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js/geometry/GeometryLine.js

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+import GeometryPoint from "./GeometryPoint.js";
+import GeometryStroke from "./GeometryStroke.js";
+
+export default class GeometryLine
+{
+    constructor(pointA, pointB)
+    {
+        this.pointA = pointA;
+        this.pointB = pointB;
+    }
+
+    getIntersectionWithLine(line)
+    {
+        try {
+            let xa = (line.pointB.x - line.pointA.x) * (this.pointB.x * this.pointA.y - this.pointA.x * this.pointB.y);
+            let xb = (this.pointB.x - this.pointA.x) * (line.pointB.x * line.pointA.y - line.pointA.x * line.pointB.y);
+            let xc = (line.pointB.y - line.pointA.y) * (this.pointB.x - this.pointA.x);
+            let xd = (this.pointB.y - this.pointA.y) * (line.pointB.x - line.pointA.x);
+
+            let x  = (xa - xb) / (xc - xd);
+
+            if (isNaN(x)) {
+                return null;
+            }
+
+            let ya = (this.pointA.y - this.pointB.y) *(line.pointB.x * line.pointA.y - line.pointA.x * line.pointB.y);
+            let yb = (line.pointA.y - line.pointB.y) *(this.pointB.x * this.pointA.y - this.pointA.x * this.pointB.y);
+            let yc = (line.pointB.y - line.pointA.y) * (this.pointB.x - this.pointA.x);
+            let yd = (this.pointB.y - this.pointA.y) * (line.pointB.x - line.pointA.x);
+
+            let y = (ya - yb) / (yc - yd);
+
+            if (isNaN(y)) {
+                return null;
+            }
+
+            return new GeometryPoint(x, y);
+        } catch (error) {
+            return null;
+        }
+    }
+
+    getStroke()
+    {
+        return new GeometryStroke(this.pointA, this.pointB);
+    }
+
+    draw(context)
+    {
+        context.beginPath();
+        context.moveTo(this.pointA.x, this.pointA.y);
+        context.lineTo(this.pointB.x, this.pointB.y);
+        context.stroke();
+    }
+}