//! Image representations for ffi. //! //! # Usage //! //! Imagine you want to offer a very simple ffi interface: The caller provides an image buffer and //! your program creates a thumbnail from it and dumps that image as `png`. This module is designed //! to help you transition from raw memory data to Rust representation. //! //! ```no_run //! use std::ptr; //! use std::slice; //! use image::Rgb; //! use image::flat::{FlatSamples, SampleLayout}; //! use image::imageops::thumbnail; //! //! #[no_mangle] //! pub extern "C" fn store_rgb8_compressed( //! data: *const u8, len: usize, //! layout: *const SampleLayout //! ) //! -> bool //! { //! let samples = unsafe { slice::from_raw_parts(data, len) }; //! let layout = unsafe { ptr::read(layout) }; //! //! let buffer = FlatSamples { //! samples, //! layout, //! color_hint: None, //! }; //! //! let view = match buffer.as_view::>() { //! Err(_) => return false, // Invalid layout. //! Ok(view) => view, //! }; //! //! thumbnail(&view, 64, 64) //! .save("output.png") //! .map(|_| true) //! .unwrap_or_else(|_| false) //! } //! ``` //! use std::marker::PhantomData; use std::ops::{Deref, Index, IndexMut}; use std::{cmp, error, fmt}; use num_traits::Zero; use crate::color::ColorType; use crate::error::{ DecodingError, ImageError, ImageFormatHint, ParameterError, ParameterErrorKind, UnsupportedError, UnsupportedErrorKind, }; use crate::image::{GenericImage, GenericImageView}; use crate::traits::Pixel; use crate::ImageBuffer; /// A flat buffer over a (multi channel) image. /// /// In contrast to `ImageBuffer`, this representation of a sample collection is much more lenient /// in the layout thereof. It also allows grouping by color planes instead of by pixel as long as /// the strides of each extent are constant. This struct itself has no invariants on the strides /// but not every possible configuration can be interpreted as a [`GenericImageView`] or /// [`GenericImage`]. The methods [`as_view`] and [`as_view_mut`] construct the actual implementors /// of these traits and perform necessary checks. To manually perform this and other layout checks /// use [`is_normal`] or [`has_aliased_samples`]. /// /// Instances can be constructed not only by hand. The buffer instances returned by library /// functions such as [`ImageBuffer::as_flat_samples`] guarantee that the conversion to a generic /// image or generic view succeeds. A very different constructor is [`with_monocolor`]. It uses a /// single pixel as the backing storage for an arbitrarily sized read-only raster by mapping each /// pixel to the same samples by setting some strides to `0`. /// /// [`GenericImage`]: ../trait.GenericImage.html /// [`GenericImageView`]: ../trait.GenericImageView.html /// [`ImageBuffer::as_flat_samples`]: ../struct.ImageBuffer.html#method.as_flat_samples /// [`is_normal`]: #method.is_normal /// [`has_aliased_samples`]: #method.has_aliased_samples /// [`as_view`]: #method.as_view /// [`as_view_mut`]: #method.as_view_mut /// [`with_monocolor`]: #method.with_monocolor #[derive(Clone, Debug)] pub struct FlatSamples { /// Underlying linear container holding sample values. pub samples: Buffer, /// A `repr(C)` description of the layout of buffer samples. pub layout: SampleLayout, /// Supplementary color information. /// /// You may keep this as `None` in most cases. This is NOT checked in `View` or other /// converters. It is intended mainly as a way for types that convert to this buffer type to /// attach their otherwise static color information. A dynamic image representation could /// however use this to resolve representational ambiguities such as the order of RGB channels. pub color_hint: Option, } /// A ffi compatible description of a sample buffer. #[repr(C)] #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)] pub struct SampleLayout { /// The number of channels in the color representation of the image. pub channels: u8, /// Add this to an index to get to the sample in the next channel. pub channel_stride: usize, /// The width of the represented image. pub width: u32, /// Add this to an index to get to the next sample in x-direction. pub width_stride: usize, /// The height of the represented image. pub height: u32, /// Add this to an index to get to the next sample in y-direction. pub height_stride: usize, } /// Helper struct for an unnamed (stride, length) pair. #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)] struct Dim(usize, usize); impl SampleLayout { /// Describe a row-major image packed in all directions. /// /// The resulting will surely be `NormalForm::RowMajorPacked`. It can therefore be converted to /// safely to an `ImageBuffer` with a large enough underlying buffer. /// /// ``` /// # use image::flat::{NormalForm, SampleLayout}; /// let layout = SampleLayout::row_major_packed(3, 640, 480); /// assert!(layout.is_normal(NormalForm::RowMajorPacked)); /// ``` /// /// # Panics /// /// On platforms where `usize` has the same size as `u32` this panics when the resulting stride /// in the `height` direction would be larger than `usize::max_value()`. On other platforms /// where it can surely accommodate `u8::max_value() * u32::max_value(), this can never happen. pub fn row_major_packed(channels: u8, width: u32, height: u32) -> Self { let height_stride = (channels as usize).checked_mul(width as usize).expect( "Row major packed image can not be described because it does not fit into memory", ); SampleLayout { channels, channel_stride: 1, width, width_stride: channels as usize, height, height_stride, } } /// Describe a column-major image packed in all directions. /// /// The resulting will surely be `NormalForm::ColumnMajorPacked`. This is not particularly /// useful for conversion but can be used to describe such a buffer without pitfalls. /// /// ``` /// # use image::flat::{NormalForm, SampleLayout}; /// let layout = SampleLayout::column_major_packed(3, 640, 480); /// assert!