fn Rav1dPictureDataComponent::with_offset: Replace manual, separate…

… `Rav1dPictureDataComponent`, `usize` offset pairs with `Rav1dPictureDataComponentOffset` (#1205)

include/dav1d/picture.rs

@@ -236,6 +236,13 @@ impl Rav1dPictureDataComponent {
         BD::pxstride(self.len() - (-stride) as usize)
     }
 
+    pub fn with_offset<BD: BitDepth>(&self) -> Rav1dPictureDataComponentOffset {
+        Rav1dPictureDataComponentOffset {
+            data: self,
+            offset: self.pixel_offset::<BD>(),
+        }
+    }
+
     /// Strided ptr to [`u8`] bytes.
     fn as_strided_byte_mut_ptr(&self) -> *mut u8 {
         let ptr = self.0.as_mut_ptr();
@@ -636,10 +643,7 @@ impl Rav1dPicture {
         array::from_fn(|i| {
             let data = &data[has_chroma as usize * i];
             let ss_ver = layout == Rav1dPixelLayout::I420 && i != 0;
-            let offset = data
-                .pixel_offset::<BD>()
-                .wrapping_add_signed(y as isize * data.pixel_stride::<BD>() >> ss_ver as u8);
-            Rav1dPictureDataComponentOffset { data, offset }
+            data.with_offset::<BD>() + (y as isize * data.pixel_stride::<BD>() >> ss_ver as u8)
         })
     }
 }

src/fg_apply.rs

@@ -168,14 +168,12 @@ pub(crate) fn rav1d_apply_grain_row<BD: BitDepth>(
 
     // extend padding pixels
     if out.p.w as usize & ss_x != 0 {
-        let luma = &in_data[0];
-        let mut offset = luma
-            .pixel_offset::<BD>()
-            .wrapping_add_signed((row * BLOCK_SIZE) as isize * luma.pixel_stride::<BD>());
-        for _ in 0..bh {
-            let padding = &mut *luma.slice_mut::<BD, _>((offset + out.p.w as usize - 1.., ..2));
+        let luma = in_data[0].with_offset::<BD>();
+        let luma = luma + (row * BLOCK_SIZE) as isize * luma.pixel_stride::<BD>();
+        for y in 0..bh {
+            let luma = luma + (y as isize * (luma.pixel_stride::<BD>() << ss_y));
+            let padding = &mut *(luma + (out.p.w as usize - 1)).slice_mut::<BD>(2);
             padding[1] = padding[0];
-            offset = offset.wrapping_add_signed(luma.pixel_stride::<BD>() << ss_y);
         }
     }