From 24591c1c22011ad8b444110e49ff1f37aec79b9c Mon Sep 17 00:00:00 2001
From: John Kenny <johnkenny54@yahoo.com>
Date: Wed, 3 Jan 2024 08:41:22 -0800
Subject: [PATCH 1/4] Fixed bug in removeHiddenElements.

---
 plugins/removeHiddenElems.js          | 31 +++++++++++++++++----------
 test/plugins/removeHiddenElems.16.svg | 23 ++++++++++++++++++++
 test/plugins/removeHiddenElems.17.svg | 23 ++++++++++++++++++++
 3 files changed, 66 insertions(+), 11 deletions(-)
 create mode 100644 test/plugins/removeHiddenElems.16.svg
 create mode 100644 test/plugins/removeHiddenElems.17.svg

diff --git a/plugins/removeHiddenElems.js b/plugins/removeHiddenElems.js
index 75720a068..320977366 100644
--- a/plugins/removeHiddenElems.js
+++ b/plugins/removeHiddenElems.js
@@ -93,6 +93,23 @@ exports.fn = (root, params) => {
    */
   let deoptimized = false;
 
+  /**
+   * Nodes can't be removed if they or any of their children have an id attribute that is referenced.
+   * @param {XastElement} node
+   * @returns boolean
+   */
+  function canRemoveNonRenderingNode(node) {
+    if (allReferences.has(node.attributes.id)) {
+      return false;
+    }
+    for (const child of node.children) {
+      if (child.type === 'element' && !canRemoveNonRenderingNode(child)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
   /**
    * @param {XastChild} node
    * @param {XastParent} parentNode
@@ -114,13 +131,7 @@ exports.fn = (root, params) => {
     element: {
       enter: (node, parentNode) => {
         // transparent non-rendering elements still apply where referenced
-        if (nonRendering.has(node.name)) {
-          if (node.attributes.id == null) {
-            detachNodeFromParent(node, parentNode);
-            return visitSkip;
-          }
-
-          nonRenderedNodes.set(node, parentNode);
+        if (nonRendering.has(node.name) || node.name === 'defs') {
           return visitSkip;
         }
         const computedStyle = computeStyle(stylesheet, node);
@@ -421,16 +432,14 @@ exports.fn = (root, params) => {
             nonRenderedNode,
             nonRenderedParent,
           ] of nonRenderedNodes.entries()) {
-            const id = nonRenderedNode.attributes.id;
-
-            if (!allReferences.has(id)) {
+            if (canRemoveNonRenderingNode(nonRenderedNode)) {
               detachNodeFromParent(nonRenderedNode, nonRenderedParent);
             }
           }
         }
 
         for (const [node, parentNode] of allDefs.entries()) {
-          if (node.children.length === 0) {
+          if (canRemoveNonRenderingNode(node)) {
             detachNodeFromParent(node, parentNode);
           }
         }
diff --git a/test/plugins/removeHiddenElems.16.svg b/test/plugins/removeHiddenElems.16.svg
new file mode 100644
index 000000000..fb29f9b8b
--- /dev/null
+++ b/test/plugins/removeHiddenElems.16.svg
@@ -0,0 +1,23 @@
+Don't remove used symbols.
+
+===
+
+<svg xmlns="http://www.w3.org/2000/svg">
+    <rect fill="url(#a)" width="64" height="64"/>
+    <symbol>
+        <linearGradient id="a">
+            <stop offset="5%" stop-color="gold" />
+        </linearGradient>
+    </symbol>
+</svg>
+
+@@@
+
+<svg xmlns="http://www.w3.org/2000/svg">
+    <rect fill="url(#a)" width="64" height="64"/>
+    <symbol>
+        <linearGradient id="a">
+            <stop offset="5%" stop-color="gold"/>
+        </linearGradient>
+    </symbol>
+</svg>
\ No newline at end of file
diff --git a/test/plugins/removeHiddenElems.17.svg b/test/plugins/removeHiddenElems.17.svg
new file mode 100644
index 000000000..ef3557e0a
--- /dev/null
+++ b/test/plugins/removeHiddenElems.17.svg
@@ -0,0 +1,23 @@
+Don't remove used symbols.
+
+===
+
+<svg xmlns="http://www.w3.org/2000/svg">
+    <rect fill="url(#a)" width="64" height="64"/>
+    <g>
+        <linearGradient id="a">
+            <stop offset="5%" stop-color="gold" />
+        </linearGradient>
+    </g>
+</svg>
+
+@@@
+
+<svg xmlns="http://www.w3.org/2000/svg">
+    <rect fill="url(#a)" width="64" height="64"/>
+    <g>
+        <linearGradient id="a">
+            <stop offset="5%" stop-color="gold"/>
+        </linearGradient>
+    </g>
+</svg>
\ No newline at end of file

