Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 1768 insertions, 0 deletions

diff --git a/vendor/image/src/buffer.rs b/vendor/image/src/buffer.rs
new file mode 100644
index 0000000..765a9de
--- /dev/null
+++ b/vendor/image/src/buffer.rs
@@ -0,0 +1,1768 @@
+//! Contains the generic `ImageBuffer` struct.
+use num_traits::Zero;
+use std::fmt;
+use std::marker::PhantomData;
+use std::ops::{Deref, DerefMut, Index, IndexMut, Range};
+use std::path::Path;
+use std::slice::{ChunksExact, ChunksExactMut};
+
+use crate::color::{FromColor, Luma, LumaA, Rgb, Rgba};
+use crate::dynimage::{save_buffer, save_buffer_with_format, write_buffer_with_format};
+use crate::error::ImageResult;
+use crate::flat::{FlatSamples, SampleLayout};
+use crate::image::{GenericImage, GenericImageView, ImageEncoder, ImageFormat, ImageOutputFormat};
+use crate::math::Rect;
+use crate::traits::{EncodableLayout, Pixel, PixelWithColorType};
+use crate::utils::expand_packed;
+
+/// Iterate over pixel refs.
+pub struct Pixels<'a, P: Pixel + 'a>
+where
+    P::Subpixel: 'a,
+{
+    chunks: ChunksExact<'a, P::Subpixel>,
+}
+
+impl<'a, P: Pixel + 'a> Iterator for Pixels<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    type Item = &'a P;
+
+    #[inline(always)]
+    fn next(&mut self) -> Option<&'a P> {
+        self.chunks.next().map(|v| <P as Pixel>::from_slice(v))
+    }
+
+    #[inline(always)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let len = self.len();
+        (len, Some(len))
+    }
+}
+
+impl<'a, P: Pixel + 'a> ExactSizeIterator for Pixels<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    fn len(&self) -> usize {
+        self.chunks.len()
+    }
+}
+
+impl<'a, P: Pixel + 'a> DoubleEndedIterator for Pixels<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    #[inline(always)]
+    fn next_back(&mut self) -> Option<&'a P> {
+        self.chunks.next_back().map(|v| <P as Pixel>::from_slice(v))
+    }
+}
+
+impl<P: Pixel> Clone for Pixels<'_, P> {
+    fn clone(&self) -> Self {
+        Pixels {
+            chunks: self.chunks.clone(),
+        }
+    }
+}
+
+impl<P: Pixel> fmt::Debug for Pixels<'_, P>
+where
+    P::Subpixel: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("Pixels")
+            .field("chunks", &self.chunks)
+            .finish()
+    }
+}
+
+/// Iterate over mutable pixel refs.
+pub struct PixelsMut<'a, P: Pixel + 'a>
+where
+    P::Subpixel: 'a,
+{
+    chunks: ChunksExactMut<'a, P::Subpixel>,
+}
+
+impl<'a, P: Pixel + 'a> Iterator for PixelsMut<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    type Item = &'a mut P;
+
+    #[inline(always)]
+    fn next(&mut self) -> Option<&'a mut P> {
+        self.chunks.next().map(|v| <P as Pixel>::from_slice_mut(v))
+    }
+
+    #[inline(always)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let len = self.len();
+        (len, Some(len))
+    }
+}
+
+impl<'a, P: Pixel + 'a> ExactSizeIterator for PixelsMut<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    fn len(&self) -> usize {
+        self.chunks.len()
+    }
+}
+
+impl<'a, P: Pixel + 'a> DoubleEndedIterator for PixelsMut<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    #[inline(always)]
+    fn next_back(&mut self) -> Option<&'a mut P> {
+        self.chunks
+            .next_back()
+            .map(|v| <P as Pixel>::from_slice_mut(v))
+    }
+}
+
+impl<P: Pixel> fmt::Debug for PixelsMut<'_, P>
+where
+    P::Subpixel: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("PixelsMut")
+            .field("chunks", &self.chunks)
+            .finish()
+    }
+}
+
+/// Iterate over rows of an image
+///
+/// This iterator is created with [`ImageBuffer::rows`]. See its document for details.
+///
+/// [`ImageBuffer::rows`]: ../struct.ImageBuffer.html#method.rows
+pub struct Rows<'a, P: Pixel + 'a>
+where
+    <P as Pixel>::Subpixel: 'a,
+{
+    pixels: ChunksExact<'a, P::Subpixel>,
+}
+
+impl<'a, P: Pixel + 'a> Rows<'a, P> {
+    /// Construct the iterator from image pixels. This is not public since it has a (hidden) panic
+    /// condition. The `pixels` slice must be large enough so that all pixels are addressable.
+    fn with_image(pixels: &'a [P::Subpixel], width: u32, height: u32) -> Self {
+        let row_len = (width as usize) * usize::from(<P as Pixel>::CHANNEL_COUNT);
+        if row_len == 0 {
+            Rows {
+                pixels: [].chunks_exact(1),
+            }
+        } else {
+            let pixels = pixels
+                .get(..row_len * height as usize)
+                .expect("Pixel buffer has too few subpixels");
+            // Rows are physically present. In particular, height is smaller than `usize::MAX` as
+            // all subpixels can be indexed.
+            Rows {
+                pixels: pixels.chunks_exact(row_len),
+            }
+        }
+    }
+}
+
+impl<'a, P: Pixel + 'a> Iterator for Rows<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    type Item = Pixels<'a, P>;
+
+    #[inline(always)]
+    fn next(&mut self) -> Option<Pixels<'a, P>> {
+        let row = self.pixels.next()?;
+        Some(Pixels {
+            // Note: this is not reached when CHANNEL_COUNT is 0.
+            chunks: row.chunks_exact(<P as Pixel>::CHANNEL_COUNT as usize),
+        })
+    }
+
+    #[inline(always)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let len = self.len();
+        (len, Some(len))
+    }
+}
+
+impl<'a, P: Pixel + 'a> ExactSizeIterator for Rows<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    fn len(&self) -> usize {
+        self.pixels.len()
+    }
+}
+
+impl<'a, P: Pixel + 'a> DoubleEndedIterator for Rows<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    #[inline(always)]
+    fn next_back(&mut self) -> Option<Pixels<'a, P>> {
+        let row = self.pixels.next_back()?;
+        Some(Pixels {
+            // Note: this is not reached when CHANNEL_COUNT is 0.
+            chunks: row.chunks_exact(<P as Pixel>::CHANNEL_COUNT as usize),
+        })
+    }
+}
+
+impl<P: Pixel> Clone for Rows<'_, P> {
+    fn clone(&self) -> Self {
+        Rows {
+            pixels: self.pixels.clone(),
+        }
+    }
+}
+
+impl<P: Pixel> fmt::Debug for Rows<'_, P>
+where
+    P::Subpixel: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("Rows")
+            .field("pixels", &self.pixels)
+            .finish()
+    }
+}
+
+/// Iterate over mutable rows of an image
+///
+/// This iterator is created with [`ImageBuffer::rows_mut`]. See its document for details.
+///
+/// [`ImageBuffer::rows_mut`]: ../struct.ImageBuffer.html#method.rows_mut
+pub struct RowsMut<'a, P: Pixel + 'a>
+where
+    <P as Pixel>::Subpixel: 'a,
+{
+    pixels: ChunksExactMut<'a, P::Subpixel>,
+}
+
+impl<'a, P: Pixel + 'a> RowsMut<'a, P> {
+    /// Construct the iterator from image pixels. This is not public since it has a (hidden) panic
+    /// condition. The `pixels` slice must be large enough so that all pixels are addressable.
