feat(editor): add font size adjustment in editor settings (#13549)

Co-authored-by: DarkSky <25152247+darkskygit@users.noreply.github.com>
Co-authored-by: DarkSky <darksky2048@gmail.com>

packages/frontend/core/src/desktop/dialogs/setting/general-setting/editor/general.tsx

@@ -9,6 +9,7 @@ import {
   type RadioItem,
   RowInput,
   Scrollable,
+  Slider,
   Switch,
   useConfirmModal,
 } from '@affine/component';
@@ -308,6 +309,46 @@ const CustomFontFamilySettings = () => {
   );
 };
 
+const FontSizeSettings = () => {
+  const t = useI18n();
+  const { editorSettingService } = useServices({ EditorSettingService });
+  const settings = useLiveData(editorSettingService.editorSetting.settings$);
+
+  const onFontSizeChange = useCallback(
+    (fontSize: number[]) => {
+      const size = fontSize[0];
+      editorSettingService.editorSetting.set('fontSize', size);
+      // Update CSS variable immediately
+      document.documentElement.style.setProperty('--affine-font-base', `${size}px`);
+    },
+    [editorSettingService.editorSetting]
+  );
+
+  // Apply current font size to CSS variable on mount
+  useEffect(() => {
+    document.documentElement.style.setProperty('--affine-font-base', `${settings.fontSize}px`);
+  }, [settings.fontSize]);
+
+  return (
+    <SettingRow
+      name={t['com.affine.settings.editorSettings.general.font-size.title']()}
+      desc={t['com.affine.settings.editorSettings.general.font-size.description']()}
+    >
+      <div className={styles.fontSizeContainer}>
+        <Slider
+          value={[settings.fontSize]}
+          onValueChange={onFontSizeChange}
+          min={12}
+          max={24}
+          step={1}
+          className={styles.fontSizeSlider}
+        />
+        <span className={styles.fontSizeValue}>{settings.fontSize}px</span>
+      </div>
+    </SettingRow>
+  );
+};
+
 const menuContentOptions: MenuProps['contentOptions'] = {
   align: 'end',
   sideOffset: 16,
@@ -522,6 +563,7 @@ export const General = () => {
       <AISettings />
       <FontFamilySettings />
       <CustomFontFamilySettings />
+      <FontSizeSettings />
       <NewDocDefaultModeSettings />
       {BUILD_CONFIG.isElectron && <SpellCheckSettings />}
       {environment.isLinux && <MiddleClickPasteSettings />}

packages/frontend/core/src/desktop/dialogs/setting/general-setting/editor/style.css.ts

@@ -163,3 +163,21 @@ export const spellCheckSettingDescriptionButton = style({
   color: cssVarV2('text/link'),
   fontSize: 'inherit',
 });
+
+export const fontSizeContainer = style({
+  display: 'flex',
+  alignItems: 'center',
+  gap: '12px',
+  width: '250px',
+});
+
+export const fontSizeSlider = style({
+  flex: 1,
+});
+
+export const fontSizeValue = style({
+  fontSize: cssVar('fontSm'),
+  color: cssVarV2('text/secondary'),
+  minWidth: '40px',
+  textAlign: 'right',
+});

packages/frontend/core/src/desktop/pages/root/custom-theme/index.tsx

@@ -1,4 +1,5 @@
 import { FeatureFlagService } from '@affine/core/modules/feature-flag';
+import { EditorSettingService } from '@affine/core/modules/editor-setting';
 import { ThemeEditorService } from '@affine/core/modules/theme-editor';
 import { useLiveData, useServices } from '@toeverything/infra';
 import { useTheme } from 'next-themes';
@@ -7,13 +8,15 @@ import { useEffect } from 'react';
 let _provided = false;
 
 export const CustomThemeModifier = () => {
-  const { themeEditorService, featureFlagService } = useServices({
+  const { themeEditorService, featureFlagService, editorSettingService } = useServices({
     ThemeEditorService,
     FeatureFlagService,
+    EditorSettingService,
   });
   const enableThemeEditor = useLiveData(
     featureFlagService.flags.enable_theme_editor.$
   );
+  const settings = useLiveData(editorSettingService.editorSetting.settings$);
   const { resolvedTheme } = useTheme();
 
   useEffect(() => {
@@ -45,5 +48,12 @@ export const CustomThemeModifier = () => {
     };
   }, [resolvedTheme, enableThemeEditor, themeEditorService]);
 
+  // Apply font size CSS variable when settings change
+  useEffect(() => {
+    if (settings.fontSize) {
+      document.documentElement.style.setProperty('--affine-font-base', `${settings.fontSize}px`);
+    }
+  }, [settings.fontSize]);
+
   return null;
 };

packages/frontend/core/src/modules/editor-setting/schema.ts

@@ -19,6 +19,7 @@ export const fontStyleOptions = [
 const AffineEditorSettingSchema = z.object({
   fontFamily: z.enum(['Sans', 'Serif', 'Mono', 'Custom']).default('Sans'),
   customFontFamily: z.string().default(''),
+  fontSize: z.number().min(12).max(24).default(16),
   newDocDefaultMode: z.enum(['edgeless', 'page', 'ask']).default('page'),
   fullWidthLayout: z.boolean().default(false),
   displayDocInfo: z.boolean().default(true),