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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::JxlOutputBuffer, headers::Orientation, image::Rect, util::ShiftRightCeil};
// Information for splitting the output buffers.
#[derive(Debug)]
pub(super) struct SaveStageBufferInfo {
pub(super) downsample: (u8, u8),
pub(super) orientation: Orientation,
pub(super) byte_size: usize,
pub(super) after_extend: bool,
}
/// Data structure responsible for handing out access to portions of the output buffers.
pub struct BufferSplitter<'a, 'b>(&'a mut [Option<JxlOutputBuffer<'b>>]);
impl<'a, 'b> BufferSplitter<'a, 'b> {
pub fn new(bufs: &'a mut [Option<JxlOutputBuffer<'b>>]) -> Self {
Self(bufs)
}
pub(super) fn get_local_buffers(
&mut self,
save_buffer_info: &[Option<SaveStageBufferInfo>],
rect: Rect,
outside_current_frame: bool,
frame_size: (usize, usize),
full_image_size: (usize, usize),
frame_origin: (isize, isize),
) -> Vec<Option<JxlOutputBuffer<'_>>> {
let mut local_buffers = vec![];
let buffers = &mut *self.0;
local_buffers.reserve(buffers.len());
for _ in 0..buffers.len() {
local_buffers.push(None::<JxlOutputBuffer>);
}
let rect = if !outside_current_frame {
rect.clip(frame_size)
} else {
rect
};
for (i, (info, buf)) in save_buffer_info.iter().zip(buffers.iter_mut()).enumerate() {
let Some(bi) = info else {
// We never write to this buffer.
continue;
};
let Some(buf) = buf.as_mut() else {
// The buffer to write into was not provided.
continue;
};
if outside_current_frame && !bi.after_extend {
// Before-extend stages do not write to rects outside the current frame.
continue;
}
let mut channel_rect = rect.downsample(bi.downsample);
if !outside_current_frame {
let frame_size = (
frame_size.0.shrc(bi.downsample.0),
frame_size.1.shrc(bi.downsample.1),
);
channel_rect = channel_rect.clip(frame_size);
if bi.after_extend {
// clip this rect to its visible area in the full image (in full image coordinates).
let origin = (
rect.origin.0 as isize + frame_origin.0,
rect.origin.1 as isize + frame_origin.1,
);
let end = (
origin.0 + rect.size.0 as isize,
origin.1 + rect.size.1 as isize,
);
let origin = (origin.0.max(0) as usize, origin.1.max(0) as usize);
let end = (
end.0.min(full_image_size.0 as isize).max(0) as usize,
end.1.min(full_image_size.1 as isize).max(0) as usize,
);
channel_rect = Rect {
origin,
size: (
end.0.saturating_sub(origin.0),
end.1.saturating_sub(origin.1),
),
};
}
}
if channel_rect.size.0 == 0 || channel_rect.size.1 == 0 {
// Buffer would be empty anyway.
continue;
}
let channel_rect = bi.orientation.display_rect(channel_rect, full_image_size);
let channel_rect = channel_rect.to_byte_rect_sz(bi.byte_size);
local_buffers[i] = Some(buf.rect(channel_rect));
}
local_buffers
}
pub fn get_full_buffers(&mut self) -> &mut [Option<JxlOutputBuffer<'b>>] {
&mut *self.0
}
}