Convert Feature to use foreign_types.

src/raster/gcp.rs

@@ -1,6 +1,7 @@
 //! Raster ground control point support
 
-use crate::spatial_ref::SpatialRef;
+use foreign_types::ForeignTypeRef;
+use crate::spatial_ref::SpatialRefRef;
 use crate::Dataset;
 
 impl Dataset {
@@ -11,14 +12,14 @@ impl Dataset {
     /// the representation of ground control points, when embedded.
     ///
     /// See: [`GDALGetGCPSpatialRef`](https://gdal.org/api/raster_c_api.html#_CPPv420GDALGetGCPSpatialRef12GDALDatasetH)
-    pub fn gcp_spatial_ref(&self) -> Option<SpatialRef> {
+    pub fn gcp_spatial_ref(&self) -> Option<&SpatialRefRef> {
         let c_ptr = unsafe { gdal_sys::GDALGetGCPSpatialRef(self.c_dataset()) };
 
         if c_ptr.is_null() {
             return None;
         }
 
-        unsafe { SpatialRef::from_c_obj(c_ptr) }.ok()
+        Some(unsafe { SpatialRefRef::from_ptr(c_ptr) })
     }
 }
 

src/spatial_ref/srs.rs

@@ -3,7 +3,7 @@ use gdal_sys::{self, OGRErr};
 use std::ffi::{CStr, CString};
 use std::ptr::{self};
 use std::str::FromStr;
-use foreign_types::{foreign_type, ForeignType};
+use foreign_types::{foreign_type, ForeignType, ForeignTypeRef};
 
 use crate::errors::*;
 
@@ -115,7 +115,9 @@ impl SpatialRef {
             Ok(unsafe { Self::from_ptr(c_obj) })
         }
     }
+}
 
+impl SpatialRefRef {
     pub fn to_wkt(&self) -> Result<String> {
         let mut c_wkt = ptr::null_mut();
         let rv = unsafe { gdal_sys::OSRExportToWkt(self.as_ptr(), &mut c_wkt) };