From c1d5f0f7a93a6f1c947baa5860ddd40f8d1bb701 Mon Sep 17 00:00:00 2001
From: Bogdan Chadkin <trysound@yandex.ru>
Date: Tue, 23 Feb 2021 22:36:47 +0300
Subject: [PATCH] Keep empty <g> when filter attributes is specified

---
 plugins/removeEmptyContainers.js          | 13 +++++++++----
 test/plugins/removeEmptyContainers.04.svg | 23 +++++++++++++++++++++++
 2 files changed, 32 insertions(+), 4 deletions(-)
 create mode 100644 test/plugins/removeEmptyContainers.04.svg

diff --git a/plugins/removeEmptyContainers.js b/plugins/removeEmptyContainers.js
index 356a5835b..6ef1aac33 100644
--- a/plugins/removeEmptyContainers.js
+++ b/plugins/removeEmptyContainers.js
@@ -25,8 +25,13 @@ var container = require('./_collections').elemsGroups.container;
  * @author Kir Belevich
  */
 exports.fn = function(item) {
-
-    return !(item.isElem(container) && !item.isElem('svg') && item.isEmpty() &&
-        (!item.isElem('pattern') || !item.hasAttrLocal('href')));
-
+  return (
+    item.isElem(container) === false ||
+    item.isEmpty() === false ||
+    item.isElem('svg') ||
+    (item.isElem('pattern') && item.hasAttrLocal('href')) ||
+    // The 'g' may not have content, but the filter may cause a rectangle
+    // to be created and filled with pattern.
+    (item.isElem('g') && item.hasAttr('filter'))
+  );
 };
diff --git a/test/plugins/removeEmptyContainers.04.svg b/test/plugins/removeEmptyContainers.04.svg
new file mode 100644
index 000000000..fa1698cdd
--- /dev/null
+++ b/test/plugins/removeEmptyContainers.04.svg
@@ -0,0 +1,23 @@
+<svg>
+  <defs>
+    <filter id="feTileFilter" filterUnits="userSpaceOnUse" primitiveUnits="userSpaceOnUse" x="115" y="40" width="250" height="250">
+      <feFlood x="115" y="40" width="54" height="19" flood-color="lime"/>
+      <feOffset x="115" y="40" width="50" height="25" dx="6" dy="6" result="offset"/>
+      <feTile/>
+    </filter>
+  </defs>
+  <g filter="url(#feTileFilter)"/>
+</svg>
+
+@@@
+
+<svg>
+    <defs>
+        <filter id="feTileFilter" filterUnits="userSpaceOnUse" primitiveUnits="userSpaceOnUse" x="115" y="40" width="250" height="250">
+            <feFlood x="115" y="40" width="54" height="19" flood-color="lime"/>
+            <feOffset x="115" y="40" width="50" height="25" dx="6" dy="6" result="offset"/>
+            <feTile/>
+        </filter>
+    </defs>
+    <g filter="url(#feTileFilter)"/>
+</svg>