Add changelog and some polish on documentation

canvas/Cargo.toml

@@ -12,7 +12,7 @@ repository = "https://github.com/image-rs/canvas"
 categories = ["multimedia::images"]
 
 [dependencies]
-image-texel = { path = "../texel", version = "0.3.0" }
+image-texel = { path = "../texel", version = "0.4.0" }
 bytemuck = "1.1"
 
 [dev-dependencies]

texel/Cargo.toml

@@ -1,8 +1,8 @@
 [package]
 name = "image-texel"
-version = "0.3.1"
+version = "0.4.0"
 edition = "2021"
-rust-version = "1.77"
+rust-version = "1.84"
 
 description = "A texel type and allocated buffers suitable for image data."
 authors = ["Aurelia Molzer <[email protected]>"]

texel/Changes.md

@@ -1,3 +1,14 @@
+# v0.4.0
+
+- Add `AtomicImage`, `CellImage` and several supporting types and interfaces.
+  These replicate large parts of the `Image` and `ImageMut` types but allow for
+  operations on a shared buffer, wrapping `Arc` and `Rc` respectively.
+- Added `PlaneOf` trait, a relationship between a layout, and index, and a
+  subcomponent of the layout. All image reference types implement a form of
+  `into_planes` that splits them apart by those components.
+- Added a `Relocate` trait for layouts that can be move to another location
+  in a buffer.
+
 ## v0.3.1
 
 - Fix compilation on non-explicit targets, where the maximum alignment will

texel/src/buf.rs

@@ -332,6 +332,11 @@ impl AtomicBuffer {
         }
     }
 
+    /// Query if two buffers share the same memory region.
+    pub fn ptr_eq(&self, other: &Self) -> bool {
+        Arc::ptr_eq(&self.inner, &other.inner)
+    }
+
     /// Retrieve the byte capacity of the allocated storage.
     pub fn capacity(&self) -> usize {
         core::mem::size_of_val(&*self.inner)
@@ -1014,6 +1019,14 @@ impl cmp::PartialEq<[u8]> for cell_buf {
 
 impl cmp::Eq for cell_buf {}
 
+impl cmp::PartialEq for CellBuffer {
+    fn eq(&self, other: &Self) -> bool {
+        **self == **other
+    }
+}
+
+impl cmp::Eq for CellBuffer {}
+
 impl TexelMappingBuffer for &'_ cell_buf {
     /// Internally mapping function when the mapping can be done forwards.
     fn map_forward<P, Q>(
@@ -1197,6 +1210,14 @@ impl cmp::PartialEq<[u8]> for atomic_buf {
 
 impl cmp::Eq for atomic_buf {}
 
+impl cmp::PartialEq for AtomicBuffer {
+    fn eq(&self, other: &Self) -> bool {
+        **self == **other
+    }
+}
+
+impl cmp::Eq for AtomicBuffer {}
+
 impl TexelMappingBuffer for &'_ atomic_buf {
     /// Internally mapping function when the mapping can be done forwards.
     fn map_forward<P, Q>(

texel/src/image/atomic.rs

@@ -9,7 +9,20 @@ use crate::{Texel, TexelBuffer};
 
 /// A container of allocated bytes, parameterized over the layout.
 ///
+/// This is a synchronized, shared equivalent to [`Image`][`crate::image::Image`]. That is the
+/// buffer of bytes of this container is shared between clones of this value and potentially
+/// between threads. In particular the same buffer may be owned and viewed with different layouts
+/// and modified concurrently. The guarantee, however, is merely that concurrent modification is
+/// free of undefined data races. There is no locking, implied synchronization, or ordering
+/// guarantees between edits except when you can modify disjoint parts of the buffer.
+///
 /// ## Differences to owned Image
+///
+/// Comparing values of this type is possible, but requires calling the method [`Self::compare`] to
+/// create a comparator. This is because comparing is inherently racing against modifications made
+/// on other threads. While the implementation prevents any unsound *data races* there is no
+/// specific meaning to any of its outcomes unless the caller ensure synchronization in some other
+/// manner.
 #[derive(Clone)]
 pub struct AtomicImage<Layout = Bytes> {
     inner: RawImage<AtomicBuffer, Layout>,
@@ -18,7 +31,8 @@ pub struct AtomicImage<Layout = Bytes> {
 /// A partial view of an atomic image.
 ///
 /// Note that this requires its underlying buffer to be highly aligned! For that reason it is not
-/// possible to take a reference at an arbitrary number of bytes.
+/// possible to take a reference at an arbitrary number of bytes. Values of this type are created
+/// by calling [`AtomicImage::as_ref`] or [`AtomicImage::checked_to_ref`].
 #[derive(Clone, PartialEq, Eq)]
 pub struct AtomicImageRef<'buf, Layout = &'buf Bytes> {
     inner: RawImage<&'buf atomic_buf, Layout>,
@@ -156,6 +170,26 @@ impl<L> AtomicImage<L> {
         self.inner.fits(layout)
     }
 