+    fn with_image(pixels: &'a mut [P::Subpixel], width: u32, height: u32) -> Self {
+        let row_len = (width as usize) * usize::from(<P as Pixel>::CHANNEL_COUNT);
+        if row_len == 0 {
+            RowsMut {
+                pixels: [].chunks_exact_mut(1),
+            }
+        } else {
+            let pixels = pixels
+                .get_mut(..row_len * height as usize)
+                .expect("Pixel buffer has too few subpixels");
+            // Rows are physically present. In particular, height is smaller than `usize::MAX` as
+            // all subpixels can be indexed.
+            RowsMut {
+                pixels: pixels.chunks_exact_mut(row_len),
+            }
+        }
+    }
+}
+
+impl<'a, P: Pixel + 'a> Iterator for RowsMut<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    type Item = PixelsMut<'a, P>;
+
+    #[inline(always)]
+    fn next(&mut self) -> Option<PixelsMut<'a, P>> {
+        let row = self.pixels.next()?;
+        Some(PixelsMut {
+            // Note: this is not reached when CHANNEL_COUNT is 0.
+            chunks: row.chunks_exact_mut(<P as Pixel>::CHANNEL_COUNT as usize),
+        })
+    }
+
+    #[inline(always)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let len = self.len();
+        (len, Some(len))
+    }
+}
+
+impl<'a, P: Pixel + 'a> ExactSizeIterator for RowsMut<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    fn len(&self) -> usize {
+        self.pixels.len()
+    }
+}
+
+impl<'a, P: Pixel + 'a> DoubleEndedIterator for RowsMut<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    #[inline(always)]
+    fn next_back(&mut self) -> Option<PixelsMut<'a, P>> {
+        let row = self.pixels.next_back()?;
+        Some(PixelsMut {
+            // Note: this is not reached when CHANNEL_COUNT is 0.
+            chunks: row.chunks_exact_mut(<P as Pixel>::CHANNEL_COUNT as usize),
+        })
+    }
+}
+
+impl<P: Pixel> fmt::Debug for RowsMut<'_, P>
+where
+    P::Subpixel: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("RowsMut")
+            .field("pixels", &self.pixels)
+            .finish()
+    }
+}
+
+/// Enumerate the pixels of an image.
+pub struct EnumeratePixels<'a, P: Pixel + 'a>
+where
+    <P as Pixel>::Subpixel: 'a,
+{
+    pixels: Pixels<'a, P>,
+    x: u32,
+    y: u32,
+    width: u32,
+}
+
+impl<'a, P: Pixel + 'a> Iterator for EnumeratePixels<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    type Item = (u32, u32, &'a P);
+
+    #[inline(always)]
+    fn next(&mut self) -> Option<(u32, u32, &'a P)> {
+        if self.x >= self.width {
+            self.x = 0;
+            self.y += 1;
+        }
+        let (x, y) = (self.x, self.y);
+        self.x += 1;
+        self.pixels.next().map(|p| (x, y, p))
+    }
+
+    #[inline(always)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let len = self.len();
+        (len, Some(len))
+    }
+}
+
+impl<'a, P: Pixel + 'a> ExactSizeIterator for EnumeratePixels<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    fn len(&self) -> usize {
+        self.pixels.len()
+    }
+}
+
+impl<P: Pixel> Clone for EnumeratePixels<'_, P> {
+    fn clone(&self) -> Self {
+        EnumeratePixels {
+            pixels: self.pixels.clone(),
+            ..*self
+        }
+    }
+}
+
+impl<P: Pixel> fmt::Debug for EnumeratePixels<'_, P>
+where
+    P::Subpixel: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("EnumeratePixels")
+            .field("pixels", &self.pixels)
+            .field("x", &self.x)
+            .field("y", &self.y)
+            .field("width", &self.width)
+            .finish()
+    }
+}
+
+/// Enumerate the rows of an image.
+pub struct EnumerateRows<'a, P: Pixel + 'a>
+where
+    <P as Pixel>::Subpixel: 'a,
+{
+    rows: Rows<'a, P>,
+    y: u32,
+    width: u32,
+}
+
+impl<'a, P: Pixel + 'a> Iterator for EnumerateRows<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    type Item = (u32, EnumeratePixels<'a, P>);
+
+    #[inline(always)]
+    fn next(&mut self) -> Option<(u32, EnumeratePixels<'a, P>)> {
+        let y = self.y;
+        self.y += 1;
+        self.rows.next().map(|r| {
+            (
+                y,
+                EnumeratePixels {
+                    x: 0,
+                    y,
+                    width: self.width,
+                    pixels: r,
+                },
+            )
+        })
+    }
+
+    #[inline(always)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let len = self.len();
+        (len, Some(len))
+    }
+}
+
+impl<'a, P: Pixel + 'a> ExactSizeIterator for EnumerateRows<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    fn len(&self) -> usize {
+        self.rows.len()
+    }
+}
+
+impl<P: Pixel> Clone for EnumerateRows<'_, P> {
+    fn clone(&self) -> Self {
+        EnumerateRows {
+            rows: self.rows.clone(),
+            ..*self
+        }
+    }
+}
+
+impl<P: Pixel> fmt::Debug for EnumerateRows<'_, P>
+where
+    P::Subpixel: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("EnumerateRows")
+            .field("rows", &self.rows)
+            .field("y", &self.y)
+            .field("width", &self.width)
+            .finish()
+    }
+}
+
+/// Enumerate the pixels of an image.
+pub struct EnumeratePixelsMut<'a, P: Pixel + 'a>
+where
+    <P as Pixel>::Subpixel: 'a,
+{
+    pixels: PixelsMut<'a, P>,
+    x: u32,
+    y: u32,
+    width: u32,
+}
+
+impl<'a, P: Pixel + 'a> Iterator for EnumeratePixelsMut<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    type Item = (u32, u32, &'a mut P);
+
+    #[inline(always)]
+    fn next(&mut self) -> Option<(u32, u32, &'a mut P)> {
+        if self.x >= self.width {
+            self.x = 0;
+            self.y += 1;
+        }
+        let (x, y) = (self.x, self.y);
+        self.x += 1;
+        self.pixels.next().map(|p| (x, y, p))
+    }
+
+    #[inline(always)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let len = self.len();
+        (len, Some(len))
+    }
+}
+
+impl<'a, P: Pixel + 'a> ExactSizeIterator for EnumeratePixelsMut<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    fn len(&self) -> usize {
+        self.pixels.len()
+    }
+}
+
+impl<P: Pixel> fmt::Debug for EnumeratePixelsMut<'_, P>
+where
+    P::Subpixel: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("EnumeratePixelsMut")
+            .field("pixels", &self.pixels)
+            .field("x", &self.x)
+            .field("y", &self.y)
+            .field("width", &self.width)
+            .finish()
+    }
+}
+
+/// Enumerate the rows of an image.
