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//! Minimum selection frontier.
use super::{neighbors, Frontier, RcPixel, Target};
use crate::color::{ColorSpace, Rgb8};
use crate::soft::SoftKdForest;
use acap::knn::NearestNeighbors;
use rand::Rng;
/// A pixel on a min frontier.
#[derive(Debug)]
struct MinPixel<C> {
pixel: Option<RcPixel<C>>,
filled: bool,
}
impl<C: ColorSpace> MinPixel<C>
where
C::Value: PartialOrd<C::Distance>,
{
fn new() -> Self {
Self {
pixel: None,
filled: false,
}
}
}
/// A [Frontier] that places colors on a neighbor of the closest pixel so far.
#[derive(Debug)]
pub struct MinFrontier<C, R> {
rng: R,
pixels: Vec<MinPixel<C>>,
forest: SoftKdForest<RcPixel<C>>,
width: u32,
height: u32,
x0: u32,
y0: u32,
len: usize,
deleted: usize,
}
impl<C: ColorSpace, R: Rng> MinFrontier<C, R>
where
C::Value: PartialOrd<C::Distance>,
{
/// Create a MinFrontier with the given dimensions and initial pixel location.
pub fn new(rng: R, width: u32, height: u32, x0: u32, y0: u32) -> Self {
let size = (width as usize) * (height as usize);
let mut pixels = Vec::with_capacity(size);
for _ in 0..size {
pixels.push(MinPixel::new());
}
Self {
rng,
pixels,
forest: SoftKdForest::new(),
width,
height,
x0,
y0,
len: 0,
deleted: 0,
}
}
fn pixel_index(&self, x: u32, y: u32) -> usize {
debug_assert!(x < self.width);
debug_assert!(y < self.height);
(x + y * self.width) as usize
}
fn free_neighbor(&mut self, x: u32, y: u32) -> Option<(u32, u32)> {
// Pick a pseudo-random neighbor
let offset: usize = self.rng.gen();
let neighbors = neighbors(x, y);
for i in 0..8 {
let (x, y) = neighbors[(i + offset) % 8];
if x < self.width && y < self.height {
let i = self.pixel_index(x, y);
if !self.pixels[i].filled {
return Some((x, y));
}
}
}
None
}
fn fill(&mut self, x: u32, y: u32, color: C) -> Option<(u32, u32)> {
let i = self.pixel_index(x, y);
let pixel = &mut self.pixels[i];
if pixel.filled {
return None;
}
let rc = RcPixel::new(x, y, color);
pixel.pixel = Some(rc.clone());
pixel.filled = true;
if self.free_neighbor(x, y).is_some() {
self.forest.push(rc);
self.len += 1;
}
for &(x, y) in &neighbors(x, y) {
if x < self.width && y < self.height && self.free_neighbor(x, y).is_none() {
let i = self.pixel_index(x, y);
if let Some(pixel) = self.pixels[i].pixel.take() {
pixel.delete();
self.deleted += 1;
}
}
}
if 2 * self.deleted >= self.len {
self.forest.rebuild();
self.len -= self.deleted;
self.deleted = 0;
}
Some((x, y))
}
}
impl<C: ColorSpace, R: Rng> Frontier for MinFrontier<C, R>
where
C::Value: PartialOrd<C::Distance>,
{
fn width(&self) -> u32 {
self.width
}
fn height(&self) -> u32 {
self.height
}
fn len(&self) -> usize {
self.len - self.deleted
}
fn is_empty(&self) -> bool {
self.len() == 0
}
fn place(&mut self, rgb8: Rgb8) -> Option<(u32, u32)> {
let color = C::from(rgb8);
let (x, y) = self
.forest
.nearest(&Target(color))
.map(|n| n.item.pos)
.map(|(x, y)| self.free_neighbor(x, y).unwrap())
.unwrap_or((self.x0, self.y0));
self.fill(x, y, color)
}
}
|
