How to flip horizontally the entire dxf drawing

Jun 26 at 11:23 AM
I would like to flip horizontally the entire drawing. I was not able to find how to do it. Can someone help ?
Jun 29 at 8:29 AM
To flip an object horizontally is the same as to make a symmetry of it around the Y axis, if we are working with a bi-dimensional drawing on the XY plane the symmetry of a point P(x,y) will be P'(x,-y). Therefore to make the symmetry of the entire drawing you will need to iterate through all its entities and negate the Y component of those points that define the geometry of the entity.

For example, the symmetrical line around the Y axis of a line with start point of A(x1,y1) and end point B(x2,y2) will be a line that starts at A(x1,-y1) and ends at B(x2,-y2).