From 02ae77d92a4ef2b0f37925625b6ed422331de783 Mon Sep 17 00:00:00 2001
From: John Kenny <johnkenny54@yahoo.com>
Date: Wed, 3 Jan 2024 09:29:52 -0800
Subject: [PATCH 2/4] Updated test case description.

---
 test/plugins/removeHiddenElems.16.svg | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/plugins/removeHiddenElems.16.svg b/test/plugins/removeHiddenElems.16.svg
index fb29f9b8b..9795db0b9 100644
--- a/test/plugins/removeHiddenElems.16.svg
+++ b/test/plugins/removeHiddenElems.16.svg
@@ -1,4 +1,4 @@
-Don't remove used symbols.
+Don't remove non-rendering elements if children have IDs. 
 
 ===
 

From ac57ffdab01a1794954a34c562e1bc75528cc222 Mon Sep 17 00:00:00 2001
From: John Kenny <johnkenny54@yahoo.com>
Date: Wed, 3 Jan 2024 12:55:48 -0800
Subject: [PATCH 3/4] Added test case and reverted some changes to
 removeHiddenElems.

---
 plugins/removeHiddenElems.js          |  5 +++--
 test/plugins/removeHiddenElems.18.svg | 23 +++++++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)
 create mode 100644 test/plugins/removeHiddenElems.18.svg

diff --git a/plugins/removeHiddenElems.js b/plugins/removeHiddenElems.js
index 320977366..aec69c7b7 100644
--- a/plugins/removeHiddenElems.js
+++ b/plugins/removeHiddenElems.js
@@ -131,7 +131,8 @@ exports.fn = (root, params) => {
     element: {
       enter: (node, parentNode) => {
         // transparent non-rendering elements still apply where referenced
-        if (nonRendering.has(node.name) || node.name === 'defs') {
+        if (nonRendering.has(node.name)) {
+          nonRenderedNodes.set(node, parentNode);
           return visitSkip;
         }
         const computedStyle = computeStyle(stylesheet, node);
@@ -439,7 +440,7 @@ exports.fn = (root, params) => {
         }
 
         for (const [node, parentNode] of allDefs.entries()) {
-          if (canRemoveNonRenderingNode(node)) {
+          if (node.children.length === 0) {
             detachNodeFromParent(node, parentNode);
           }
         }
diff --git a/test/plugins/removeHiddenElems.18.svg b/test/plugins/removeHiddenElems.18.svg
new file mode 100644
index 000000000..e24700598
--- /dev/null
+++ b/test/plugins/removeHiddenElems.18.svg
@@ -0,0 +1,23 @@
+XXXXXXXXX
+
+===
+
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+    <g id="test-body-content">
+        <defs>
+            <path id="reference" d="M240 1h239v358H240z"/>
+        </defs>
+        <use xlink:href="#reference" id="use" fill="gray" onclick="test(evt)"/>
+    </g>
+</svg>
+
+@@@
+
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+    <g id="test-body-content">
+        <defs>
+            <path id="reference" d="M240 1h239v358H240z"/>
+        </defs>
+        <use xlink:href="#reference" id="use" fill="gray" onclick="test(evt)"/>
+    </g>
+</svg>

From b02d26c3038f60782ab84cc3bd52988cfa64fe31 Mon Sep 17 00:00:00 2001
From: John Kenny <johnkenny54@yahoo.com>
Date: Wed, 3 Jan 2024 16:50:12 -0800
Subject: [PATCH 4/4] Added test case description.

---
 test/plugins/removeHiddenElems.18.svg | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/plugins/removeHiddenElems.18.svg b/test/plugins/removeHiddenElems.18.svg
index e24700598..ad1bb7f34 100644
--- a/test/plugins/removeHiddenElems.18.svg
+++ b/test/plugins/removeHiddenElems.18.svg
@@ -1,4 +1,4 @@
-XXXXXXXXX
+Preserve <defs> with referenced path.
 
 ===