Update Caption Presets - Svelte

Add custom caption presets to CE.SDK’s video caption feature. A caption preset is a declarative style preset: you describe the look as JSON and the engine applies it to a caption block with a single click.

Update Caption Presets example showing a styled neon glow caption preset

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CE.SDK ships built-in caption presets so users can restyle their captions in one click, and you can add your own. A preset is just a JSON object that describes the look, so there are no blocks to build or files to serialize. This guide shows how to define a preset, register it at runtime, and host your own set.

import type {
  AssetStylePreset,
  EditorPlugin,
  EditorPluginContext
} from '@cesdk/cesdk-js';

import {
  BlurAssetSource,
  CaptionPresetsAssetSource,
  ImageColorsAssetSource,
  ColorPaletteAssetSource,
  CropPresetsAssetSource,
  DemoAssetSources,
  EffectsAssetSource,
  FiltersAssetSource,
  PagePresetsAssetSource,
  StickerAssetSource,
  TextAssetSource,
  TextComponentAssetSource,
  TypefaceAssetSource,
  UploadAssetSources,
  VectorShapeAssetSource
} from '@cesdk/cesdk-js/plugins';
import { VideoEditorConfig } from '@cesdk/core-configs-web/video-editor';
import packageJson from './package.json';

/**
 * CE.SDK Plugin: Update Caption Presets Guide
 *
 * Demonstrates creating custom caption presets in CE.SDK:
 * - Defining a declarative style preset for a caption look
 * - Registering the preset so it appears in the caption presets panel
 * - Understanding the content.json structure for hosted caption presets
 */
class Example implements EditorPlugin {
  name = packageJson.name;

  version = packageJson.version;

  async initialize({ cesdk }: EditorPluginContext): Promise<void> {
    if (!cesdk) {
      throw new Error('CE.SDK instance is required for this plugin');
    }

    await cesdk.addPlugin(new VideoEditorConfig());

    // Add asset source plugins
    await cesdk.addPlugin(new BlurAssetSource());
    await cesdk.addPlugin(new CaptionPresetsAssetSource());
    await cesdk.addPlugin(new ImageColorsAssetSource());
    await cesdk.addPlugin(new ColorPaletteAssetSource());
    await cesdk.addPlugin(new CropPresetsAssetSource());
    await cesdk.addPlugin(
      new UploadAssetSources({
        include: [
          'ly.img.image.upload',
          'ly.img.video.upload',
          'ly.img.audio.upload'
        ]
      })
    );
    await cesdk.addPlugin(
      new DemoAssetSources({
        include: [
          'ly.img.templates.video.*',
          'ly.img.image.*',
          'ly.img.audio.*',
          'ly.img.video.*'
        ]
      })
    );
    await cesdk.addPlugin(new EffectsAssetSource());
    await cesdk.addPlugin(new FiltersAssetSource());
    await cesdk.addPlugin(
      new PagePresetsAssetSource({
        include: [
          'ly.img.page.presets.instagram.*',
          'ly.img.page.presets.facebook.*',
          'ly.img.page.presets.x.*',
          'ly.img.page.presets.linkedin.*',
          'ly.img.page.presets.pinterest.*',
          'ly.img.page.presets.tiktok.*',
          'ly.img.page.presets.youtube.*',
          'ly.img.page.presets.video.*'
        ]
      })
    );
    await cesdk.addPlugin(new StickerAssetSource());
    await cesdk.addPlugin(new TextAssetSource());
    await cesdk.addPlugin(new TextComponentAssetSource());
    await cesdk.addPlugin(new TypefaceAssetSource());
    await cesdk.addPlugin(new VectorShapeAssetSource());

    await cesdk.actions.run('scene.create', {
      layout: 'DepthStack',
      page: {
        sourceId: 'ly.img.page.presets',
        assetId: 'ly.img.page.presets.instagram.story',
        color: { r: 0, g: 0, b: 0, a: 1 }
      }
    });

    const engine = cesdk.engine;

