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-rw-r--r--src/frontier.rs61
-rw-r--r--src/frontier/min.rs150
2 files changed, 211 insertions, 0 deletions
diff --git a/src/frontier.rs b/src/frontier.rs
index 1c5a173..e1b6528 100644
--- a/src/frontier.rs
+++ b/src/frontier.rs
@@ -1,6 +1,7 @@
//! Frontiers on which to place pixels.
pub mod image;
+pub mod min;
use crate::color::{ColorSpace, Rgb8};
use crate::metric::kd::Cartesian;
@@ -8,6 +9,7 @@ use crate::metric::soft::SoftDelete;
use crate::metric::Metric;
use std::cell::Cell;
+use std::rc::Rc;
/// A frontier of pixels.
pub trait Frontier {
@@ -85,3 +87,62 @@ impl<C> SoftDelete for Pixel<C> {
self.deleted.get()
}
}
+
+impl<C: Metric<[f64]>> Metric<[f64]> for Rc<Pixel<C>> {
+ type Distance = C::Distance;
+
+ fn distance(&self, other: &[f64]) -> Self::Distance {
+ (**self).distance(other)
+ }
+}
+
+impl<C: Metric> Metric<Rc<Pixel<C>>> for C {
+ type Distance = C::Distance;
+
+ fn distance(&self, other: &Rc<Pixel<C>>) -> Self::Distance {
+ self.distance(&other.color)
+ }
+}
+
+impl<C: Metric> Metric for Rc<Pixel<C>> {
+ type Distance = C::Distance;
+
+ fn distance(&self, other: &Self) -> Self::Distance {
+ (**self).distance(&**other)
+ }
+}
+
+impl<C: Cartesian> Cartesian for Rc<Pixel<C>> {
+ fn dimensions(&self) -> usize {
+ (**self).dimensions()
+ }
+
+ fn coordinate(&self, i: usize) -> f64 {
+ (**self).coordinate(i)
+ }
+}
+
+impl<C> SoftDelete for Rc<Pixel<C>> {
+ fn is_deleted(&self) -> bool {
+ (**self).is_deleted()
+ }
+}
+
+/// Return all the neighbors of a pixel location.
+fn neighbors(x: u32, y: u32) -> [(u32, u32); 8] {
+ let xm1 = x.wrapping_sub(1);
+ let ym1 = y.wrapping_sub(1);
+ let xp1 = x + 1;
+ let yp1 = y + 1;
+
+ [
+ (xm1, ym1),
+ (xm1, y),
+ (xm1, yp1),
+ (x, ym1),
+ (x, yp1),
+ (xp1, ym1),
+ (xp1, y),
+ (xp1, yp1),
+ ]
+}
diff --git a/src/frontier/min.rs b/src/frontier/min.rs
new file mode 100644
index 0000000..b22b290
--- /dev/null
+++ b/src/frontier/min.rs
@@ -0,0 +1,150 @@
+//! Minimum selection frontier.
+
+use super::{neighbors, Frontier, Pixel};
+
+use crate::color::{ColorSpace, Rgb8};
+use crate::metric::soft::SoftKdForest;
+use crate::metric::NearestNeighbors;
+
+use rand::Rng;
+
+use std::rc::Rc;
+
+/// A pixel on a min frontier.
+#[derive(Debug)]
+struct MinPixel<C> {
+ pixel: Option<Rc<Pixel<C>>>,
+ filled: bool,
+}
+
+impl<C: ColorSpace> MinPixel<C> {
+ 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<Rc<Pixel<C>>>,
+ width: u32,
+ height: u32,
+ x0: u32,
+ y0: u32,
+ len: usize,
+ deleted: usize,
+}
+
+impl<C: ColorSpace, R: Rng> MinFrontier<C, R> {
+ /// 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 = Rc::new(Pixel::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> {
+ fn width(&self) -> u32 {
+ self.width
+ }
+
+ fn height(&self) -> u32 {
+ self.height
+ }
+
+ fn len(&self) -> usize {
+ self.len - self.deleted
+ }
+
+ fn place(&mut self, rgb8: Rgb8) -> Option<(u32, u32)> {
+ let color = C::from(rgb8);
+ let (x, y) = self
+ .forest
+ .nearest(&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)
+ }
+}