From 21db91d0f5fdea629302cbde881cbafb1e68fd18 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 11 Jul 2025 06:44:20 +0000
Subject: [PATCH 1/2] Initial plan


From 27d6d236318f9159a548e4f8f259231829d01562 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 11 Jul 2025 06:51:45 +0000
Subject: [PATCH 2/2] Fix eraser tool to properly erase instead of painting
 white

Co-authored-by: A1L13N <193832434+A1L13N@users.noreply.github.com>
---
 web/templates/whiteboard.html | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/web/templates/whiteboard.html b/web/templates/whiteboard.html
index e2380d29c..2154ae4cf 100644
--- a/web/templates/whiteboard.html
+++ b/web/templates/whiteboard.html
@@ -86,10 +86,16 @@ <h1 class="text-2xl font-bold mb-4">Advanced Whiteboard</h1>
       toolSelect.addEventListener('change', function() {
           currentTool = this.value;
           if (currentTool === 'pen') {
+              ctx.globalCompositeOperation = 'source-over';
               ctx.globalAlpha = 1.0;
           } else if (currentTool === 'highlighter') {
+              ctx.globalCompositeOperation = 'source-over';
               ctx.globalAlpha = 0.3;
+          } else if (currentTool === 'eraser') {
+              ctx.globalCompositeOperation = 'destination-out';
+              ctx.globalAlpha = 1.0;
           } else {
+              ctx.globalCompositeOperation = 'source-over';
               ctx.globalAlpha = 1.0;
           }
       });
@@ -213,12 +219,14 @@ <h1 class="text-2xl font-bold mb-4">Advanced Whiteboard</h1>
 
           if (currentTool === 'pen' || currentTool === 'eraser' || currentTool === 'highlighter') {
               if (currentTool === 'eraser') {
-                  ctx.strokeStyle = "#FFFFFF";
+                  ctx.globalCompositeOperation = 'destination-out';
                   ctx.globalAlpha = 1.0;
               } else if (currentTool === 'pen') {
+                  ctx.globalCompositeOperation = 'source-over';
                   ctx.strokeStyle = penColor;
                   ctx.globalAlpha = 1.0;
               } else if (currentTool === 'highlighter') {
+                  ctx.globalCompositeOperation = 'source-over';
                   ctx.strokeStyle = penColor;
                   ctx.globalAlpha = 0.3;
               }
@@ -227,6 +235,7 @@ <h1 class="text-2xl font-bold mb-4">Advanced Whiteboard</h1>
               ctx.stroke();
           } else if (currentTool === 'line' || currentTool === 'rectangle' || currentTool === 'circle' || currentTool === 'arrow') {
               restoreSnapshot();
+              ctx.globalCompositeOperation = 'source-over';
               ctx.lineWidth = penWidth;
               ctx.strokeStyle = penColor;
 
@@ -261,23 +270,27 @@ <h1 class="text-2xl font-bold mb-4">Advanced Whiteboard</h1>
 
           if (currentTool === 'line') {
               restoreSnapshot();
+              ctx.globalCompositeOperation = 'source-over';
               ctx.beginPath();
               ctx.moveTo(startX, startY);
               ctx.lineTo(currentX, currentY);
               ctx.stroke();
           } else if (currentTool === 'rectangle') {
               restoreSnapshot();
+              ctx.globalCompositeOperation = 'source-over';
               const width = currentX - startX;
               const height = currentY - startY;
               ctx.strokeRect(startX, startY, width, height);
           } else if (currentTool === 'circle') {
               restoreSnapshot();
+              ctx.globalCompositeOperation = 'source-over';
               const radius = Math.sqrt(Math.pow(currentX - startX, 2) + Math.pow(currentY - startY, 2));
               ctx.beginPath();
               ctx.arc(startX, startY, radius, 0, Math.PI * 2);
               ctx.stroke();
           } else if (currentTool === 'arrow') {
               restoreSnapshot();
+              ctx.globalCompositeOperation = 'source-over';
               drawArrow(startX, startY, currentX, currentY);
           }
       });