    // Describe the look as a declarative style preset. The engine reads this
    // object and applies it to a caption block, so there is no styled block to
    // serialize. Colors are RGB(A) objects in the 0-1 range.
    const neonGlowStylePreset: AssetStylePreset = {
      blockType: '//ly.img.ubq/caption',
      // `replace` resets the properties the preset does not list, so switching
      // presets never stacks leftover decorations.
      mode: 'replace',
      typeface: {
        family: 'Monoton',
        weight: 'normal',
        style: 'normal'
      },
      properties: {
        // Keys without a slash are namespaced to the block (caption/*).
        'caption/horizontalAlignment': 'Center',
        'caption/verticalAlignment': 'Center',
        // Bright cyan text fill.
        'fill/enabled': true,
        'fill/solid/color': { r: 0, g: 1, b: 1, a: 1 },
        // Semi-transparent background so captions stay readable over video.
        'backgroundColor/enabled': true,
        'backgroundColor/color': { r: 0, g: 0, b: 0.1, a: 0.7 },
        // A matching glow built from a soft drop shadow.
        'dropShadow/enabled': true,
        'dropShadow/color': { r: 0, g: 1, b: 1, a: 0.8 },
        'dropShadow/clip': false
      },
      // Keep the background rounding and the glow proportional to the font size
      // instead of baking in fixed pixel values. Each entry sets its property to
      // `ratio * fontSize`.
      scaleWithFontSize: [
        { property: 'backgroundColor/cornerRadius', ratio: 0.2 },
        { property: 'dropShadow/blurRadius/x', ratio: 0.8 },
        { property: 'dropShadow/blurRadius/y', ratio: 0.8 }
      ]
    };

    // Add the preset to the existing caption presets source so it shows up in
    // the caption presets panel next to the built-in presets.
    engine.asset.addAssetToSource('ly.img.caption.presets', {
      id: 'ly.img.caption.presets.neon-glow',
      label: { en: 'Neon Glow' },
      meta: {
        thumbUri: '{{base_url}}/ly.img.caption.presets/thumbnails/neon-glow.png'
      },
      groups: ['caption'],
      payload: { stylePreset: neonGlowStylePreset }
    });

    // To host the preset instead of registering it at runtime, add the same
    // entry to your content.json. The style preset lives in payload.stylePreset
    // and meta only needs a thumbUri.
    const contentJsonEntry = {
      id: 'ly.img.caption.presets.neon-glow',
      label: { en: 'Neon Glow' },
      meta: {
        thumbUri: '{{base_url}}/ly.img.caption.presets/thumbnails/neon-glow.png'
      },
      groups: ['caption'],
      payload: { stylePreset: neonGlowStylePreset }
    };

    console.log('=== content.json Entry ===');
    console.log('Add this entry to your content.json assets array:');
    console.log(JSON.stringify(contentJsonEntry, null, 2));

    // A complete content.json wraps the preset entries in the assets array.
    const completeContentJson = {
      version: '7.0.0',
      id: 'ly.img.caption.presets',
      assets: [contentJsonEntry]
    };

    console.log('\n=== Complete content.json Example ===');
    console.log(JSON.stringify(completeContentJson, null, 2));

    console.log('\n=== Caption Preset Guide ===');
    console.log(
      'Open the caption presets panel to apply the "Neon Glow" preset to a caption.'
    );
    console.log('To host this preset:');
    console.log('1. Add the content.json entry to your assets folder');
    console.log('2. Create a thumbnail image showing the preset appearance');
    console.log('3. Configure CE.SDK baseURL to point to your assets location');
  }
}

export default Example;

Define a caption style preset#

Describe the look as a plain object. The engine applies it to a caption block, so you never create or serialize a styled block yourself.

// Describe the look as a declarative style preset. The engine reads this
// object and applies it to a caption block, so there is no styled block to
// serialize. Colors are RGB(A) objects in the 0-1 range.
const neonGlowStylePreset: AssetStylePreset = {
  blockType: '//ly.img.ubq/caption',
  // `replace` resets the properties the preset does not list, so switching
  // presets never stacks leftover decorations.
  mode: 'replace',
  typeface: {
    family: 'Monoton',
    weight: 'normal',
    style: 'normal'
  },
  properties: {
    // Keys without a slash are namespaced to the block (caption/*).
    'caption/horizontalAlignment': 'Center',
    'caption/verticalAlignment': 'Center',
    // Bright cyan text fill.
    'fill/enabled': true,
    'fill/solid/color': { r: 0, g: 1, b: 1, a: 1 },
    // Semi-transparent background so captions stay readable over video.
    'backgroundColor/enabled': true,
    'backgroundColor/color': { r: 0, g: 0, b: 0.1, a: 0.7 },
    // A matching glow built from a soft drop shadow.
    'dropShadow/enabled': true,
    'dropShadow/color': { r: 0, g: 1, b: 1, a: 0.8 },
    'dropShadow/clip': false
  },
  // Keep the background rounding and the glow proportional to the font size
  // instead of baking in fixed pixel values. Each entry sets its property to
  // `ratio * fontSize`.
  scaleWithFontSize: [
    { property: 'backgroundColor/cornerRadius', ratio: 0.2 },
    { property: 'dropShadow/blurRadius/x', ratio: 0.8 },
    { property: 'dropShadow/blurRadius/y', ratio: 0.8 }
  ]
};

