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Specialize the decoder by source channels as well

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This commit is contained in:
Ivan Smirnov 2021-12-31 02:00:53 +03:00
parent 9e7c508a34
commit 5b0d420200
1 changed files with 9 additions and 8 deletions
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17
src/decode.rs
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@ -10,7 +10,9 @@ use crate::header::Header;
use crate::pixel::{Pixel, SupportedChannels};
use crate::utils::{cold, unlikely};
pub fn qoi_decode_impl<const N: usize>(data: &[u8], n_pixels: usize) -> Result<Vec<u8>>
pub fn qoi_decode_impl<const N: usize, const RGBA: bool>(
data: &[u8], n_pixels: usize,
) -> Result<Vec<u8>>
where
Pixel<N>: SupportedChannels,
[u8; N]: Pod,
@ -49,10 +51,7 @@ where
px = Pixel::from_rgb(Pixel::from_array([*r, *g, *b]), px.a_or(0xff));
data = dtail;
}
[QOI_OP_RGBA, r, g, b, a, dtail @ ..] => {
if N == 4 {
cold();
}
[QOI_OP_RGBA, r, g, b, a, dtail @ ..] if RGBA => {
px = Pixel::from_array([*r, *g, *b, *a]);
data = dtail;
}
@ -127,9 +126,11 @@ pub fn qoi_decode_to_vec(
let header = qoi_decode_header(data)?;
header.validate()?;
let channels = channels.maybe_channels().unwrap_or(header.channels);
match channels {
3 => Ok((header, qoi_decode_impl::<3>(data, header.n_pixels())?)),
4 => Ok((header, qoi_decode_impl::<4>(data, header.n_pixels())?)),
match (channels, header.channels) {
(3, 3) => Ok((header, qoi_decode_impl::<3, false>(data, header.n_pixels())?)),
(3, 4) => Ok((header, qoi_decode_impl::<3, true>(data, header.n_pixels())?)),
(4, 3) => Ok((header, qoi_decode_impl::<4, false>(data, header.n_pixels())?)),
(4, 4) => Ok((header, qoi_decode_impl::<4, true>(data, header.n_pixels())?)),
_ => Err(Error::InvalidChannels { channels }),
}
}