+pub struct EnumerateRowsMut<'a, P: Pixel + 'a>
+where
+    <P as Pixel>::Subpixel: 'a,
+{
+    rows: RowsMut<'a, P>,
+    y: u32,
+    width: u32,
+}
+
+impl<'a, P: Pixel + 'a> Iterator for EnumerateRowsMut<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    type Item = (u32, EnumeratePixelsMut<'a, P>);
+
+    #[inline(always)]
+    fn next(&mut self) -> Option<(u32, EnumeratePixelsMut<'a, P>)> {
+        let y = self.y;
+        self.y += 1;
+        self.rows.next().map(|r| {
+            (
+                y,
+                EnumeratePixelsMut {
+                    x: 0,
+                    y,
+                    width: self.width,
+                    pixels: r,
+                },
+            )
+        })
+    }
+
+    #[inline(always)]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let len = self.len();
+        (len, Some(len))
+    }
+}
+
+impl<'a, P: Pixel + 'a> ExactSizeIterator for EnumerateRowsMut<'a, P>
+where
+    P::Subpixel: 'a,
+{
+    fn len(&self) -> usize {
+        self.rows.len()
+    }
+}
+
+impl<P: Pixel> fmt::Debug for EnumerateRowsMut<'_, P>
+where
+    P::Subpixel: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("EnumerateRowsMut")
+            .field("rows", &self.rows)
+            .field("y", &self.y)
+            .field("width", &self.width)
+            .finish()
+    }
+}
+
+/// Generic image buffer
+///
+/// This is an image parameterised by its Pixel types, represented by a width and height and a
+/// container of channel data. It provides direct access to its pixels and implements the
+/// [`GenericImageView`] and [`GenericImage`] traits. In many ways, this is the standard buffer
+/// implementing those traits. Using this concrete type instead of a generic type parameter has
+/// been shown to improve performance.
+///
+/// The crate defines a few type aliases with regularly used pixel types for your convenience, such
+/// as [`RgbImage`], [`GrayImage`] etc.
+///
+/// [`GenericImage`]: trait.GenericImage.html
+/// [`GenericImageView`]: trait.GenericImageView.html
+/// [`RgbImage`]: type.RgbImage.html
+/// [`GrayImage`]: type.GrayImage.html
+///
+/// To convert between images of different Pixel types use [`DynamicImage`].
+///
+/// You can retrieve a complete description of the buffer's layout and contents through
+/// [`as_flat_samples`] and [`as_flat_samples_mut`]. This can be handy to also use the contents in
+/// a foreign language, map it as a GPU host buffer or other similar tasks.
+///
+/// [`DynamicImage`]: enum.DynamicImage.html
+/// [`as_flat_samples`]: #method.as_flat_samples
+/// [`as_flat_samples_mut`]: #method.as_flat_samples_mut
+///
+/// ## Examples
+///
+/// Create a simple canvas and paint a small cross.
+///
+/// ```
+/// use image::{RgbImage, Rgb};
+///
+/// let mut img = RgbImage::new(32, 32);
+///
+/// for x in 15..=17 {
+///     for y in 8..24 {
+///         img.put_pixel(x, y, Rgb([255, 0, 0]));
+///         img.put_pixel(y, x, Rgb([255, 0, 0]));
+///     }
+/// }
+/// ```
+///
+/// Overlays an image on top of a larger background raster.
+///
+/// ```no_run
+/// use image::{GenericImage, GenericImageView, ImageBuffer, open};
+///
+/// let on_top = open("path/to/some.png").unwrap().into_rgb8();
+/// let mut img = ImageBuffer::from_fn(512, 512, |x, y| {
+///     if (x + y) % 2 == 0 {
+///         image::Rgb([0, 0, 0])
+///     } else {
+///         image::Rgb([255, 255, 255])
+///     }
+/// });
+///
+/// image::imageops::overlay(&mut img, &on_top, 128, 128);
+/// ```
+///
+/// Convert an RgbaImage to a GrayImage.
+///
+/// ```no_run
+/// use image::{open, DynamicImage};
+///
+/// let rgba = open("path/to/some.png").unwrap().into_rgba8();
+/// let gray = DynamicImage::ImageRgba8(rgba).into_luma8();
+/// ```
+#[derive(Debug, Hash, PartialEq, Eq)]
+pub struct ImageBuffer<P: Pixel, Container> {
+    width: u32,
+    height: u32,
+    _phantom: PhantomData<P>,
+    data: Container,
+}
+
+// generic implementation, shared along all image buffers
+impl<P, Container> ImageBuffer<P, Container>
+where
+    P: Pixel,
+    Container: Deref<Target = [P::Subpixel]>,
+{
+    /// Constructs a buffer from a generic container
+    /// (for example a `Vec` or a slice)
+    ///
+    /// Returns `None` if the container is not big enough (including when the image dimensions
+    /// necessitate an allocation of more bytes than supported by the container).
+    pub fn from_raw(width: u32, height: u32, buf: Container) -> Option<ImageBuffer<P, Container>> {
+        if Self::check_image_fits(width, height, buf.len()) {
+            Some(ImageBuffer {
+                data: buf,
+                width,
+                height,
+                _phantom: PhantomData,
+            })
+        } else {
+            None
+        }
+    }
+
+    /// Returns the underlying raw buffer
+    pub fn into_raw(self) -> Container {
+        self.data
+    }
+
+    /// Returns the underlying raw buffer
+    pub fn as_raw(&self) -> &Container {
+        &self.data
+    }
+
+    /// The width and height of this image.
+    pub fn dimensions(&self) -> (u32, u32) {
+        (self.width, self.height)
+    }
+
+    /// The width of this image.
+    pub fn width(&self) -> u32 {
+        self.width
+    }
+
+    /// The height of this image.
+    pub fn height(&self) -> u32 {
+        self.height
+    }
+
+    // TODO: choose name under which to expose.
+    pub(crate) fn inner_pixels(&self) -> &[P::Subpixel] {
+        let len = Self::image_buffer_len(self.width, self.height).unwrap();
+        &self.data[..len]
+    }
+
+    /// Returns an iterator over the pixels of this image.
+    /// The iteration order is x = 0 to width then y = 0 to height
+    pub fn pixels(&self) -> Pixels<P> {
+        Pixels {
+            chunks: self
+                .inner_pixels()
+                .chunks_exact(<P as Pixel>::CHANNEL_COUNT as usize),
+        }
+    }
+
+    /// Returns an iterator over the rows of this image.
+    ///
+    /// Only non-empty rows can be iterated in this manner. In particular the iterator will not
+    /// yield any item when the width of the image is `0` or a pixel type without any channels is
+    /// used. This ensures that its length can always be represented by `usize`.
+    pub fn rows(&self) -> Rows<P> {
+        Rows::with_image(&self.data, self.width, self.height)
+    }
+
+    /// Enumerates over the pixels of the image.
+    /// The iterator yields the coordinates of each pixel
+    /// along with a reference to them.
+    /// The iteration order is x = 0 to width then y = 0 to height
+    /// Starting from the top left.
+    pub fn enumerate_pixels(&self) -> EnumeratePixels<P> {
+        EnumeratePixels {
+            pixels: self.pixels(),
+            x: 0,
+            y: 0,
+            width: self.width,
+        }
+    }
+
+    /// Enumerates over the rows of the image.
+    /// The iterator yields the y-coordinate of each row
+    /// along with a reference to them.
+    pub fn enumerate_rows(&self) -> EnumerateRows<P> {
+        EnumerateRows {
+            rows: self.rows(),
+            y: 0,
+            width: self.width,
+        }
+    }
+
+    /// Gets a reference to the pixel at location `(x, y)`
+    ///
+    /// # Panics
+    ///
+    /// Panics if `(x, y)` is out of the bounds `(width, height)`.
