How to Copy Dimension Value via Driver

Is it possible to copy the value of the Y Dimension to the X Dimension of an Object via Driver so that the whenever the Y Dimension changes, the X Dimension changes as well?

I am asking because i have a setup with one bone stretching to an empty while parented to another empty. Basically it is Sebastian Koenigs 2 Point Tracking setup to copy the Rotation
Then i have a plane parented to the Bone. When the bone stretches, so does the plane. But unfortunately only in one direction, which distorts the aspect ratio of the planes image texture.
I checked out the plane object porperties and saw that the dimension y value is the value that changes during streching. I was wondering if and how it would be possible to constantly copy the value of one dimension field to the other. I belive drivers would be the way to go, but unfortunately have never used them.

Stretch sounds like IK. Drivers for this purpose seem quite unnecessary. It should scale uniformly automatically, unless perhaps you have some scale on the bone to begin with, I don’t know the tut you are referring to, but here’s a file that might help you even though it’s not the same structure as you describe!

In the video the ball just shows the location of the controlling empty.


imagescaling.blend (430 KB)