Module labels 

Atom-label orientation and backbone bond insets.

Caller supplies SVG-space atom coordinates. Labels split into an atom-center part (sits on the atom) and an optional traveling part (extends away from the molecule). OH on the left of a mol becomes HO with O still at the atom; abbreviations like GlcA have no traveling part — the first or last glyph is the center depending on the bond approach side.

Orientation follows RDKit MolDraw2D (E/W/N/S). All chem scripts (H-counts, charges, star-label markup, symbols, bold/italic) go through crate::markup::parse_label_markup → ScriptRole fake scripts, outlined as glyph paths, not <text>.

Structs

AtomIn

Atom input for backbone + label placement.

BondIn

Bond as atom index pair into place_backbone atoms slice.

BondOut

Shortened bond endpoints in SVG space.

LabelParts

Atom-center glyph(s) vs optional traveling H / charge.

PlacedLabel

One placed atom label in SVG space (+Y down).

Enums

LabelSide

Which side the traveling text extends toward (RDKit OrientType).

Functions

compose_label

Plain display string after orientation (OH / HO / NH₂⁺).

label_ink_shape

Glyph ink for a placed label (halo / occupancy).

label_side

Orient a label from the sum of neighbor vectors (SVG +Y down).

label_side_for

Like label_side but degree-0 Hs-first elements use West (RDKit).

place_backbone

Place all atom labels and shorten bond endpoints into label clearances.

place_label

Place one label so the atom-center glyph sits on (atom_x, atom_y).

place_label_weighted

Like place_label, with mol weight increasing bond↔label clearance.

shorten_bond

Shorten a bond segment by end insets (same as Python bonds.shorten).

split_label

Split a raw label into center + traveling H + charge.