From d979b40f0a3eaf4f196f20cd03d0ff0658ce3d15 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Tainon?= <arkandias1@hotmail.fr>
Date: Wed, 5 Nov 2025 16:05:04 +0100
Subject: [PATCH] Add LaTeX expressions using Mathjax lib

---
 frontend/index.tsx                            |  1 +
 frontend/submission/task_platform.ts          | 12 ++++++++++-
 frontend/task/instructions/instructions.scss  |  4 ++++
 frontend/task/libs/import_modules.ts          | 21 +++++++++++++++++++
 .../task/libs/quickalgo_library_factory.ts    |  6 ++++--
 frontend/task/task_types.ts                   |  1 +
 6 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/frontend/index.tsx b/frontend/index.tsx
index 1376f89c3..73ad19d96 100644
--- a/frontend/index.tsx
+++ b/frontend/index.tsx
@@ -149,6 +149,7 @@ declare global {
         taskSettings?: any,
         initBlocklySubTask?: () => void,
         instructionsPostProcessing?: (() => void)[],
+        MathJax: any,
     }
 }
 
diff --git a/frontend/submission/task_platform.ts b/frontend/submission/task_platform.ts
index 5a28837c6..facceff9e 100644
--- a/frontend/submission/task_platform.ts
+++ b/frontend/submission/task_platform.ts
@@ -123,7 +123,7 @@ export function getTaskDataFromTaskSettings(taskSettings: any) {
     return taskData;
 }
 
-export function getServerTaskFromTaskData(taskData: any, task: TaskServer = null) {
+export function getServerTaskFromTaskData(taskData: any, task: TaskServer = null): Task {
     if (taskData.data) {
         taskData.gridInfos.allowClientExecution = true;
     }
@@ -136,6 +136,16 @@ export function getServerTaskFromTaskData(taskData: any, task: TaskServer = null
         if (window.PEMTaskMetaData.supportedLanguages) {
             taskData.supportedLanguages = window.PEMTaskMetaData.supportedLanguages.join(',');
         }
+        if (window.PEMTaskMetaData.useLatex) {
+            taskData.useLatex = !!window.PEMTaskMetaData.useLatex;
+        }
+    }
+
+    if (task.useLatex) {
+        taskData.gridInfos.importModules = [
+            ...(taskData.gridInfos.importModules ?? []),
+            'mathjax',
+        ];
     }
 
     return {
diff --git a/frontend/task/instructions/instructions.scss b/frontend/task/instructions/instructions.scss
index e063c77ab..a24a38d75 100644
--- a/frontend/task/instructions/instructions.scss
+++ b/frontend/task/instructions/instructions.scss
@@ -46,3 +46,7 @@
 .task-instructions-video.is-not-shown {
   cursor: pointer;
 }
+
+.mjx-chtml {
+  font-size: 100% !important;
+}
diff --git a/frontend/task/libs/import_modules.ts b/frontend/task/libs/import_modules.ts
index 752a0d9d7..60fb217fb 100644
--- a/frontend/task/libs/import_modules.ts
+++ b/frontend/task/libs/import_modules.ts
@@ -361,6 +361,27 @@ export function loadFonts(theme: string, task: Task|null) {
     }
 }
 
+let mathJaxConfigured = false;
+export function loadMathJax() {
+    if (mathJaxConfigured) {
+        return;
+    }
+
+    window.MathJax.Hub.Config({
+        tex2jax: {inlineMath: [['$','$'], ['\\(','\\)']]},
+        messageStyle: "none",
+    });
+    window.MathJax.Hub.processSectionDelay = 0;
+
+    window.instructionsPostProcessing = [
+        ...(window.instructionsPostProcessing ?? []),
+        () => {
+            window.MathJax.Hub.Queue(['Typeset', window.MathJax.Hub]);
+        },
+    ];
+    mathJaxConfigured = true;
+}
+
 export function getJsLibLoaded() {
     return jsLibLoaded;
 }
diff --git a/frontend/task/libs/quickalgo_library_factory.ts b/frontend/task/libs/quickalgo_library_factory.ts
index babbce232..e8bdda93e 100644
--- a/frontend/task/libs/quickalgo_library_factory.ts
+++ b/frontend/task/libs/quickalgo_library_factory.ts
@@ -2,8 +2,8 @@ import {appSelect} from '../../hooks';
 import {quickAlgoLibraries} from './quick_algo_libraries_model';
 import log from 'loglevel';
 import {extractLevelSpecific, extractVariantSpecific} from '../utils';
-import {call, put, select} from 'typed-redux-saga';
-import {importModules, importPlatformModules, loadFonts} from './import_modules';
+import {call, put} from 'typed-redux-saga';
+import {importModules, importPlatformModules, loadFonts, loadMathJax} from './import_modules';
 import {SmartContractLib} from './smart_contract/smart_contract_lib';
 import {DefaultQuickalgoLibrary} from './default_quickalgo_library';
 import {PrinterLib} from './printer/printer_lib';
@@ -81,6 +81,8 @@ export function* createQuickalgoLibrary(platformAlreadyChanged: boolean = false)
             yield* call(importModules, levelGridInfos.importModules, window.modulesPath);
         }
     }
+
+    yield* call(loadMathJax);
     yield* call(loadFonts, state.options.theme, currentTask);
 
     // Reset fully local strings when creating a new context to avoid keeping strings from an other language
diff --git a/frontend/task/task_types.ts b/frontend/task/task_types.ts
index 31b289e0c..fd01fb555 100644
--- a/frontend/task/task_types.ts
+++ b/frontend/task/task_types.ts
@@ -164,6 +164,7 @@ export interface TaskNormalized {
     author: string,
     showLimits: boolean,
     userTests: boolean,
+    useLatex: boolean,
     isEvaluable: boolean,
     scriptAnimation: string,
     hasSubtasks: boolean,