Moved to use ZeroPadder with conv

Now just need to make the padder injectable for convolutions

Author: xd009642

src/processing/conv.rs

@@ -1,4 +1,5 @@
 use crate::core::{ColourModel, Image};
+use crate::core::padding::*;
 use crate::processing::Error;
 use ndarray::prelude::*;
 use ndarray::{s, Zip};
@@ -40,24 +41,11 @@ where
             // Bit icky but handles fact that uncentred convolutions will cross the bounds
             // otherwise
             let (row_offset, col_offset) = kernel_centre(k_s[0], k_s[1]);
-            // row_offset * 2 may not equal k_s[0] due to truncation
-            let shape_ext = (
-                self.shape()[0] + row_offset * 2,
-                self.shape()[1] + col_offset * 2,
-                self.shape()[2],
-            );
             let shape = (self.shape()[0], self.shape()[1], self.shape()[2]);
 
             if shape.0 > 0 && shape.1 > 0 {
                 let mut result = Self::zeros(shape);
-
-                let mut tmp = Self::zeros(shape_ext);
-                tmp.slice_mut(s![
-                    row_offset..shape_ext.0 - row_offset,
-                    col_offset..shape_ext.1 - col_offset,
-                    ..
-                ])
-                .assign(&self);
+                let tmp = self.pad((row_offset, col_offset), &ZeroPadding {});
 
                 Zip::indexed(tmp.windows(kernel.dim())).apply(|(i, j, _), window| {
                     let mult = &window * &kernel;