Merge pull request #2765 from okaneco/convert_to_as_chunks

Refactor: Convert `chunks_exact[_mut]` iterators to `as_chunks[_mut]` iterators

Author: 197g

src/codecs/avif/decoder.rs

@@ -170,8 +170,8 @@ fn reshape_plane(source: &[u8], stride: usize, width: usize, height: usize) -> V
         .chunks_exact_mut(width)
         .zip(source.chunks_exact(stride))
     {
-        for (dst, src) in shaped_row.iter_mut().zip(src_row.chunks_exact(2)) {
-            *dst = u16::from_ne_bytes([src[0], src[1]]);
+        for (dst, src) in shaped_row.iter_mut().zip(src_row.as_chunks::<2>().0) {
+            *dst = u16::from_ne_bytes(*src);
         }
     }
     target_plane
@@ -500,7 +500,7 @@ impl<R: Read> ImageDecoder for AvifDecoder<R> {
                     buf.chunks_exact_mut(width as usize * 4),
                     plane.as_ref().chunks_exact(stride),
                 ) {
-                    for (rgba, a_src) in buf.chunks_exact_mut(4).zip(slice) {
+                    for (rgba, a_src) in buf.as_chunks_mut::<4>().0.iter_mut().zip(slice) {
                         rgba[3] = *a_src;
                     }
                 }
@@ -514,10 +514,9 @@ impl<R: Read> ImageDecoder for AvifDecoder<R> {
                 // If buffer from Decoder is unaligned
                 let mut aligned_store = vec![0u16; buf.len() / 2];
                 self.process_16bit_picture(&mut aligned_store, yuv_range, matrix_strategy)?;
-                for (dst, src) in buf.chunks_exact_mut(2).zip(aligned_store.iter()) {
-                    let bytes = src.to_ne_bytes();
-                    dst[0] = bytes[0];
-                    dst[1] = bytes[1];
+                let buf_chunks = buf.as_chunks_mut::<2>().0.iter_mut();
+                for (dst, src) in buf_chunks.zip(aligned_store.iter()) {
+                    *dst = src.to_ne_bytes();
                 }
             }
         }
@@ -686,7 +685,7 @@ impl<R: Read> AvifDecoder<R> {
                 target.chunks_exact_mut(width as usize * 4),
                 a_plane_view.data.as_ref().chunks_exact(a_plane_view.stride),
             ) {
-                for (rgba, a_src) in buf.chunks_exact_mut(4).zip(slice) {
+                for (rgba, a_src) in buf.as_chunks_mut::<4>().0.iter_mut().zip(slice) {
                     rgba[3] = *a_src;
                 }
             }

src/codecs/avif/ycgco.rs

@@ -119,12 +119,14 @@ fn process_halved_chroma_row_cgco<
 
     let bias_y = range.bias_y as i32;
     let bias_uv = range.bias_uv as i32;
-    let y_iter = y_plane.chunks_exact(2);
-    let rgb_chunks = rgba.chunks_exact_mut(CHANNELS * 2);
+    let (y_iter, y_left) = y_plane.as_chunks::<2>();
+    let mut rgb_chunks = rgba.chunks_exact_mut(CHANNELS * 2);
 
     let scale_coef = ((max_value as f32 / range.range_y as f32) * (1 << PRECISION) as f32) as i32;
 
-    for (((y_src, &u_src), &v_src), rgb_dst) in y_iter.zip(u_plane).zip(v_plane).zip(rgb_chunks) {
+    for (((y_src, &u_src), &v_src), rgb_dst) in
+        y_iter.iter().zip(u_plane).zip(v_plane).zip(&mut rgb_chunks)
+    {
         let y_value0: i32 = y_src[0].as_() - bias_y;
         let cg_value: i32 = u_src.as_() - bias_uv;
         let co_value: i32 = v_src.as_() - bias_uv;
@@ -154,11 +156,11 @@ fn process_halved_chroma_row_cgco<
 