+    #[inline]
+    #[track_caller]
+    pub fn get_pixel(&self, x: u32, y: u32) -> &P {
+        match self.pixel_indices(x, y) {
+            None => panic!(
+                "Image index {:?} out of bounds {:?}",
+                (x, y),
+                (self.width, self.height)
+            ),
+            Some(pixel_indices) => <P as Pixel>::from_slice(&self.data[pixel_indices]),
+        }
+    }
+
+    /// Gets a reference to the pixel at location `(x, y)` or returns `None` if
+    /// the index is out of the bounds `(width, height)`.
+    pub fn get_pixel_checked(&self, x: u32, y: u32) -> Option<&P> {
+        if x >= self.width {
+            return None;
+        }
+        let num_channels = <P as Pixel>::CHANNEL_COUNT as usize;
+        let i = (y as usize)
+            .saturating_mul(self.width as usize)
+            .saturating_add(x as usize)
+            .saturating_mul(num_channels);
+
+        self.data
+            .get(i..i + num_channels)
+            .map(|pixel_indices| <P as Pixel>::from_slice(pixel_indices))
+    }
+
+    /// Test that the image fits inside the buffer.
+    ///
+    /// Verifies that the maximum image of pixels inside the bounds is smaller than the provided
+    /// length. Note that as a corrolary we also have that the index calculation of pixels inside
+    /// the bounds will not overflow.
+    fn check_image_fits(width: u32, height: u32, len: usize) -> bool {
+        let checked_len = Self::image_buffer_len(width, height);
+        checked_len.map(|min_len| min_len <= len).unwrap_or(false)
+    }
+
+    fn image_buffer_len(width: u32, height: u32) -> Option<usize> {
+        Some(<P as Pixel>::CHANNEL_COUNT as usize)
+            .and_then(|size| size.checked_mul(width as usize))
+            .and_then(|size| size.checked_mul(height as usize))
+    }
+
+    #[inline(always)]
+    fn pixel_indices(&self, x: u32, y: u32) -> Option<Range<usize>> {
+        if x >= self.width || y >= self.height {
+            return None;
+        }
+
+        Some(self.pixel_indices_unchecked(x, y))
+    }
+
+    #[inline(always)]
+    fn pixel_indices_unchecked(&self, x: u32, y: u32) -> Range<usize> {
+        let no_channels = <P as Pixel>::CHANNEL_COUNT as usize;
+        // If in bounds, this can't overflow as we have tested that at construction!
+        let min_index = (y as usize * self.width as usize + x as usize) * no_channels;
+        min_index..min_index + no_channels
+    }
+
+    /// Get the format of the buffer when viewed as a matrix of samples.
+    pub fn sample_layout(&self) -> SampleLayout {
+        // None of these can overflow, as all our memory is addressable.
+        SampleLayout::row_major_packed(<P as Pixel>::CHANNEL_COUNT, self.width, self.height)
+    }
+
+    /// Return the raw sample buffer with its stride an dimension information.
+    ///
+    /// The returned buffer is guaranteed to be well formed in all cases. It is laid out by
+    /// colors, width then height, meaning `channel_stride <= width_stride <= height_stride`. All
+    /// strides are in numbers of elements but those are mostly `u8` in which case the strides are
+    /// also byte strides.
+    pub fn into_flat_samples(self) -> FlatSamples<Container>
+    where
+        Container: AsRef<[P::Subpixel]>,
+    {
+        // None of these can overflow, as all our memory is addressable.
+        let layout = self.sample_layout();
+        FlatSamples {
+            samples: self.data,
+            layout,
+            color_hint: None, // TODO: the pixel type might contain P::COLOR_TYPE if it satisfies PixelWithColorType
+        }
+    }
+
+    /// Return a view on the raw sample buffer.
+    ///
+    /// See [`into_flat_samples`](#method.into_flat_samples) for more details.
+    pub fn as_flat_samples(&self) -> FlatSamples<&[P::Subpixel]>
+    where
+        Container: AsRef<[P::Subpixel]>,
+    {
+        let layout = self.sample_layout();
+        FlatSamples {
+            samples: self.data.as_ref(),
+            layout,
+            color_hint: None, // TODO: the pixel type might contain P::COLOR_TYPE if it satisfies PixelWithColorType
+        }
+    }
+
+    /// Return a mutable view on the raw sample buffer.
+    ///
+    /// See [`into_flat_samples`](#method.into_flat_samples) for more details.
+    pub fn as_flat_samples_mut(&mut self) -> FlatSamples<&mut [P::Subpixel]>
+    where
+        Container: AsMut<[P::Subpixel]>,
+    {
+        let layout = self.sample_layout();
+        FlatSamples {
+            samples: self.data.as_mut(),
+            layout,
+            color_hint: None, // TODO: the pixel type might contain P::COLOR_TYPE if it satisfies PixelWithColorType
+        }
+    }
+}
+
+impl<P, Container> ImageBuffer<P, Container>
+where
+    P: Pixel,
+    Container: Deref<Target = [P::Subpixel]> + DerefMut,
+{
+    // TODO: choose name under which to expose.
+    fn inner_pixels_mut(&mut self) -> &mut [P::Subpixel] {
+        let len = Self::image_buffer_len(self.width, self.height).unwrap();
+        &mut self.data[..len]
+    }
+
+    /// Returns an iterator over the mutable pixels of this image.
+    pub fn pixels_mut(&mut self) -> PixelsMut<P> {
+        PixelsMut {
+            chunks: self
+                .inner_pixels_mut()
+                .chunks_exact_mut(<P as Pixel>::CHANNEL_COUNT as usize),
+        }
+    }
+
+    /// Returns an iterator over the mutable rows of this image.
+    ///
+    /// Only non-empty rows can be iterated in this manner. In particular the iterator will not
+    /// yield any item when the width of the image is `0` or a pixel type without any channels is
+    /// used. This ensures that its length can always be represented by `usize`.
+    pub fn rows_mut(&mut self) -> RowsMut<P> {
+        RowsMut::with_image(&mut self.data, self.width, self.height)
+    }
+
+    /// Enumerates over the pixels of the image.
+    /// The iterator yields the coordinates of each pixel
+    /// along with a mutable reference to them.
+    pub fn enumerate_pixels_mut(&mut self) -> EnumeratePixelsMut<P> {
+        let width = self.width;
+        EnumeratePixelsMut {
+            pixels: self.pixels_mut(),
+            x: 0,
+            y: 0,
+            width,
+        }
+    }
+
+    /// Enumerates over the rows of the image.
+    /// The iterator yields the y-coordinate of each row
+    /// along with a mutable reference to them.
+    pub fn enumerate_rows_mut(&mut self) -> EnumerateRowsMut<P> {
+        let width = self.width;
+        EnumerateRowsMut {
+            rows: self.rows_mut(),
+            y: 0,
+            width,
+        }
+    }
+
+    /// Gets a reference to the mutable pixel at location `(x, y)`
+    ///
+    /// # Panics
+    ///
+    /// Panics if `(x, y)` is out of the bounds `(width, height)`.
+    #[inline]
+    #[track_caller]
+    pub fn get_pixel_mut(&mut self, x: u32, y: u32) -> &mut P {
+        match self.pixel_indices(x, y) {
+            None => panic!(
+                "Image index {:?} out of bounds {:?}",
+                (x, y),
+                (self.width, self.height)
+            ),
+            Some(pixel_indices) => <P as Pixel>::from_slice_mut(&mut self.data[pixel_indices]),
+        }
+    }
+
+    /// Gets a reference to the mutable pixel at location `(x, y)` or returns
+    /// `None` if the index is out of the bounds `(width, height)`.
