How to stop the while loop when using imrect() draw many rectangles in an image?

I use the while loop to enable me extract many rectangle areas of an image by imrect function, and I want to stop the loop when I input the "Enter" from the keyboard. The thing is it won't stop the drawing immediately after I enter the button but until the next draw. How should I avoid this??? Thanks so much! The code is below:

function [ImgPatch_Cluster,ShowMask] = seletpatch()
%%%this function is to let users crop any image patches
temp=imread('./train images/1.png');
OrigImg=rgb2gray(temp);
fprintf('Start to crop the image patches from the whole image.\n');

imgSz = size(OrigImg);
PatchCount = 0;
ImgPatch_Cluster = cell(1,1);
FLAG = 1;
ShowMask = uint8(mat2gray(OrigImg)*255);

global KEY_IS_PRESSED
KEY_IS_PRESSED = 0;

figure('KeyPressFcn', @myKeyPressFcn);
imshow(OrigImg,'Border','tight');

fprintf('If you want to stop selecting on the current image.\n');
fprintf('Press "Enter" button, then drag any size rectangle to finish.\n');

 while KEY_IS_PRESSED == 0
    %     set(gcf, 'KeyPressFcn', @myKeyPressFcn);

    if KEY_IS_PRESSED==1
        break;
    end

    H = imrect;

    if KEY_IS_PRESSED==1
        fprintf('Finish selecting on the current image.\n Drag any size rectangle to finish.\n');
        break;
    else
        position = wait(H);
        setColor(H,[1 0 0]);

        xmin = round(position(1));
        ymin = round(position(2));
        width = position(3);
        height = position(4);

        xmax = xmin+width-1;
        ymax = ymin+height-1;

        if xmin<=0
            xmin = 1;
        end
        if ymin<=0
            ymin = 1;
        end
        if xmax>=imgSz(2)
            xmax = imgSz(2)-1;
        end
        if ymax>=imgSz(1)
            ymax = imgSz(1)-1;
        end

        new_width = xmax-xmin+1;
        new_height = ymax-ymin+1;

        if mod(new_width,2)==0
            new_width = new_width+1;
        end
        if mod(new_height,2)==0
            new_height = new_height+1;
        end

        ImgPatch = zeros(new_height,new_width);
        ImgPatch(1:new_height,1:new_width) = ...
            OrigImg(ymin:ymin+new_height-1,xmin:xmin+new_width-1);

        BinaryMask = zeros(imgSz(1),imgSz(2));
        BinaryMask(ymin:ymin+new_height-1,xmin:xmin+new_width-1) = 1;
        BinaryContour = bwmorph(BinaryMask,'remove');
        BinaryContour = imdilate(BinaryContour,ones(5));

        ShowMask(BinaryContour) = 255;
        %     contour(BinaryMask*2-1,[0 0],'r');

        %     api = iptgetapi(H);
        %     position = api.getPosition();

        PatchCount = PatchCount+1;
        ImgPatch_Cluster{1,PatchCount} = ImgPatch;
    end
end
hold off;
close;

function myKeyPressFcn(hObject, event)
global KEY_IS_PRESSED
if strcmp(event.Key,'return')
  KEY_IS_PRESSED = 1;
end

Answer 1

[Image Analyst]

Why not just put code like this at the end of the loop:

message = sprintf('Do you want to continue saving rectangular regions?');
reply = questdlg(message, 'Continue with Loop?', 'OK','Cancel', 'OK');
if strcmpi(reply, 'Cancel')
  % User canceled so exit.
  break;
end

[Han Li]

Thanks for your advice. It sounds great, but generally, the user has to input around 10 rectangles at the same time. It will be a little noisy though since it

[Image Analyst]

So? If you just go as fast as you can until the user hits a key then how do you have any control at all over how many rectangles are created? It would be almost random. Why is my method a little noisy?