Switch from zerocopy to bytemuck

Bytemuck is more feature constrained and builds on Rust 1.34.2.

Cargo.toml

@@ -20,6 +20,7 @@ name = "image"
 path = "./src/lib.rs"
 
 [dependencies]
+bytemuck = "1"
 byteorder = "1.3.2"
 num-iter = "0.1.32"
 num-rational = { version = "0.2.1", default-features = false }
@@ -29,7 +30,6 @@ jpeg = { package = "jpeg-decoder", version = "0.1", default-features = false, op
 png = { version = "0.15.2", optional = true }
 scoped_threadpool = { version = "0.1", optional = true }
 tiff = { version = "0.4.0", optional = true }
-zerocopy = "0.2.8"
 
 [dev-dependencies]
 crc32fast = "1.2.0"

src/dynimage.rs

@@ -851,7 +851,7 @@ fn decoder_to_image<'a, I: ImageDecoder<'a>>(decoder: I) -> ImageResult<DynamicI
 
 #[allow(deprecated)]
 fn image_to_bytes(image: &DynamicImage) -> Vec<u8> {
-    use zerocopy::AsBytes;
+    use traits::EncodableLayout;
 
     match *image {
         // TODO: consider transmuting

src/image.rs

@@ -10,7 +10,6 @@ use std::ops::{Deref, DerefMut};
 
 use buffer::{ImageBuffer, Pixel};
 use color::{ColorType, ExtendedColorType};
-use zerocopy::{AsBytes, FromBytes};
 
 use animation::Frames;
 
@@ -373,10 +372,10 @@ pub(crate) fn load_rect<'a, D, F, F1, F2, E>(x: u32, y: u32, width: u32, height:
 /// Panics if there isn't enough memory to decode the image.
 pub(crate) fn decoder_to_vec<'a, T>(decoder: impl ImageDecoder<'a>) -> ImageResult<Vec<T>>
 where
-    T: ::traits::Primitive + AsBytes + FromBytes,
+    T: ::traits::Primitive + bytemuck::Pod,
 {
     let mut buf = vec![num_traits::Zero::zero(); usize::try_from(decoder.total_bytes()).unwrap() / std::mem::size_of::<T>()];
-    decoder.read_image(buf.as_bytes_mut())?;
+    decoder.read_image(bytemuck::cast_slice_mut(buf.as_mut_slice()))?;
     Ok(buf)
 }
 

src/lib.rs

@@ -11,6 +11,7 @@
 // it's a bit of a pain otherwise
 #![allow(clippy::many_single_char_names)]
 
+extern crate bytemuck;
 extern crate byteorder;
 extern crate num_iter;
 extern crate num_rational;
@@ -19,7 +20,6 @@ extern crate num_traits;
 extern crate scoped_threadpool;
 #[cfg(all(test, feature = "benchmarks"))]
 extern crate test;
-extern crate zerocopy;
 
 #[cfg(test)]
 #[macro_use]

src/tiff.rs

@@ -130,10 +130,10 @@ pub struct TiffEncoder<W> {
 }
 
 // Utility to simplify and deduplicate error handling during 16-bit encoding.
-fn u8_slice_as_u16(buf: &[u8]) -> ImageResult<zerocopy::LayoutVerified<&[u8], [u16]>> {
-    zerocopy::LayoutVerified::new_slice(buf)
+fn u8_slice_as_u16(buf: &[u8]) -> ImageResult<&[u16]> {
+    bytemuck::try_cast_slice(buf)
         // If the buffer is not aligned or the correct length for a u16 slice, err.
-        .ok_or_else(|| ImageError::IoError(std::io::ErrorKind::InvalidData.into()))
+        .map_err(|_| ImageError::IoError(std::io::ErrorKind::InvalidData.into()))
 }
 
 impl<W: Write + Seek> TiffEncoder<W> {

src/traits.rs

@@ -14,13 +14,13 @@ pub trait EncodableLayout: seals::EncodableLayout {
 
 impl EncodableLayout for [u8] {
     fn as_bytes(&self) -> &[u8] {
-        zerocopy::AsBytes::as_bytes(self)
+        bytemuck::cast_slice(self)
     }
 }
 
 impl EncodableLayout for [u16] {
     fn as_bytes(&self) -> &[u8] {
-        zerocopy::AsBytes::as_bytes(self)
+        bytemuck::cast_slice(self)
     }
 }