From b911464472f2394fba02ba40ddaa9fbe91b74261 Mon Sep 17 00:00:00 2001
From: Artem Pavlenko <artem@mapnik.org>
Date: Mon, 26 Feb 2024 14:40:36 +0000
Subject: [PATCH] correct 'is_empty' implementation for multi geometries

---
 include/mapnik/geometry/is_empty.hpp | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/include/mapnik/geometry/is_empty.hpp b/include/mapnik/geometry/is_empty.hpp
index fccf7eae0..e39a5b9f7 100644
--- a/include/mapnik/geometry/is_empty.hpp
+++ b/include/mapnik/geometry/is_empty.hpp
@@ -39,18 +39,36 @@ struct geometry_is_empty
 
     bool operator()(mapnik::geometry::point<double> const&) const { return false; }
 
-    bool operator()(mapnik::geometry::line_string<double> const& geom) const { return geom.empty(); }
+    bool operator()(mapnik::geometry::line_string<double> const& line) const { return line.empty(); }
 
-    bool operator()(mapnik::geometry::polygon<double> const& geom) const
+    bool operator()(mapnik::geometry::polygon<double> const& poly) const
     {
-        return geom.empty() || geom.front().empty();
+        for (auto const& ring : poly)
+        {
+            if (!ring.empty()) return false;
+        }
+        return true;
     }
 
     bool operator()(mapnik::geometry::multi_point<double> const& geom) const { return geom.empty(); }
 
-    bool operator()(mapnik::geometry::multi_line_string<double> const& geom) const { return geom.empty(); }
+    bool operator()(mapnik::geometry::multi_line_string<double> const& mline) const
+    {
+        for (auto const& line : mline)
+        {
+            if (!line.empty()) return false;
+        }
+        return true;
+    }
 
-    bool operator()(mapnik::geometry::multi_polygon<double> const& geom) const { return geom.empty(); }
+    bool operator()(mapnik::geometry::multi_polygon<double> const& mpoly) const
+    {
+        for (auto const& poly : mpoly)
+        {
+            if (!operator()(poly)) return false;
+        }
+        return true;
+    }
 
     bool operator()(mapnik::geometry::geometry_collection<double> const& geom) const { return geom.empty(); }