If you've been exploring Drupal's Canvas module (also known as Experience Builder), you've probably noticed its powerful component-based page-building capabilities. However, you may have also encountered a few limitations:

Canvas limits WYSIWYG editing within its own text formats. This leaves content editors with a limited toolbar and restricted HTML options.

While working with Canvas, I noticed that several people in the Drupal community were struggling with this restricted WYSIWYG setup. Canvas currently allows only its own canvas_html_block and canvas_html_inline text formats, which means there's no flexibility to customize the toolbar or apply additional text formats that your site might already have configured.

To solve this problem, I built the Canvas Full HTML module - a simple yet effective solution that enables full HTML text format support within Canvas, giving your content editors the complete CKEditor 5 experience they're used to.

In this tutorial, I’ll guide you through the entire process - from installing Canvas to utilizing the Canvas Full HTML module to enhance your editing experience.

What is Drupal Canvas (Experience Builder)?

Drupal Canvas is the next-generation page-building tool as part of Drupal’s Starshot Initiative. It offers a modern, React-based interface and uses reusable components to build pages.

Key features of Drupal Canvas

• Component-based architecture: Use drag and drop pre-built components to build pages.
• Real-time preview: You’ll see instant changes as you edit the pages.
• Single Directory Components (SDC): Canvas uses Drupal’s modern component system.
• Developer-friendly: Canvas uses developer-friendly tools like Twig, CSS, and JavaScript for its components.

Why consider Canvas?

Canvas represents the future of content editing in Drupal. It bridges the gap between the developer experience (building components) and the editor experience (assembling pages), making it easier for both parties to collaborate effectively.

How to set up Drupal Canvas: A quick-start guide

Before we dive into the use cases of the Canvas Full HTML module, let’s start with setting up Canvas. Here’s how you can set up Drupal Canvas:

Prerequisites

• Drupal 10.3+ or Drupal 11
• PHP 8.1 or higher
• Composer

Step 1: Install Canvas

composer require drupal/canvas

drush en canvas

Step 2: Use the right admin theme (Gin recommended)

While Canvas works with any admin theme, Gin provides the best experience.

Here's why:

• Modern UI: Gin's clean interface complements Canvas's React-based UI.
• Better toolbar integration: Gin Toolbar provides a streamlined navigation experience that works well alongside Canvas.
• Consistent design language: Both Canvas and Gin follow modern design principles, creating a cohesive editing experience.
• Active development: Gin is actively maintained and regularly updated for compatibility with new Drupal features.

To install Gin:

composer require drupal/gin drupal/gin_toolbar

drush en gin gin_toolbar

Then set Gin as your admin theme at Administration → Appearance.

Step 3: Create your first Canvas page

1. Navigate to Drupal Canvas by clicking on “Drupal Canvas” on top right corner of the admin toolbar → New Page
2. Click to create a new Canvas page
3. The Canvas editor will show an empty canvas ready for components

Step 4: Add components to your page

1. In the Canvas editor, look for the component panel (usually on the left side). Click on the “+” icon
2. Browse available components or search for specific ones
3. Drag a component onto your canvas
4. Click on the component to edit its properties in the right panel
5. Fill in the required fields and see your changes in real-time

The Problem: Restricted WYSIWYG in Canvas

Now that you have Canvas running, try adding a component with a rich text field. You'll notice something limiting: the CKEditor toolbar is minimal, and not all the formatting options will be accessible to you.

Why does this happen?

Canvas creates its own text formats for security and consistency:

• canvas_html_block: For block-level content (paragraphs, headings, lists)
• canvas_html_inline: For inline content (bold, italic, links)

These formats intentionally restrict which HTML tags and CKEditor plugins are available. While this is great for security, it can be frustrating when you need:

• Source code editing
• More heading levels
• Special characters
• Custom styles
• Media embeds
• And other advanced formatting options

The community's struggle

Through discussions in the Drupal community, I found that many site builders and content editors were facing the same challenges:

• "How do I add a table in Canvas?"
• "Why can't I access the source code?"
• "I need more toolbar options for my editors."

Canvas's architecture doesn't allow toggling between text formats directly during page editing. The format is determined at the component level, making it impossible to switch formats on the fly.

The Solution: Canvas Full HTML Module

The Canvas Full HTML module addresses these limitations by replacing Canvas's restricted text formats with Drupal's full_html format, giving editors complete control over their content.

