Programmatic Editing

Pro 0.11 lets your own UI drive gm.edit. In-place edits record history and emit gm:edit, then gm:editend, so the same persistence handler can cover interactive and programmatic changes.

gm.edit.setGeometry(featureId, geometry);
gm.edit.setProperties(featureId, properties);
gm.edit.repairGeometry(featureId);
gm.edit.snapToGrid(featureId, 0.00001);
gm.edit.buffer(featureId, 10, { units: 'meters' });

Inspect operation results and listen for rejection events before presenting an edit as successful. Repair/snap operations that change nothing do not add an unnecessary history entry. Buffering in place requires a polygon and rejects collapsed results.

Pure geometry utilities

Import these from @geoman-io/maplibre-geoman-pro:

Utility	Purpose
validateFeatureGeometry(geometry)	Report too few vertices and polygon self-intersections
repairFeatureGeometry(geometry)	Remove duplicate vertices and split self-intersections into valid parts
snapGeometryToGrid(geometry, size, origin?)	Round geometry coordinates
snapLngLatToGrid(lngLat, size, origin?)	Round one coordinate
bufferGeometry(geometry, distance, options?)	Produce a Polygon/MultiPolygon area, or null if it collapses
geometryToWkt(geometry)	Serialize geometry as WKT
wktToGeometry(wkt)	Parse WKT, returning null for malformed input

Grid size and origin use coordinate units (degrees), not metres. Interactive grid snapping is enabled with settings.gridSnap = { size, origin? }. Buffer distance defaults to metres; negative values shrink. Use the pure buffer utility for points/lines, then explicitly add its resulting area to your app. WKT uses @terraformer/wkt, including its supported empty geometry behavior.

Merge and explode attributes

const gm = new Geoman(map, {
  settings: { mergeAttributeStrategy: 'union' },
});
gm.edit.merge(featureIds, { attributes: 'primary' });

primary (default) keeps the first feature's properties. union combines properties with the primary feature winning collisions. none starts with no custom properties. Explode copies source attributes onto every part; generated features always receive fresh identities.

Persist compound operations once

Explode, merge-parts, and split emit granular create/remove events plus lineage events. Lineage payloads always use originalFeatures and features arrays. Choose one persistence channel to avoid double-counting; set settings.compoundLineageEvents: false for granular events only.