Refactor eraser tool to use drawing logic

The eraser tool now uses the same drawing logic as the pen, creating white strokes instead of removing elements by proximity. This simplifies the eraser implementation and improves consistency between tools.

Author: DongDuong2001

app/dashboard/whiteboard/[id]/page.tsx

@@ -163,10 +163,10 @@ export default function WhiteboardEditorPage() {
     setIsDrawing(true)
     setStartPoint(point)
 
-    if (state.currentTool === "pen") {
+    if (state.currentTool === "pen" || state.currentTool === "eraser") {
       const element = createDrawingElement(state.currentTool, currentUser, currentUser, {
         points: [point],
-        color: state.currentColor,
+        color: state.currentTool === "eraser" ? "#ffffff" : state.currentColor,
         strokeWidth: state.currentStrokeWidth,
       })
       setCurrentElement(element)
@@ -192,6 +192,7 @@ export default function WhiteboardEditorPage() {
 
     switch (state.currentTool) {
       case "pen":
+      case "eraser":
         if (currentElement) {
           setCurrentElement({
             ...currentElement,
@@ -240,18 +241,9 @@ export default function WhiteboardEditorPage() {
         setCurrentElement(circleElement)
         break
 
-      case "eraser":
-        // Find and remove elements at this point
-        setState((prev) => ({
-          ...prev,
-          elements: prev.elements.filter((el) => {
-            // Simple proximity-based erasing
-            return !el.points.some(
-              (p) => Math.abs(p.x - point.x) < 10 && Math.abs(p.y - point.y) < 10
-            )
-          }),
-        }))
-        break
+      // Eraser handled in pen/eraser case above
+      // case "eraser": 
+      //   break
     }
   }