+    pub fn get_pixel_mut_checked(&mut self, x: u32, y: u32) -> Option<&mut P> {
+        if x >= self.width {
+            return None;
+        }
+        let num_channels = <P as Pixel>::CHANNEL_COUNT as usize;
+        let i = (y as usize)
+            .saturating_mul(self.width as usize)
+            .saturating_add(x as usize)
+            .saturating_mul(num_channels);
+
+        self.data
+            .get_mut(i..i + num_channels)
+            .map(|pixel_indices| <P as Pixel>::from_slice_mut(pixel_indices))
+    }
+
+    /// Puts a pixel at location `(x, y)`
+    ///
+    /// # Panics
+    ///
+    /// Panics if `(x, y)` is out of the bounds `(width, height)`.
+    #[inline]
+    #[track_caller]
+    pub fn put_pixel(&mut self, x: u32, y: u32, pixel: P) {
+        *self.get_pixel_mut(x, y) = pixel
+    }
+}
+
+impl<P, Container> ImageBuffer<P, Container>
+where
+    P: Pixel,
+    [P::Subpixel]: EncodableLayout,
+    Container: Deref<Target = [P::Subpixel]>,
+{
+    /// Saves the buffer to a file at the path specified.
+    ///
+    /// The image format is derived from the file extension.
+    pub fn save<Q>(&self, path: Q) -> ImageResult<()>
+    where
+        Q: AsRef<Path>,
+        P: PixelWithColorType,
+    {
+        save_buffer(
+            path,
+            self.inner_pixels().as_bytes(),
+            self.width(),
+            self.height(),
+            <P as PixelWithColorType>::COLOR_TYPE,
+        )
+    }
+}
+
+impl<P, Container> ImageBuffer<P, Container>
+where
+    P: Pixel,
+    [P::Subpixel]: EncodableLayout,
+    Container: Deref<Target = [P::Subpixel]>,
+{
+    /// Saves the buffer to a file at the specified path in
+    /// the specified format.
+    ///
+    /// See [`save_buffer_with_format`](fn.save_buffer_with_format.html) for
+    /// supported types.
+    pub fn save_with_format<Q>(&self, path: Q, format: ImageFormat) -> ImageResult<()>
+    where
+        Q: AsRef<Path>,
+        P: PixelWithColorType,
+    {
+        // This is valid as the subpixel is u8.
+        save_buffer_with_format(
+            path,
+            self.inner_pixels().as_bytes(),
+            self.width(),
+            self.height(),
+            <P as PixelWithColorType>::COLOR_TYPE,
+            format,
+        )
+    }
+}
+
+impl<P, Container> ImageBuffer<P, Container>
+where
+    P: Pixel,
+    [P::Subpixel]: EncodableLayout,
+    Container: Deref<Target = [P::Subpixel]>,
+{
+    /// Writes the buffer to a writer in the specified format.
+    ///
+    /// Assumes the writer is buffered. In most cases,
+    /// you should wrap your writer in a `BufWriter` for best performance.
+    ///
+    /// See [`ImageOutputFormat`](enum.ImageOutputFormat.html) for
+    /// supported types.
+    pub fn write_to<W, F>(&self, writer: &mut W, format: F) -> ImageResult<()>
+    where
+        W: std::io::Write + std::io::Seek,
+        F: Into<ImageOutputFormat>,
+        P: PixelWithColorType,
+    {
+        // This is valid as the subpixel is u8.
+        write_buffer_with_format(
+            writer,
+            self.inner_pixels().as_bytes(),
+            self.width(),
+            self.height(),
+            <P as PixelWithColorType>::COLOR_TYPE,
+            format,
+        )
+    }
+}
+
+impl<P, Container> ImageBuffer<P, Container>
+where
+    P: Pixel,
+    [P::Subpixel]: EncodableLayout,
+    Container: Deref<Target = [P::Subpixel]>,
+{
+    /// Writes the buffer with the given encoder.
+    pub fn write_with_encoder<E>(&self, encoder: E) -> ImageResult<()>
+    where
+        E: ImageEncoder,
+        P: PixelWithColorType,
+    {
+        // This is valid as the subpixel is u8.
+        encoder.write_image(
+            self.inner_pixels().as_bytes(),
+            self.width(),
+            self.height(),
+            <P as PixelWithColorType>::COLOR_TYPE,
+        )
+    }
+}
+
+impl<P, Container> Default for ImageBuffer<P, Container>
+where
+    P: Pixel,
+    Container: Default,
+{
+    fn default() -> Self {
+        Self {
+            width: 0,
+            height: 0,
+            _phantom: PhantomData,
+            data: Default::default(),
+        }
+    }
+}
+
+impl<P, Container> Deref for ImageBuffer<P, Container>
+where
+    P: Pixel,
+    Container: Deref<Target = [P::Subpixel]>,
+{
+    type Target = [P::Subpixel];
+
+    fn deref(&self) -> &<Self as Deref>::Target {
+        &self.data
+    }
+}
+
+impl<P, Container> DerefMut for ImageBuffer<P, Container>
+where
+    P: Pixel,
+    Container: Deref<Target = [P::Subpixel]> + DerefMut,
+{
+    fn deref_mut(&mut self) -> &mut <Self as Deref>::Target {
+        &mut self.data
+    }
+}
+
+impl<P, Container> Index<(u32, u32)> for ImageBuffer<P, Container>
+where
+    P: Pixel,
+    Container: Deref<Target = [P::Subpixel]>,
+{
+    type Output = P;
+
+    fn index(&self, (x, y): (u32, u32)) -> &P {
+        self.get_pixel(x, y)
+    }
+}
+
+impl<P, Container> IndexMut<(u32, u32)> for ImageBuffer<P, Container>
+where
+    P: Pixel,
+    Container: Deref<Target = [P::Subpixel]> + DerefMut,
+{
+    fn index_mut(&mut self, (x, y): (u32, u32)) -> &mut P {
+        self.get_pixel_mut(x, y)
+    }
+}
+
+impl<P, Container> Clone for ImageBuffer<P, Container>
+where
+    P: Pixel,
+    Container: Deref<Target = [P::Subpixel]> + Clone,
+{
+    fn clone(&self) -> ImageBuffer<P, Container> {
+        ImageBuffer {
+            data: self.data.clone(),
+            width: self.width,
+            height: self.height,
+            _phantom: PhantomData,
+        }
+    }
+}
+
+impl<P, Container> GenericImageView for ImageBuffer<P, Container>
+where
+    P: Pixel,
+    Container: Deref<Target = [P::Subpixel]> + Deref,
+{
+    type Pixel = P;
+
+    fn dimensions(&self) -> (u32, u32) {
+        self.dimensions()
+    }
+
+    fn bounds(&self) -> (u32, u32, u32, u32) {
+        (0, 0, self.width, self.height)
+    }
+
+    fn get_pixel(&self, x: u32, y: u32) -> P {
+        *self.get_pixel(x, y)
+    }
+
+    /// Returns the pixel located at (x, y), ignoring bounds checking.
+    #[inline(always)]
+    unsafe fn unsafe_get_pixel(&self, x: u32, y: u32) -> P {
+        let indices = self.pixel_indices_unchecked(x, y);
+        *<P as Pixel>::from_slice(self.data.get_unchecked(indices))
+    }
+}
+
+impl<P, Container> GenericImage for ImageBuffer<P, Container>
+where
+    P: Pixel,
+    Container: Deref<Target = [P::Subpixel]> + DerefMut,
+{
+    fn get_pixel_mut(&mut self, x: u32, y: u32) -> &mut P {
+        self.get_pixel_mut(x, y)
+    }
+
+    fn put_pixel(&mut self, x: u32, y: u32, pixel: P) {
+        *self.get_pixel_mut(x, y) = pixel
+    }
+
+    /// Puts a pixel at location (x, y), ignoring bounds checking.
