mermaid-js · sidharthv96 · Apr 3, 2024 · Mar 30, 2024 · Mar 30, 2024 · Mar 30, 2024
diff --git a/docs/syntax/flowchart.md b/docs/syntax/flowchart.md
@@ -1178,6 +1178,36 @@ Adding this snippet in the `<head>` would add support for Font Awesome v6.5.1
 />
 ```
 
+### Custom icons
+
+It is possible to use custom icons served from Font Awesome as long as the website imports the corresponding kit.
+
+Note that this is currently a paid feature from Font Awesome.
+
+For custom icons, you need to use the `fak` prefix.
+
+**Example**
+
+```
+flowchart TD
+    B[fa:fa-twitter] %% standard icon
+    B-->E(fak:fa-custom-icon-name) %% custom icon
+```
+
+And trying to render it
+
+```mermaid-example
+flowchart TD
+    B["fa:fa-twitter for peace"]
+    B-->C["fab:fa-truck-bold a custom icon"]
+```
+
+```mermaid
+flowchart TD
+    B["fa:fa-twitter for peace"]
+    B-->C["fab:fa-truck-bold a custom icon"]
+```
+
 ## Graph declarations with spaces between vertices and link and without semicolon
 
 - In graph declarations, the statements also can now end without a semicolon. After release 0.2.16, ending a graph statement with semicolon is just optional. So the below graph declaration is also valid along with the old declarations of the graph.

diff --git a/packages/mermaid/src/dagre-wrapper/createLabel.js b/packages/mermaid/src/dagre-wrapper/createLabel.js
@@ -3,6 +3,7 @@ import { log } from '../logger.js';
 import { getConfig } from '../diagram-api/diagramAPI.js';
 import { evaluate } from '../diagrams/common/common.js';
 import { decodeEntities } from '../utils.js';
+import { replaceIconSubstring } from '../rendering-util/createText.js';
 
 /**
  * @param dom
@@ -59,10 +60,7 @@ const createLabel = (_vertexText, style, isTitle, isNode) => {
     log.debug('vertexText' + vertexText);
     const node = {
       isNode,
-      label: decodeEntities(vertexText).replace(
-        /fa[blrs]?:fa-[\w-]+/g, // cspell: disable-line
-        (s) => `<i class='${s.replace(':', ' ')}'></i>`
-      ),
+      label: replaceIconSubstring(decodeEntities(vertexText)),
       labelStyle: style.replace('fill:', 'color:'),
     };
     let vertexNode = addHtmlLabel(node);

diff --git a/packages/mermaid/src/diagrams/flowchart/flowRenderer.js b/packages/mermaid/src/diagrams/flowchart/flowRenderer.js
@@ -9,6 +9,7 @@ import common, { evaluate, renderKatex } from '../common/common.js';
 import { interpolateToCurve, getStylesFromArray } from '../../utils.js';
 import { setupGraphViewbox } from '../../setupGraphViewbox.js';
 import flowChartShapes from './flowChartShapes.js';
+import { replaceIconSubstring } from '../../rendering-util/createText.js';
 
 const conf = {};
 export const setConf = function (cnf) {
@@ -56,14 +57,9 @@ export const addVertices = async function (vert, g, svgId, root, _doc, diagObj)
     let vertexNode;
     if (evaluate(getConfig().flowchart.htmlLabels)) {
       // TODO: addHtmlLabel accepts a labelStyle. Do we possibly have that?
+      const replacedVertexText = replaceIconSubstring(vertexText);
       const node = {
-        label: await renderKatex(
-          vertexText.replace(
-            /fa[blrs]?:fa-[\w-]+/g, // cspell:disable-line
-            (s) => `<i class='${s.replace(':', ' ')}'></i>`
-          ),
-          getConfig()
-        ),
+        label: await renderKatex(replacedVertexText, getConfig()),
       };
       vertexNode = addHtmlLabel(svg, node).node();
       vertexNode.parentNode.removeChild(vertexNode);
@@ -242,13 +238,7 @@ export const addEdges = async function (edges, g, diagObj) {
         edgeData.labelType = 'html';
         edgeData.label = `<span id="L-${linkId}" class="edgeLabel L-${linkNameStart}' L-${linkNameEnd}" style="${
           edgeData.labelStyle
-        }">${await renderKatex(
-          edge.text.replace(
-            /fa[blrs]?:fa-[\w-]+/g, // cspell:disable-line
-            (s) => `<i class='${s.replace(':', ' ')}'></i>`
-          ),
-          getConfig()
-        )}</span>`;
+        }">${await renderKatex(replaceIconSubstring(edge.text), getConfig())}</span>`;
       } else {
         edgeData.labelType = 'text';
         edgeData.label = edge.text.replace(common.lineBreakRegex, '\n');

diff --git a/packages/mermaid/src/docs/syntax/flowchart.md b/packages/mermaid/src/docs/syntax/flowchart.md
@@ -799,6 +799,30 @@ Adding this snippet in the `<head>` would add support for Font Awesome v6.5.1
 />
 ```
 