     // Process remainder if width is odd.
     if image.width & 1 != 0 {
-        let y_left = y_plane.chunks_exact(2).remainder();
-        let rgb_chunks = rgba
-            .chunks_exact_mut(CHANNELS * 2)
+        let rgb_chunks = rgb_chunks
             .into_remainder()
-            .chunks_exact_mut(CHANNELS);
+            .as_chunks_mut::<CHANNELS>()
+            .0
+            .iter_mut();
         let u_iter = u_plane.iter().rev();
         let v_iter = v_plane.iter().rev();
 
@@ -170,11 +172,7 @@ fn process_halved_chroma_row_cgco<
             let co_value = v_src.as_() - bias_uv;
 
             ycgco_execute_limited::<V, PRECISION, CHANNELS, BIT_DEPTH>(
-                rgb_dst.try_into().unwrap(),
-                y_value,
-                cg_value,
-                co_value,
-                scale_coef,
+                rgb_dst, y_value, cg_value, co_value, scale_coef,
             );
         }
     }
@@ -249,7 +247,7 @@ where
 
     // All branches on generic const will be optimized out.
     for (((y_src, u_src), v_src), rgb) in y_iter.zip(u_iter).zip(v_iter).zip(rgb_iter) {
-        let rgb_chunks = rgb.chunks_exact_mut(CHANNELS);
+        let rgb_chunks = rgb.as_chunks_mut::<CHANNELS>().0.iter_mut();
         match yuv_range {
             YuvIntensityRange::Tv => {
                 let y_coef =
@@ -262,11 +260,7 @@ where
                     let co_value = v_src.as_() - bias_uv;
 
                     ycgco_execute_limited::<V, PRECISION, CHANNELS, BIT_DEPTH>(
-                        rgb_dst.try_into().unwrap(),
-                        y_value,
-                        cg_value,
-                        co_value,
-                        y_coef,
+                        rgb_dst, y_value, cg_value, co_value, y_coef,
                     );
                 }
             }
@@ -279,10 +273,7 @@ where
                     let co_value = v_src.as_() - bias_uv;
 
                     ycgco_execute_full::<V, PRECISION, CHANNELS, BIT_DEPTH>(
-                        rgb_dst.try_into().unwrap(),
-                        y_value,
-                        cg_value,
-                        co_value,
+                        rgb_dst, y_value, cg_value, co_value,
                     );
                 }
             }

src/codecs/avif/yuv.rs

@@ -367,7 +367,7 @@ where
 
         // All branches on generic const will be optimized out.
         for (y_src, rgb) in y_iter.zip(rgb_iter) {
-            let rgb_chunks = rgb.chunks_exact_mut(CHANNELS);
+            let rgb_chunks = rgb.as_chunks_mut::<CHANNELS>().0.iter_mut();
 
             for (y_src, rgb_dst) in y_src.iter().zip(rgb_chunks) {
                 let r = *y_src;
@@ -403,7 +403,7 @@ where
 
     // All branches on generic const will be optimized out.
     for (y_src, rgb) in y_iter.zip(rgb_iter) {
-        let rgb_chunks = rgb.chunks_exact_mut(CHANNELS);
+        let rgb_chunks = rgb.as_chunks_mut::<CHANNELS>().0.iter_mut();
 
         for (y_src, rgb_dst) in y_src.iter().zip(rgb_chunks) {
             let y_value = (y_src.as_() - bias_y) * y_coef;
@@ -567,9 +567,11 @@ fn process_halved_chroma_row_cbcr<
 
     let bias_y = range.bias_y as i32;
     let bias_uv = range.bias_uv as i32;
-    let y_iter = y_plane.chunks_exact(2);
-    let rgb_chunks = rgba.chunks_exact_mut(CHANNELS * 2);
-    for (((y_src, &u_src), &v_src), rgb_dst) in y_iter.zip(u_plane).zip(v_plane).zip(rgb_chunks) {
+    let (y_iter, y_left) = y_plane.as_chunks::<2>();
+    let mut rgb_chunks = rgba.chunks_exact_mut(CHANNELS * 2);
+    for (((y_src, &u_src), &v_src), rgb_dst) in
+        y_iter.iter().zip(u_plane).zip(v_plane).zip(&mut rgb_chunks)
+    {
         let y_value0: i32 = y_src[0].as_() - bias_y;
         let cb_value: i32 = u_src.as_() - bias_uv;
         let cr_value: i32 = v_src.as_() - bias_uv;
@@ -599,11 +601,11 @@ fn process_halved_chroma_row_cbcr<
 
