviously the above code didnt delete the previously drawn line as expected
               
                 %selecting starting point of area
                 [clickedX, clickedY] = ginput(1);
                 app.XdirEditField.Value=round(clickedX);
                 app.YdirEditField.Value=round(clickedY);
                 
                 %% ploting on the image
                 Y1=app.YdirEditField.Value+800;
                 X1=app.XdirEditField.Value+1000;
                 side1=app.XdirEditField.Value:1:X1;
                 side2=app.YdirEditField.Value:1:Y1;
                 hold(app.UIAxesImage,'on');
                 plot(app.UIAxesImage,side1,app.YdirEditField.Value,'r.',...
                     side1,Y1,'r.',X1,side2,'r.',app.XdirEditField.Value,side2,'r.');
                 hold(app.UIAxesImage,'off');

Each time its drawing a new area along with the old.

Please let me know How to achieve this.

Answer 1

[Cris LaPierre]

Your current code is drawing a dot at every interger increment in X and Y. That along with your plotting syntax is creating a rectangle made up of thousands of lines.

Try using a different syntax for your findobj command.

h = findobj(app.UIAxesImage,'Type','Line');
delete(h)

You can make this a single line by creating a vector of your X and Y points

X = [side1'; ones(size(side2'))*X1; flipud(side1'); ones(size(side2'))*app.XdirEditField.Value];
Y = [ones(size(side1'))*app.YdirEditField.Value; side2'; ones(size(side1'))*Y1; flipud(side2')];
plot(X,Y,'r.');

If you don't need a dot at every integer, then just use the vertices

X = [app.XdirEditField.Value X1 X1 app.XdirEditField.Value app.XdirEditField.Value];
Y = [app.YdirEditField.Value app.YdirEditField.Value Y1 Y1 app.YdirEditField.Value];
plot(X,Y,'r:','LineWidth',2);

Of course, if you are going to do that, you might as well use rectangle

rectangle('Position',[app.XdirEditField.Value app.YdirEditField.Value X1 Y1],...
    'LineStyle',':','EdgeColor','r','LineWidth',2)
% use 'Type','Rectangle' with findobj to delete this object

[Chandrashekar D S]

Thanks you so much @Cris LaPierre, rectangle thing is worked like a charm.