+### Custom icons
+
+It is possible to use custom icons served from Font Awesome as long as the website imports the corresponding kit.
+
+Note that this is currently a paid feature from Font Awesome.
+
+For custom icons, you need to use the `fak` prefix.
+
+**Example**
+
+```
+flowchart TD
+    B[fa:fa-twitter] %% standard icon
+    B-->E(fak:fa-custom-icon-name) %% custom icon
+```
+
+And trying to render it
+
+```mermaid-example
+flowchart TD
+    B["fa:fa-twitter for peace"]
+    B-->C["fab:fa-truck-bold a custom icon"]
+```
+
 ## Graph declarations with spaces between vertices and link and without semicolon
 
 - In graph declarations, the statements also can now end without a semicolon. After release 0.2.16, ending a graph statement with semicolon is just optional. So the below graph declaration is also valid along with the old declarations of the graph.

diff --git a/packages/mermaid/src/rendering-util/createText.spec.ts b/packages/mermaid/src/rendering-util/createText.spec.ts
@@ -0,0 +1,34 @@
+import { describe, it, expect } from 'vitest';
+import { replaceIconSubstring } from './createText.js';
+
+describe('replaceIconSubstring', () => {
+  it('converts FontAwesome icon notations to HTML tags', () => {
+    const input = 'This is an icon: fa:fa-user and fab:fa-github';
+    const output = replaceIconSubstring(input);
+    const expected =
+      "This is an icon: <i class='fa fa-user'></i> and <i class='fab fa-github'></i>";
+    expect(output).toEqual(expected);
+  });
+
+  it('handles strings without FontAwesome icon notations', () => {
+    const input = 'This string has no icons';
+    const output = replaceIconSubstring(input);
+    expect(output).toEqual(input); // No change expected
+  });
+
+  it('correctly processes multiple FontAwesome icon notations in one string', () => {
+    const input = 'Icons galore: fa:fa-arrow-right, fak:fa-truck, fas:fa-home';
+    const output = replaceIconSubstring(input);
+    const expected =
+      "Icons galore: <i class='fa fa-arrow-right'></i>, <i class='fak fa-truck'></i>, <i class='fas fa-home'></i>";
+    expect(output).toEqual(expected);
+  });
+
+  it('correctly replaces a very long icon name with the fak prefix', () => {
+    const input = 'Here is a long icon: fak:fa-truck-driving-long-winding-road in use';
+    const output = replaceIconSubstring(input);
+    const expected =
+      "Here is a long icon: <i class='fak fa-truck-driving-long-winding-road'></i> in use";
+    expect(output).toEqual(expected);
+  });
+});
diff --git a/packages/mermaid/src/rendering-util/createText.ts b/packages/mermaid/src/rendering-util/createText.ts
@@ -168,6 +168,19 @@ function updateTextContentAndStyles(tspan: any, wrappedLine: MarkdownWord[]) {
   });
 }
 
+/**
+ * Convert fontawesome labels into fontawesome icons by using a regex pattern
+ * @param text - The raw string to convert
+ * @returns string with fontawesome icons as i tags
+ */
+export function replaceIconSubstring(text: string) {
+  // The letters 'bklrs' stand for possible endings of the fontawesome prefix (e.g. 'fab' for brands, 'fak' for fa-kit) // cspell: disable-line
+  return text.replace(
+    /fa[bklrs]?:fa-[\w-]+/g, // cspell: disable-line
+    (s) => `<i class='${s.replace(':', ' ')}'></i>`
+  );
+}
+
 // Note when using from flowcharts converting the API isNode means classes should be set accordingly. When using htmlLabels => to sett classes to'nodeLabel' when isNode=true otherwise 'edgeLabel'
 // When not using htmlLabels => to set classes to 'title-row' when isTitle=true otherwise 'title-row'
 export const createText = (
@@ -189,12 +202,10 @@ export const createText = (
     // TODO: addHtmlLabel accepts a labelStyle. Do we possibly have that?
 
     const htmlText = markdownToHTML(text, config);
+    const decodedReplacedText = replaceIconSubstring(decodeEntities(htmlText));
     const node = {
       isNode,
-      label: decodeEntities(htmlText).replace(
-        /fa[blrs]?:fa-[\w-]+/g, // cspell: disable-line
-        (s) => `<i class='${s.replace(':', ' ')}'></i>`
-      ),
+      label: decodedReplacedText,
       labelStyle: style.replace('fill:', 'color:'),
     };
     const vertexNode = addHtmlSpan(el, node, width, classes, addSvgBackground);