Merge #375

375: Add Geometry::from_geojson r=metasim a=lnicola

- [x] I agree to follow the project's [code of conduct](https://github.com/georust/gdal/blob/master/CODE_OF_CONDUCT.md).
- [x] I added an entry to `CHANGES.md` if knowledge of this change could be valuable to users.
---



Co-authored-by: Laurențiu Nicola <[email protected]>

CHANGES.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+- Added `Geometry::from_geojson`
+
+  - <https://github.com/georust/gdal/pull/375>
+
 - Added `CslStringList::add_string`
 
   - <https://github.com/georust/gdal/pull/364>

src/vector/ops/conversions/formats.rs

@@ -57,6 +57,17 @@ impl Geometry {
         Ok(unsafe { Geometry::with_c_geometry(c_geom, true) })
     }
 
+    /// Create a geometry by parsing a
+    /// [GeoJSON](https://en.wikipedia.org/wiki/GeoJSON) string.
+    pub fn from_geojson(json: &str) -> Result<Geometry> {
+        let c_geojson = CString::new(json)?;
+        let c_geom = unsafe { gdal_sys::OGR_G_CreateGeometryFromJson(c_geojson.as_ptr()) };
+        if c_geom.is_null() {
+            return Err(_last_null_pointer_err("OGR_G_ExportToJson"));
+        }
+        Ok(unsafe { Geometry::with_c_geometry(c_geom, true) })
+    }
+
     /// Serialize the geometry as WKT.
     pub fn wkt(&self) -> Result<String> {
         let mut c_wkt = null_mut();
@@ -118,4 +129,17 @@ mod tests {
         let new_geom = Geometry::from_wkb(&wkb).unwrap();
         assert_eq!(new_geom, orig_geom);
     }
+
+    #[test]
+    pub fn test_geojson() {
+        let json = r#"{ "type": "Point", "coordinates": [10, 20] }"#;
+        let geom = Geometry::from_geojson(json).unwrap();
+        let (x, y, _) = geom.get_point(0);
+        assert_eq!(x, 10.0);
+        assert_eq!(y, 20.0);
+
+        let json = r#"{ "type": "Point", "coordinates": [10, 20 }"#;
+        let res = Geometry::from_geojson(json);
+        assert!(res.is_err());
+    }
 }