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backend/node_modules/svgo/plugins/removeHiddenElems.js

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+'use strict';
+
+/**
+ * @typedef {import('../lib/types').XastChild} XastChild
+ * @typedef {import('../lib/types').XastElement} XastElement
+ * @typedef {import('../lib/types').XastParent} XastParent
+ */
+
+const { elemsGroups } = require('./_collections.js');
+const {
+  visit,
+  visitSkip,
+  querySelector,
+  detachNodeFromParent,
+} = require('../lib/xast.js');
+const { collectStylesheet, computeStyle } = require('../lib/style.js');
+const { parsePathData } = require('../lib/path.js');
+const { hasScripts, findReferences } = require('../lib/svgo/tools.js');
+
+const nonRendering = elemsGroups.nonRendering;
+
+exports.name = 'removeHiddenElems';
+exports.description =
+  'removes hidden elements (zero sized, with absent attributes)';
+
+/**
+ * Remove hidden elements with disabled rendering:
+ * - display="none"
+ * - opacity="0"
+ * - circle with zero radius
+ * - ellipse with zero x-axis or y-axis radius
+ * - rectangle with zero width or height
+ * - pattern with zero width or height
+ * - image with zero width or height
+ * - path with empty data
+ * - polyline with empty points
+ * - polygon with empty points
+ *
+ * @author Kir Belevich
+ *
+ * @type {import('./plugins-types').Plugin<'removeHiddenElems'>}
+ */
+exports.fn = (root, params) => {
+  const {
+    isHidden = true,
+    displayNone = true,
+    opacity0 = true,
+    circleR0 = true,
+    ellipseRX0 = true,
+    ellipseRY0 = true,
+    rectWidth0 = true,
+    rectHeight0 = true,
+    patternWidth0 = true,
+    patternHeight0 = true,
+    imageWidth0 = true,
+    imageHeight0 = true,
+    pathEmptyD = true,
+    polylineEmptyPoints = true,
+    polygonEmptyPoints = true,
+  } = params;
+  const stylesheet = collectStylesheet(root);
+
+  /**
+   * Skip non-rendered nodes initially, and only detach if they have no ID, or
+   * their ID is not referenced by another node.
+   *
+   * @type {Map<XastElement, XastParent>}
+   */
+  const nonRenderedNodes = new Map();
+
+  /**
+   * IDs for removed hidden definitions.
+   *
+   * @type {Set<string>}
+   */
+  const removedDefIds = new Set();
+
+  /**
+   * @type {Map<XastElement, XastParent>}
+   */
+  const allDefs = new Map();
+
+  /** @type {Set<string>} */
+  const allReferences = new Set();
+
+  /**
+   * @type {Map<string, Array<{ node: XastElement, parentNode: XastParent }>>}
+   */
+  const referencesById = new Map();
+
+  /**
+   * If styles are present, we can't be sure if a definition is unused or not
+   */
+  let deoptimized = false;
+
+  /**
+   * @param {XastChild} node
+   * @param {XastParent} parentNode
+   */
+  function removeElement(node, parentNode) {
+    if (
+      node.type === 'element' &&
+      node.attributes.id != null &&
+      parentNode.type === 'element' &&
+      parentNode.name === 'defs'
+    ) {
+      removedDefIds.add(node.attributes.id);
+    }
+
+    detachNodeFromParent(node, parentNode);
+  }
+
+  visit(root, {
+    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);
+          return visitSkip;
+        }
+        const computedStyle = computeStyle(stylesheet, node);
+        // opacity="0"
+        //
+        // https://www.w3.org/TR/SVG11/masking.html#ObjectAndGroupOpacityProperties
+        if (
+          opacity0 &&
+          computedStyle.opacity &&
+          computedStyle.opacity.type === 'static' &&
+          computedStyle.opacity.value === '0'
+        ) {
+          removeElement(node, parentNode);
+        }
+      },
+    },
+  });
+
+  return {
+    element: {
+      enter: (node, parentNode) => {
+        if (
+          (node.name === 'style' && node.children.length !== 0) ||
+          hasScripts(node)
+        ) {
+          deoptimized = true;
+          return;
+        }
+
+        if (node.name === 'defs') {
+          allDefs.set(node, parentNode);
+        }
+
+        if (node.name === 'use') {
+          for (const attr of Object.keys(node.attributes)) {
+            if (attr !== 'href' && !attr.endsWith(':href')) continue;
+            const value = node.attributes[attr];
+            const id = value.slice(1);
+
+            let refs = referencesById.get(id);
+            if (!refs) {
+              refs = [];
+              referencesById.set(id, refs);
+            }
+            refs.push({ node, parentNode });
+          }
+        }
+
+        // Removes hidden elements
+        // https://www.w3schools.com/cssref/pr_class_visibility.asp
+        const computedStyle = computeStyle(stylesheet, node);
+        if (
+          isHidden &&
+          computedStyle.visibility &&
+          computedStyle.visibility.type === 'static' &&
+          computedStyle.visibility.value === 'hidden' &&
+          // keep if any descendant enables visibility
+          querySelector(node, '[visibility=visible]') == null
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        // display="none"
+        //
+        // https://www.w3.org/TR/SVG11/painting.html#DisplayProperty
+        // "A value of display: none indicates that the given element
+        // and its children shall not be rendered directly"
+        if (
+          displayNone &&
+          computedStyle.display &&
+          computedStyle.display.type === 'static' &&
+          computedStyle.display.value === 'none' &&
+          // markers with display: none still rendered
+          node.name !== 'marker'
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        // Circles with zero radius
+        //
+        // https://www.w3.org/TR/SVG11/shapes.html#CircleElementRAttribute
+        // "A value of zero disables rendering of the element"
+        //
+        // <circle r="0">
+        if (
+          circleR0 &&
+          node.name === 'circle' &&
+          node.children.length === 0 &&
+          node.attributes.r === '0'
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        // Ellipse with zero x-axis radius
+        //