(layout.is_normal(NormalForm::ColumnMajorPacked)); /// ``` /// /// # Panics /// /// On platforms where `usize` has the same size as `u32` this panics when the resulting stride /// in the `width` direction would be larger than `usize::max_value()`. On other platforms /// where it can surely accommodate `u8::max_value() * u32::max_value(), this can never happen. pub fn column_major_packed(channels: u8, width: u32, height: u32) -> Self { let width_stride = (channels as usize).checked_mul(height as usize).expect( "Column major packed image can not be described because it does not fit into memory", ); SampleLayout { channels, channel_stride: 1, height, height_stride: channels as usize, width, width_stride, } } /// Get the strides for indexing matrix-like `[(c, w, h)]`. /// /// For a row-major layout with grouped samples, this tuple is strictly /// increasing. pub fn strides_cwh(&self) -> (usize, usize, usize) { (self.channel_stride, self.width_stride, self.height_stride) } /// Get the dimensions `(channels, width, height)`. /// /// The interface is optimized for use with `strides_cwh` instead. The channel extent will be /// before width and height. pub fn extents(&self) -> (usize, usize, usize) { ( self.channels as usize, self.width as usize, self.height as usize, ) } /// Tuple of bounds in the order of coordinate inputs. /// /// This function should be used whenever working with image coordinates opposed to buffer /// coordinates. The only difference compared to `extents` is the output type. pub fn bounds(&self) -> (u8, u32, u32) { (self.channels, self.width, self.height) } /// Get the minimum length of a buffer such that all in-bounds samples have valid indices. /// /// This method will allow zero strides, allowing compact representations of monochrome images. /// To check that no aliasing occurs, try `check_alias_invariants`. For compact images (no /// aliasing and no unindexed samples) this is `width*height*channels`. But for both of the /// other cases, the reasoning is slightly more involved. /// /// # Explanation /// /// Note that there is a difference between `min_length` and the index of the sample /// 'one-past-the-end`. This is due to strides that may be larger than the dimension below. /// /// ## Example with holes /// /// Let's look at an example of a grayscale image with /// * `width_stride = 1` /// * `width = 2` /// * `height_stride = 3` /// * `height = 2` /// /// ```text /// | x x | x x m | $ /// min_length m ^ /// ^ one-past-the-end $ /// ``` /// /// The difference is also extreme for empty images with large strides. The one-past-the-end /// sample index is still as large as the largest of these strides while `min_length = 0`. /// /// ## Example with aliasing /// /// The concept gets even more important when you allow samples to alias each other. Here we /// have the buffer of a small grayscale image where this is the case, this time we will first /// show the buffer and then the individual rows below. /// /// * `width_stride = 1` /// * `width = 3` /// * `height_stride = 2` /// * `height = 2` /// /// ```text /// 1 2 3 4 5 m /// |1 2 3| row one /// |3 4 5| row two /// ^ m min_length /// ^ ??? one-past-the-end /// ``` /// /// This time 'one-past-the-end' is not even simply the largest stride times the extent of its /// dimension. That still points inside the image because `height*height_stride = 4` but also /// `index_of(1, 2) = 4`. pub fn min_length(&self) -> Option { if self.width == 0 || self.height == 0 || self.channels == 0 { return Some(0); } self.index(self.channels - 1, self.width - 1, self.height - 1) .and_then(|idx| idx.checked_add(1)) } /// Check if a buffer of length `len` is large enough. pub fn fits(&self, len: usize) -> bool { self.min_length().map(|min| len >= min).unwrap_or(false) } /// The extents of this array, in order of increasing strides. fn increasing_stride_dims(&self) -> [Dim; 3] { // Order extents by strides, then check that each is less equal than the next stride. let mut grouped: [Dim; 3] = [ Dim(self.channel_stride, self.channels as usize), Dim(self.width_stride, self.width as usize), Dim(self.height_stride, self.height as usize), ]; grouped.sort(); let (min_dim, mid_dim, max_dim) = (grouped[0], grouped[1], grouped[2]); assert!(min_dim.stride() <= mid_dim.stride() && mid_dim.stride() <= max_dim.stride()); grouped } /// If there are any samples aliasing each other. /// /// If this is not the case, it would always be safe to allow mutable access to two different /// samples at the same time. Otherwise, this operation would need additional checks. When one /// dimension overflows `usize` with its stride we also consider this aliasing. pub fn has_aliased_samples(&self) -> bool { let grouped = self.increasing_stride_dims(); let (min_dim, mid_dim, max_dim) = (grouped[0], grouped[1], grouped[2]); let min_size = match min_dim.checked_len() { None => return true, Some(size) => size, }; let mid_size = match mid_dim.checked_len() { None => return true, Some(size) => size, }; match max_dim.checked_len() { None => return true, Some(_) => (), // Only want to know this didn't overflow. }; // Each higher dimension must walk over all of one lower dimension. min_size > mid_dim.stride() || mid_size > max_dim.stride() } /// Check if a buffer fulfills the requirements of a normal form. /// /// Certain conversions have preconditions on the structure of the sample buffer that are not /// captured (by design) by the type system. These are then checked before the conversion. Such /// checks can all be done in constant time and will not inspect the buffer content. You can /// perform these checks yourself when the conversion is not required at this moment but maybe /// still performed later. pub fn is_normal(&self, form: NormalForm) -> bool { if self.has_aliased_samples() { return false; } if form >= NormalForm::PixelPacked && self.channel_stride != 1 { return false; } if form >= NormalForm::ImagePacked { // has aliased already checked for overflows. let grouped = self.increasing_stride_dims(); let (min_dim, mid_dim, max_dim) = (grouped[0], grouped[1], grouped[2]); if 1 != min_dim.stride() { return false; } if min_dim.len() != mid_dim.stride() { return false; } if mid_dim.len() != max_dim.stride() { return false; } } if form >= NormalForm::RowMajorPacked { if self.width_stride != self.channels as usize { return false; } if self.width as usize * self.width_stride != self.height_stride { return false; } } if form >= NormalForm::ColumnMajorPacked { if self.height_stride != self.channels as usize { return false; } if self.height as usize * self.height_stride != self.width_stride { return false; } } true } /// Check that the pixel and the channel index are in bounds. /// /// An in-bound coordinate does not yet guarantee that the corresponding calculation of a /// buffer index does not overflow. However, if such a buffer large enough to hold all samples /// actually exists in memory, this property of course follows. pub fn in_bounds(&self, channel: u8, x: u32, y: u32) -> bool { channel < self.channels && x < self.width && y < self.height } /// Resolve the index of a particular sample. /// /// `None` if the index is outside the bounds or does not fit into a `usize`. pub fn index(&self, channel: u8, x: u32, y: u32) -> Option { if !self.in_bounds(channel, x, y) { return None; } self.index_ignoring_bounds(channel as usize, x as usize, y as usize) } /// Get the theoretical position of sample (channel, x, y). /// /// The 'check' is for overflow during index calculation, not that it is contained in the /// image. Two