4 files changed, 167 insertions, 0 deletions
diff --git a/libhitomezashi/.gitignore b/libhitomezashi/.gitignore
new file mode 100644
index 0000000..4fffb2f
--- /dev/null
+++ b/libhitomezashi/.gitignore
@@ -0,0 +1,2 @@
+/target
+/Cargo.lock
diff --git a/libhitomezashi/Cargo.toml b/libhitomezashi/Cargo.toml
new file mode 100644
index 0000000..48e2935
--- /dev/null
+++ b/libhitomezashi/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "libhitomezashi"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+bitvec = "1.0.1"
diff --git a/libhitomezashi/src/lib.rs b/libhitomezashi/src/lib.rs
new file mode 100644
index 0000000..b07057a
--- /dev/null
+++ b/libhitomezashi/src/lib.rs
@@ -0,0 +1,63 @@
+mod pixel_buffer;
+pub use bitvec::vec::BitVec;
+use pixel_buffer::PixelBuffer;
+
+pub fn get_hitomezashi_pattern(
+    x_pattern: BitVec,
+    y_pattern: BitVec,
+    gap: usize,
+    line_thickness: usize,
+) -> PixelBuffer {
+    let mut buf = PixelBuffer::new(x_pattern.len() * gap, y_pattern.len() * gap);
+    // Draw y pattern (horizontal) lines
+    for i in 0..y_pattern.len() {
+        for j in 0..x_pattern.len() {
+            if (j % 2 != 0) == y_pattern[i] {
+                let x = j * gap;
+                let y = i * gap;
+                let width = gap;
+                let height = line_thickness;
+                buf.fill_rect(x, y, width, height);
+            }
+        }
+    }
+    // Draw x pattern (vertical) lines
+    for i in 0..x_pattern.len() {
+        for j in 0..y_pattern.len() {
+            if (j % 2 != 0) == x_pattern[i] {
+                let x = i * gap;
+                let y = j * gap;
+                let width = line_thickness;
+                let height = gap;
+                buf.fill_rect(x, y, width, height)
+            }
+        }
+    }
+
+    // Join up the lines to avoid leaving holes at the intersections
+    // The best way to understand how this works is to try commenting it out
+    for x in (gap..buf.width).step_by(gap) {
+        for y in (gap..buf.height).step_by(gap) {
+            let width = line_thickness;
+            let height = line_thickness;
+            buf.fill_rect(x, y, width, height);
+        }
+    }
+    buf
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        let mut x_pattern = BitVec::new();
+        x_pattern.resize(40, false);
+        x_pattern.set(1, true);
+        let mut y_pattern = BitVec::new();
+        y_pattern.resize(40, false);
+        y_pattern.set(1, true);
+        println!("{}", get_hitomezashi_pattern(x_pattern, y_pattern, 3, 1));
+    }
+}
diff --git a/libhitomezashi/src/pixel_buffer.rs b/libhitomezashi/src/pixel_buffer.rs
new file mode 100644
index 0000000..b151906
--- /dev/null
+++ b/libhitomezashi/src/pixel_buffer.rs
@@ -0,0 +1,93 @@
+use bitvec::prelude::*;
+use std::fmt;
+use std::ops::{Index, IndexMut};
+
+/// 2D buffer of monochrome (white/black i.e. true/false) pixels
+pub struct PixelBuffer {
+    buffer: BitVec,
+    pub width: usize,
+    pub height: usize,
+}
+
+impl PixelBuffer {
+    pub fn new(width: usize, height: usize) -> Self {
+        let mut buffer = BitVec::with_capacity(width * height);
+        buffer.resize(width * height, false);
+        PixelBuffer {
+            buffer,
+            width,
+            height,
+        }
+    }
+    pub fn fill_rect(&mut self, x: usize, y: usize, width: usize, height: usize) {
+        for i in x..(x + width) {
+            for j in y..(y + height) {
+                self[i].set(j, true);
+            }
+        }
+    }
+}
+
+impl Index<usize> for PixelBuffer {
+    type Output = BitSlice;
+
+    fn index(&self, column: usize) -> &Self::Output {
+        &self.buffer[(column * self.height)..((column + 1) * self.height)]
+    }
+}
+
+impl IndexMut<usize> for PixelBuffer {
+    fn index_mut(&mut self, column: usize) -> &mut Self::Output {
+        &mut self.buffer[(column * self.height)..((column + 1) * self.height)]
+    }
+}
+
+impl fmt::Display for PixelBuffer {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut result = String::new();
+        for y in 0..self.height {
+            for x in 0..self.width {
+                result.push(if self[x][y] { '1' } else { '0' })
+            }
+            result.push('\n')
+        }
+        write!(f, "{}", result)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn access_default() {
+        let pixel_buffer = PixelBuffer::new(2, 3);
+        assert!(pixel_buffer[0][0] == false);
+    }
+    #[test]
+    fn mutate() {
+        let mut pixel_buffer = PixelBuffer::new(2, 3);
+        pixel_buffer[1].set(2, true);
+        assert!(pixel_buffer[1][2] == true);
+    }
+    #[test]
+    #[should_panic]
+    fn access_out_of_bounds() {
+        let pixel_buffer = PixelBuffer::new(10, 20);
+        assert!(pixel_buffer[10][0] == false);
+    }
+    #[test]
+    fn print() {
+        let mut pixel_buffer = PixelBuffer::new(3, 3);
+        pixel_buffer[1].set(1, true);
+        let result = format!("{}", pixel_buffer);
+        assert!(result == "000\n010\n000\n");
+    }
+    #[test]
+    fn rect() {
+        let mut pixel_buffer = PixelBuffer::new(5, 3);
+        pixel_buffer.fill_rect(1, 0, 2, 2);
+        let result = format!("{}", pixel_buffer);
+        assert!(result == "01100\n01100\n00000\n");
+    }
+}