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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
use crate::{
api::{Endianness, JxlDataFormat, JxlOutputBuffer},
error::Result,
headers::Orientation,
render::save::SaveStage,
};
use super::row_buffers::RowBuffer;
mod identity;
// Placeholder slow implementation.
impl SaveStage {
// Takes as input only those channels that are *actually* saved.
#[allow(clippy::too_many_arguments)]
pub(super) fn save_lowmem(
&self,
data: &[&RowBuffer],
buffers: &mut [Option<JxlOutputBuffer>],
group_size: (usize, usize),
frame_y: usize,
group_origin: (usize, usize),
full_image_size: (usize, usize),
frame_origin: (isize, isize),
) -> Result<()> {
let Some(buf) = buffers[self.output_buffer_index].as_mut() else {
return Ok(());
};
let group_y = frame_y - group_origin.1;
let relative_full_image_start = (
-frame_origin.0 - (group_origin.0 as isize),
-frame_origin.1 - (group_origin.1 as isize),
);
let relative_full_image_end = (
relative_full_image_start.0 + full_image_size.0 as isize,
relative_full_image_start.1 + full_image_size.1 as isize,
);
let save_start = (
relative_full_image_start.0.max(0) as usize,
relative_full_image_start.1.max(0) as usize,
);
let save_end = (
relative_full_image_end.0.clamp(0, group_size.0 as isize) as usize,
relative_full_image_end.1.clamp(0, group_size.1 as isize) as usize,
);
// If the visible area were empty, we'd have gotten None for the buffer.
assert!(save_start.0 < save_end.0);
assert!(save_start.1 < save_end.1);
if !(save_start.1..save_end.1).contains(&group_y) {
// The current row is outside the visible area - skip rendering it.
return Ok(());
}
let relative_y = group_y - save_start.1;
let save_size = (save_end.0 - save_start.0, save_end.1 - save_start.1);
let num_fast = match self.orientation {
Orientation::Identity => identity::store(
data,
frame_y,
save_start.0..save_end.0,
buf,
relative_y,
self.data_format,
),
Orientation::FlipVertical => identity::store(
data,
frame_y,
save_start.0..save_end.0,
buf,
save_size.1 - 1 - relative_y,
self.data_format,
),
_ => 0,
};
macro_rules! write_pixel {
($px: expr, $endianness: expr, $y: expr, $x: expr) => {
let px = $px;
let px_bytes = if $endianness == Endianness::LittleEndian {
px.to_le_bytes()
} else {
px.to_be_bytes()
};
buf.write_bytes($y, $x, &px_bytes);
};
}
for (c, d) in data.iter().enumerate() {
let nc = self.output_channels();
let (x0, y0) = self.orientation.display_pixel((0, relative_y), save_size);
let (x1, y1) = self.orientation.display_pixel((1, relative_y), save_size);
let x0 = x0 as isize;
let y0 = y0 as isize;
let dx = x1 as isize - x0;
let dy = y1 as isize - y0;
match self.data_format {
JxlDataFormat::U8 { .. } => {
let src_row = d.get_row::<u8>(frame_y);
for ix in (save_start.0..save_end.0).skip(num_fast) {
let px = src_row[RowBuffer::x0_offset::<u8>() + ix];
let y = (y0 + (dy * (ix - save_start.0) as isize)) as usize;
let x = (x0 + (dx * (ix - save_start.0) as isize)) as usize;
write_pixel!(px, Endianness::LittleEndian, y, x * nc + c);
}
}
JxlDataFormat::U16 { endianness, .. } | JxlDataFormat::F16 { endianness, .. } => {
let src_row = d.get_row::<u16>(frame_y);
for ix in (save_start.0..save_end.0).skip(num_fast) {
let px = src_row[RowBuffer::x0_offset::<u16>() + ix];
let y = (y0 + (dy * (ix - save_start.0) as isize)) as usize;
let x = (x0 + (dx * (ix - save_start.0) as isize)) as usize;
write_pixel!(px, endianness, y, (x * nc + c) * 2);
}
}
JxlDataFormat::F32 { endianness, .. } => {
let src_row = d.get_row::<f32>(frame_y);
for ix in (save_start.0..save_end.0).skip(num_fast) {
let px = src_row[RowBuffer::x0_offset::<f32>() + ix];
let y = (y0 + (dy * (ix - save_start.0) as isize)) as usize;
let x = (x0 + (dx * (ix - save_start.0) as isize)) as usize;
write_pixel!(px, endianness, y, (x * nc + c) * 4);
}
}
}
}
Ok(())
}
}