samples may return the same index, even when one of them is out of bounds. This /// happens when all strides are `0`, i.e. the image is an arbitrarily large monochrome image. pub fn index_ignoring_bounds(&self, channel: usize, x: usize, y: usize) -> Option { let idx_c = channel.checked_mul(self.channel_stride); let idx_x = x.checked_mul(self.width_stride); let idx_y = y.checked_mul(self.height_stride); let (idx_c, idx_x, idx_y) = match (idx_c, idx_x, idx_y) { (Some(idx_c), Some(idx_x), Some(idx_y)) => (idx_c, idx_x, idx_y), _ => return None, }; Some(0usize) .and_then(|b| b.checked_add(idx_c)) .and_then(|b| b.checked_add(idx_x)) .and_then(|b| b.checked_add(idx_y)) } /// Get an index provided it is inbouds. /// /// Assumes that the image is backed by some sufficiently large buffer. Then computation can /// not overflow as we could represent the maximum coordinate. Since overflow is defined either /// way, this method can not be unsafe. pub fn in_bounds_index(&self, c: u8, x: u32, y: u32) -> usize { let (c_stride, x_stride, y_stride) = self.strides_cwh(); (y as usize * y_stride) + (x as usize * x_stride) + (c as usize * c_stride) } /// Shrink the image to the minimum of current and given extents. /// /// This does not modify the strides, so that the resulting sample buffer may have holes /// created by the shrinking operation. Shrinking could also lead to an non-aliasing image when /// samples had aliased each other before. pub fn shrink_to(&mut self, channels: u8, width: u32, height: u32) { self.channels = self.channels.min(channels); self.width = self.width.min(width); self.height = self.height.min(height); } } impl Dim { fn stride(self) -> usize { self.0 } /// Length of this dimension in memory. fn checked_len(self) -> Option { self.0.checked_mul(self.1) } fn len(self) -> usize { self.0 * self.1 } } impl FlatSamples { /// Get the strides for indexing matrix-like `[(c, w, h)]`. /// /// For a row-major layout with grouped samples, this tuple is strictly /// increasing. pub fn strides_cwh(&self) -> (usize, usize, usize) { self.layout.strides_cwh() } /// Get the dimensions `(channels, width, height)`. /// /// The interface is optimized for use with `strides_cwh` instead. The channel extent will be /// before width and height. pub fn extents(&self) -> (usize, usize, usize) { self.layout.extents() } /// Tuple of bounds in the order of coordinate inputs. /// /// This function should be used whenever working with image coordinates opposed to buffer /// coordinates. The only difference compared to `extents` is the output type. pub fn bounds(&self) -> (u8, u32, u32) { self.layout.bounds() } /// Get a reference based version. pub fn as_ref(&self) -> FlatSamples<&[T]> where Buffer: AsRef<[T]>, { FlatSamples { samples: self.samples.as_ref(), layout: self.layout, color_hint: self.color_hint, } } /// Get a mutable reference based version. pub fn as_mut(&mut self) -> FlatSamples<&mut [T]> where Buffer: AsMut<[T]>, { FlatSamples { samples: self.samples.as_mut(), layout: self.layout, color_hint: self.color_hint, } } /// Copy the data into an owned vector. pub fn to_vec(&self) -> FlatSamples> where T: Clone, Buffer: AsRef<[T]>, { FlatSamples { samples: self.samples.as_ref().to_vec(), layout: self.layout, color_hint: self.color_hint, } } /// Get a reference to a single sample. /// /// This more restrictive than the method based on `std::ops::Index` but guarantees to properly /// check all bounds and not panic as long as `Buffer::as_ref` does not do so. /// /// ``` /// # use image::{RgbImage}; /// let flat = RgbImage::new(480, 640).into_flat_samples(); /// /// // Get the blue channel at (10, 10). /// assert!(flat.get_sample(1, 10, 10).is_some()); /// /// // There is no alpha channel. /// assert!(flat.get_sample(3, 10, 10).is_none()); /// ``` /// /// For cases where a special buffer does not provide `AsRef<[T]>`, consider encapsulating /// bounds checks with `min_length` in a type similar to `View`. Then you may use /// `in_bounds_index` as a small speedup over the index calculation of this method which relies /// on `index_ignoring_bounds` since it can not have a-priori knowledge that the sample /// coordinate is in fact backed by any memory buffer. pub fn get_sample(&self, channel: u8, x: u32, y: u32) -> Option<&T> where Buffer: AsRef<[T]>, { self.index(channel, x, y) .and_then(|idx| self.samples.as_ref().get(idx)) } /// Get a mutable reference to a single sample. /// /// This more restrictive than the method based on `std::ops::IndexMut` but guarantees to /// properly check all bounds and not panic as long as `Buffer::as_ref` does not do so. /// Contrary to conversion to `ViewMut`, this does not require that samples are packed since it /// does not need to convert samples to a color representation. /// /// **WARNING**: Note that of course samples may alias, so that the mutable reference returned /// here can in fact modify more than the coordinate in the argument. /// /// ``` /// # use image::{RgbImage}; /// let mut flat = RgbImage::new(480, 640).into_flat_samples(); /// /// // Assign some new color to the blue channel at (10, 10). /// *flat.get_mut_sample(1, 10, 10).unwrap() = 255; /// /// // There is no alpha channel. /// assert!(flat.get_mut_sample(3, 10, 10).is_none()); /// ``` /// /// For cases where a special buffer does not provide `AsRef<[T]>`, consider encapsulating /// bounds checks with `min_length` in a type similar to `View`. Then you may use /// `in_bounds_index` as a small speedup over the index calculation of this method which relies /// on `index_ignoring_bounds` since it can not have a-priori knowledge that the sample /// coordinate is in fact backed by any memory buffer. pub fn get_mut_sample(&mut self, channel: u8, x: u32, y: u32) -> Option<&mut T> where Buffer: AsMut<[T]>, { match self.index(channel, x, y) { None => None, Some(idx) => self.samples.as_mut().get_mut(idx), } } /// View this buffer as an image over some type of pixel. /// /// This first ensures that all in-bounds coordinates refer to valid indices in the sample /// buffer. It also checks that the specified pixel format expects the same number of channels /// that are present in this buffer. Neither are larger nor a smaller number will be accepted. /// There is no automatic conversion. pub fn as_view

