From 51abbb484fadf43e9ce2691b305eede48eb70378 Mon Sep 17 00:00:00 2001
From: Fabrice Mouhartem <fabrice.mouhartem@xwiki.com>
Date: Thu, 16 Nov 2023 15:44:43 +0100
Subject: [PATCH] Set default size for empty whiteboard
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Previously, empty whiteboards were exported as a 0×0 pixel image, which
raised an error in fabric.js.
To address this issue, the default empty image is set to be a 600×600
pixel transparent png file.

Also fix #1267 that is a consequence of the aforementioned issue.
---
 www/whiteboard/export.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/www/whiteboard/export.js b/www/whiteboard/export.js
index 300085c92..7c9253fea 100644
--- a/www/whiteboard/export.js
+++ b/www/whiteboard/export.js
@@ -25,8 +25,9 @@ define([
                     if (c[k].y > h) { h = c[k].y + 1; }
                 });
             });
-            w = Math.min(w, MAX);
-            h = Math.min(h, MAX);
+            // Empty documents are rendered as a 600x600 transparent PNG image
+            w = w === 0 ? 600 : Math.min(w, MAX);
+            h = h === 0 ? 600 : Math.min(h, MAX);
             canvas.setWidth(w);
             canvas.setHeight(h);
             canvas.calcOffset();