feat: 实现曲线功能

src/mscanvas.rs

@@ -599,4 +599,48 @@ impl MSCanvas {
             }
         }
     }
+
+    fn recursive_bezier(&mut self, control_points: &[Point], t: f32) -> Point {
+        // Implement de Casteljau's algorithm
+        let n = control_points.len();
+        if n == 1 {
+            return control_points[0];
+        }
+        let mut new_points: Vec<Point> = Vec::with_capacity(n - 1);
+        for i in 0..(n - 1) {
+            let p0 = control_points[i];
+            let p1 = control_points[i + 1];
+            let point = point_add(point_muln(p0, 1.0 - t), point_muln(p1, t));
+            new_points.push(point);
+        }
+        self.recursive_bezier(&new_points[..], t)
+    }
+
+    pub fn bezier(&mut self, control_points: Vec<Point>) {
+        // Iterate through all t = 0 to t = 1 with small steps, and call de Casteljau's recursive Bezier algorithm.
+        let mut t = 0.0;
+        while t <= 1.0 {
+            let point = self.recursive_bezier(&control_points, t);
+            self.brush_circle(point);
+            t += 0.001;
+        }
+    }
+
+    pub fn quadratic_bezier(&mut self, begin: Point, end: Point, p1: Point) {
+        let points = vec![begin, p1, end];
+        self.bezier(points);
+    }
+
+    pub fn cubic_bezier(&mut self, begin: Point, end: Point, p1: Point, p2: Point) {
+        let points = vec![begin, p1, p2, end];
+        self.bezier(points);
+    }
+}
+
+fn point_muln(point: Point, t: f32) -> Point {
+    Point::new(point.x * t, point.y * t)
+}
+
+fn point_add(p1: Point, p2: Point) -> Point {
+    Point::new(p1.x + p2.x, p1.y + p2.y)
 }