(&self) -> Result, Error> where P: Pixel, Buffer: AsRef<[P::Subpixel]>, { if self.layout.channels != P::CHANNEL_COUNT { return Err(Error::ChannelCountMismatch( self.layout.channels, P::CHANNEL_COUNT, )); } let as_ref = self.samples.as_ref(); if !self.layout.fits(as_ref.len()) { return Err(Error::TooLarge); } Ok(View { inner: FlatSamples { samples: as_ref, layout: self.layout, color_hint: self.color_hint, }, phantom: PhantomData, }) } /// View this buffer but keep mutability at a sample level. /// /// This is similar to `as_view` but subtly different from `as_view_mut`. The resulting type /// can be used as a `GenericImage` with the same prior invariants needed as for `as_view`. /// It can not be used as a mutable `GenericImage` but does not need channels to be packed in /// their pixel representation. /// /// This first ensures that all in-bounds coordinates refer to valid indices in the sample /// buffer. It also checks that the specified pixel format expects the same number of channels /// that are present in this buffer. Neither are larger nor a smaller number will be accepted. /// There is no automatic conversion. /// /// **WARNING**: Note that of course samples may alias, so that the mutable reference returned /// for one sample can in fact modify other samples as well. Sometimes exactly this is /// intended. pub fn as_view_with_mut_samples

(&mut self) -> Result, Error> where P: Pixel, Buffer: AsMut<[P::Subpixel]>, { if self.layout.channels != P::CHANNEL_COUNT { return Err(Error::ChannelCountMismatch( self.layout.channels, P::CHANNEL_COUNT, )); } let as_mut = self.samples.as_mut(); if !self.layout.fits(as_mut.len()) { return Err(Error::TooLarge); } Ok(View { inner: FlatSamples { samples: as_mut, layout: self.layout, color_hint: self.color_hint, }, phantom: PhantomData, }) } /// Interpret this buffer as a mutable image. /// /// To succeed, the pixels in this buffer may not alias each other and the samples of each /// pixel must be packed (i.e. `channel_stride` is `1`). The number of channels must be /// consistent with the channel count expected by the pixel format. /// /// This is similar to an `ImageBuffer` except it is a temporary view that is not normalized as /// strongly. To get an owning version, consider copying the data into an `ImageBuffer`. This /// provides many more operations, is possibly faster (if not you may want to open an issue) is /// generally polished. You can also try to convert this buffer inline, see /// `ImageBuffer::from_raw`. pub fn as_view_mut

(&mut self) -> Result, Error> where P: Pixel, Buffer: AsMut<[P::Subpixel]>, { if !self.layout.is_normal(NormalForm::PixelPacked) { return Err(Error::NormalFormRequired(NormalForm::PixelPacked)); } if self.layout.channels != P::CHANNEL_COUNT { return Err(Error::ChannelCountMismatch( self.layout.channels, P::CHANNEL_COUNT, )); } let as_mut = self.samples.as_mut(); if !self.layout.fits(as_mut.len()) { return Err(Error::TooLarge); } Ok(ViewMut { inner: FlatSamples { samples: as_mut, layout: self.layout, color_hint: self.color_hint, }, phantom: PhantomData, }) } /// View the samples as a slice. /// /// The slice is not limited to the region of the image and not all sample indices are valid /// indices into this buffer. See `image_mut_slice` as an alternative. pub fn as_slice(&self) -> &[T] where Buffer: AsRef<[T]>, { self.samples.as_ref() } /// View the samples as a slice. /// /// The slice is not limited to the region of the image and not all sample indices are valid /// indices into this buffer. See `image_mut_slice` as an alternative. pub fn as_mut_slice(&mut self) -> &mut [T] where Buffer: AsMut<[T]>, { self.samples.as_mut() } /// Return the portion of the buffer that holds sample values. /// /// This may fail when the coordinates in this image are either out-of-bounds of the underlying /// buffer or can not be represented. Note that the slice may have holes that do not correspond /// to any sample in the image represented by it. pub fn image_slice(&self) -> Option<&[T]> where Buffer: AsRef<[T]>, { let min_length = match self.min_length() { None => return None, Some(index) => index, }; let slice = self.samples.as_ref(); if slice.len() < min_length { return None; } Some(&slice[..min_length]) } /// Mutable portion of the buffer that holds sample values. pub fn image_mut_slice(&mut self) -> Option<&mut [T]> where Buffer: AsMut<[T]>, { let min_length = match self.min_length() { None => return None, Some(index) => index, }; let slice = self.samples.as_mut(); if slice.len() < min_length { return None; } Some(&mut slice[..min_length]) } /// Move the data into an image buffer. /// /// This does **not** convert the sample layout. The buffer needs to be in packed row-major form /// before calling this function. In case of an error, returns the buffer again so that it does /// not release any allocation. pub fn try_into_buffer

(self) -> Result, (Error, Self)> where P: Pixel + 'static, P::Subpixel: 'static, Buffer: Deref, { if !self.is_normal(NormalForm::RowMajorPacked) { return Err((Error::NormalFormRequired(NormalForm::RowMajorPacked), self)); } if self.layout.channels != P::CHANNEL_COUNT { return Err(( Error::ChannelCountMismatch(self.layout.channels, P::CHANNEL_COUNT), self, )); } if !self.fits(self.samples.deref().len()) { return Err((Error::TooLarge, self)); } Ok( ImageBuffer::from_raw(self.layout.width, self.layout.height, self.samples) .unwrap_or_else(|| { panic!("Preconditions should have been ensured before conversion") }), ) } /// Get the minimum length of a buffer such that all in-bounds samples have valid indices. /// /// This method will allow zero strides, allowing compact representations of monochrome images. /// To check that no aliasing occurs, try `check_alias_invariants`. For compact images (no /// aliasing and no unindexed samples) this is `width*height*channels`. But for both of the /// other cases, the reasoning is slightly more involved. /// /// # Explanation /// /// Note that there is a difference between `min_length` and the index of the sample /// 'one-past-the-end`. This is due to strides that may be larger than the dimension below. /// /// ## Example with holes /// /// Let's look at an example of a grayscale image with /// * `width_stride = 1` /// * `width = 2` /// * `height_stride = 3` /// * `height = 2` /// /// ```text /// | x x | x x m | $ /// min_length m ^ /// ^ one-past-the-end $ /// ``` /// /// The difference is also extreme for empty images with large strides. The one-past-the-end /// sample index is still as large as the largest of these strides while `min_length = 0`. /// /// ## Example with aliasing /// /// The concept gets even more important when you allow samples to alias each other. Here we /// have the buffer of a small grayscale image where this is the case, this time we will first /// show the buffer and then the individual rows below. /// /// * `width_stride = 1` /// * `width = 3` /// * `height_stride = 2` /// * `height = 2` /// /// ```text /// 1 2 3 4 5 m /// |1 2 3| row one /// |3 4 5| row two /// ^ m min_length /// ^ ??? one-past-the-end /// ``` /// /// This time 'one-past-the-end' is not even simply the largest stride times the extent