#![deny(missing_docs)]
use std::sync::Arc;
use std::collections::HashMap;
use std::f32;
mod px;
#[allow(deprecated)]
use px::PixelFormatBackCompatShim;
pub use px::PixelFormat;
pub enum Type {
Point,
Triangle,
Catrom,
Mitchell,
Lanczos3,
Custom(Filter),
}
pub struct Filter {
kernel: Box<dyn Fn(f32) -> f32>,
support: f32,
}
impl Filter {
#[must_use]
pub fn new(kernel: Box<dyn Fn(f32) -> f32>, support: f32) -> Self {
Self { kernel, support }
}
#[must_use]
#[deprecated(note = "use Type enum")]
pub fn new_cubic(b: f32, c: f32) -> Self {
Self::new(Box::new(move |x| cubic_bc(b, c, x)), 2.0)
}
#[must_use]
#[deprecated(note = "use Type enum")]
pub fn new_lanczos(radius: f32) -> Self {
Self::new(Box::new(move |x| lanczos(radius, x)), radius)
}
}
#[inline]
fn point_kernel(_: f32) -> f32 {
1.0
}
#[inline]
fn triangle_kernel(x: f32) -> f32 {
f32::max(1.0 - x.abs(), 0.0)
}
#[inline(always)]
fn cubic_bc(b: f32, c: f32, x: f32) -> f32 {
let a = x.abs();
let k = if a < 1.0 {
(12.0 - 9.0 * b - 6.0 * c) * a.powi(3) +
(-18.0 + 12.0 * b + 6.0 * c) * a.powi(2) +
(6.0 - 2.0 * b)
} else if a < 2.0 {
(-b - 6.0 * c) * a.powi(3) +
(6.0 * b + 30.0 * c) * a.powi(2) +
(-12.0 * b - 48.0 * c) * a +
(8.0 * b + 24.0 * c)
} else {
0.0
};
k / 6.0
}
#[inline]
fn sinc(x: f32) -> f32 {
if x == 0.0 {
1.0
} else {
let a = x * f32::consts::PI;
a.sin() / a
}
}
#[inline(always)]
fn lanczos(taps: f32, x: f32) -> f32 {
if x.abs() < taps {
sinc(x) * sinc(x / taps)
} else {
0.0
}
}
#[allow(non_snake_case)]
#[allow(non_upper_case_globals)]
pub mod Pixel {
use std::marker::PhantomData;
pub(crate) mod generic {
use std::marker::PhantomData;
#[derive(Debug, Copy, Clone)]
pub struct RgbFormats<InputSubpixel, OutputSubpixel>(pub PhantomData<(InputSubpixel, OutputSubpixel)>);
#[derive(Debug, Copy, Clone)]
pub struct RgbaFormats<InputSubpixel, OutputSubpixel>(pub PhantomData<(InputSubpixel, OutputSubpixel)>);
#[derive(Debug, Copy, Clone)]
pub struct GrayFormats<InputSubpixel, OutputSubpixel>(pub PhantomData<(InputSubpixel, OutputSubpixel)>);
}
use self::generic::*;
pub const Gray8: GrayFormats<u8, u8> = GrayFormats(PhantomData);
pub const Gray16: GrayFormats<u16, u16> = GrayFormats(PhantomData);
pub const RGB24: RgbFormats<u8, u8> = RgbFormats(PhantomData);
pub const RGB48: RgbFormats<u16, u16> = RgbFormats(PhantomData);
pub const RGBA: RgbaFormats<u8, u8> = RgbaFormats(PhantomData);
pub const RGBA64: RgbaFormats<u16, u16> = RgbaFormats(PhantomData);
}
#[derive(Debug)]
pub struct Resizer<Format: PixelFormat> {
scale: Scale,
pix_fmt: Format,
tmp: Vec<Format::Accumulator>,
}
#[derive(Debug)]
struct Scale {
w1: usize,
h1: usize,
coeffs_w: Vec<CoeffsLine>,
coeffs_h: Vec<CoeffsLine>,
}
impl Scale {
#[inline]
fn w2(&self) -> usize {
self.coeffs_w.len()
}
#[inline]
fn h2(&self) -> usize {
self.coeffs_h.len()
}
}
#[derive(Debug, Clone)]
struct CoeffsLine {
start: usize,
coeffs: Arc<[f32]>,
}
type DynCallback<'a> = &'a dyn Fn(f32) -> f32;
impl Scale {
pub fn new(source_width: usize, source_heigth: usize, dest_width: usize, dest_height: usize, filter_type: Type) -> Self {
let filter = match filter_type {
Type::Point => (&point_kernel as DynCallback, 0.0_f32),
Type::Triangle => (&triangle_kernel as DynCallback, 1.0),
Type::Catrom => ((&|x| cubic_bc(0.0, 0.5, x)) as DynCallback, 2.0),
Type::Mitchell => ((&|x| cubic_bc(1.0/3.0, 1.0/3.0, x)) as DynCallback, 2.0),
Type::Lanczos3 => ((&|x| lanczos(3.0, x)) as DynCallback, 3.0),
Type::Custom(ref f) => (&f.kernel as DynCallback, f.support),
};
let mut recycled_coeffs = HashMap::new();
let coeffs_w = Self::calc_coeffs(source_width, dest_width, filter, &mut recycled_coeffs);
let coeffs_h = if source_heigth == source_width && dest_height == dest_width {
coeffs_w.clone()
} else {
Self::calc_coeffs(source_heigth, dest_height, filter, &mut recycled_coeffs)
};
Self {
w1: source_width,
h1: source_heigth,
coeffs_w,
coeffs_h,
}
}
fn calc_coeffs(s1: usize, s2: usize, (kernel, support): (&dyn Fn(f32) -> f32, f32), recycled_coeffs: &mut HashMap<(usize, [u8; 4], [u8; 4]), Arc<[f32]>>) -> Vec<CoeffsLine> {
