From a5efce4c84e93b5d4822bff3720747e03ed70e43 Mon Sep 17 00:00:00 2001
From: Frank Stolle <f.stolle@hosting-agency.de>
Date: Tue, 22 Feb 2022 17:50:12 +0100
Subject: [PATCH] Fix rendering with tileMargin on top and bottom border of map

---
 src/serve_rendered.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/serve_rendered.js b/src/serve_rendered.js
index 11b6bfb..47131ba 100644
--- a/src/serve_rendered.js
+++ b/src/serve_rendered.js
@@ -302,9 +302,11 @@ module.exports = {
           });
 
           if (z > 2 && tileMargin > 0) {
+            const [_, y] = mercator.px(params.center, z);
+            let yoffset = Math.max(Math.min(0, y - 128 - tileMargin), y + 128 + tileMargin - Math.pow(2, z + 8));
             image.extract({
               left: tileMargin * scale,
-              top: tileMargin * scale,
+              top: (tileMargin + yoffset) * scale,
               width: width * scale,
               height: height * scale
             });