of its /// dimension. That still points inside the image because `height*height_stride = 4` but also /// `index_of(1, 2) = 4`. pub fn min_length(&self) -> Option { self.layout.min_length() } /// Check if a buffer of length `len` is large enough. pub fn fits(&self, len: usize) -> bool { self.layout.fits(len) } /// If there are any samples aliasing each other. /// /// If this is not the case, it would always be safe to allow mutable access to two different /// samples at the same time. Otherwise, this operation would need additional checks. When one /// dimension overflows `usize` with its stride we also consider this aliasing. pub fn has_aliased_samples(&self) -> bool { self.layout.has_aliased_samples() } /// Check if a buffer fulfills the requirements of a normal form. /// /// Certain conversions have preconditions on the structure of the sample buffer that are not /// captured (by design) by the type system. These are then checked before the conversion. Such /// checks can all be done in constant time and will not inspect the buffer content. You can /// perform these checks yourself when the conversion is not required at this moment but maybe /// still performed later. pub fn is_normal(&self, form: NormalForm) -> bool { self.layout.is_normal(form) } /// Check that the pixel and the channel index are in bounds. /// /// An in-bound coordinate does not yet guarantee that the corresponding calculation of a /// buffer index does not overflow. However, if such a buffer large enough to hold all samples /// actually exists in memory, this property of course follows. pub fn in_bounds(&self, channel: u8, x: u32, y: u32) -> bool { self.layout.in_bounds(channel, x, y) } /// Resolve the index of a particular sample. /// /// `None` if the index is outside the bounds or does not fit into a `usize`. pub fn index(&self, channel: u8, x: u32, y: u32) -> Option { self.layout.index(channel, x, y) } /// Get the theoretical position of sample (x, y, channel). /// /// The 'check' is for overflow during index calculation, not that it is contained in the /// image. Two samples may return the same index, even when one of them is out of bounds. This /// happens when all strides are `0`, i.e. the image is an arbitrarily large monochrome image. pub fn index_ignoring_bounds(&self, channel: usize, x: usize, y: usize) -> Option { self.layout.index_ignoring_bounds(channel, x, y) } /// Get an index provided it is inbouds. /// /// Assumes that the image is backed by some sufficiently large buffer. Then computation can /// not overflow as we could represent the maximum coordinate. Since overflow is defined either /// way, this method can not be unsafe. pub fn in_bounds_index(&self, channel: u8, x: u32, y: u32) -> usize { self.layout.in_bounds_index(channel, x, y) } /// Shrink the image to the minimum of current and given extents. /// /// This does not modify the strides, so that the resulting sample buffer may have holes /// created by the shrinking operation. Shrinking could also lead to an non-aliasing image when /// samples had aliased each other before. pub fn shrink_to(&mut self, channels: u8, width: u32, height: u32) { self.layout.shrink_to(channels, width, height) } } impl<'buf, Subpixel> FlatSamples<&'buf [Subpixel]> { /// Create a monocolor image from a single pixel. /// /// This can be used as a very cheap source of a `GenericImageView` with an arbitrary number of /// pixels of a single color, without any dynamic allocation. /// /// ## Examples /// /// ``` /// # fn paint_something(_: T) {} /// use image::{flat::FlatSamples, GenericImage, RgbImage, Rgb}; /// /// let background = Rgb([20, 20, 20]); /// let bg = FlatSamples::with_monocolor(&background, 200, 200);; /// /// let mut image = RgbImage::new(200, 200); /// paint_something(&mut image); /// /// // Reset the canvas /// image.copy_from(&bg.as_view().unwrap(), 0, 0); /// ``` pub fn with_monocolor

(pixel: &'buf P, width: u32, height: u32) -> Self where P: Pixel, Subpixel: crate::Primitive, { FlatSamples { samples: pixel.channels(), layout: SampleLayout { channels: P::CHANNEL_COUNT, channel_stride: 1, width, width_stride: 0, height, height_stride: 0, }, // TODO this value is never set. It should be set in all places where the Pixel type implements PixelWithColorType color_hint: None, } } } /// A flat buffer that can be used as an image view. /// /// This is a nearly trivial wrapper around a buffer but at least sanitizes by checking the buffer /// length first and constraining the pixel type. /// /// Note that this does not eliminate panics as the `AsRef<[T]>` implementation of `Buffer` may be /// unreliable, i.e. return different buffers at different times. This of course is a non-issue for /// all common collections where the bounds check once must be enough. /// /// # Inner invariants /// /// * For all indices inside bounds, the corresponding index is valid in the buffer /// * `P::channel_count()` agrees with `self.inner.layout.channels` /// #[derive(Clone, Debug)] pub struct View where Buffer: AsRef<[P::Subpixel]>, { inner: FlatSamples, phantom: PhantomData

, } /// A mutable owning version of a flat buffer. /// /// While this wraps a buffer similar to `ImageBuffer`, this is mostly intended as a utility. The /// library endorsed normalized representation is still `ImageBuffer`. Also, the implementation of /// `AsMut<[P::Subpixel]>` must always yield the same buffer. Therefore there is no public way to /// construct this with an owning buffer. /// /// # Inner invariants /// /// * For all indices inside bounds, the corresponding index is valid in the buffer /// * There is no aliasing of samples /// * The samples are packed, i.e. `self.inner.layout.sample_stride == 1` /// * `P::channel_count()` agrees with `self.inner.layout.channels` /// #[derive(Clone, Debug)] pub struct ViewMut where Buffer: AsMut<[P::Subpixel]>, { inner: FlatSamples, phantom: PhantomData