     // Process remainder if width is odd.
     if image.width & 1 != 0 {
-        let y_left = y_plane.chunks_exact(2).remainder();
-        let rgb_chunks = rgba
-            .chunks_exact_mut(CHANNELS * 2)
+        let rgb_chunks = rgb_chunks
             .into_remainder()
-            .chunks_exact_mut(CHANNELS);
+            .as_chunks_mut::<CHANNELS>()
+            .0
+            .iter_mut();
         let u_iter = u_plane.iter().rev();
         let v_iter = v_plane.iter().rev();
 
@@ -615,11 +617,7 @@ fn process_halved_chroma_row_cbcr<
             let cr_value = v_src.as_() - bias_uv;
 
             ycbcr_execute::<V, PRECISION, CHANNELS, BIT_DEPTH>(
-                rgb_dst.try_into().unwrap(),
-                y_value,
-                cb_value,
-                cr_value,
-                transform,
+                rgb_dst, y_value, cb_value, cr_value, transform,
             );
         }
     }
@@ -1098,7 +1096,7 @@ where
 
     // All branches on generic const will be optimized out.
     for (((y_src, u_src), v_src), rgb) in y_iter.zip(u_iter).zip(v_iter).zip(rgb_iter) {
-        let rgb_chunks = rgb.chunks_exact_mut(CHANNELS);
+        let rgb_chunks = rgb.as_chunks_mut::<CHANNELS>().0.iter_mut();
 
         for (((y_src, u_src), v_src), rgb_dst) in y_src.iter().zip(u_src).zip(v_src).zip(rgb_chunks)
         {
@@ -1107,7 +1105,7 @@ where
             let cr_value = v_src.as_() - bias_uv;
 
             ycbcr_execute::<V, PRECISION, CHANNELS, BIT_DEPTH>(
-                rgb_dst.try_into().unwrap(),
+                rgb_dst,
                 y_value,
                 cb_value,
                 cr_value,
@@ -1240,7 +1238,7 @@ where
             let y_bias = range.bias_y as i32;
 
             for (((y_src, u_src), v_src), rgb) in y_iter.zip(u_iter).zip(v_iter).zip(rgb_iter) {
-                let rgb_chunks = rgb.chunks_exact_mut(CHANNELS);
+                let rgb_chunks = rgb.as_chunks_mut::<CHANNELS>().0.iter_mut();
 
                 for (((&y_src, &u_src), &v_src), rgb_dst) in
                     y_src.iter().zip(u_src).zip(v_src).zip(rgb_chunks)
@@ -1259,7 +1257,7 @@ where
         }
         YuvIntensityRange::Pc => {
             for (((y_src, u_src), v_src), rgb) in y_iter.zip(u_iter).zip(v_iter).zip(rgb_iter) {
-                let rgb_chunks = rgb.chunks_exact_mut(CHANNELS);
+                let rgb_chunks = rgb.as_chunks_mut::<CHANNELS>().0.iter_mut();
 
                 for (((&y_src, &u_src), &v_src), rgb_dst) in
                     y_src.iter().zip(u_src).zip(v_src).zip(rgb_chunks)

src/codecs/bmp/decoder.rs

@@ -1567,7 +1567,10 @@ impl<R: BufRead + Seek> BmpDecoder<R> {
 
         // Set alpha to opaque for all pixels if needed (only on first call)
         if start_row == 0 && num_channels == 4 {
-            buf.chunks_exact_mut(4).for_each(|c| c[3] = ALPHA_OPAQUE);
+            buf.as_chunks_mut::<4>()
+                .0
+                .iter_mut()
+                .for_each(|c| c[3] = ALPHA_OPAQUE);
         }
 
