How can i measure length interactively in axes in gui?

I need to use interactive rulers for one of my axes in my gui. I need to measure length of a line i draw interactively in image. And see its length. All of my pictures are 20cm x 20cm so i know the lenght of my image so it will be easier. But i dont know how can i do it interactively in my gui creating ruler button. Thanks for helps...

Respectfully yours; Abarairenji

Answer 1

[Image Analyst]

Use imdistline() in the Image Processing Toolbox.

Answer 2

[Caleb]

You should be able to use something like this:

figure;
axis manual
ruler = imline(gca);

% Get original position
pos = getPosition(ruler);

% Get updated position as the ruler is moved around
id = addNewPositionCallback(ruler,@(pos) title(mat2str(pos,3)));

You can use the getPosition function to get the original position and as you stretch it or drag it around, you use addNewPositionCallback to get the updated position. From here you can calculate the length using Pythagorean's theorem.

[Zoltan]

You need Image Processing Toolbox.