, } /// Denotes invalid flat sample buffers when trying to convert to stricter types. /// /// The biggest use case being `ImageBuffer` which expects closely packed /// samples in a row major matrix representation. But this error type may be /// resused for other import functions. A more versatile user may also try to /// correct the underlying representation depending on the error variant. #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)] pub enum Error { /// The represented image was too large. /// /// The optional value denotes a possibly accepted maximal bound. TooLarge, /// The represented image can not use this representation. /// /// Has an additional value of the normalized form that would be accepted. NormalFormRequired(NormalForm), /// The color format did not match the channel count. /// /// In some cases you might be able to fix this by lowering the reported pixel count of the /// buffer without touching the strides. /// /// In very special circumstances you *may* do the opposite. This is **VERY** dangerous but not /// directly memory unsafe although that will likely alias pixels. One scenario is when you /// want to construct an `Rgba` image but have only 3 bytes per pixel and for some reason don't /// care about the value of the alpha channel even though you need `Rgba`. ChannelCountMismatch(u8, u8), /// Deprecated - ChannelCountMismatch is used instead WrongColor(ColorType), } /// Different normal forms of buffers. /// /// A normal form is an unaliased buffer with some additional constraints. The `ÌmageBuffer` uses /// row major form with packed samples. #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)] pub enum NormalForm { /// No pixel aliases another. /// /// Unaliased also guarantees that all index calculations in the image bounds using /// `dim_index*dim_stride` (such as `x*width_stride + y*height_stride`) do not overflow. Unaliased, /// At least pixels are packed. /// /// Images of these types can wrap `[T]`-slices into the standard color types. This is a /// precondition for `GenericImage` which requires by-reference access to pixels. PixelPacked, /// All samples are packed. /// /// This is orthogonal to `PixelPacked`. It requires that there are no holes in the image but /// it is not necessary that the pixel samples themselves are adjacent. An example of this /// behaviour is a planar image layout. ImagePacked, /// The samples are in row-major form and all samples are packed. /// /// In addition to `PixelPacked` and `ImagePacked` this also asserts that the pixel matrix is /// in row-major form. RowMajorPacked, /// The samples are in column-major form and all samples are packed. /// /// In addition to `PixelPacked` and `ImagePacked` this also asserts that the pixel matrix is /// in column-major form. ColumnMajorPacked, } impl View where Buffer: AsRef<[P::Subpixel]>, { /// Take out the sample buffer. /// /// Gives up the normalization invariants on the buffer format. pub fn into_inner(self) -> FlatSamples { self.inner } /// Get a reference on the inner sample descriptor. /// /// There is no mutable counterpart as modifying the buffer format, including strides and /// lengths, could invalidate the accessibility invariants of the `View`. It is not specified /// if the inner buffer is the same as the buffer of the image from which this view was /// created. It might have been truncated as an optimization. pub fn flat(&self) -> &FlatSamples { &self.inner } /// Get a reference on the inner buffer. /// /// There is no mutable counter part since it is not intended to allow you to reassign the /// buffer or otherwise change its size or properties. pub fn samples(&self) -> &Buffer { &self.inner.samples } /// Get a reference to a selected subpixel if it is in-bounds. /// /// This method will return `None` when the sample is out-of-bounds. All errors that could /// occur due to overflow have been eliminated while construction the `View`. pub fn get_sample(&self, channel: u8, x: u32, y: u32) -> Option<&P::Subpixel> { if !self.inner.in_bounds(channel, x, y) { return None; } let index = self.inner.in_bounds_index(channel, x, y); // Should always be `Some(_)` but checking is more costly. self.samples().as_ref().get(index) } /// Get a mutable reference to a selected subpixel if it is in-bounds. /// /// This is relevant only when constructed with `FlatSamples::as_view_with_mut_samples`. This /// method will return `None` when the sample is out-of-bounds. All errors that could occur due /// to overflow have been eliminated while construction the `View`. /// /// **WARNING**: Note that of course samples may alias, so that the mutable reference returned /// here can in fact modify more than the coordinate in the argument. pub fn get_mut_sample(&mut self, channel: u8, x: u32, y: u32) -> Option<&mut P::Subpixel> where Buffer: AsMut<[P::Subpixel]>, { if !self.inner.in_bounds(channel, x, y) { return None; } let index = self.inner.in_bounds_index(channel, x, y); // Should always be `Some(_)` but checking is more costly. self.inner.samples.as_mut().get_mut(index) } /// Get the minimum length of a buffer such that all in-bounds samples have valid indices. /// /// See `FlatSamples::min_length`. This method will always succeed. pub fn min_length(&self) -> usize { self.inner.min_length().unwrap() } /// Return the portion of the buffer that holds sample values. /// /// While this can not fail–the validity of all coordinates has been validated during the /// conversion from `FlatSamples`–the resulting slice may still contain holes. pub fn image_slice(&self) -> &[P::Subpixel] { &self.samples().as_ref()[..self.min_length()] } /// Return the mutable portion of the buffer that holds sample values. /// /// This is relevant only when constructed with `FlatSamples::as_view_with_mut_samples`. While /// this can not fail–the validity of all coordinates has been validated during the conversion /// from `FlatSamples`–the resulting slice may still contain holes. pub fn image_mut_slice(&mut self) -> &mut [P::Subpixel] where Buffer: AsMut<[P::Subpixel]>, { let min_length = self.min_length(); &mut self.inner.samples.as_mut()[..min_length] } /// Shrink the inner image. /// /// The new dimensions will be the minimum of the previous dimensions. Since the set of /// in-bounds pixels afterwards is a subset of the current ones, this is allowed on a `View`. /// Note that you can not change the number of channels as an intrinsic property of `P`. pub fn shrink_to(&mut self, width: u32, height: u32) { let channels = self.inner.layout.channels; self.inner.shrink_to(channels, width, height) } /// Try to convert this into an image with mutable pixels. /// /// The resulting image implements `GenericImage` in addition to `GenericImageView`. While this /// has mutable samples, it does not enforce that pixel can not alias and that samples are /// packed enough for a mutable pixel reference. This is slightly cheaper than the chain /// `self.into_inner().as_view_mut()` and keeps the `View` alive on failure. /// /// ``` /// # use image::RgbImage; /// # use image::Rgb; /// let mut buffer = RgbImage::new(480, 640).into_flat_samples(); /// let view = buffer.as_view_with_mut_samples::>().unwrap(); /// /// // Inspect some pixels, … /// /// // Doesn't fail because it was originally an `RgbImage`. /// let view_mut = view.try_upgrade().unwrap(); /// ``` pub fn try_upgrade(self) -> Result, (Error, Self)> where Buffer: AsMut<[P::Subpixel]>, { if !self.inner.is_normal(NormalForm::PixelPacked) { return Err((Error::NormalFormRequired(NormalForm::PixelPacked), self)); } // No length