QGIS/resources/function_help/json/extend

{
  "name": "extend",
  "type": "function",
  "groups": ["GeometryGroup"],
  "description": "Extends the start and end of a linestring geometry by a specified amount. Lines are extended using the bearing of the first and last segment in the line. For a multilinestring, all the parts are extended. Distances are in the Spatial Reference System of this geometry.",
  "arguments": [ {"arg":"geometry","description":"a (multi)linestring geometry"},
                 {"arg":"start_distance","description":"distance to extend the start of the line"},
                 {"arg":"end_distance","description":"distance to extend the end of the line."}],
  "examples": [ { "expression":"geom_to_wkt(extend(geom_from_wkt('LineString(0 0, 1 0, 1 1)'),1,2))", "returns":"'LineString (-1 0, 1 0, 1 3)'"},
                { "expression":"geom_to_wkt(extend(geom_from_wkt('MultiLineString((0 0, 1 0, 1 1), (2 2, 0 2, 0 5))'),1,2))", "returns":"'MultiLineString ((-1 0, 1 0, 1 3),(3 2, 0 2, 0 7))'"}]
}