+    #[inline(always)]
+    unsafe fn unsafe_put_pixel(&mut self, x: u32, y: u32, pixel: P) {
+        let indices = self.pixel_indices_unchecked(x, y);
+        let p = <P as Pixel>::from_slice_mut(self.data.get_unchecked_mut(indices));
+        *p = pixel
+    }
+
+    /// Put a pixel at location (x, y), taking into account alpha channels
+    ///
+    /// DEPRECATED: This method will be removed. Blend the pixel directly instead.
+    fn blend_pixel(&mut self, x: u32, y: u32, p: P) {
+        self.get_pixel_mut(x, y).blend(&p)
+    }
+
+    fn copy_within(&mut self, source: Rect, x: u32, y: u32) -> bool {
+        let Rect {
+            x: sx,
+            y: sy,
+            width,
+            height,
+        } = source;
+        let dx = x;
+        let dy = y;
+        assert!(sx < self.width() && dx < self.width());
+        assert!(sy < self.height() && dy < self.height());
+        if self.width() - dx.max(sx) < width || self.height() - dy.max(sy) < height {
+            return false;
+        }
+
+        if sy < dy {
+            for y in (0..height).rev() {
+                let sy = sy + y;
+                let dy = dy + y;
+                let Range { start, .. } = self.pixel_indices_unchecked(sx, sy);
+                let Range { end, .. } = self.pixel_indices_unchecked(sx + width - 1, sy);
+                let dst = self.pixel_indices_unchecked(dx, dy).start;
+                self.data.copy_within(start..end, dst);
+            }
+        } else {
+            for y in 0..height {
+                let sy = sy + y;
+                let dy = dy + y;
+                let Range { start, .. } = self.pixel_indices_unchecked(sx, sy);
+                let Range { end, .. } = self.pixel_indices_unchecked(sx + width - 1, sy);
+                let dst = self.pixel_indices_unchecked(dx, dy).start;
+                self.data.copy_within(start..end, dst);
+            }
+        }
+        true
+    }
+}
+
+// concrete implementation for `Vec`-backed buffers
+// TODO: I think that rustc does not "see" this impl any more: the impl with
+// Container meets the same requirements. At least, I got compile errors that
+// there is no such function as `into_vec`, whereas `into_raw` did work, and
+// `into_vec` is redundant anyway, because `into_raw` will give you the vector,
+// and it is more generic.
+impl<P: Pixel> ImageBuffer<P, Vec<P::Subpixel>> {
+    /// Creates a new image buffer based on a `Vec<P::Subpixel>`.
+    ///
+    /// # Panics
+    ///
+    /// Panics when the resulting image is larger the the maximum size of a vector.
+    pub fn new(width: u32, height: u32) -> ImageBuffer<P, Vec<P::Subpixel>> {
+        let size = Self::image_buffer_len(width, height)
+            .expect("Buffer length in `ImageBuffer::new` overflows usize");
+        ImageBuffer {
+            data: vec![Zero::zero(); size],
+            width,
+            height,
+            _phantom: PhantomData,
+        }
+    }
+
+    /// Constructs a new ImageBuffer by copying a pixel
+    ///
+    /// # Panics
+    ///
+    /// Panics when the resulting image is larger the the maximum size of a vector.
+    pub fn from_pixel(width: u32, height: u32, pixel: P) -> ImageBuffer<P, Vec<P::Subpixel>> {
+        let mut buf = ImageBuffer::new(width, height);
+        for p in buf.pixels_mut() {
+            *p = pixel
+        }
+        buf
+    }
+
+    /// Constructs a new ImageBuffer by repeated application of the supplied function.
+    ///
+    /// The arguments to the function are the pixel's x and y coordinates.
+    ///
+    /// # Panics
+    ///
+    /// Panics when the resulting image is larger the the maximum size of a vector.
+    pub fn from_fn<F>(width: u32, height: u32, mut f: F) -> ImageBuffer<P, Vec<P::Subpixel>>
+    where
+        F: FnMut(u32, u32) -> P,
+    {
+        let mut buf = ImageBuffer::new(width, height);
+        for (x, y, p) in buf.enumerate_pixels_mut() {
+            *p = f(x, y)
+        }
+        buf
+    }
+
+    /// Creates an image buffer out of an existing buffer.
+    /// Returns None if the buffer is not big enough.
+    pub fn from_vec(
+        width: u32,
+        height: u32,
+        buf: Vec<P::Subpixel>,
+    ) -> Option<ImageBuffer<P, Vec<P::Subpixel>>> {
+        ImageBuffer::from_raw(width, height, buf)
+    }
+
+    /// Consumes the image buffer and returns the underlying data
+    /// as an owned buffer
+    pub fn into_vec(self) -> Vec<P::Subpixel> {
+        self.into_raw()
+    }
+}
+
+/// Provides color conversions for whole image buffers.
+pub trait ConvertBuffer<T> {
+    /// Converts `self` to a buffer of type T
+    ///
+    /// A generic implementation is provided to convert any image buffer to a image buffer
+    /// based on a `Vec<T>`.
+    fn convert(&self) -> T;
+}
+
+// concrete implementation Luma -> Rgba
+impl GrayImage {
+    /// Expands a color palette by re-using the existing buffer.
+    /// Assumes 8 bit per pixel. Uses an optionally transparent index to
+    /// adjust it's alpha value accordingly.
+    pub fn expand_palette(
+        self,
+        palette: &[(u8, u8, u8)],
+        transparent_idx: Option<u8>,
+    ) -> RgbaImage {
+        let (width, height) = self.dimensions();
+        let mut data = self.into_raw();
+        let entries = data.len();
+        data.resize(entries.checked_mul(4).unwrap(), 0);
+        let mut buffer = ImageBuffer::from_vec(width, height, data).unwrap();
+        expand_packed(&mut buffer, 4, 8, |idx, pixel| {
+            let (r, g, b) = palette[idx as usize];
+            let a = if let Some(t_idx) = transparent_idx {
+                if t_idx == idx {
+                    0
+                } else {
+                    255
+                }
+            } else {
+                255
+            };
+            pixel[0] = r;
+            pixel[1] = g;
+            pixel[2] = b;
+            pixel[3] = a;
+        });
+        buffer
+    }
+}
+
+// TODO: Equality constraints are not yet supported in where clauses, when they
+// are, the T parameter should be removed in favor of ToType::Subpixel, which
+// will then be FromType::Subpixel.
+impl<Container, FromType: Pixel, ToType: Pixel>
+    ConvertBuffer<ImageBuffer<ToType, Vec<ToType::Subpixel>>> for ImageBuffer<FromType, Container>
+where
+    Container: Deref<Target = [FromType::Subpixel]>,
+    ToType: FromColor<FromType>,
+{
+    /// # Examples
+    /// Convert RGB image to gray image.