         let reader = &mut self.reader;
@@ -1643,11 +1646,10 @@ impl<R: BufRead + Seek> BmpDecoder<R> {
             start_row,
             |row| {
                 reader.read_exact(&mut row_buffer)?;
-                for (row_data, pixel) in row_buffer
-                    .chunks_exact(2)
-                    .zip(row.chunks_exact_mut(num_channels))
+                let row_buffer_chunks = row_buffer.as_chunks::<2>().0.iter();
+                for (&row_data, pixel) in row_buffer_chunks.zip(row.chunks_exact_mut(num_channels))
                 {
-                    let data = u32::from(u16::from_le_bytes(row_data.try_into().unwrap()));
+                    let data = u32::from(u16::from_le_bytes(row_data));
                     pixel[0] = bitfields.r.read(data);
                     pixel[1] = bitfields.g.read(data);
                     pixel[2] = bitfields.b.read(data);
@@ -1694,11 +1696,10 @@ impl<R: BufRead + Seek> BmpDecoder<R> {
             start_row,
             |row| {
                 reader.read_exact(&mut row_buffer)?;
-                for (row_data, pixel) in row_buffer
-                    .chunks_exact(4)
-                    .zip(row.chunks_exact_mut(num_channels))
+                let row_buffer_chunks = row_buffer.as_chunks::<4>().0.iter();
+                for (&row_data, pixel) in row_buffer_chunks.zip(row.chunks_exact_mut(num_channels))
                 {
-                    let data = u32::from_le_bytes(row_data.try_into().unwrap());
+                    let data = u32::from_le_bytes(row_data);
                     pixel[0] = bitfields.r.read(data);
                     pixel[1] = bitfields.g.read(data);
                     pixel[2] = bitfields.b.read(data);

src/codecs/farbfeld.rs

@@ -99,7 +99,7 @@ impl<R: Read> Read for FarbfeldReader<R> {
             bytes_written += 1;
             self.current_offset += 1;
         } else {
-            for channel_out in buf.chunks_exact_mut(2) {
+            for channel_out in buf.as_chunks_mut::<2>().0 {
                 consume_channel(&mut self.inner, channel_out)?;
                 bytes_written += 2;
                 self.current_offset += 2;
@@ -165,10 +165,10 @@ impl<R: Read + Seek> Seek for FarbfeldReader<R> {
     }
 }
 
-fn consume_channel<R: Read>(from: &mut R, mut to: &mut [u8]) -> io::Result<()> {
+fn consume_channel<R: Read>(from: &mut R, to: &mut [u8; 2]) -> io::Result<()> {
     let mut ibuf = [0u8; 2];
     from.read_exact(&mut ibuf)?;
-    to.write_all(&u16::from_be_bytes(ibuf).to_ne_bytes())?;
+    to.copy_from_slice(&u16::from_be_bytes(ibuf).to_ne_bytes());
 
     Ok(())
 }
@@ -249,9 +249,9 @@ impl<W: Write> FarbfeldEncoder<W> {
         self.w.write_all(&width.to_be_bytes())?;
         self.w.write_all(&height.to_be_bytes())?;
 
-        for channel in data.chunks_exact(2) {
+        for &channel in data.as_chunks::<2>().0 {
             self.w
-                .write_all(&u16::from_ne_bytes(channel.try_into().unwrap()).to_be_bytes())?;
+                .write_all(&u16::from_ne_bytes(channel).to_be_bytes())?;
         }
 
         Ok(())

src/codecs/hdr/decoder.rs

@@ -295,7 +295,8 @@ impl<R: Read> ImageDecoder for HdrDecoder<R> {
             // read_scanline overwrites the entire buffer or returns an Err,
             // so not resetting the buffer here is ok.
             read_scanline(&mut self.r, &mut scanline[..])?;
-            for (dst, &pix) in chunk.chunks_exact_mut(PIXEL_SIZE).zip(scanline.iter()) {
+            let dst_chunks = chunk.as_chunks_mut::<PIXEL_SIZE>().0.iter_mut();
+            for (dst, &pix) in dst_chunks.zip(scanline.iter()) {
                 dst.copy_from_slice(bytemuck::cast_slice(&pix.to_hdr().0));
             }
         }

