How to determine which object is "on top"

[bpugnaire]

Hello,

My question is quite simple but I didn't find a way to answer it : let's imagine that we have two rectangles on our pdf page, they are practically identical in size and position but one if black and the other is white, is there a way to know which of those rectangles is "on top" of the other ?

This is useful and has many applications like discarding unnecessary information or accurately reading forms with tickboxes I think.

Thanks!
Baptiste

[jsvine]

I believe that the PDF Reference specifies that objects are drawn on top of one another, in the order that the document creates them. And I believe that pdfminer.six extracts objects in that same order. So for two rectangles, the "top" one would be the rectangle that appears later in page.rects than the other. Does that seem to be the case for your PDF?

For two objects of the same pdfminer.six type (e.g., two rects, two lines, two chars), the comparison should be easy. But if you're comparing across types (e.g., a rect vs. a line), you'll want to run something like ordered_objects = list(page.iter_layout_objects(page.layout._objs)) and then do the comparison based on that list.

[bpugnaire]

Hello,
Thank you for your answer, that was my hunch (actually I though the first one would be on top) but indeed it seems to work.
Kind regards