Merge pull request #164 from lnicola/dataset-build-overviews

Add Dataset::build_overviews

CHANGES.md

@@ -9,7 +9,7 @@
 
         let dataset = Dataset::open_ex(
             "roads.geojson",
-            DatasetOptions { 
+            DatasetOptions {
                 open_flags: GdalOpenFlags::GDAL_OF_UPDATE|GdalOpenFlags::GDAL_OF_VECTOR,
                 ..DatasetOptions::default()
             }
@@ -31,7 +31,7 @@
     ```
 
 * Add more functions to SpatialRef implementation
-    * <https://github.com/georust/gdal/pull/145>   
+    * <https://github.com/georust/gdal/pull/145>
 * **Breaking**: Change `Feature::field` return type from
   `Result<FieldValue>` to `Result<Option<FieldValue>>`. Fields
   can be null. Before this change, if a field was null, the value
@@ -64,6 +64,8 @@
   ```
     * <https://github.com/georust/gdal/pull/134>
 * Add basic support to read overviews
+* Added a `Dataset::build_overviews` method
+    * <https://github.com/georust/gdal/pull/164>
 * BREAKING: update geo-types to 0.7.0. geo-types Coordinate<T> now implement `Debug`
   * <https://github.com/georust/gdal/pull/146>
 * Deprecated `SpatialRef::get_axis_mapping_strategy` - migrate to

build.rs

@@ -26,10 +26,10 @@ fn main() {
     let detected_version = Version::parse(semver_substring).expect("Could not parse gdal version!");
 
     if detected_version.major < 2 {
-        panic!(format!(
+        panic!(
             "The GDAL crate requires a GDAL version >= 2.0.0. Found {}",
             detected_version.to_string()
-        ));
+        );
     }
 
     println!("cargo:rustc-cfg=gdal_{}", detected_version.major);

examples/read_write_ogr_datetime.rs

@@ -1,7 +1,5 @@
-use gdal::errors::Result;
-
 #[cfg(feature = "datetime")]
-fn run() -> Result<()> {
+fn run() -> gdal::errors::Result<()> {
     use chrono::Duration;
     use gdal::vector::{Defn, Feature, FieldDefn, FieldValue};
     use gdal::{Dataset, Driver};
@@ -60,11 +58,13 @@ fn run() -> Result<()> {
 }
 
 #[cfg(not(feature = "datetime"))]
-fn run() -> Result<()> {
+fn run() {
     println!("gdal crate was build without datetime support");
-    Ok(())
 }
 
 fn main() {
+    #[cfg(feature = "datetime")]
     run().unwrap();
+    #[cfg(not(feature = "datetime"))]
+    run();
 }

src/dataset.rs

@@ -146,7 +146,9 @@ impl Dataset {
     }
 
     /// Open a dataset with extended options. See
-    /// [GDALOpenEx].
+    /// [`GDALOpenEx`].
+    ///
+    /// [`GDALOpenEx`]: https://gdal.org/doxygen/gdal_8h.html#a9cb8585d0b3c16726b08e25bcc94274a
     pub fn open_ex(path: &Path, options: DatasetOptions) -> Result<Dataset> {
         _register_drivers();
         let filename = path.to_string_lossy();
@@ -315,6 +317,39 @@ impl Dataset {
         }
     }
 
+    /// Builds overviews for the current `Dataset`. See [`GDALBuildOverviews`].
+    ///
+    /// # Arguments
+    /// * `resampling` - resampling method, as accepted by GDAL, e.g. `"CUBIC"`
+    /// * `overviews` - list of overview decimation factors, e.g. `&[2, 4, 8, 16, 32]`
+    /// * `bands` - list of bands to build the overviews for, or empty for all bands
+    ///
+    /// [`GDALBuildOverviews`]: https://gdal.org/doxygen/gdal_8h.html#a767f4456a6249594ee18ea53f68b7e80
+    pub fn build_overviews(
+        &mut self,
+        resampling: &str,
+        overviews: &[i32],
+        bands: &[i32],
+    ) -> Result<()> {
+        let c_resampling = CString::new(resampling)?;
+        let rv = unsafe {
+            gdal_sys::GDALBuildOverviews(
+                self.c_dataset,
+                c_resampling.as_ptr(),
+                overviews.len() as i32,
+                overviews.as_ptr() as *mut i32,
+                bands.len() as i32,
+                bands.as_ptr() as *mut i32,
+                None,
+                null_mut(),
+            )
+        };
+        if rv != CPLErr::CE_None {
+            return Err(_last_cpl_err(rv));
+        }
+        Ok(())
+    }
+
     fn child_layer(&self, c_layer: OGRLayerH) -> Layer {
         unsafe { Layer::from_c_layer(self, c_layer) }
     }