+    /// ```no_run
+    /// use image::buffer::ConvertBuffer;
+    /// use image::GrayImage;
+    ///
+    /// let image_path = "examples/fractal.png";
+    /// let image = image::open(&image_path)
+    ///     .expect("Open file failed")
+    ///     .to_rgba8();
+    ///
+    /// let gray_image: GrayImage = image.convert();
+    /// ```
+    fn convert(&self) -> ImageBuffer<ToType, Vec<ToType::Subpixel>> {
+        let mut buffer: ImageBuffer<ToType, Vec<ToType::Subpixel>> =
+            ImageBuffer::new(self.width, self.height);
+        for (to, from) in buffer.pixels_mut().zip(self.pixels()) {
+            to.from_color(from)
+        }
+        buffer
+    }
+}
+
+/// Sendable Rgb image buffer
+pub type RgbImage = ImageBuffer<Rgb<u8>, Vec<u8>>;
+/// Sendable Rgb + alpha channel image buffer
+pub type RgbaImage = ImageBuffer<Rgba<u8>, Vec<u8>>;
+/// Sendable grayscale image buffer
+pub type GrayImage = ImageBuffer<Luma<u8>, Vec<u8>>;
+/// Sendable grayscale + alpha channel image buffer
+pub type GrayAlphaImage = ImageBuffer<LumaA<u8>, Vec<u8>>;
+/// Sendable 16-bit Rgb image buffer
+pub(crate) type Rgb16Image = ImageBuffer<Rgb<u16>, Vec<u16>>;
+/// Sendable 16-bit Rgb + alpha channel image buffer
+pub(crate) type Rgba16Image = ImageBuffer<Rgba<u16>, Vec<u16>>;
+/// Sendable 16-bit grayscale image buffer
+pub(crate) type Gray16Image = ImageBuffer<Luma<u16>, Vec<u16>>;
+/// Sendable 16-bit grayscale + alpha channel image buffer
+pub(crate) type GrayAlpha16Image = ImageBuffer<LumaA<u16>, Vec<u16>>;
+
+/// An image buffer for 32-bit float RGB pixels,
+/// where the backing container is a flattened vector of floats.
+pub type Rgb32FImage = ImageBuffer<Rgb<f32>, Vec<f32>>;
+
+/// An image buffer for 32-bit float RGBA pixels,
+/// where the backing container is a flattened vector of floats.
+pub type Rgba32FImage = ImageBuffer<Rgba<f32>, Vec<f32>>;
+
+#[cfg(test)]
+mod test {
+    use super::{GrayImage, ImageBuffer, ImageOutputFormat, RgbImage};
+    use crate::math::Rect;
+    use crate::GenericImage as _;
+    use crate::{color, Rgb};
+
+    #[test]
+    /// Tests if image buffers from slices work
+    fn slice_buffer() {
+        let data = [0; 9];
+        let buf: ImageBuffer<color::Luma<u8>, _> = ImageBuffer::from_raw(3, 3, &data[..]).unwrap();
+        assert_eq!(&*buf, &data[..])
+    }
+
+    #[test]
+    fn get_pixel() {
+        let mut a: RgbImage = ImageBuffer::new(10, 10);
+        {
+            let b = a.get_mut(3 * 10).unwrap();
+            *b = 255;
+        }
+        assert_eq!(a.get_pixel(0, 1)[0], 255)
+    }
+
+    #[test]
+    fn get_pixel_checked() {
+        let mut a: RgbImage = ImageBuffer::new(10, 10);
+        a.get_pixel_mut_checked(0, 1).map(|b| b[0] = 255);
+
+        assert_eq!(a.get_pixel_checked(0, 1), Some(&Rgb([255, 0, 0])));
+        assert_eq!(a.get_pixel_checked(0, 1).unwrap(), a.get_pixel(0, 1));
+        assert_eq!(a.get_pixel_checked(10, 0), None);
+        assert_eq!(a.get_pixel_checked(0, 10), None);
+        assert_eq!(a.get_pixel_mut_checked(10, 0), None);
+        assert_eq!(a.get_pixel_mut_checked(0, 10), None);
+
+        // From image/issues/1672
+        const WHITE: Rgb<u8> = Rgb([255_u8, 255, 255]);
+        let mut a = RgbImage::new(2, 1);
+        a.put_pixel(1, 0, WHITE);
+
+        assert_eq!(a.get_pixel_checked(1, 0), Some(&WHITE));
+        assert_eq!(a.get_pixel_checked(1, 0).unwrap(), a.get_pixel(1, 0));
+    }
+
+    #[test]
+    fn mut_iter() {
+        let mut a: RgbImage = ImageBuffer::new(10, 10);
+        {
+            let val = a.pixels_mut().next().unwrap();
+            *val = Rgb([42, 0, 0]);
+        }
+        assert_eq!(a.data[0], 42)
+    }
+
+    #[test]
+    fn zero_width_zero_height() {
+        let mut image = RgbImage::new(0, 0);
+
+        assert_eq!(image.rows_mut().count(), 0);
+        assert_eq!(image.pixels_mut().count(), 0);
+        assert_eq!(image.rows().count(), 0);
+        assert_eq!(image.pixels().count(), 0);
+    }
+
+    #[test]
+    fn zero_width_nonzero_height() {
+        let mut image = RgbImage::new(0, 2);
+
+        assert_eq!(image.rows_mut().count(), 0);
+        assert_eq!(image.pixels_mut().count(), 0);
+        assert_eq!(image.rows().count(), 0);
+        assert_eq!(image.pixels().count(), 0);
+    }
+
+    #[test]
+    fn nonzero_width_zero_height() {
+        let mut image = RgbImage::new(2, 0);
+
+        assert_eq!(image.rows_mut().count(), 0);
+        assert_eq!(image.pixels_mut().count(), 0);
+        assert_eq!(image.rows().count(), 0);
+        assert_eq!(image.pixels().count(), 0);
+    }
+
+    #[test]
+    fn pixels_on_large_buffer() {
+        let mut image = RgbImage::from_raw(1, 1, vec![0; 6]).unwrap();
+
+        assert_eq!(image.pixels().count(), 1);
+        assert_eq!(image.enumerate_pixels().count(), 1);
+        assert_eq!(image.pixels_mut().count(), 1);
+        assert_eq!(image.enumerate_pixels_mut().count(), 1);
+
+        assert_eq!(image.rows().count(), 1);
+        assert_eq!(image.rows_mut().count(), 1);
+    }
+
+    #[test]
+    fn default() {
+        let image = ImageBuffer::<Rgb<u8>, Vec<u8>>::default();
+        assert_eq!(image.dimensions(), (0, 0));
+    }
+
+    #[test]
+    #[rustfmt::skip]
+    fn test_image_buffer_copy_within_oob() {
+        let mut image: GrayImage = ImageBuffer::from_raw(4, 4, vec![0u8; 16]).unwrap();
+        assert!(!image.copy_within(Rect { x: 0, y: 0, width: 5, height: 4 }, 0, 0));
+        assert!(!image.copy_within(Rect { x: 0, y: 0, width: 4, height: 5 }, 0, 0));
+        assert!(!image.copy_within(Rect { x: 1, y: 0, width: 4, height: 4 }, 0, 0));
+        assert!(!image.copy_within(Rect { x: 0, y: 0, width: 4, height: 4 }, 1, 0));
+        assert!(!image.copy_within(Rect { x: 0, y: 1, width: 4, height: 4 }, 0, 0));
+        assert!(!image.copy_within(Rect { x: 0, y: 0, width: 4, height: 4 }, 0, 1));
+        assert!(!image.copy_within(Rect { x: 1, y: 1, width: 4, height: 4 }, 0, 0));
+    }
+
+    #[test]
+    fn test_image_buffer_copy_within_tl() {
+        let data = &[
+            00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15,
+        ];
+        let expected = [
+            00, 01, 02, 03, 04, 00, 01, 02, 08, 04, 05, 06, 12, 08, 09, 10,
+        ];
+        let mut image: GrayImage = ImageBuffer::from_raw(4, 4, Vec::from(&data[..])).unwrap();
+        assert!(image.copy_within(
+            Rect {
+                x: 0,
+                y: 0,
+                width: 3,
+                height: 3
+            },
+            1,
+            1
+        ));
+        assert_eq!(&image.into_raw(), &expected);
