Given an microscopy image, I want to add a scale bar on the bottom left or right corner of the image. This is not hard to do.
But when I zoom in to a small area of the image, the bar will go out of the screen. I want the scale bar to automatically adjust its length acording to the zoom ratio, and also a suitable label (e.g., 10um --> 5um --> 2um) and stay inside the image when I zoom in. How to realize it? I was trying to use the zoom(on) that enables the zoom tool of my axes, but then where to write the callback function that allows me to draw the scale bar everytime the mouse button (or scrollwheel) is clicked?