Module corner_layout 

Shared geometry for stacking panel-corner “furniture” clear of each other — annotation_scale()/annotation_attribution()’s scale bar and attribution text, bivariate_legend()’s square guide, and an ordinary legend placed with legend_position_inside — so two of them anchored to the same or adjacent corners don’t draw on top of one another (sipemu/ggplot-rs#273).

Each corner geom draws in plot-layer order (the order layers were added to the plot). Before drawing, it asks DrawBackend::corner_claims what boxes earlier geoms in this render pass already placed, stack_clears its own measured box away from its own anchor edge until it no longer overlaps any of them, draws at the (possibly shifted) result, then registers that box with DrawBackend::claim_corner_box so a later geom in the same render pass sees it too.

An ordinary inside legend (legend_position_inside) draws after every geom (renderer.rs’s draw order: layers, then the legend), so there’s no later geom for it to defer to in the usual way — instead its box is pre-claimed before any geom draws, computed the same way draw_legend_planned itself positions it (see guide::legend::inside_legend_box), so attribution/scale-bar/bivariate geoms drawn first still see it and stack clear of it.

Functions

rects_intersect

true if a and b overlap with positive area — touching edges (sharing a boundary with zero-width overlap) don’t count, so two items placed flush against each other aren’t flagged as colliding.

stack_clear

Shifts rect along the y axis, away from its own anchor edge, just far enough to clear every rect in claims it would otherwise overlap, plus [CORNER_STACK_GAP] of real clearance — “stack them” (#273). away_sign is the direction away from the anchor edge: -1.0 shifts up (decreases y), the right direction for a bottom-anchored corner’s items (they stack upward, away from the bottom edge); any other value shifts down (increases y), for a top-anchored corner. A claim with no horizontal overlap with rect is never a reason to move (rects_intersect requires both axes).