diff --git a/packages/board/__tests__/__snapshots__/index.test.ts.snap b/packages/board/__tests__/__snapshots__/index.test.ts.snap
index 49f584a..82f09ed 100644
--- a/packages/board/__tests__/__snapshots__/index.test.ts.snap
+++ b/packages/board/__tests__/__snapshots__/index.test.ts.snap
@@ -170,13 +170,16 @@ Array [
   },
   Object {
     "props": Object {
-      "dHeight": 150,
-      "dWidth": 300,
+      "dHeight": 3600,
+      "dWidth": 4000,
       "dx": 0,
       "dy": 0,
-      "img": <canvas />,
-      "sHeight": 150,
-      "sWidth": 300,
+      "img": <canvas
+        height="3600"
+        width="4000"
+      />,
+      "sHeight": 3600,
+      "sWidth": 4000,
       "sx": 0,
       "sy": 0,
     },
diff --git a/packages/board/__tests__/__snapshots__/other-api.test.ts.snap b/packages/board/__tests__/__snapshots__/other-api.test.ts.snap
index ff9ac7e..7a032cb 100644
--- a/packages/board/__tests__/__snapshots__/other-api.test.ts.snap
+++ b/packages/board/__tests__/__snapshots__/other-api.test.ts.snap
@@ -170,13 +170,16 @@ Array [
   },
   Object {
     "props": Object {
-      "dHeight": 150,
-      "dWidth": 300,
+      "dHeight": 1600,
+      "dWidth": 2400,
       "dx": -2400,
       "dy": -1600,
-      "img": <canvas />,
-      "sHeight": 150,
-      "sWidth": 300,
+      "img": <canvas
+        height="1600"
+        width="2400"
+      />,
+      "sHeight": 1600,
+      "sWidth": 2400,
       "sx": 0,
       "sy": 0,
     },
diff --git a/packages/board/__tests__/__snapshots__/scale.test.ts.snap b/packages/board/__tests__/__snapshots__/scale.test.ts.snap
index bd59c39..b931f2d 100644
--- a/packages/board/__tests__/__snapshots__/scale.test.ts.snap
+++ b/packages/board/__tests__/__snapshots__/scale.test.ts.snap
@@ -170,13 +170,16 @@ Array [
   },
   Object {
     "props": Object {
-      "dHeight": 150,
-      "dWidth": 300,
+      "dHeight": 3600,
+      "dWidth": 4000,
       "dx": 200,
       "dy": 0,
-      "img": <canvas />,
-      "sHeight": 150,
-      "sWidth": 300,
+      "img": <canvas
+        height="3600"
+        width="4000"
+      />,
+      "sHeight": 3600,
+      "sWidth": 4000,
       "sx": 0,
       "sy": 0,
     },
@@ -363,13 +366,16 @@ Array [
   },
   Object {
     "props": Object {
-      "dHeight": 150,
-      "dWidth": 300,
+      "dHeight": 2400,
+      "dWidth": 4800,
       "dx": 0,
       "dy": 200,
-      "img": <canvas />,
-      "sHeight": 150,
-      "sWidth": 300,
+      "img": <canvas
+        height="2400"
+        width="4800"
+      />,
+      "sHeight": 2400,
+      "sWidth": 4800,
       "sx": 0,
       "sy": 0,
     },
@@ -556,13 +562,16 @@ Array [
   },
   Object {
     "props": Object {
-      "dHeight": 150,
-      "dWidth": 300,
+      "dHeight": 2400,
+      "dWidth": 4000,
       "dx": 0,
       "dy": 0,
-      "img": <canvas />,
-      "sHeight": 150,
-      "sWidth": 300,
+      "img": <canvas
+        height="2400"
+        width="4000"
+      />,
+      "sHeight": 2400,
+      "sWidth": 4000,
       "sx": 0,
       "sy": 0,
     },
@@ -749,13 +758,16 @@ Array [
   },
   Object {
     "props": Object {
-      "dHeight": 150,
-      "dWidth": 300,
+      "dHeight": 1600,
+      "dWidth": 2400,
       "dx": 600,
       "dy": 400,
-      "img": <canvas />,
-      "sHeight": 150,
-      "sWidth": 300,
+      "img": <canvas
+        height="1600"
+        width="2400"
+      />,
+      "sHeight": 1600,
+      "sWidth": 2400,
       "sx": 0,
       "sy": 0,
     },
diff --git a/packages/board/__tests__/__snapshots__/scroll.test.ts.snap b/packages/board/__tests__/__snapshots__/scroll.test.ts.snap
