I have an extension I am writing to create a line, copy it and rotate the copy.  I need to swap the beginning node with the end node of the copy before rotating.  How can I accomplish this?

Thank you,

Can you give more information.

When you  say 'line' do you mean a path with just two points - or any type of path ? 

Swapping the beginning and end nodes - do you mean to really swap the nodes, or change the centre of rotation ? 

Can give an example of before and after what you want to achieve ? 

I am brand new to this, so this might not be the best way to do this...  and yes, I actually want to swap the beginning and ending nodes.  Same as doing a horizontal or vertical flip.

layer = self.svg.get_current_layer()

        elem1 = layer.add(inkex.PathElement())

        elem1.update(

        **{

            "style": style,

            "inkscape:label": name,

            "d": "M "

            + str(x1)

            + ","

            + str(y1 - y2)

            + " L "

            + str(x1)

            + ","

            + str(y1)

            + " z"

        } )

Swapping the start and end nodes will not flip the object.

It will just reverse the path direction. Like travelling to B to A instead of A to B.

You would need to flip the x or flip the y values of the start and end points as needed.

You could write a little function to do that, and return flipped x or flip y.

This approach would only work however for a path made from two points ( a straight line )

Normally in SVG documents, flipping is achieved by applying a transform instead of dealing with the points.

Also the 'z' you have at the end of the statement - that is to close the path, not needed for a straight line.

I made an example here with a menu - my coding style is not very pythonic,  but it works lol.

https://gitlab.com/inklinea/flip-path

In the example - I just made a function to flip the points in a list, then generate a new path for each change.

If you want to manipulate existing paths - then that is different to just building the 'd' attribute and updating.

https://inkscape.gitlab.io/extensions/documentation/source/inkex.paths.html
 

Thank you so much.  That helped a lot.