check or channel count check required, all the same. Ok(ViewMut { inner: self.inner, phantom: PhantomData, }) } } impl ViewMut where Buffer: AsMut<[P::Subpixel]>, { /// Take out the sample buffer. /// /// Gives up the normalization invariants on the buffer format. pub fn into_inner(self) -> FlatSamples { self.inner } /// Get a reference on the sample buffer descriptor. /// /// There is no mutable counterpart as modifying the buffer format, including strides and /// lengths, could invalidate the accessibility invariants of the `View`. It is not specified /// if the inner buffer is the same as the buffer of the image from which this view was /// created. It might have been truncated as an optimization. pub fn flat(&self) -> &FlatSamples { &self.inner } /// Get a reference on the inner buffer. /// /// There is no mutable counter part since it is not intended to allow you to reassign the /// buffer or otherwise change its size or properties. However, its contents can be accessed /// mutable through a slice with `image_mut_slice`. pub fn samples(&self) -> &Buffer { &self.inner.samples } /// Get the minimum length of a buffer such that all in-bounds samples have valid indices. /// /// See `FlatSamples::min_length`. This method will always succeed. pub fn min_length(&self) -> usize { self.inner.min_length().unwrap() } /// Get a reference to a selected subpixel. /// /// This method will return `None` when the sample is out-of-bounds. All errors that could /// occur due to overflow have been eliminated while construction the `View`. pub fn get_sample(&self, channel: u8, x: u32, y: u32) -> Option<&P::Subpixel> where Buffer: AsRef<[P::Subpixel]>, { if !self.inner.in_bounds(channel, x, y) { return None; } let index = self.inner.in_bounds_index(channel, x, y); // Should always be `Some(_)` but checking is more costly. self.samples().as_ref().get(index) } /// Get a mutable reference to a selected sample. /// /// This method will return `None` when the sample is out-of-bounds. All errors that could /// occur due to overflow have been eliminated while construction the `View`. pub fn get_mut_sample(&mut self, channel: u8, x: u32, y: u32) -> Option<&mut P::Subpixel> { if !self.inner.in_bounds(channel, x, y) { return None; } let index = self.inner.in_bounds_index(channel, x, y); // Should always be `Some(_)` but checking is more costly. self.inner.samples.as_mut().get_mut(index) } /// Return the portion of the buffer that holds sample values. /// /// While this can not fail–the validity of all coordinates has been validated during the /// conversion from `FlatSamples`–the resulting slice may still contain holes. pub fn image_slice(&self) -> &[P::Subpixel] where Buffer: AsRef<[P::Subpixel]>, { &self.inner.samples.as_ref()[..self.min_length()] } /// Return the mutable buffer that holds sample values. pub fn image_mut_slice(&mut self) -> &mut [P::Subpixel] { let length = self.min_length(); &mut self.inner.samples.as_mut()[..length] } /// Shrink the inner image. /// /// The new dimensions will be the minimum of the previous dimensions. Since the set of /// in-bounds pixels afterwards is a subset of the current ones, this is allowed on a `View`. /// Note that you can not change the number of channels as an intrinsic property of `P`. pub fn shrink_to(&mut self, width: u32, height: u32) { let channels = self.inner.layout.channels; self.inner.shrink_to(channels, width, height) } } // The out-of-bounds panic for single sample access similar to `slice::index`. #[inline(never)] #[cold] fn panic_cwh_out_of_bounds( (c, x, y): (u8, u32, u32), bounds: (u8, u32, u32), strides: (usize, usize, usize), ) -> ! { panic!( "Sample coordinates {:?} out of sample matrix bounds {:?} with strides {:?}", (c, x, y), bounds, strides ) } // The out-of-bounds panic for pixel access similar to `slice::index`. #[inline(never)] #[cold] fn panic_pixel_out_of_bounds((x, y): (u32, u32), bounds: (u32, u32)) -> ! { panic!("Image index {:?} out of bounds {:?}", (x, y), bounds) } impl Index<(u8, u32, u32)> for FlatSamples where Buffer: Index, { type Output = Buffer::Output; /// Return a reference to a single sample at specified coordinates. /// /// # Panics /// /// When the coordinates are out of bounds or the index calculation fails. fn index(&self, (c, x, y): (u8, u32, u32)) -> &Self::Output { let bounds = self.bounds(); let strides = self.strides_cwh(); let index = self .index(c, x, y) .unwrap_or_else(|| panic_cwh_out_of_bounds((c, x, y), bounds, strides)); &self.samples[index] } } impl IndexMut<(u8, u32, u32)> for FlatSamples where Buffer: IndexMut, { /// Return a mutable reference to a single sample at specified coordinates. /// /// # Panics /// /// When the coordinates are out of bounds or the index calculation fails. fn index_mut(&mut self, (c, x, y): (u8, u32, u32)) -> &mut Self::Output { let bounds = self.bounds(); let strides = self.strides_cwh(); let index = self .index(c, x, y) .unwrap_or_else(|| panic_cwh_out_of_bounds((c, x, y), bounds, strides)); &mut self.samples[index] } } impl GenericImageView for View where Buffer: AsRef<[P::Subpixel]>, { type Pixel = P; fn dimensions(&self) -> (u32, u32) { (self.inner.layout.width, self.inner.layout.height) } fn bounds(&self) -> (u32, u32, u32, u32) { let (w, h) = self.dimensions(); (0, w, 0, h) } fn in_bounds(&self, x: u32, y: u32) -> bool { let (w, h) = self.dimensions(); x < w && y < h } fn get_pixel(&self, x: u32, y: u32) -> Self::Pixel { if !self.inner.in_bounds(0, x, y) { panic_pixel_out_of_bounds((x, y), self.dimensions()) } let image = self.inner.samples.as_ref(); let base_index = self.inner.in_bounds_index(0, x, y); let channels = P::CHANNEL_COUNT as usize; let mut buffer = [Zero::zero(); 256]; buffer .iter_mut() .enumerate() .take(channels) .for_each(|(c, to)| { let index = base_index + c * self.inner.layout.channel_stride; *to = image[index]; }); *P::from_slice(&buffer[..channels]) } } impl GenericImageView for ViewMut where Buffer: AsMut<[P::Subpixel]> + AsRef<[P::Subpixel]>, { type Pixel = P; fn dimensions(&self) -> (u32, u32) { (self.inner.layout.width, self.inner.layout.height) } fn bounds(&self) -> (u32, u32, u32, u32) { let (w, h) = self.dimensions(); (0, w, 0, h) } fn in_bounds(&self, x: u32, y: u32) -> bool { let (w, h) = self.dimensions(); x < w && y < h } fn get_pixel(&self, x: u32, y: u32) -> Self::Pixel { if !self.inner.in_bounds(0, x, y) { panic_pixel_out_of_bounds((x, y), self.dimensions()) } let image = self.inner.samples.as_ref(); let base_index = self.inner.in_bounds_index(0, x, y); let channels = P::CHANNEL_COUNT as usize; let mut buffer = [Zero::zero(); 256]; buffer .iter_mut() .enumerate() .take(channels) .for_each(|(c, to)| { let index = base_index + c * self.inner.layout.channel_stride; *to = image[index]; }); *P::from_slice(&buffer[..channels]) } } impl GenericImage for ViewMut where Buffer: AsMut<[P::Subpixel]> + AsRef<[P::Subpixel]>, { fn get_pixel_mut(&mut self, x: u32, y: u32) -> &mut Self::Pixel { if !self.inner.in_bounds(0, x, y) { panic_pixel_out_of_bounds((x, y), self.dimensions()) } let base_index = self.inner.in_bounds_index(0, x, y); let channel_count =

