유틸 콜백 추가

@@ -4,6 +4,35 @@ import { Vector } from './types';
 export const Canvas: React.FC = () => {
   const canvasRef = useRef<HTMLCanvasElement>(null);
 
+  const getCoordinates = useCallback((event: MouseEvent): Vector | undefined => {
+    if (!canvasRef.current) {
+      return;
+    } else {
+      return {
+        x: event.pageX - canvasRef.current.offsetLeft,
+        y: event.pageY - canvasRef.current.offsetTop
+      };
+    }
+  }, []);
+
+  const drawLine = useCallback((prev: Vector, current: Vector) => {
+    if (canvasRef.current) {
+      const context = canvasRef.current!.getContext('2d');
+      if (context) {
+        context.strokeStyle = 'black';
+        context.lineJoin = 'round';
+        context.lineWidth = 5;
+
+        context.beginPath();
+        context.moveTo(prev.x, prev.y);
+        context.lineTo(current.x, current.y);
+        context.closePath();
+
+        context.stroke();
+      }
+    }
+  }, []);
+
   return (
     <div className='mx-3 px-2 py-1 rounded shadow'>
       <canvas ref={canvasRef} width='512' height='384' />