eulerr (version 8.3.0)

build_leader_grob: Build the polyline leader for an exterior tag, or grid::nullGrob() for interior / missing-tether placements.

Description

Draws the polyline tether → waypoints[1..] → leader_end. For straight leaders (raycast / force-directed) waypoints_* are empty, so the polyline collapses to the single tether → leader_end segment. For elbow leaders eunoia emits one knee waypoint, producing the orthogonal tether → knee → leader_end bend.

Usage

build_leader_grob(
  ax,
  ay,
  kind,
  tx,
  ty,
  lend_x,
  lend_y,
  waypoints_x = numeric(0),
  waypoints_y = numeric(0),
  leader_gp_list,
  fallback_gp,
  name
)

Arguments

ax, ay

the tag anchor, in native units

kind

the placement kind eunoia returned; anything other than "interior" gets a leader

tx, ty

the tether point on the shape, in native units

lend_x, lend_y

the leader endpoint on the tag bbox, in native units

waypoints_x, waypoints_y

intermediate leader vertices, in native units

leader_gp_list

grid::gpar() for the leader line, or NULL

fallback_gp

grid::gpar() used when leader_gp_list is NULL

name

name to give the returned grob

Details

Terminates at (lend_x, lend_y) — the point on the label box AABB edge supplied by eunoia (LabelPlacement::leader_end). Falls back to the anchor when the leader endpoint isn't finite so older / partial placement results still draw something sensible.