index 47ad42e..31ee226 100644
--- a/packages/board/__tests__/__snapshots__/scroll.test.ts.snap
+++ b/packages/board/__tests__/__snapshots__/scroll.test.ts.snap
@@ -170,13 +170,16 @@ Array [
   },
   Object {
     "props": Object {
-      "dHeight": 150,
-      "dWidth": 300,
+      "dHeight": 1600,
+      "dWidth": 2400,
       "dx": -2400,
       "dy": -1600,
-      "img": <canvas />,
-      "sHeight": 150,
-      "sWidth": 300,
+      "img": <canvas
+        height="1600"
+        width="2400"
+      />,
+      "sHeight": 1600,
+      "sWidth": 2400,
       "sx": 0,
       "sy": 0,
     },
diff --git a/packages/board/__tests__/__snapshots__/wheel.test.ts.snap b/packages/board/__tests__/__snapshots__/wheel.test.ts.snap
index 8da0ae8..0b49daf 100644
--- a/packages/board/__tests__/__snapshots__/wheel.test.ts.snap
+++ b/packages/board/__tests__/__snapshots__/wheel.test.ts.snap
@@ -170,13 +170,16 @@ Array [
   },
   Object {
     "props": Object {
-      "dHeight": 150,
-      "dWidth": 300,
+      "dHeight": 1600,
+      "dWidth": 2400,
       "dx": -2400,
       "dy": -1600,
-      "img": <canvas />,
-      "sHeight": 150,
-      "sWidth": 300,
+      "img": <canvas
+        height="1600"
+        width="2400"
+      />,
+      "sHeight": 1600,
+      "sWidth": 2400,
       "sx": 0,
       "sy": 0,
     },
diff --git a/packages/board/examples/features/lib/action.js b/packages/board/examples/features/lib/action.js
index fe4ce3d..f6cb461 100644
--- a/packages/board/examples/features/lib/action.js
+++ b/packages/board/examples/features/lib/action.js
@@ -33,7 +33,7 @@ function moveElement(board, idx, moveX, moveY) {
     data.elements[idx].x += (moveX / scale);
     data.elements[idx].y += (moveY / scale);
   }
-  drawData(board)
+  drawData(board, idx)
 }
 
 const cursor = document.querySelector('#cursor');
diff --git a/packages/board/examples/features/lib/draw.js b/packages/board/examples/features/lib/draw.js
index 28e2b70..7a817ff 100644
--- a/packages/board/examples/features/lib/draw.js
+++ b/packages/board/examples/features/lib/draw.js
@@ -1,16 +1,37 @@
 import opts from './opts.js';
 import { getData } from './data.js';
 
-export function drawData(board) {
+export function drawData(board, idx) {
   const ctx = board.getContext();
+  const helperCtx = board.getHelperContext();
   const data = getData();
   board.clear();
   ctx.clearRect(0, 0, opts.width, opts.height);
+  helperCtx.clearRect(0, 0, opts.width, opts.height);
+
   // ctx.setFillStyle('#ffffff');
   // ctx.fillRect(0, 0, opts.width, opts.height);
-  data.elements.forEach(ele => {
+
+  data.elements.forEach((ele, i) => {
     ctx.setFillStyle(ele.desc.color);
     ctx.fillRect(ele.x, ele.y, ele.w, ele.h);
+
+    // helperCtx.setFillStyle('#2196f3');
+    // helperCtx.fillRect(ele.x, ele.y, ele.w, ele.h);
+
+    if (i === idx) {
+      helperCtx.beginPath();
+      helperCtx.setLineDash([4, 4]);
+      helperCtx.setLineWidth(2);
+      helperCtx.setStrokeStyle('#2196f3');
+      helperCtx.moveTo(ele.x, ele.y);
+      helperCtx.lineTo(ele.x + ele.w, ele.y);
+      helperCtx.lineTo(ele.x + ele.w, ele.y + ele.h);
+      helperCtx.lineTo(ele.x, ele.y + ele.h);
+      helperCtx.lineTo(ele.x, ele.y);
+      helperCtx.stroke();
+      helperCtx.closePath();
+    }
   });
   board.draw();
 }
\ No newline at end of file
diff --git a/packages/board/src/index.ts b/packages/board/src/index.ts
index 67cadd9..8c18bcf 100644
--- a/packages/board/src/index.ts
+++ b/packages/board/src/index.ts
@@ -49,16 +49,17 @@ class Board {