src/codecs/png.rs

@@ -270,8 +270,6 @@ impl<R: BufRead + Seek> ImageDecoder for PngDecoder<R> {
     }
 
     fn read_image(mut self, buf: &mut [u8]) -> ImageResult<()> {
-        use byteorder_lite::{BigEndian, ByteOrder, NativeEndian};
-
         assert_eq!(u64::try_from(buf.len()), Ok(self.total_bytes()));
         self.reader.next_frame(buf).map_err(ImageError::from_png)?;
         // PNG images are big endian. For 16 bit per channel and larger types,
@@ -282,9 +280,8 @@ impl<R: BufRead + Seek> ImageDecoder for PngDecoder<R> {
 
         match bpc {
             1 => (), // No reodering necessary for u8
-            2 => buf.chunks_exact_mut(2).for_each(|c| {
-                let v = BigEndian::read_u16(c);
-                NativeEndian::write_u16(c, v);
+            2 => buf.as_chunks_mut::<2>().0.iter_mut().for_each(|c| {
+                *c = u16::from_be_bytes(*c).to_ne_bytes();
             }),
             _ => unreachable!(),
         }
@@ -800,7 +797,7 @@ impl<W: Write> ImageEncoder for PngEncoder<W> {
                 let mut reordered;
                 let buf = if cfg!(target_endian = "little") {
                     reordered = vec_try_with_capacity(buf.len())?;
-                    reordered.extend(buf.chunks_exact(2).flat_map(|le| [le[1], le[0]]));
+                    reordered.extend(buf.as_chunks::<2>().0.iter().flat_map(|le| [le[1], le[0]]));
                     &reordered
                 } else {
                     buf

src/codecs/pnm/decoder.rs

@@ -14,8 +14,6 @@ use crate::error::{
 use crate::io::ReadExt;
 use crate::{utils, ImageDecoder, ImageFormat};
 
-use byteorder_lite::{BigEndian, ByteOrder, NativeEndian};
-
 /// All errors that can occur when attempting to parse a PNM
 #[derive(Debug, Clone)]
 enum DecoderError {
@@ -689,9 +687,9 @@ impl<R: Read> PnmDecoder<R> {
                     *v = (f32::from(*v) * factor).round() as u8;
                 }
             } else if S::sample_size() == 2 {
-                for chunk in buf.chunks_exact_mut(2) {
-                    let v = NativeEndian::read_u16(chunk);
-                    NativeEndian::write_u16(chunk, (f32::from(v) * factor).round() as u16);
+                for chunk in buf.as_chunks_mut::<2>().0.iter_mut() {
+                    let v = (f32::from(u16::from_ne_bytes(*chunk)) * factor).round() as u16;
+                    chunk.copy_from_slice(&v.to_ne_bytes());
                 }
             }
         }
@@ -762,17 +760,17 @@ impl Sample for U16 {
 
     fn from_bytes(bytes: &[u8], _row_size: usize, output_buf: &mut [u8]) -> ImageResult<()> {
         output_buf.copy_from_slice(bytes);
-        for chunk in output_buf.chunks_exact_mut(2) {
-            let v = BigEndian::read_u16(chunk);
-            NativeEndian::write_u16(chunk, v);
+        for chunk in output_buf.as_chunks_mut::<2>().0.iter_mut() {
+            let v = u16::from_be_bytes(*chunk);
+            chunk.copy_from_slice(&v.to_ne_bytes());
         }
         Ok(())
     }
 
     fn from_ascii(reader: &mut dyn Read, output_buf: &mut [u8]) -> ImageResult<()> {
-        for chunk in output_buf.chunks_exact_mut(2) {
+        for chunk in output_buf.as_chunks_mut::<2>().0.iter_mut() {
             let v = read_separated_ascii::<u16>(reader)?;
-            NativeEndian::write_u16(chunk, v);
+            chunk.copy_from_slice(&v.to_ne_bytes());
         }
         Ok(())
     }