Introduce QR Code node (#3565)

Co-authored-by: Timon <me@timon.zip>

node-graph/nodes/vector/src/merge_qr_squares.rs

@@ -0,0 +1,118 @@
+use glam::DVec2;
+use graphic_types::Vector;
+use std::collections::VecDeque;
+use vector_types::subpath;
+
+pub fn merge_qr_squares(qr_code: &qrcodegen::QrCode, vector: &mut Vector) {
+	let size = qr_code.size() as usize;
+
+	// 0 = empty
+	// 1 = black, unvisited
+	// 2 = black, current island
+	let mut remaining = vec![vec![0u8; size]; size];
+
+	for y in 0..size {
+		for x in 0..size {
+			if qr_code.get_module(x as i32, y as i32) {
+				remaining[y][x] = 1;
+			}
+		}
+	}
+
+	for y in 0..size {
+		for x in 0..size {
+			if remaining[y][x] != 1 {
+				continue;
+			}
+
+			// fill island
+			let mut island = Vec::new();
+			let mut queue = VecDeque::new();
+			queue.push_back((x, y));
+			remaining[y][x] = 2;
+
+			while let Some((ix, iy)) = queue.pop_front() {
+				island.push((ix, iy));
+
+				for (dx, dy) in [(0, 1), (0, -1), (1, 0), (-1, 0)] {
+					let nx = ix as i32 + dx;
+					let ny = iy as i32 + dy;
+
+					if nx >= 0 && nx < size as i32 && ny >= 0 && ny < size as i32 && remaining[ny as usize][nx as usize] == 1 {
+						remaining[ny as usize][nx as usize] = 2;
+						queue.push_back((nx as usize, ny as usize));
+					}
+				}
+			}
+
+			// boundary detection
+			let mut outbound = vec![vec![0u8; size + 1]; size + 1];
+
+			for &(ix, iy) in &island {
+				if iy == 0 || remaining[iy - 1][ix] != 2 {
+					outbound[iy][ix] |= 1 << 0;
+				}
+				if ix == size - 1 || remaining[iy][ix + 1] != 2 {
+					outbound[iy][ix + 1] |= 1 << 1;
+				}
+				if iy == size - 1 || remaining[iy + 1][ix] != 2 {
+					outbound[iy + 1][ix + 1] |= 1 << 2;
+				}
+				if ix == 0 || remaining[iy][ix - 1] != 2 {
+					outbound[iy + 1][ix] |= 1 << 3;
+				}
+			}
+
+			// tracing loops
+			for vy in 0..=size {
+				for vx in 0..=size {
+					while outbound[vy][vx] != 0 {
+						let mut dir = outbound[vy][vx].trailing_zeros() as usize;
+						let start = (vx, vy);
+						let mut current = start;
+						let mut points = Vec::new();
+
+						loop {
+							points.push(DVec2::new(current.0 as f64, current.1 as f64));
+							outbound[current.1][current.0] &= !(1 << dir);
+
+							current = match dir {
+								0 => (current.0 + 1, current.1),
+								1 => (current.0, current.1 + 1),
+								2 => (current.0 - 1, current.1),
+								3 => (current.0, current.1 - 1),
+								_ => unreachable!(),
+							};
+
+							if current == start {
+								break;
+							}
+							dir = outbound[current.1][current.0].trailing_zeros() as usize;
+						}
+
+						if points.len() > 2 {
+							let mut simplified = Vec::new();
+							for i in 0..points.len() {
+								let prev = points[(i + points.len() - 1) % points.len()];
+								let curr = points[i];
+								let next = points[(i + 1) % points.len()];
+								if (curr - prev).perp_dot(next - curr).abs() > 1e-6 {
+									simplified.push(curr);
+								}
+							}
+
+							if !simplified.is_empty() {
+								vector.append_subpath(subpath::Subpath::from_anchors(simplified, true), false);
+							}
+						}
+					}
+				}
+			}
+
+			// marking island as processed
+			for &(ix, iy) in &island {
+				remaining[iy][ix] = 0;
+			}
+		}
+	}
+}