How can I make the XY coordinate to be symmetrical and stay
symmetrical also after zooming.
That is including the case the user is zooming by selecting unsymmetrical area (rectangle ).
In symmetrical XY both axis have the same scale, meaning the real distance on the screen of 1 in the X axis is exactly the same as 1 in the Y axis.
One of the results of symmetrical XY axis is the grid lines creates squares instead of rectangles.
See the attached figure for example of symmetrical XY axis.