From 161ac5ff84a627ec23e8183066b438fb835ca9bb Mon Sep 17 00:00:00 2001
From: Frank <frank@stolle.email>
Date: Fri, 23 Sep 2022 05:22:06 +0200
Subject: [PATCH] Fix rendering with tileMargin on top and bottom border of map
 (#571)

Co-authored-by: Frank Stolle <f.stolle@hosting-agency.de>
---
 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 3a264fd..e39d8d5 100644
--- a/src/serve_rendered.js
+++ b/src/serve_rendered.js
@@ -305,9 +305,11 @@ 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
             });