@Grace i think there is not a way to measure entire length from edge to edge, including the curve. Do you know something I do not?
The best way I would know today is to artificially create a line with a formula. This is not the way the formula would look inside valentina but I hope it makes sense.
Use point at distance and angle tool. select ANY arbitrary point as origin Stretch the new line in ANY direction. Press enter to finish the creation.
Inside the dialog box that appears:
click on f(x) for the length.
Inside the “edit length” dialog box that appears, create your formula.
At that point you will have access to all of the length of lines and length of curves that exist and you can add them together. the result will be the length of your new line and valentina will do the math for you.
Do not add the line to any detail and change it to a color that does not offend you and ignore it.
I believe there is an existing issue to request a “ruler” line. The addition of curves to that should be added to the existing issue