feat(removeHiddenElems): remove shapes that aren't rendered in any way

docs/03-plugins/remove-hidden-elems.mdx

@@ -10,6 +10,9 @@ svgo:
     displayNone:
       description: Removes elements where <a href="https://developer.mozilla.org/docs/Web/SVG/Attribute/display" target="_blank"><code>display</code></a> is <code>none</code>.
       default: true
+    noColor:
+      description: Removes shapes that aren't rendered in any way (no fill/stroke/markers).
+      default: true
     opacity0:
       description: Removes element where <a href="https://developer.mozilla.org/docs/Web/SVG/Attribute/opacity" target="_blank"><code>opacity</code></a> is <code>0</code>.
       default: true

plugins/plugins-types.d.ts

@@ -159,6 +159,7 @@ type DefaultPlugins = {
   removeHiddenElems: {
     isHidden?: boolean;
     displayNone?: boolean;
+    noColor?: boolean;
     opacity0?: boolean;
     circleR0?: boolean;
     ellipseRX0?: boolean;

plugins/removeHiddenElems.js

@@ -27,6 +27,7 @@ exports.description =
  * Remove hidden elements with disabled rendering:
  * - display="none"
  * - opacity="0"
+ * - shapes with no fill/stroke/markers
  * - circle with zero radius
  * - ellipse with zero x-axis or y-axis radius
  * - rectangle with zero width or height
@@ -44,6 +45,7 @@ exports.fn = (root, params) => {
   const {
     isHidden = true,
     displayNone = true,
+    noColor = true,
     opacity0 = true,
     circleR0 = true,
     ellipseRX0 = true,
@@ -201,6 +203,27 @@ exports.fn = (root, params) => {
           return;
         }
 
+        // Shapes that aren't rendered in any way
+        if (
+          noColor &&
+          elemsGroups.shape.has(node.name) &&
+          computedStyle.fill &&
+          computedStyle.fill.type === 'static' &&
+          computedStyle.fill.value === 'none' &&
+          (computedStyle.stroke
+            ? computedStyle.stroke.type === 'static' &&
+              computedStyle.stroke.value === 'none'
+            : true) &&
+          !computedStyle['marker-start'] &&
+          !computedStyle['marker-mid'] &&
+          !computedStyle['marker-end'] &&
+          (parentNode.type !== 'element' ||
+            (parentNode.name !== 'defs' && parentNode.name !== 'clipPath'))
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
         // Circles with zero radius
         //
         // https://www.w3.org/TR/SVG11/shapes.html#CircleElementRAttribute