::CHANNEL_COUNT as usize; let pixel_range = base_index..base_index + channel_count; P::from_slice_mut(&mut self.inner.samples.as_mut()[pixel_range]) } #[allow(deprecated)] fn put_pixel(&mut self, x: u32, y: u32, pixel: Self::Pixel) { *self.get_pixel_mut(x, y) = pixel; } #[allow(deprecated)] fn blend_pixel(&mut self, x: u32, y: u32, pixel: Self::Pixel) { self.get_pixel_mut(x, y).blend(&pixel); } } impl From for ImageError { fn from(error: Error) -> ImageError { #[derive(Debug)] struct NormalFormRequiredError(NormalForm); impl fmt::Display for NormalFormRequiredError { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "Required sample buffer in normal form {:?}", self.0) } } impl error::Error for NormalFormRequiredError {} match error { Error::TooLarge => ImageError::Parameter(ParameterError::from_kind( ParameterErrorKind::DimensionMismatch, )), Error::NormalFormRequired(form) => ImageError::Decoding(DecodingError::new( ImageFormatHint::Unknown, NormalFormRequiredError(form), )), Error::ChannelCountMismatch(_lc, _pc) => ImageError::Parameter( ParameterError::from_kind(ParameterErrorKind::DimensionMismatch), ), Error::WrongColor(color) => { ImageError::Unsupported(UnsupportedError::from_format_and_kind( ImageFormatHint::Unknown, UnsupportedErrorKind::Color(color.into()), )) } } } } impl fmt::Display for Error { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match self { Error::TooLarge => write!(f, "The layout is too large"), Error::NormalFormRequired(form) => write!( f, "The layout needs to {}", match form { NormalForm::ColumnMajorPacked => "be packed and in column major form", NormalForm::ImagePacked => "be fully packed", NormalForm::PixelPacked => "have packed pixels", NormalForm::RowMajorPacked => "be packed and in row major form", NormalForm::Unaliased => "not have any aliasing channels", } ), Error::ChannelCountMismatch(layout_channels, pixel_channels) => write!( f, "The channel count of the chosen pixel (={}) does agree with the layout (={})", pixel_channels, layout_channels ), Error::WrongColor(color) => write!( f, "The chosen color type does not match the hint {:?}", color ), } } } impl error::Error for Error {} impl PartialOrd for NormalForm { /// Compares the logical preconditions. /// /// `a < b` if the normal form `a` has less preconditions than `b`. fn partial_cmp(&self, other: &Self) -> Option { match (*self, *other) { (NormalForm::Unaliased, NormalForm::Unaliased) => Some(cmp::Ordering::Equal), (NormalForm::PixelPacked, NormalForm::PixelPacked) => Some(cmp::Ordering::Equal), (NormalForm::ImagePacked, NormalForm::ImagePacked) => Some(cmp::Ordering::Equal), (NormalForm::RowMajorPacked, NormalForm::RowMajorPacked) => Some(cmp::Ordering::Equal), (NormalForm::ColumnMajorPacked, NormalForm::ColumnMajorPacked) => { Some(cmp::Ordering::Equal) } (NormalForm::Unaliased, _) => Some(cmp::Ordering::Less), (_, NormalForm::Unaliased) => Some(cmp::Ordering::Greater), (NormalForm::PixelPacked, NormalForm::ColumnMajorPacked) => Some(cmp::Ordering::Less), (NormalForm::PixelPacked, NormalForm::RowMajorPacked) => Some(cmp::Ordering::Less), (NormalForm::RowMajorPacked, NormalForm::PixelPacked) => Some(cmp::Ordering::Greater), (NormalForm::ColumnMajorPacked, NormalForm::PixelPacked) => { Some(cmp::Ordering::Greater) } (NormalForm::ImagePacked, NormalForm::ColumnMajorPacked) => Some(cmp::Ordering::Less), (NormalForm::ImagePacked, NormalForm::RowMajorPacked) => Some(cmp::Ordering::Less), (NormalForm::RowMajorPacked, NormalForm::ImagePacked) => Some(cmp::Ordering::Greater), (NormalForm::ColumnMajorPacked, NormalForm::ImagePacked) => { Some(cmp::Ordering::Greater) } (NormalForm::ImagePacked, NormalForm::PixelPacked) => None, (NormalForm::PixelPacked, NormalForm::ImagePacked) => None, (NormalForm::RowMajorPacked, NormalForm::ColumnMajorPacked) => None, (NormalForm::ColumnMajorPacked, NormalForm::RowMajorPacked) => None, } } } #[cfg(test)] mod tests { use super::*; use crate::buffer_::GrayAlphaImage; use crate::color::{LumaA, Rgb}; #[test] fn aliasing_view() { let buffer = FlatSamples { samples: &[42], layout: SampleLayout { channels: 3, channel_stride: 0, width: 100, width_stride: 0, height: 100, height_stride: 0, }, color_hint: None, }; let view = buffer.as_view::>().expect("This is a valid view"); let pixel_count = view .pixels() .inspect(|pixel| assert!(pixel.2 == Rgb([42, 42, 42]))) .count(); assert_eq!(pixel_count, 100 * 100); } #[test] fn mutable_view() { let mut buffer = FlatSamples { samples: [0; 18], layout: SampleLayout { channels: 2, channel_stride: 1, width: 3, width_stride: 2, height: 3, height_stride: 6, }, color_hint: None, }; { let mut view = buffer .as_view_mut::>() .expect("This should be a valid mutable buffer"); assert_eq!(view.dimensions(), (3, 3)); #[allow(deprecated)] for i in 0..9 { *view.get_pixel_mut(i % 3, i / 3) = LumaA([2 * i as u16, 2 * i as u16 + 1]); } } buffer .samples .iter() .enumerate() .for_each(|(idx, sample)| assert_eq!(idx, *sample as usize)); } #[test] fn normal_forms() { assert!(FlatSamples { samples: [0u8; 0], layout: SampleLayout { channels: 2, channel_stride: 1, width: 3, width_stride: 9, height: 3, height_stride: 28, }, color_hint: None, } .is_normal(NormalForm::PixelPacked)); assert!(FlatSamples { samples: [0u8; 0], layout: SampleLayout { channels: 2, channel_stride: 8, width: 4, width_stride: 1, height: 2, height_stride: 4, }, color_hint: None, } .is_normal(NormalForm::ImagePacked)); assert!(FlatSamples { samples: [0u8; 0], layout: SampleLayout { channels: 2, channel_stride: 1, width: 4, width_stride: 2, height: 2, height_stride: 8, }, color_hint: None, } .is_normal(NormalForm::RowMajorPacked)); assert!(FlatSamples { samples: [0u8; 0], layout: SampleLayout { channels: 2, channel_stride: 1, width: 4, width_stride: 4, height: 2, height_stride: 2, }, color_hint: None, } .is_normal(NormalForm::ColumnMajorPacked)); } #[test] fn image_buffer_conversion() { let expected_layout = SampleLayout { channels: 2, channel_stride: 1, width: 4, width_stride: 2, height: 2, height_stride: 8, }; let initial = GrayAlphaImage::new(expected_layout.width, expected_layout.height); let buffer = initial.into_flat_samples(); assert_eq!(buffer.layout, expected_layout); let _: GrayAlphaImage = buffer.try_into_buffer().unwrap_or_else(|(error, _)| { panic!("Expected buffer to be convertible but {:?}", error) }); } }