I have some shape in inkscape, say two concentric rings (of some width). Now, I want to get a shape which covers exactly the complement of these two rings w.r.t. some rectangle, or the page, or whatever. So, a rectangle with two concentric ring-shaped holes in it.
Can I do that in Inkscape? I remember that in apps like MS Visio or LO Draw there are shape algebra operations which you can apply; does Inkscape have something like that?
In Inkscape Path > Difference does it.
The circles must at first be converted to filled areas which have no stroke. To do it select a circle which has the right stroke to be a good ring, but no fill. Apply to that circle Path > Stroke to Path. The result can be subtracted from an underlying rectangle by applying Path > Difference. Subtract one ring at a time.
The blue rings are at first converted to strokeless filled areas and then subtracted from the grey rectangle. White rings are holes, as it hopefully is shown in the right.
If there's too many rings to be subtracted one by one from the background, it's useful to select them all (after making them strokeless filled areas) and to apply Path > Union. Then one subtraction is enough.
