How i can loop a video until a button is pushed or a condition is given?

I have my code already set down. but i am having problems with telling Matlab how I can continues executing the code until the user closes the video, or Give it a condition for stopping.

vid=videoinput('winvideo',1);                                            
figure(3);preview(vid);                    
set(vid,'ReturnedColorspace','rgb')
img = getsnapshot(vid);
figure (2); imagesc(img);
red = img(:,:,1); % Canal Rojo
green = img(:,:,2); % Canal Verde
blue = img(:,:,3); % Canal Azul
a = zeros(size(img, 1), size(img, 2));
just_red = cat(3, red, a, a);
just_green = cat(3, a, green, a);
just_blue = cat(3, a, a, blue);
I= just_red - just_green; 
I2=im2bw(I, graythresh(I));  
I3= bwareaopen(I2, 100);  
se=strel('disk',6);
I4=imclose(I3,se); 
Ic=imfill(I4,'holes');

I tried with a toggle button, but i a newbie, and i know nothing about programming.

Thanks, Alex

[Stephen23]

This time I formatted your code for you, but in future you can do this yourself by simply selecting the code and then pressing the {} Code button that you will find above the textbox. And please do not put empty lines between every line of your code: this is a waste of your time and ours.

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

Answer 1

[Walter Roberson]

http://blogs.mathworks.com/videos/2010/12/03/how-to-loop-until-a-button-is-pushed-in-matlab/