Set color of Mathjax depending on nightMode

ts/editable/Mathjax.svelte

@@ -3,12 +3,17 @@ Copyright: Ankitects Pty Ltd and contributors
 License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 -->
 <script lang="ts">
+    import { getContext } from "svelte";
+    import { nightModeKey } from "components/context-keys";
     import { convertMathjax } from "./mathjax";
 
     export let mathjax: string;
     export let block: boolean;
+    export let fontSize: number = 20;
 
-    $: [converted, title] = convertMathjax(mathjax);
+    const nightMode = getContext(nightModeKey);
+
+    $: [converted, title] = convertMathjax(mathjax, nightMode, fontSize);
     $: encoded = encodeURIComponent(converted);
 </script>
 

ts/editable/mathjax-component.ts

@@ -3,6 +3,7 @@ import "mathjax/es5/tex-svg-full";
 import type { DecoratedElement, DecoratedElementConstructor } from "./decorated";
 import { decoratedComponents } from "./decorated";
 import { nodeIsElement } from "lib/dom";
+import { nightModeKey } from "components/context-keys";
 
 import Mathjax_svelte from "./Mathjax.svelte";
 
@@ -154,10 +155,17 @@ export const Mathjax: DecoratedElementConstructor = class Mathjax
         this.innerHTML = "";
         this.style.whiteSpace = "normal";
 
+        const context = new Map();
+        context.set(
+            nightModeKey,
+            document.documentElement.classList.contains("night-mode")
+        );
+
         this.component = new Mathjax_svelte({
             target: this,
             props: { mathjax, block: this.block },
-        });
+            context,
+        } as any);
     }
 
     undecorate(): void {

ts/editable/mathjax.ts

@@ -5,17 +5,19 @@ import { mathIcon } from "./icons";
 
 const parser = new DOMParser();
 
-function getStyle(): HTMLStyleElement {
+function getStyle(nightMode: boolean, fontSize: number): HTMLStyleElement {
     const style = document.createElement("style") as HTMLStyleElement;
+    const color = nightMode ? "white" : "black";
+
     /* color is set for Maths, fill for the empty icon */
-    const css = `svg { color: white; fill: white; font-size: 20px; }`;
+    const css = `svg { color: ${color}; fill: ${color}; font-size: ${fontSize}px; }`;
     style.appendChild(document.createTextNode(css));
 
     return style;
 }
 
-function getEmptyIcon(): [string, string] {
+function getEmptyIcon(nightMode: boolean, fontSize: number): [string, string] {
-    const style = getStyle();
+    const style = getStyle(nightMode, fontSize);
 
     const icon = parser.parseFromString(mathIcon, "image/svg+xml");
     const svg = icon.children[0];
@@ -24,16 +26,20 @@ function getEmptyIcon(): [string, string] {
     return [svg.outerHTML, ""];
 }
 
-export function convertMathjax(input: string): [string, string] {
+export function convertMathjax(
+    input: string,
+    nightMode: boolean,
+    fontSize: number
+): [string, string] {
     if (input.trim().length === 0) {
-        return getEmptyIcon();
+        return getEmptyIcon(nightMode, fontSize);
     }
 
     const output = globalThis.MathJax.tex2svg(input);
     const svg = output.children[0];
 
     if (svg.viewBox.baseVal.height === 16) {
-        return getEmptyIcon();
+        return getEmptyIcon(nightMode, fontSize);
     }
 
     let title = "";
@@ -43,7 +49,7 @@ export function convertMathjax(input: string): [string, string] {
         svg.querySelector("text").setAttribute("color", "red");
         title = svg.querySelector("title").innerHTML;
     } else {
-        const style = getStyle();
+        const style = getStyle(nightMode, fontSize);
         svg.insertBefore(style, svg.children[0]);
     }