diff --git a/packages/core/src/app.ts b/packages/core/src/app.ts
index 669a1250..e1a45398 100644
--- a/packages/core/src/app.ts
+++ b/packages/core/src/app.ts
@@ -3,6 +3,7 @@ import Konva from 'konva';
 
 import { MouseService } from './services/mouse';
 import { ChildType, EventArgs, Plugin, Tool } from './types';
+import { Point } from './utils';
 
 export class App extends BaseService<EventArgs> {
   public stage: Konva.Stage;
@@ -41,8 +42,9 @@ export class App extends BaseService<EventArgs> {
     this.mouse = new MouseService(this);
   }
 
-  public get pointer(): Konva.Vector2d {
-    return this.stage.getPointerPosition() ?? { x: 0, y: 0 };
+  public get pointer(): Point {
+    const { x, y } = this.stage.getPointerPosition() ?? { x: 0, y: 0 };
+    return new Point(x, y);
   }
 
   public mount(element: HTMLElement) {
diff --git a/packages/core/src/tools/ellipse-tool.ts b/packages/core/src/tools/ellipse-tool.ts
index a61285ea..93881de6 100644
--- a/packages/core/src/tools/ellipse-tool.ts
+++ b/packages/core/src/tools/ellipse-tool.ts
@@ -1,14 +1,13 @@
-import Konva from 'konva';
-
 import App from '../app';
 import { Ellipse } from '../customs/ellipse';
 import { AppMouseEvent, Tool } from '../types';
+import { Point } from '../utils';
 
 import { selectTool } from './select-tool';
 
 class EllipseTool implements Tool {
   public name: string = 'ellipseTool';
-  private startPointer: Konva.Vector2d = { x: 0, y: 0 };
+  private startPointer: Point = new Point(0, 0);
   private ellipse: Ellipse | null = null;
 
   public onActive(app: App): void {
@@ -17,7 +16,7 @@ class EllipseTool implements Tool {
 
   public onInactive(): void {
     this.ellipse = null;
-    this.startPointer = { x: 0, y: 0 };
+    this.startPointer.setXY(0, 0);
   }
 
   public onMouseDown({ app }: AppMouseEvent): void {
diff --git a/packages/core/src/tools/line-tool.ts b/packages/core/src/tools/line-tool.ts
index 1d4c53b7..ba150f88 100644
--- a/packages/core/src/tools/line-tool.ts
+++ b/packages/core/src/tools/line-tool.ts
@@ -1,12 +1,11 @@
-import Konva from 'konva';
-
 import App from '../app';
 import { Line } from '../customs/line';
 import { AppMouseEvent, Tool } from '../types';
+import { Point } from '../utils';
 
 class LineTool implements Tool {
   public name: string = 'polylineTool';
-  private points: Konva.Vector2d[] = [];
+  private points: Point[] = [];
   private line: Line | null = null;
 
   public onActive(app: App): void {
diff --git a/packages/core/src/tools/rect-tool.ts b/packages/core/src/tools/rect-tool.ts
index f8a31385..e256842f 100644
--- a/packages/core/src/tools/rect-tool.ts
+++ b/packages/core/src/tools/rect-tool.ts
@@ -1,24 +1,22 @@
-import Konva from 'konva';
-
 import App from '../app';
 import { Rect } from '../customs/rect';
 import { AppMouseEvent, Tool } from '../types';
+import { Point } from '../utils';
 
 import { selectTool } from './select-tool';
 
 class RectTool implements Tool {
   public name: string = 'rectTool';
-  private startPointer: Konva.Vector2d = { x: 0, y: 0 };
+  private startPointer: Point = new Point(0, 0);
   private rectangle: Rect | null = null;
 
   public onActive(app: App): void {
     app.select();
-    this.startPointer = { x: 0, y: 0 };
   }
 
   public onInactive(): void {
     this.rectangle = null;
-    this.startPointer = { x: 0, y: 0 };
+    this.startPointer.setXY(0, 0);
   }
 
   public onMouseDown({ app }: AppMouseEvent): void {
diff --git a/packages/core/src/tools/triangle-tool.ts b/packages/core/src/tools/triangle-tool.ts
index d488d105..4f648947 100644
--- a/packages/core/src/tools/triangle-tool.ts
+++ b/packages/core/src/tools/triangle-tool.ts
@@ -1,11 +1,10 @@
-import Konva from 'konva';
-
 import { Triangle } from '../customs/triangle';
 import { Tool } from '../types';
+import { Point } from '../utils';
 
 class TriangleTool implements Tool {
   public name: string = 'triangleTool';
-  private startPointer: Konva.Vector2d = { x: 0, y: 0 };
+  private startPointer: Point = new Point(0, 0);
   private triangle: Triangle | null = null;
 
   public onActive(): void {}
diff --git a/packages/core/src/utils/index.ts b/packages/core/src/utils/index.ts
index 8dc74ae7..871a9637 100644
--- a/packages/core/src/utils/index.ts
+++ b/packages/core/src/utils/index.ts
@@ -1,5 +1,7 @@
 import { AppConfig } from '../types';
 
+export * from './math';
+
 export const DEFAULT_APP_CONFIG: AppConfig = {
   backgroundColor: '#ffffff',
 };
diff --git a/packages/core/src/utils/math.ts b/packages/core/src/utils/math.ts
new file mode 100644
index 00000000..5beb161d
--- /dev/null
+++ b/packages/core/src/utils/math.ts
@@ -0,0 +1,24 @@
+import Konva from 'konva';
+
+export class Point implements Konva.Vector2d {
+  public x: number;
+  public y: number;
+
+  constructor(x: number, y: number) {
+    this.x = x;
+    this.y = y;
+  }
+
+  public setX(x: number) {
+    this.x = x;
+  }
+
+  public setY(y: number) {
+    this.y = y;
+  }
+
+  public setXY(x: number, y: number) {
+    this.x = x;
+    this.y = y;
+  }
+}