+    }
+
+    #[test]
+    fn test_image_buffer_copy_within_tr() {
+        let data = &[
+            00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15,
+        ];
+        let expected = [
+            00, 01, 02, 03, 01, 02, 03, 07, 05, 06, 07, 11, 09, 10, 11, 15,
+        ];
+        let mut image: GrayImage = ImageBuffer::from_raw(4, 4, Vec::from(&data[..])).unwrap();
+        assert!(image.copy_within(
+            Rect {
+                x: 1,
+                y: 0,
+                width: 3,
+                height: 3
+            },
+            0,
+            1
+        ));
+        assert_eq!(&image.into_raw(), &expected);
+    }
+
+    #[test]
+    fn test_image_buffer_copy_within_bl() {
+        let data = &[
+            00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15,
+        ];
+        let expected = [
+            00, 04, 05, 06, 04, 08, 09, 10, 08, 12, 13, 14, 12, 13, 14, 15,
+        ];
+        let mut image: GrayImage = ImageBuffer::from_raw(4, 4, Vec::from(&data[..])).unwrap();
+        assert!(image.copy_within(
+            Rect {
+                x: 0,
+                y: 1,
+                width: 3,
+                height: 3
+            },
+            1,
+            0
+        ));
+        assert_eq!(&image.into_raw(), &expected);
+    }
+
+    #[test]
+    fn test_image_buffer_copy_within_br() {
+        let data = &[
+            00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15,
+        ];
+        let expected = [
+            05, 06, 07, 03, 09, 10, 11, 07, 13, 14, 15, 11, 12, 13, 14, 15,
+        ];
+        let mut image: GrayImage = ImageBuffer::from_raw(4, 4, Vec::from(&data[..])).unwrap();
+        assert!(image.copy_within(
+            Rect {
+                x: 1,
+                y: 1,
+                width: 3,
+                height: 3
+            },
+            0,
+            0
+        ));
+        assert_eq!(&image.into_raw(), &expected);
+    }
+
+    #[test]
+    #[cfg(feature = "png")]
+    fn write_to_with_large_buffer() {
+        // A buffer of 1 pixel, padded to 4 bytes as would be common in, e.g. BMP.
+        let img: GrayImage = ImageBuffer::from_raw(1, 1, vec![0u8; 4]).unwrap();
+        let mut buffer = std::io::Cursor::new(vec![]);
+        assert!(img.write_to(&mut buffer, ImageOutputFormat::Png).is_ok());
+    }
+
+    #[test]
+    fn exact_size_iter_size_hint() {
+        // The docs for `std::iter::ExactSizeIterator` requires that the implementation of
+        // `size_hint` on the iterator returns the same value as the `len` implementation.
+
+        // This test should work for any size image.
+        const N: u32 = 10;
+
+        let mut image = RgbImage::from_raw(N, N, vec![0; (N * N * 3) as usize]).unwrap();
+
+        let iter = image.pixels();
+        let exact_len = ExactSizeIterator::len(&iter);
+        assert_eq!(iter.size_hint(), (exact_len, Some(exact_len)));
+
+        let iter = image.pixels_mut();
+        let exact_len = ExactSizeIterator::len(&iter);
+        assert_eq!(iter.size_hint(), (exact_len, Some(exact_len)));
+
+        let iter = image.rows();
+        let exact_len = ExactSizeIterator::len(&iter);
+        assert_eq!(iter.size_hint(), (exact_len, Some(exact_len)));
+
+        let iter = image.rows_mut();
+        let exact_len = ExactSizeIterator::len(&iter);
+        assert_eq!(iter.size_hint(), (exact_len, Some(exact_len)));
+
+        let iter = image.enumerate_pixels();
+        let exact_len = ExactSizeIterator::len(&iter);
+        assert_eq!(iter.size_hint(), (exact_len, Some(exact_len)));
+
+        let iter = image.enumerate_rows();
+        let exact_len = ExactSizeIterator::len(&iter);
+        assert_eq!(iter.size_hint(), (exact_len, Some(exact_len)));
+
+        let iter = image.enumerate_pixels_mut();
+        let exact_len = ExactSizeIterator::len(&iter);
+        assert_eq!(iter.size_hint(), (exact_len, Some(exact_len)));
+
+        let iter = image.enumerate_rows_mut();
+        let exact_len = ExactSizeIterator::len(&iter);
+        assert_eq!(iter.size_hint(), (exact_len, Some(exact_len)));
+    }
+}
+
+#[cfg(test)]
+#[cfg(feature = "benchmarks")]
+mod benchmarks {
+    use super::{ConvertBuffer, GrayImage, ImageBuffer, Pixel, RgbImage};
+    use crate::GenericImage;
+    use test;
+
+    #[bench]
+    fn conversion(b: &mut test::Bencher) {
+        let mut a: RgbImage = ImageBuffer::new(1000, 1000);
+        for p in a.pixels_mut() {
+            let rgb = p.channels_mut();
+            rgb[0] = 255;
+            rgb[1] = 23;
+            rgb[2] = 42;
+        }
+        assert!(a.data[0] != 0);
+        b.iter(|| {
+            let b: GrayImage = a.convert();
+            assert!(0 != b.data[0]);
+            assert!(a.data[0] != b.data[0]);
+            test::black_box(b);
+        });
+        b.bytes = 1000 * 1000 * 3
+    }
+
+    #[bench]
+    fn image_access_row_by_row(b: &mut test::Bencher) {
+        let mut a: RgbImage = ImageBuffer::new(1000, 1000);
+        for p in a.pixels_mut() {
+            let rgb = p.channels_mut();
+            rgb[0] = 255;
+            rgb[1] = 23;
+            rgb[2] = 42;
+        }
+
+        b.iter(move || {
+            let image: &RgbImage = test::black_box(&a);
+            let mut sum: usize = 0;
+            for y in 0..1000 {
+                for x in 0..1000 {
+                    let pixel = image.get_pixel(x, y);
+                    sum = sum.wrapping_add(pixel[0] as usize);
+                    sum = sum.wrapping_add(pixel[1] as usize);
+                    sum = sum.wrapping_add(pixel[2] as usize);
+                }
+            }
+            test::black_box(sum)
+        });
+
+        b.bytes = 1000 * 1000 * 3;
+    }
+
+    #[bench]
+    fn image_access_col_by_col(b: &mut test::Bencher) {
+        let mut a: RgbImage = ImageBuffer::new(1000, 1000);
+        for p in a.pixels_mut() {
+            let rgb = p.channels_mut();
+            rgb[0] = 255;
+            rgb[1] = 23;
+            rgb[2] = 42;
+        }
+
+        b.iter(move || {
+            let image: &RgbImage = test::black_box(&a);
+            let mut sum: usize = 0;
+            for x in 0..1000 {
+                for y in 0..1000 {
+                    let pixel = image.get_pixel(x, y);
+                    sum = sum.wrapping_add(pixel[0] as usize);
+                    sum = sum.wrapping_add(pixel[1] as usize);
+                    sum = sum.wrapping_add(pixel[2] as usize);
+                }
+            }
+            test::black_box(sum)
+        });
+
+        b.bytes = 1000 * 1000 * 3;
+    }
+}