     this[_displayCanvas] = document.createElement('canvas');
     this[_mount].appendChild(this[_displayCanvas]);
     this[_opts] = this[_parsePrivateOptions](opts);
-    const originCtx = this[_canvas].getContext('2d') as CanvasRenderingContext2D;
-    const displayCtx = this[_displayCanvas].getContext('2d') as CanvasRenderingContext2D;
-    const helperCtx = this[_displayCanvas].getContext('2d') as CanvasRenderingContext2D;
-    this[_ctx] = new Context(originCtx, this[_opts]);
-    this[_helperCtx] = new Context(helperCtx, this[_opts]);
+
+    const originCtx2d = this[_canvas].getContext('2d') as CanvasRenderingContext2D;
+    const displayCtx2d = this[_displayCanvas].getContext('2d') as CanvasRenderingContext2D;
+    const helperCtx2d = this[_helperCanvas].getContext('2d') as CanvasRenderingContext2D;
+    this[_ctx] = new Context(originCtx2d, this[_opts]);
+    this[_helperCtx] = new Context(helperCtx2d, this[_opts]);
     this[_screen] = new Screen(this[_ctx], this[_opts]);
     // this[_watcher] = new Watcher(this[_displayCanvas]);
     this[_watcher] = new ScreenWatcher(this[_displayCanvas], this[_ctx]);
     this[_scroller] = new Scroller(
-      displayCtx, {
+      displayCtx2d, {
         width: opts.width,
         height: opts.height,
         devicePixelRatio: opts.devicePixelRatio || 1,
@@ -245,6 +246,9 @@ class Board {
     this[_canvas].width = contextWidth * devicePixelRatio;
     this[_canvas].height = contextHeight * devicePixelRatio;
 
+    this[_helperCanvas].width = contextWidth * devicePixelRatio;
+    this[_helperCanvas].height = contextHeight * devicePixelRatio;
+
     this[_displayCanvas].width = width * devicePixelRatio;
     this[_displayCanvas].height = height * devicePixelRatio;
 
diff --git a/packages/core/__tests__/__snapshots__/index.test.ts.snap b/packages/core/__tests__/__snapshots__/index.test.ts.snap
index c9ebfdb..10bcf8f 100644
--- a/packages/core/__tests__/__snapshots__/index.test.ts.snap
+++ b/packages/core/__tests__/__snapshots__/index.test.ts.snap
@@ -591,13 +591,16 @@ Array [
   },
   Object {
     "props": Object {
-      "dHeight": 150,
-      "dWidth": 300,
+      "dHeight": 1600,
+      "dWidth": 2400,
       "dx": 0,
       "dy": 0,
-      "img": <canvas />,
-      "sHeight": 150,
-      "sWidth": 300,
+      "img": <canvas
+        height="1600"
+        width="2400"
+      />,
+      "sHeight": 1600,
+      "sWidth": 2400,
       "sx": 0,
       "sy": 0,
     },
diff --git a/packages/core/__tests__/__snapshots__/move.test.ts.snap b/packages/core/__tests__/__snapshots__/move.test.ts.snap
index f4e1987..98062eb 100644
--- a/packages/core/__tests__/__snapshots__/move.test.ts.snap
+++ b/packages/core/__tests__/__snapshots__/move.test.ts.snap
@@ -591,13 +591,16 @@ Array [
   },
   Object {
     "props": Object {
-      "dHeight": 150,
-      "dWidth": 300,
+      "dHeight": 1600,
+      "dWidth": 2400,
       "dx": 0,
       "dy": 0,
-      "img": <canvas />,
-      "sHeight": 150,
-      "sWidth": 300,
+      "img": <canvas
+        height="1600"
+        width="2400"
+      />,
+      "sHeight": 1600,
+      "sWidth": 2400,
       "sx": 0,
       "sy": 0,
     },
@@ -1205,13 +1208,16 @@ Array [
   },
   Object {
     "props": Object {
-      "dHeight": 150,
-      "dWidth": 300,
+      "dHeight": 1600,
+      "dWidth": 2400,
       "dx": 0,
       "dy": 0,
-      "img": <canvas />,
-      "sHeight": 150,
-      "sWidth": 300,
+      "img": <canvas
+        height="1600"
+        width="2400"
+      />,
+      "sHeight": 1600,
+      "sWidth": 2400,
       "sx": 0,
       "sy": 0,
     },