Making callout lines follow feature offset with line direction as offset parameter

Question

I have a problem. I'm offsetting lines with the attribute field "offset". In the image the blue line is the original geometry. I was able to retrieve the offset value the attribute. (The callout line is now on the red line). But lines have a direction and so the offsetvalue depends on their direction. If i add a minus before offset it moves to the brown line where it should be automatically.

How do I have to change the code to get the geometry direction automatically instead of using the minus symbol which just works for one direction?

make_line(
    start_point($geometry),      
        project(                 
        end_point($geometry),
            -"Offset",            
        radians(90)              
    )
)

The original thread was: Making callout lines follow feature offset

Answer 1

A problem you face is that the offset of the callout end point is taking place only in the x direction, so the end of the callout is not perfectly aligned with the offset line.

Try this expression:

-- make variables of the start and end points of the original callout  
with_variable('start', start_point($geometry),
    with_variable('end', end_point($geometry),
        make_line(
            @start,
            project(
                @end,
                "Offset",
                azimuth(@start, @end)   -- get the callout line direction for the point projection
            )               
        )
    )
)

You may have to add the minus sign before "Offset", depending on your line directions.

Important

Be sure to enable the Line orientation dependent position option in the label placement tab:

Result