The fields:

blockType: the target block. Use '//ly.img.ubq/caption'.
mode: 'replace' (the default) clears anything the preset omits, so presets never stack. 'merge' layers the preset on top and keeps untouched properties.
typeface: the font, resolved by family with optional weight and style.
properties: a flat map of property paths to values. Keys without a slash are namespaced to the block (for example caption/horizontalAlignment); colors are RGB(A) objects in the 0-1 range. Common paths are fill/solid/color, backgroundColor/color, dropShadow/color, and caption/horizontalAlignment.
scaleWithFontSize (optional): keeps a decoration proportional to the font size. Each { property, ratio } entry sets property to ratio × fontSize. Supported for stroke/width, the dropShadow offset and blur radius, and backgroundColor/cornerRadius.

Register the preset#

CE.SDK already includes the ly.img.caption.presets source. Add your preset to it so it appears in the caption presets panel:

// Add the preset to the existing caption presets source so it shows up in
// the caption presets panel next to the built-in presets.
engine.asset.addAssetToSource('ly.img.caption.presets', {
  id: 'ly.img.caption.presets.neon-glow',
  label: { en: 'Neon Glow' },
  meta: {
    thumbUri: '{{base_url}}/ly.img.caption.presets/thumbnails/neon-glow.png'
  },
  groups: ['caption'],
  payload: { stylePreset: neonGlowStylePreset }
});

Users apply it from the panel like any built-in preset. To apply it in code, use engine.asset.applyToBlock('ly.img.caption.presets', asset, captionBlockId).

Host your own presets#

To serve presets from your own server instead of registering them at runtime, host a content.json and point the engine’s baseURL at it. The source needs only the index file and a thumbnails folder:

assets/v7/ly.img.caption.presets/
├── content.json
└── thumbnails/
    └── neon-glow.png

Each asset carries its look inline in payload.stylePreset and a preview in meta.thumbUri. There are no separate preset files:

{
  "version": "7.0.0",
  "id": "ly.img.caption.presets",
  "assets": [
    {
      "id": "ly.img.caption.presets.neon-glow",
      "label": { "en": "Neon Glow" },
      "meta": {
        "thumbUri": "{{base_url}}/ly.img.caption.presets/thumbnails/neon-glow.png"
      },
      "groups": ["caption"],
      "payload": {
        "stylePreset": {
          "blockType": "//ly.img.ubq/caption",
          "mode": "replace",
          "typeface": { "family": "Monoton", "weight": "normal" },
          "properties": {
            "fill/enabled": true,
            "fill/solid/color": { "r": 0, "g": 1, "b": 1, "a": 1 }
          }
        }
      }
    }
  ]
}

CE.SDK loads ly.img.caption.presets/content.json relative to baseURL, so your presets replace the defaults automatically:

const cesdk = await CreativeEditorSDK.create('#cesdk_container', {
  baseURL: 'https://your-server.com/assets/'
});

Troubleshooting#

Preset not loading: confirm content.json is reachable with no 404 or CORS errors, and that version is 7.0.0.
Styles not applying: set blockType to '//ly.img.ubq/caption' and check the property paths. mode: 'replace' drops anything the preset omits, so switch to 'merge' to layer on top.
Color or decoration missing: use RGB(A) values in the 0-1 range, and enable a decoration before coloring it (for example dropShadow/enabled: true alongside dropShadow/color).
Thumbnail blank: verify the thumbUri path resolves and the image is a PNG.

API Reference#

Method	Purpose
`engine.asset.addAssetToSource(sourceId, asset)`	Register a custom preset in an asset source
`engine.asset.applyToBlock(sourceId, asset, block)`	Apply a preset to a caption block
`CreativeEditorSDK.create(container, config)`	Initialize the editor with a `baseURL`