feat: implement Validify repair trait

geo/src/algorithm/mod.rs

@@ -258,6 +258,10 @@ pub mod triangulate_spade;
 #[cfg(feature = "spade")]
 pub use triangulate_spade::TriangulateSpade;
 
+/// Operations on invalid polygons to make them valid
+mod validity;
+pub use validity::Validify;
+
 /// Vector Operations for 2D coordinates
 mod vector_ops;
 pub use vector_ops::Vector2DOps;

geo/src/algorithm/validity/impls.rs

@@ -0,0 +1,32 @@
+use super::*;
+
+use geo_types::{MultiPolygon, Polygon};
+
+use crate::GeoFloat;
+
+/// Splits self intersecting polygons into individual valid polygons
+///
+/// Self intersecting here includes banana polygons
+///
+/// There are no real guarantees in terms of minimality we can give since the algorithms is a
+/// heuristic. In practice it turned out to work quiet well though.
+///
+/// # Validity
+///
+/// The algo will return non-sense if the input is non-sense. This mainly means:
+///
+/// - a polygon including a weird, disconnected linestring
+impl<F: GeoFloat> Validify for Polygon<F> {
+ type ValidResult = MultiPolygon<F>;
+ fn split_into_valid(&self) -> Self::ValidResult {
+ let mp = MultiPolygon::new(vec![self.clone()]);
+ split::split_invalid_multipolygon(&mp)
+ }
+}
+
+impl<F: GeoFloat> Validify for MultiPolygon<F> {
+ type ValidResult = MultiPolygon<F>;
+ fn split_into_valid(&self) -> Self::ValidResult {
+ split::split_invalid_multipolygon(self)
+ }
+}

geo/src/algorithm/validity/mod.rs

@@ -0,0 +1,20 @@
+mod impls;
+mod split;
+
+/// Trait which includes a bunch of methods for dealing with invalid polygons.
+///
+/// There are a few implicit assumptions that are made when dealing with geo's types. You can read
+/// more about the specific assumptions of a kind of geometry in it's own documentation.
+///
+/// Some of geo's algorithms act in unexpected ways if those validity assumptions are not
+/// respected. An example of this is `.make_ccw_winding()` on [`LineStrings`] which might fail if
+/// the linestring doesn't include unique points.
+pub trait Validify {
+ type ValidResult;
+
+ /// splits invalid geometries into valid ones
+ fn split_into_valid(&self) -> Self::ValidResult;
+}
+
+#[cfg(test)]
+mod split_tests;