picto 0.4.4

Image handling library.
Documentation 
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//            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
//                    Version 2, December 2004
//
// Copyleft (ↄ) meh. <meh@schizofreni.co> | http://meh.schizofreni.co
//
// Everyone is permitted to copy and distribute verbatim or modified
// copies of this license document, and changing it is allowed as long
// as the name is changed.
//
//            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
//   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
//
//  0. You just DO WHAT THE FUCK YOU WANT TO.

use std::{marker::PhantomData, slice};

use crate::{iter::Coordinates, pixel, region::Region};

/// Mutable iterator over pixels.
pub struct Iter<'a, P, C>
where
	P: pixel::Read<C> + pixel::Write<C>,
	C: pixel::Channel,
{
	inner: Coordinates,
	owner: Region,

	data: &'a mut [C],
	stride: usize,

	pixel: PhantomData<P>,
	channel: PhantomData<C>,
}

impl<'a, P, C> Iter<'a, P, C>
where
	P: pixel::Read<C> + pixel::Write<C>,
	C: pixel::Channel,
{
	#[doc(hidden)]
	#[inline]
	pub fn new(data: &mut [C], stride: usize, owner: Region, region: Region) -> Iter<P, C> {
		Iter {
			inner: Coordinates::new(region),
			owner,

			data,
			stride,

			pixel: PhantomData,
			channel: PhantomData,
		}
	}
}

/// A readable and writable pixel from the iterator.
#[derive(Eq, PartialEq, Debug)]
pub struct Item<'a, P, C>
where
	P: pixel::Read<C> + pixel::Write<C>,
	C: pixel::Channel,
{
	pixel: PhantomData<P>,
	channel: PhantomData<C>,
	data: &'a mut [C],
}

impl<'a, P, C> Item<'a, P, C>
where
	P: pixel::Read<C> + pixel::Write<C>,
	C: pixel::Channel,
{
	#[doc(hidden)]
	#[inline]
	pub fn new(data: &mut [C]) -> Item<P, C> {
		Item {
			pixel: PhantomData,
			channel: PhantomData,
			data,
		}
	}

	/// Get the pixel value.
	#[inline]
	pub fn get(&self) -> P {
		P::read(self.data)
	}

	/// Set the pixel value.
	#[inline]
	pub fn set(&mut self, pixel: &P) {
		pixel.write(self.data)
	}
}

impl<'a, P, C> Iterator for Iter<'a, P, C>
where
	P: pixel::Read<C> + pixel::Write<C>,
	C: pixel::Channel,
{
	type Item = (u32, u32, Item<'a, P, C>);

	#[inline]
	fn next(&mut self) -> Option<Self::Item> {
		let (x, y) = if let Some((x, y)) = self.inner.next() {
			(x, y)
		}
		else {
			return None;
		};

		let channels = P::channels();
		let index = (y as usize * self.stride) + (x as usize * channels);

		Some((
			x - self.inner.region().x,
			y - self.inner.region().y,
			Item::new(unsafe {
				let slice = &self.data[index..index + channels];
				slice::from_raw_parts_mut(slice.as_ptr() as *mut _, slice.len())
			}),
		))
	}

	#[inline]
	fn size_hint(&self) -> (usize, Option<usize>) {
		self.inner.size_hint()
	}
}

impl<'a, P, C> ExactSizeIterator for Iter<'a, P, C>
where
	P: pixel::Read<C> + pixel::Write<C>,
	C: pixel::Channel,
{
	#[inline]
	fn len(&self) -> usize {
		self.inner.len()
	}
}