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#[cfg(any(feature = "std", feature = "alloc"))]
use alloc::{vec, vec::Vec};
use core::convert::TryFrom;
#[cfg(feature = "std")]
use std::io::Write;
use bytemuck::Pod;
use crate::consts::{QOI_HEADER_SIZE, QOI_OP_INDEX, QOI_OP_RUN, QOI_PADDING, QOI_PADDING_SIZE};
use crate::error::{Error, Result};
use crate::header::Header;
use crate::pixel::{Pixel, SupportedChannels};
use crate::types::{Channels, ColorSpace};
#[cfg(feature = "std")]
use crate::utils::GenericWriter;
use crate::utils::{unlikely, BytesMut, Writer};
#[allow(clippy::cast_possible_truncation, unused_assignments, unused_variables)]
fn encode_impl<W: Writer, const N: usize>(mut buf: W, data: &[u8]) -> Result<usize>
where
Pixel<N>: SupportedChannels,
[u8; N]: Pod,
{
let cap = buf.capacity();
let mut index = [Pixel::new(); 256];
let mut px_prev = Pixel::new().with_a(0xff);
let mut hash_prev = px_prev.hash_index();
let mut run = 0_u8;
let mut px = Pixel::<N>::new().with_a(0xff);
let mut index_allowed = false;
let n_pixels = data.len() / N;
for (i, chunk) in data.chunks_exact(N).enumerate() {
px.read(chunk);
if px == px_prev {
run += 1;
if run == 62 || unlikely(i == n_pixels - 1) {
buf = buf.write_one(QOI_OP_RUN | (run - 1))?;
run = 0;
}
} else {
if run != 0 {
#[cfg(not(feature = "reference"))]
{
buf = buf.write_one(if run == 1 && index_allowed {
QOI_OP_INDEX | hash_prev
} else {
QOI_OP_RUN | (run - 1)
})?;
}
#[cfg(feature = "reference")]
{
buf = buf.write_one(QOI_OP_RUN | (run - 1))?;
}
run = 0;
}
index_allowed = true;
let px_rgba = px.as_rgba(0xff);
hash_prev = px_rgba.hash_index();
let index_px = &mut index[hash_prev as usize];
if *index_px == px_rgba {
buf = buf.write_one(QOI_OP_INDEX | hash_prev)?;
} else {
*index_px = px_rgba;
buf = px.encode_into(px_prev, buf)?;
}
px_prev = px;
}
}
buf = buf.write_many(&QOI_PADDING)?;
Ok(cap.saturating_sub(buf.capacity()))
}
#[inline]
fn encode_impl_all<W: Writer>(out: W, data: &[u8], channels: Channels) -> Result<usize> {
match channels {
Channels::Rgb => encode_impl::<_, 3>(out, data),
Channels::Rgba => encode_impl::<_, 4>(out, data),
}
}
#[inline]
pub fn encode_max_len(width: u32, height: u32, channels: impl Into<u8>) -> usize {
let (width, height) = (width as usize, height as usize);
let n_pixels = width.saturating_mul(height);
QOI_HEADER_SIZE
+ n_pixels.saturating_mul(channels.into() as usize)
+ n_pixels
+ QOI_PADDING_SIZE
}
#[inline]
pub fn encode_to_buf(
buf: impl AsMut<[u8]>, data: impl AsRef<[u8]>, width: u32, height: u32,
) -> Result<usize> {
Encoder::new(&data, width, height)?.encode_to_buf(buf)
}
#[cfg(any(feature = "alloc", feature = "std"))]
#[inline]
pub fn encode_to_vec(data: impl AsRef<[u8]>, width: u32, height: u32) -> Result<Vec<u8>> {
Encoder::new(&data, width, height)?.encode_to_vec()
}
pub struct Encoder<'a> {
data: &'a [u8],
header: Header,
}
impl<'a> Encoder<'a> {
#[inline]
#[allow(clippy::cast_possible_truncation)]
pub fn new(data: &'a (impl AsRef<[u8]> + ?Sized), width: u32, height: u32) -> Result<Self> {
let data = data.as_ref();
let mut header =
Header::try_new(width, height, Channels::default(), ColorSpace::default())?;
let size = data.len();
let n_channels = size / header.n_pixels();
if header.n_pixels() * n_channels != size {
return Err(Error::InvalidImageLength { size, width, height });
}
header.channels = Channels::try_from(n_channels.min(0xff) as u8)?;
Ok(Self { data, header })
}
#[inline]
pub const fn with_colorspace(mut self, colorspace: ColorSpace) -> Self {
self.header = self.header.with_colorspace(colorspace);
self
}
#[inline]
pub const fn channels(&self) -> Channels {
self.header.channels
}
#[inline]
pub const fn header(&self) -> &Header {
&self.header
}
#[inline]
pub fn required_buf_len(&self) -> usize {
self.header.encode_max_len()
}
#[inline]
pub fn encode_to_buf(&self, mut buf: impl AsMut<[u8]>) -> Result<usize> {
let buf = buf.as_mut();
let size_required = self.required_buf_len();
if unlikely(buf.len() < size_required) {
return Err(Error::OutputBufferTooSmall { size: buf.len(), required: size_required });
}
let (head, tail) = buf.split_at_mut(QOI_HEADER_SIZE);
head.copy_from_slice(&self.header.encode());
let n_written = encode_impl_all(BytesMut::new(tail), self.data, self.header.channels)?;
Ok(QOI_HEADER_SIZE + n_written)
}
#[cfg(any(feature = "alloc", feature = "std"))]
#[inline]
pub fn encode_to_vec(&self) -> Result<Vec<u8>> {
let mut out = vec![0_u8; self.required_buf_len()];
let size = self.encode_to_buf(&mut out)?;
out.truncate(size);
Ok(out)
}
#[cfg(feature = "std")]
#[inline]
pub fn encode_to_stream<W: Write>(&self, writer: &mut W) -> Result<usize> {
writer.write_all(&self.header.encode())?;
let n_written =
encode_impl_all(GenericWriter::new(writer), self.data, self.header.channels)?;
Ok(n_written + QOI_HEADER_SIZE)
}
}