Support for accessing the SpatialRef of GCPs.

CHANGES.md

@@ -81,6 +81,10 @@
 
   - <https://github.com/georust/gdal/pull/370>
 
+- Added support for getting the `SpatialRef` of embedded ground control points (GCPs) via `Dataset::gcp_spatial_ref`.
+
+  - <https://github.com/georust/gdal/pull/397>
+
 ## 0.14
 
 - Added new content to `README.md` and the root docs.

src/dataset.rs

@@ -191,6 +191,7 @@ bitflags! {
     ///
     /// [`GDALOpenEx`]: https://gdal.org/doxygen/gdal_8h.html#a9cb8585d0b3c16726b08e25bcc94274a
     #[derive(Debug)]
+    #[allow(clippy::assign_op_pattern)]
     pub struct GdalOpenFlags: c_uint {
         /// Open in read-only mode (default).
         const GDAL_OF_READONLY = 0x00;

src/raster/gcp.rs

@@ -0,0 +1,37 @@
+//! Raster ground control point support
+
+use crate::spatial_ref::SpatialRef;
+use crate::Dataset;
+
+impl Dataset {
+    /// Get output spatial reference system for GCPs.
+    ///
+    /// # Notes
+    /// * This is separate and distinct from [`Dataset::spatial_ref`], and only applies to
+    /// 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> {
+        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()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::test_utils::fixture;
+    use crate::Dataset;
+
+    #[test]
+    fn test_gcp_spatial_ref() {
+        let dataset = Dataset::open(fixture("gcp.tif")).unwrap();
+        let gcp_srs = dataset.gcp_spatial_ref();
+        let auth = gcp_srs.and_then(|s| s.authority().ok());
+        assert_eq!(auth.unwrap(), "EPSG:4326");
+    }
+}

src/raster/mod.rs

@@ -74,6 +74,7 @@
 //!     ...
 //! ```
 
+mod gcp;
 #[cfg(all(major_ge_3, minor_ge_1))]
 mod mdarray;
 mod rasterband;