Add method to set default histogram for RasterBand

CHANGES.md

@@ -50,9 +50,11 @@
 
   - <https://github.com/georust/gdal/pull/439>
 
-- Added histogram calculation
+- Added raster histogram methods (setter and getter)
+
+  - Getter: <https://github.com/georust/gdal/pull/468>
+  - Setter: <https://github.com/georust/gdal/pull/486>
 
-  - <https://github.com/georust/gdal/pull/468>
 
 ## 0.16
 

src/raster/rasterband.rs

@@ -8,7 +8,7 @@ use gdal_sys::{
     GDALCreateColorRamp, GDALCreateColorTable, GDALDestroyColorTable, GDALGetDefaultHistogramEx,
     GDALGetPaletteInterpretation, GDALGetRasterHistogramEx, GDALGetRasterStatistics,
     GDALMajorObjectH, GDALPaletteInterp, GDALRIOResampleAlg, GDALRWFlag, GDALRasterBandH,
-    GDALRasterIOExtraArg, GDALSetColorEntry, GDALSetRasterColorTable,
+    GDALRasterIOExtraArg, GDALSetColorEntry, GDALSetDefaultHistogramEx, GDALSetRasterColorTable,
 };
 use libc::c_int;
 use std::ffi::CString;
@@ -884,6 +884,36 @@ impl<'a> RasterBand<'a> {
         }
     }
 
+    /// Set default raster histogram.
+    ///
+    /// # Arguments
+    ///
+    /// * `min` - Histogram lower bound
+    /// * `max` - Histogram upper bound
+    /// * `counts` - Histogram values for each bucket
+    ///
+    /// # Panics
+    /// Panics if the `counts.len()` is greater than `i32::MAX`.
+    pub fn set_default_histogram(&self, min: f64, max: f64, counts: &mut [u64]) -> Result<()> {
+        let n_buckets = counts.len();
+        assert!(n_buckets <= i32::MAX as usize);
+
+        let rv = unsafe {
+            GDALSetDefaultHistogramEx(
+                self.c_rasterband,
+                min,
+                max,
+                n_buckets as i32,
+                counts.as_mut_ptr(),
+            )
+        };
+
+        match CplErrType::from(rv) {
+            CplErrType::None => Ok(()),
+            _ => Err(_last_cpl_err(rv)),
+        }
+    }
+
     /// Compute raster histogram.
     ///
     /// # Arguments
@@ -907,6 +937,8 @@ impl<'a> RasterBand<'a> {
             ));
         }
 
+        assert!(n_buckets <= i32::MAX as usize);
+
         let mut counts = vec![0; n_buckets];
 
         let rv = unsafe {

src/raster/tests.rs

@@ -752,7 +752,7 @@ fn test_raster_stats() {
 }
 
 #[test]
-fn test_raster_histogram() {
+fn test_raster_get_histogram() {
     let fixture = TempFixture::fixture("tinymarble.tif");
 
     let dataset = Dataset::open(&fixture).unwrap();
@@ -788,6 +788,38 @@ fn test_raster_histogram() {
     hist.expect_err("histogram with 0 buckets should panic");
 }
 
+#[test]
+fn test_raster_set_histogram() {
+    let fixture = TempFixture::fixture("tinymarble.tif");
+
+    let dataset = Dataset::open(&fixture).unwrap();
+    let rb = dataset.rasterband(1).unwrap();
+
+    let hist = rb.default_histogram(false).unwrap();
+    assert!(hist.is_none());
+
+    let mut expected = [
+        548, 104, 133, 127, 141, 125, 156, 129, 130, 117, 94, 94, 80, 81, 78, 63, 50, 66, 48, 48,
+        33, 38, 41, 35, 41, 39, 32, 40, 26, 27, 25, 24, 18, 25, 29, 27, 20, 34, 17, 24, 29, 11, 20,
+        21, 12, 19, 16, 16, 11, 10, 19, 5, 11, 10, 6, 9, 7, 12, 13, 6, 8, 7, 8, 14, 9, 14, 4, 8, 5,
+        12, 6, 10, 7, 9, 8, 6, 3, 7, 5, 8, 9, 5, 4, 8, 3, 9, 3, 6, 11, 7, 6, 3, 9, 9, 7, 6, 9, 10,
+        10, 4, 7, 2, 4, 7, 2, 12, 7, 10, 4, 6, 5, 2, 4, 5, 7, 3, 5, 7, 7, 14, 9, 12, 6, 6, 8, 5, 8,
+        3, 3, 5, 11, 4, 9, 7, 14, 7, 10, 11, 6, 6, 5, 4, 9, 6, 6, 9, 5, 12, 11, 9, 3, 8, 5, 6, 4,
+        2, 9, 7, 9, 9, 9, 6, 6, 8, 5, 9, 13, 4, 9, 4, 7, 13, 10, 5, 7, 8, 11, 12, 5, 17, 9, 11, 9,
+        8, 9, 5, 8, 9, 5, 6, 9, 11, 8, 7, 7, 6, 7, 8, 8, 8, 5, 6, 7, 5, 8, 5, 6, 8, 7, 4, 8, 6, 5,
+        11, 8, 8, 5, 4, 6, 4, 9, 7, 6, 6, 7, 7, 12, 6, 9, 17, 12, 20, 18, 17, 21, 24, 30, 29, 57,
+        72, 83, 21, 11, 9, 18, 7, 13, 10, 2, 4, 0, 1, 3, 4, 1, 1,
+    ];
+
+    // This values come from test_raster_get_histogram
+    rb.set_default_histogram(-0.5, 255.5, &mut expected)
+        .unwrap();
+
+    let hist = rb.default_histogram(false).unwrap();
+    assert!(hist.is_some());
+    assert_eq!(hist.unwrap().counts(), expected);
+}
+
 #[test]
 fn test_resample_str() {
     assert!(ResampleAlg::from_str("foobar").is_err());