feat(markdown): set the preview font size apart from the UI font (#1045)

The Markdown preview had a fixed 14px body and notebook Markdown cells inherited the UI font size, so enlarging them meant scaling the whole UI. Languages & Frameworks › Markdown › Preview font size (application-level, 8–72, following the editor font size until set) now drives the preview and notebook Markdown cells; fenced code scales with it, and notebook code cells and outputs follow the editor font.

Fixes #768

Co-authored-by: jaw52 <[email protected]>

src/platform/languageSettings.ts

@@ -51,6 +51,8 @@ export interface LanguagesValid {
     gradle: { jvm: string; distribution: "wrapper" | "local"; home: string; userHome: string };
     maven: { home: string; userSettings: string; localRepository: string; unlinkedProjects: string[] };
   };
+  /** Preview font size in px; `null` follows the editor font size. */
+  markdown: { previewFontSize: number | null };
 }
 
 export interface ProjectStructureValid {
@@ -111,6 +113,7 @@ export const DEFAULT_LANGUAGES: LanguagesValid = {
     gradle: { jvm: "", distribution: "wrapper", home: "", userHome: "" },
     maven: { home: "", userSettings: "", localRepository: "", unlinkedProjects: [] },
   },
+  markdown: { previewFontSize: null },
 };
 
 export const DEFAULT_PROJECT_STRUCTURE: ProjectStructureValid = {
@@ -140,6 +143,9 @@ export function normalizeFolder(path: string): string {
     .replace(/^\/+|\/+$/g, "");
 }
 
+/** A stored preview font size within IDEA's 8..72, or `null` (follow the editor font). */
+const previewSize = (v: unknown): number | null =>
+  typeof v === "number" && Number.isFinite(v) ? Math.min(72, Math.max(8, Math.round(v))) : null;
 const folders = (v: unknown): string[] =>
   Array.isArray(v)
     ? [
@@ -171,6 +177,7 @@ export function validateLanguages(raw: unknown): LanguagesValid {
   const java = obj(l.java);
   const maven = obj(java.maven);
   const gradle = obj(java.gradle);
+  const markdown = obj(l.markdown);
   return {
     python: {
       interpreter: text(py.interpreter, d.python.interpreter),
@@ -229,9 +236,29 @@ export function validateLanguages(raw: unknown): LanguagesValid {
         unlinkedProjects: folders(maven.unlinkedProjects),
       },
     },
+    markdown: { previewFontSize: previewSize(markdown.previewFontSize) },
   };
 }
 
+/**
+ * Markdown preview (and notebook Markdown cell) font size in px: Languages &
+ * Frameworks › Markdown, else the editor font size, as IDEA defaults it.
+ */
+export function markdownPreviewFontSize(settings: unknown): number {
+  const s = obj(settings);
+  const editorSize = obj(s.editor).fontSize;
+  return (
+    previewSize(obj(obj(s.languages).markdown).previewFontSize) ??
+    // 13: the editor's default font size.
+    (typeof editorSize === "number" && editorSize > 0 ? editorSize : 13)
+  );
+}
+
+/** Reactive `markdownPreviewFontSize` of the open project. */
+export function useMarkdownPreviewFontSize(): number {
+  return useProject((s) => markdownPreviewFontSize(s.settings));
+}
+
 export function validateProjectStructure(raw: unknown): ProjectStructureValid {
   const p = obj(raw);
   return {

src/platform/locales/text/zh.json

@@ -5373,6 +5373,8 @@
   "Pull Request branch update failed": "拉取请求分支更新失败",
   "#{n} on {branch}": "#{n} 位于 {branch}",
   "Markdown Images": "Markdown 图片",
+  "Preview font size": "预览字号",
+  "Also used by Markdown cells in Jupyter notebooks. Defaults to the editor font size, independent of the UI font size.": "同时用于 Jupyter 笔记本中的 Markdown 单元格。默认跟随编辑器字号，与 UI 字号相互独立。",
   "Image folder": "图片文件夹",
   "Relative to the Markdown file.": "相对于 Markdown 文件。",
   "Image name pattern": "图片名称格式",