Enforce (at compile-time) that imageops::filter3x3() is provided an array of length 9

src/imageops/sample.rs

@@ -868,7 +868,7 @@ where
 ///
 /// This method typically assumes that the input is scene-linear light.
 /// If it is not, color distortion may occur.
-pub fn filter3x3<I, P, S>(image: &I, kernel: &[f32]) -> ImageBuffer<P, Vec<S>>
+pub fn filter3x3<I, P, S>(image: &I, kernel: &[f32; 9]) -> ImageBuffer<P, Vec<S>>
 where
     I: GenericImageView<Pixel = P>,
     P: Pixel<Subpixel = S> + 'static,

src/images/dynimage.rs

@@ -1039,15 +1039,13 @@ impl DynamicImage {
     ///
     /// # Arguments
     ///
-    /// * `kernel` - slice contains filter. Only slice len is 9 length is accepted.
+    /// * `kernel` - array contains filter.
     ///
     /// This method typically assumes that the input is scene-linear light. It operates on pixel
     /// channel values directly without taking into account color space data. If it is not, color
     /// distortion may occur.
     #[must_use]
-    pub fn filter3x3(&self, kernel: &[f32]) -> DynamicImage {
-        assert_eq!(9, kernel.len(), "filter must be 3 x 3");
-
+    pub fn filter3x3(&self, kernel: &[f32; 9]) -> DynamicImage {
         dynamic_map!(*self, ref p => imageops::filter3x3(p, kernel))
     }