Fix axis ordering in read_region/write_region

fitsio/src/fitsfile.rs

@@ -1401,8 +1401,8 @@ mod test {
                 .unwrap();
 
             assert_eq!(read_data.len(), (6 - 2) * (17 - 11) * (7 - 3));
-            assert_eq!(read_data[0], 614);
-            assert_eq!(read_data[50], 958);
+            assert_eq!(read_data[0], 689);
+            assert_eq!(read_data[50], 1223);
         });
     }
 

fitsio/src/images.rs

@@ -166,7 +166,9 @@ macro_rules! read_image_impl_vec {
                         let mut lpixel = Vec::with_capacity(n_ranges);
 
                         let mut nelements = 1;
-                        for range in ranges {
+                        // Reverse the ranges to match CFITSIO's Fortran column-major
+                        // convention, since the user provides ranges in C row-major order
+                        for range in ranges.iter().rev() {
                             let start = range.start + 1;
                             // No +1 as the range is exclusive
                             let end = range.end;
@@ -254,7 +256,9 @@ macro_rules! write_image_impl {
                         let mut fpixel = Vec::with_capacity(n_ranges);
                         let mut lpixel = Vec::with_capacity(n_ranges);
 
-                        for range in ranges {
+                        // Reverse the ranges to match CFITSIO's Fortran column-major
+                        // convention, since the user provides ranges in C row-major order
+                        for range in ranges.iter().rev() {
                             let start = range.start + 1;
                             // No +1 as the range is exclusive
                             let end = range.end;
@@ -441,8 +445,8 @@ mod tests {
 
         let chunk: Vec<i32> = hdu.read_region(&mut f, &[&ycoord, &xcoord]).unwrap();
         assert_eq!(chunk.len(), (7 - 5) * (3 - 2));
-        assert_eq!(chunk[0], 168);
-        assert_eq!(chunk[chunk.len() - 1], 112);
+        assert_eq!(chunk[0], 101);
+        assert_eq!(chunk[chunk.len() - 1], 171);
     }
 
     #[test]
@@ -494,7 +498,7 @@ mod tests {
             let chunk: Vec<i64> = hdu.read_region(&mut f, &[&(0..10), &(0..5)]).unwrap();
             assert_eq!(chunk.len(), 10 * 5);
             assert_eq!(chunk[0], 50);
-            assert_eq!(chunk[25], 80);
+            assert_eq!(chunk[25], 75);
         });
     }
 

fitsio/tests/test_square_array.rs

@@ -10,14 +10,15 @@ fn test_square_array() {
      *  15, 16, 17, 18, 19,
      *  20, 21, 22, 23, 24]
      *
-     *  We check that the x-values (1..3) (exclusive of the top end), and y-values (2..4)
+     *  We check that rows (1..3) (exclusive of the top end), and columns (2..4)
      *  (exclusive of the top end) return what we expect.
+     *  Ranges follow C row-major convention: [rows, columns].
      */
     let filename = "../testdata/square_array.fits";
     let mut f = FitsFile::open(filename).unwrap();
     let phdu = f.primary_hdu().unwrap();
 
     let ranges = vec![&(1..3), &(2..4)];
     let data: Vec<u32> = phdu.read_region(&mut f, &ranges).unwrap();
-    assert_eq!(data, vec![11, 12, 16, 17]);
+    assert_eq!(data, vec![7, 8, 12, 13]);
 }