2 files changed, 19 insertions, 0 deletions
diff --git a/src/frontier.rs b/src/frontier.rs
new file mode 100644
index 0000000..2c6f43a
--- /dev/null
+++ b/src/frontier.rs
@@ -0,0 +1,18 @@
+//! Frontiers on which to place pixels.
+
+use crate::color::Rgb8;
+
+/// A frontier of pixels.
+pub trait Frontier {
+    /// The width of the image.
+    fn width(&self) -> u32;
+
+    /// The height of the image.
+    fn height(&self) -> u32;
+
+    /// The number of pixels currently on the frontier.
+    fn len(&self) -> usize;
+
+    /// Place the given color on the frontier, and return its position.
+    fn place(&mut self, rgb8: Rgb8) -> Option<(u32, u32)>;
+}
diff --git a/src/main.rs b/src/main.rs
index a59a0cf..07e138a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,4 +1,5 @@
 pub mod color;
+pub mod frontier;
 pub mod hilbert;
 pub mod metric;