+        // https://www.w3.org/TR/SVG11/shapes.html#EllipseElementRXAttribute
+        // "A value of zero disables rendering of the element"
+        //
+        // <ellipse rx="0">
+        if (
+          ellipseRX0 &&
+          node.name === 'ellipse' &&
+          node.children.length === 0 &&
+          node.attributes.rx === '0'
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        // Ellipse with zero y-axis radius
+        //
+        // https://www.w3.org/TR/SVG11/shapes.html#EllipseElementRYAttribute
+        // "A value of zero disables rendering of the element"
+        //
+        // <ellipse ry="0">
+        if (
+          ellipseRY0 &&
+          node.name === 'ellipse' &&
+          node.children.length === 0 &&
+          node.attributes.ry === '0'
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        // Rectangle with zero width
+        //
+        // https://www.w3.org/TR/SVG11/shapes.html#RectElementWidthAttribute
+        // "A value of zero disables rendering of the element"
+        //
+        // <rect width="0">
+        if (
+          rectWidth0 &&
+          node.name === 'rect' &&
+          node.children.length === 0 &&
+          node.attributes.width === '0'
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        // Rectangle with zero height
+        //
+        // https://www.w3.org/TR/SVG11/shapes.html#RectElementHeightAttribute
+        // "A value of zero disables rendering of the element"
+        //
+        // <rect height="0">
+        if (
+          rectHeight0 &&
+          rectWidth0 &&
+          node.name === 'rect' &&
+          node.children.length === 0 &&
+          node.attributes.height === '0'
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        // Pattern with zero width
+        //
+        // https://www.w3.org/TR/SVG11/pservers.html#PatternElementWidthAttribute
+        // "A value of zero disables rendering of the element (i.e., no paint is applied)"
+        //
+        // <pattern width="0">
+        if (
+          patternWidth0 &&
+          node.name === 'pattern' &&
+          node.attributes.width === '0'
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        // Pattern with zero height
+        //
+        // https://www.w3.org/TR/SVG11/pservers.html#PatternElementHeightAttribute
+        // "A value of zero disables rendering of the element (i.e., no paint is applied)"
+        //
+        // <pattern height="0">
+        if (
+          patternHeight0 &&
+          node.name === 'pattern' &&
+          node.attributes.height === '0'
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        // Image with zero width
+        //
+        // https://www.w3.org/TR/SVG11/struct.html#ImageElementWidthAttribute
+        // "A value of zero disables rendering of the element"
+        //
+        // <image width="0">
+        if (
+          imageWidth0 &&
+          node.name === 'image' &&
+          node.attributes.width === '0'
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        // Image with zero height
+        //
+        // https://www.w3.org/TR/SVG11/struct.html#ImageElementHeightAttribute
+        // "A value of zero disables rendering of the element"
+        //
+        // <image height="0">
+        if (
+          imageHeight0 &&
+          node.name === 'image' &&
+          node.attributes.height === '0'
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        // Path with empty data
+        //
+        // https://www.w3.org/TR/SVG11/paths.html#DAttribute
+        //
+        // <path d=""/>
+        if (pathEmptyD && node.name === 'path') {
+          if (node.attributes.d == null) {
+            removeElement(node, parentNode);
+            return;
+          }
+          const pathData = parsePathData(node.attributes.d);
+          if (pathData.length === 0) {
+            removeElement(node, parentNode);
+            return;
+          }
+          // keep single point paths for markers
+          if (
+            pathData.length === 1 &&
+            computedStyle['marker-start'] == null &&
+            computedStyle['marker-end'] == null
+          ) {
+            removeElement(node, parentNode);
+            return;
+          }
+        }
+
+        // Polyline with empty points
+        //
+        // https://www.w3.org/TR/SVG11/shapes.html#PolylineElementPointsAttribute
+        //
+        // <polyline points="">
+        if (
+          polylineEmptyPoints &&
+          node.name === 'polyline' &&
+          node.attributes.points == null
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        // Polygon with empty points
+        //
+        // https://www.w3.org/TR/SVG11/shapes.html#PolygonElementPointsAttribute
+        //
+        // <polygon points="">
+        if (
+          polygonEmptyPoints &&
+          node.name === 'polygon' &&
+          node.attributes.points == null
+        ) {
+          removeElement(node, parentNode);
+          return;
+        }
+
+        for (const [name, value] of Object.entries(node.attributes)) {
+          const ids = findReferences(name, value);
+
+          for (const id of ids) {
+            allReferences.add(id);
+          }
+        }
+      },
+    },
+    root: {
+      exit: () => {
+        for (const id of removedDefIds) {
+          const refs = referencesById.get(id);
+          if (refs) {
+            for (const { node, parentNode } of refs) {
+              detachNodeFromParent(node, parentNode);
+            }
+          }
+        }
+
+        if (!deoptimized) {
+          for (const [
+            nonRenderedNode,
+            nonRenderedParent,
+          ] of nonRenderedNodes.entries()) {
+            const id = nonRenderedNode.attributes.id;
+
+            if (!allReferences.has(id)) {
+              detachNodeFromParent(nonRenderedNode, nonRenderedParent);
+            }
+          }
+        }
+
+        for (const [node, parentNode] of allDefs.entries()) {
+          if (node.children.length === 0) {
+            detachNodeFromParent(node, parentNode);
+          }
+        }
+      },
+    },
+  };
+};