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#![warn(missing_docs)]
use image::{Rgb, RgbImage};
mod interpolation;
#[allow(clippy::type_complexity)]
pub fn reverse_dense(
img_src: &RgbImage,
controls_src: &[(f32, f32)],
controls_dst: &[(f32, f32)],
deform_function: fn(&[(f32, f32)], &[(f32, f32)], (f32, f32)) -> (f32, f32),
) -> RgbImage {
let (width, height) = img_src.dimensions();
let color_outside = Rgb([0, 0, 0]);
RgbImage::from_fn(width, height, |x, y| {
let (x2, y2) = deform_function(controls_dst, controls_src, (x as f32, y as f32));
interpolation::bilinear(img_src, x2, y2).unwrap_or(color_outside)
})
}
#[allow(clippy::type_complexity)]
pub fn reverse_sparse(
img_src: &RgbImage,
controls_src: &[(f32, f32)],
controls_dst: &[(f32, f32)],
subresolution_factor: u32,
deform_function: fn(&[(f32, f32)], &[(f32, f32)], (f32, f32)) -> (f32, f32),
) -> RgbImage {
let (width, height) = img_src.dimensions();
let color_outside = Rgb([0, 0, 0]);
let sub_width = (width - 1) / subresolution_factor + 2;
let sub_height = (height - 1) / subresolution_factor + 2;
let anchors: Vec<Vec<(f32, f32)>> = (0..sub_height)
.map(|v| {
let y = (v * subresolution_factor) as f32;
(0..sub_width)
.map(|u| {
let x = (u * subresolution_factor) as f32;
deform_function(controls_dst, controls_src, (x, y))
})
.collect()
})
.collect();
RgbImage::from_fn(width, height, |x, y| {
let sub_left = x / subresolution_factor;
let sub_top = y / subresolution_factor;
let top_left_corner = (
subresolution_factor * sub_left,
subresolution_factor * sub_top,
);
let bot_right_corner = (
top_left_corner.0 + subresolution_factor,
top_left_corner.1 + subresolution_factor,
);
let sub_left = sub_left as usize;
let sub_top = sub_top as usize;
let corners_dst = [
anchors[sub_top][sub_left],
anchors[sub_top][sub_left + 1],
anchors[sub_top + 1][sub_left],
anchors[sub_top + 1][sub_left + 1],
];
let (x2, y2) = bilinear_warp(top_left_corner, bot_right_corner, corners_dst, (x, y));
interpolation::bilinear(img_src, x2, y2).unwrap_or(color_outside)
})
}
fn bilinear_warp(
top_left_corner: (u32, u32),
bot_right_corner: (u32, u32),
corners_dst: [(f32, f32); 4],
src_pos: (u32, u32),
) -> (f32, f32) {
let (u, v) = src_pos;
let (left, top) = top_left_corner;
let (right, bottom) = bot_right_corner;
let [dst_tl, dst_tr, dst_bl, dst_br] = corners_dst;
let coef_left = right - u;
let coef_right = u - left;
let coef_top = bottom - v;
let coef_bot = v - top;
let coef_tl = (coef_top * coef_left) as f32;
let coef_tr = (coef_top * coef_right) as f32;
let coef_bl = (coef_bot * coef_left) as f32;
let coef_br = (coef_bot * coef_right) as f32;
let area = ((right - left) * (bottom - top)) as f32;
let x =
((coef_tl * dst_tl.0) + (coef_tr * dst_tr.0) + (coef_bl * dst_bl.0) + (coef_br * dst_br.0))
/ area;
let y =
((coef_tl * dst_tl.1) + (coef_tr * dst_tr.1) + (coef_bl * dst_bl.1) + (coef_br * dst_br.1))
/ area;
(x, y)
}