let ratio = s1 as f64 / s2 as f64;
let filter_scale = ratio.max(1.);
let filter_radius = (support as f64 * filter_scale).ceil();
(0..s2).map(|x2| {
let x1 = (x2 as f64 + 0.5) * ratio - 0.5;
let start = (x1 - filter_radius).ceil() as isize;
let start = Self::clamp(start, 0, s1 as isize - 1) as usize;
let end = (x1 + filter_radius).floor() as isize;
let end = Self::clamp(end, 0, s1 as isize - 1) as usize;
let sum: f64 = (start..=end).map(|i| (kernel)(((i as f64 - x1) / filter_scale) as f32) as f64).sum();
let key = (end - start, (filter_scale as f32).to_ne_bytes(), (start as f32 - x1 as f32).to_ne_bytes());
let coeffs = recycled_coeffs.entry(key).or_insert_with(|| {
(start..=end).map(|i| {
let n = ((i as f64 - x1) / filter_scale) as f32;
((kernel)(n.min(support).max(-support)) as f64 / sum) as f32
}).collect::<Arc<[_]>>()
}).clone();
CoeffsLine { start, coeffs }
}).collect()
}
#[inline]
fn clamp<N: PartialOrd>(input: N, min: N, max: N) -> N {
if input > max {
max
} else if input < min {
min
} else {
input
}
}
}
impl<Format: PixelFormat> Resizer<Format> {
pub fn new(source_width: usize, source_heigth: usize, dest_width: usize, dest_height: usize, pixel_format: Format, filter_type: Type) -> Self {
Self {
scale: Scale::new(source_width, source_heigth, dest_width, dest_height, filter_type),
tmp: Vec::new(),
pix_fmt: pixel_format,
}
}
fn resample_both_axes(&mut self, src: &[Format::InputPixel], stride: usize, mut dst: &mut [Format::OutputPixel]) {
self.tmp.clear();
self.tmp.reserve(self.scale.w2() * self.scale.h1);
let mut src_rows = src.chunks(stride);
for row in &self.scale.coeffs_h {
let w2 = self.scale.w2();
while self.tmp.len() < w2 * (row.start + row.coeffs.len()) {
let row = src_rows.next().unwrap();
let pix_fmt = &self.pix_fmt;
self.tmp.extend(self.scale.coeffs_w.iter().map(|col| {
let mut accum = Format::new();
let in_px = &row[col.start..col.start + col.coeffs.len()];
for (coeff, in_px) in col.coeffs.iter().copied().zip(in_px.iter().copied()) {
pix_fmt.add(&mut accum, in_px, coeff)
}
accum
}));
}
let tmp_rows = &self.tmp[w2 * row.start..];
for (col, dst_px) in dst[0..w2].iter_mut().enumerate() {
let mut accum = Format::new();
for (coeff, other_row) in row.coeffs.iter().copied().zip(tmp_rows.chunks_exact(w2)) {
Format::add_acc(&mut accum, other_row[col], coeff);
}
*dst_px = self.pix_fmt.into_pixel(accum);
}
dst = &mut dst[w2..];
}
}
pub(crate) fn resize_internal(&mut self, src: &[Format::InputPixel], src_stride: usize, dst: &mut [Format::OutputPixel]) {
assert!(self.scale.w1 <= src_stride);
assert!(src.len() >= src_stride * self.scale.h1);
assert_eq!(dst.len(), self.scale.w2() * self.scale.h2());
self.resample_both_axes(src, src_stride, dst);
}
}
#[allow(deprecated)]
impl<Format: PixelFormatBackCompatShim> Resizer<Format> {
pub fn resize(&mut self, src: &[Format::Subpixel], dst: &mut [Format::Subpixel]) {
self.resize_internal(Format::input(src), self.scale.w1, Format::output(dst))
}
pub fn resize_stride(&mut self, src: &[Format::Subpixel], src_stride: usize, dst: &mut [Format::Subpixel]) {
self.resize_internal(Format::input(src), src_stride, Format::output(dst))
}
}
pub fn new<Format: PixelFormat>(src_width: usize, src_height: usize, dest_width: usize, dest_height: usize, pixel_format: Format, filter_type: Type) -> Resizer<Format> {
Resizer::new(src_width, src_height, dest_width, dest_height, pixel_format, filter_type)
}
#[deprecated(note="Use resize::new().resize()")]
#[allow(deprecated)]
pub fn resize<Format: PixelFormatBackCompatShim>(
src_width: usize, src_height: usize, dest_width: usize, dest_height: usize,
pixel_format: Format, filter_type: Type,
src: &[Format::Subpixel], dst: &mut [Format::Subpixel],
) {
Resizer::<Format>::new(src_width, src_height, dest_width, dest_height, pixel_format, filter_type).resize(src, dst)
}
#[test]
fn resize_stride() {
let mut r = new(2, 2, 3, 4, Pixel::Gray16, Type::Triangle);
let mut dst = vec![0; 12];
r.resize_stride(&[
65535,65535,1,2,
65535,65535,3,4,
], 4, &mut dst);
assert_eq!(&dst, &[65535; 12]);
}