pub fn marks_for_nodes(root: &UiNode, map: &ScreenshotMap) -> Vec<MarkBox>Expand description
Numbered boxes for every node of root whose frame lands inside map.
Element frames are in screen points while map describes the pixels of one
capture, so every frame goes through [screen_rect_to_image]. A node with no
frame contributes no box but its children are still walked: a frameless
group must never hide the subtree below it.
Indices mirror crate::tree::render exactly — same preorder, same
CHILD_CAP / DEPTH_CAP / LINE_CAP budget — so the number drawn on the
image is the number tree prints for that element.