how to fill bounded areas perfectly in inkscape

Question

I have a PNG with transparent background. I want to draw a rectangle over it (the dashed rectangle) and then fill it with some color because for my text, I need to add a rectangle over some areas to show that they are part of a module.

I first tried to fill the rectangle and adjust the alpha, but as you can see it covers the whole thing

Then I used FILL BOUNDED AREAS (the bucket icon) but it does not do a clean job as I expected as it does not fill inside the small texts (Q1, R1, R2).

My question is, does the goal that I have in mind make sense in Inkscape? if so how can I do it, otherwise do you have any suggestion how can I approach such a design problem!?

Answer 1

With high zoom in, you can separately fill the interiors of those A, B, D, O, Q and P letters. But that's tiresome and inaccurate.

The bucket fill works with the rendered screen image. It has only 1 px accuracy, and that depends on the current zoom level. It can still be good for artistic purposes, but not in technical drawings. Forget it if you expect perfect results.

What to do: The rounded rectangle hopefully is a closed shape. Give to it a fill color and send it to the back in the layering order, as you already have tried. Give white fills to the component shapes. Those shapes can be reused, so no need to do it more than once. Better to ungroup the component shape temporarily before inserting the fill.

Done.