How it works:

The module uses Drupal's hook system to intercept Canvas's component configuration:

1. hook_canvas_storable_prop_shape_alter(): When Canvas builds a component form, this hook detects rich text properties (those with contentMediaType: text/html) and replaces the allowed text format from canvas_html_block to full_html.
2. Library integration: Since Canvas bypasses normal Drupal page rendering, the module uses hook_library_info_alter() to inject its CSS and JavaScript directly into the Canvas UI.
3. CKEditor toolbar fix: Canvas uses Radix UI components with overflow: hidden on scroll containers, which can clip CKEditor's toolbar dropdowns. The module includes JavaScript that detects when a dropdown is open and temporarily adjusts the overflow settings.

Installation and Configuration

Step 1: Install the module

composer require drupal/canvas_full_html

drush en canvas_full_html

Step 2: Configure the module

1. Navigate to Administration → Configuration → Content → Canvas Full HTML (or go directly to /admin/config/content/canvas-full-html)
2. Check the box for "Enable Full HTML format in Canvas"
3. Click Save configuration

You’re done. The module is set up.

Step 3: Clear caches and test

drush cr

Now open the Canvas editor and add a component with a rich text field. You should see the full CKEditor 5 toolbar with all available options.

Use Cases

Marketing teams

Marketing teams often need to create landing pages with rich formatting - pull quotes, styled callouts, embedded media, and custom HTML snippets. With Canvas Full HTML, they can access all these features without developer intervention.

Content-heavy websites

News sites, blogs, and documentation portals need flexible text formatting. The ability to access source code and use the complete CKEditor toolbar makes content creation faster and more efficient.

Migration projects

If you're migrating from another CMS or an older Drupal site, your existing content might use HTML that Canvas's restricted formats don't support. Canvas Full HTML ensures compatibility with your existing content.

Agencies and freelancers

When building sites for clients, you want to give them the tools they need without constantly fielding support requests about "missing" features. Full HTML support means fewer limitations and happier clients.

Included example component

The module includes a sample Rich Text Block component that demonstrates how to create components with full HTML support:

rich_text_block.component.yml

name: Rich Text Block

description: A rich text block component with full HTML support for Canvas.

  props:
    type: object
    required:
      - heading
    properties:
      heading:
        type: string
        title: Heading
      content:
        type: string
        title: Content
        contentMediaType: text/html      
        x-formatting-context: block
      background_color:
        type: string
        title: Background Color
        enum:
          - white  
          - light-gray
          - light-blue
        default: white
  slots:
    footer:
      title: Footer

The key part is the content property with contentMediaType: text/html and x-formatting-context: block. This tells Canvas that this field should use a rich text editor, and the Canvas Full HTML module ensures it uses the full_html format.

Troubleshooting

CKEditor Toolbar Dropdown is Cut Off

Clear all caches after enabling the module:

drush cr

The module includes CSS fixes for this issue, but they require a cache clear to take effect.

Full HTML format not being used

1. Ensure the setting is enabled at /admin/config/content/canvas-full-html
2. Clear all caches
3. Add a new component instance — existing instances may have cached settings
4. Verify that the full_html text format exists at

/admin/config/content/formats/manage/full_html

Switching back to Canvas default formats

If you need to revert to Canvas's restricted formats:

1. Go to /admin/config/content/canvas-full-html
2. Uncheck "Enable Full HTML format in Canvas"
3. Save configuration (caches are automatically cleared)
4. Create new component instances to use the default formats

Future plans

This module marks the beginning of what's actually on the roadmap:

Component-Level Text Format Switching: Currently, the module applies full_html globally to all rich text fields. In future versions, we plan to add the ability to configure text formats on a per-component basis, giving site builders more granular control.

We welcome contributions and feedback from the community. If you have ideas or want to help develop new features, check out the issue queue on Drupal.org.

Final thoughts

The Canvas Full HTML module solves a real pain point in the Canvas editing experience. Removing the restrictions on text formatting empowers content editors to create richer, more engaging content while maintaining the benefits of Canvas's component-based architecture.

Whether you're a developer building custom components, a site builder configuring Canvas for clients, or a content editor creating pages, this module gives you the flexibility you need.

Ready to get started?

• Download Canvas Full HTML on Drupal.org: https://www.drupal.org/project/canvas_full_html
• Report issues or request features: https://www.drupal.org/project/issues/canvas_full_html
• Learn more about Canvas: https://www.drupal.org/project/canva