+    /// Check if two images refer to the same buffer.
+    pub fn ptr_eq(&self, other: &Self) -> bool {
+        AtomicBuffer::ptr_eq(self.inner.get(), other.inner.get())
+    }
+
+    /// Create a comparator to another image.
+    ///
+    /// Note that comparing is inherently racing against modifications made on other threads. While
+    /// the implementation prevents any unsound *data races* there is no specific meaning to any of
+    /// its outcomes unless the caller ensure synchronization in some other manner.
+    ///
+    /// You can also compare the allocation with [`Self::ptr_eq`] or ignore the layout and compare
+    /// buffer contents with [`Self::as_capacity_atomic_buf`].
+    pub fn compare(&self) -> impl core::cmp::Eq + core::cmp::PartialEq + '_
+    where
+        L: core::cmp::Eq,
+    {
+        (self.inner.layout(), self.inner.get())
+    }
+
     /// Get a reference to the aligned unstructured bytes of the image.
     ///
     /// Note that this may return more bytes than required for the specific layout for various

texel/src/image/cell.rs

@@ -10,19 +10,19 @@ use core::cell::Cell;
 
 /// A container of allocated bytes, parameterized over the layout.
 ///
-/// ## Differences to owned Image
-///
-/// The implementations for [`PartialEq`] and [`Eq`] are not provided. In many containers and
-/// contexts these two traits are required to rule out absence of interior mutability.
-#[derive(Clone)]
+/// This is a unsynchronized, shared equivalent to [`Image`][`crate::image::Image`]. That is the
+/// buffer of bytes of this container is shared between clones of this value but can not be sent
+/// between threads. In particular the same buffer may be owned and viewed with different layouts.
+#[derive(Clone, PartialEq, Eq)]
 pub struct CellImage<Layout = Bytes> {
     inner: RawImage<CellBuffer, Layout>,
 }
 
 /// A partial view of an atomic image.
 ///
 /// Note that this requires its underlying buffer to be highly aligned! For that reason it is not
-/// possible to take a reference at an arbitrary number of bytes.
+/// possible to take a reference at an arbitrary number of bytes. Values of this type are created
+/// by calling [`CellImage::as_ref`] or [`CellImage::checked_to_ref`].
 #[derive(Clone, PartialEq, Eq)]
 pub struct CellImageRef<'buf, Layout = &'buf Bytes> {
     inner: RawImage<&'buf cell_buf, Layout>,
@@ -160,6 +160,11 @@ impl<L> CellImage<L> {
         self.inner.fits(layout)
     }
 
+    /// Check if two images refer to the same buffer.
+    pub fn ptr_eq(&self, other: &Self) -> bool {
+        CellBuffer::ptr_eq(self.inner.get(), other.inner.get())
+    }
+
     /// Get a reference to the aligned unstructured bytes of the image.
     ///
     /// Note that this may return more bytes than required for the specific layout for various

texel/src/image/raw.rs

@@ -320,6 +320,11 @@ impl<B, L> RawImage<B, L> {
         texel.cast_buf(self.as_buf())
     }
 
+    /// Get mutable reference to the buffer.
+    pub(crate) fn get(&self) -> &B {
+        &self.buffer
+    }
+
     /// Get a mutable reference to the buffer. It is inadvisible to modify the buffer in a way that
     /// it can no longer hold the layout.
     pub(crate) fn get_mut(&mut self) -> &mut B {