1 files changed, 74 insertions, 0 deletions
diff --git a/src/frontier/image.rs b/src/frontier/image.rs
new file mode 100644
index 0000000..3655580
--- /dev/null
+++ b/src/frontier/image.rs
@@ -0,0 +1,74 @@
+//! Frontier that targets an image.
+
+use super::{Frontier, Pixel};
+
+use crate::color::{ColorSpace, Rgb8};
+use crate::metric::soft::SoftKdTree;
+use crate::metric::NearestNeighbors;
+
+use image::RgbImage;
+
+/// A [Frontier] that places colors on the closest pixel of a target image.
+#[derive(Debug)]
+pub struct ImageFrontier<C: ColorSpace> {
+    nodes: SoftKdTree<Pixel<C>>,
+    width: u32,
+    height: u32,
+    len: usize,
+    deleted: usize,
+}
+
+impl<C: ColorSpace> ImageFrontier<C> {
+    /// Create an ImageFrontier from an image.
+    pub fn new(img: &RgbImage) -> Self {
+        let width = img.width();
+        let height = img.height();
+        let len = (width as usize) * (height as usize);
+
+        Self {
+            nodes: img
+                .enumerate_pixels()
+                .map(|(x, y, p)| Pixel::new(x, y, C::from(*p)))
+                .collect(),
+            width,
+            height,
+            len,
+            deleted: 0,
+        }
+    }
+}
+
+impl<C: ColorSpace> Frontier for ImageFrontier<C> {
+    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);
+
+        if let Some(node) = self.nodes.nearest(&color).map(|n| n.item) {
+            let pos = node.pos;
+
+            node.delete();
+            self.deleted += 1;
+
+            if 32 * self.deleted >= self.len {
+                self.nodes.rebuild();
+                self.len -= self.deleted;
+                self.deleted = 0;
+            }
+
+            Some(pos)
+        } else {
+            None
+        }
+    }
+}