CKEditor Plugin: Font Mapper

Module: @coremedia/ckeditor5-font-mapper

The Font Mapper plugin extends the CKEditor 5 Clipboard Feature.

When pasting rich text from external sources into the editor, some characters of the pasted text might originate from an unsupported font. This plugin maps such characters to their named entities or Unicode equivalents using a mapping table.

By default, this plugin already contains a mapping table for the Word Symbol font, and automatically converts input content (for instance while pasting from Microsoft Word) accordingly. This mapping table can be replaced or extended.

Clipboard Pipeline Integration

The Font Mapper plugin listens to the ClipboardPipeline’s inputTransformation event with normal priority. This way, it works fine in combination with CKEditor’s PasteFromOffice plugin, which also listens to the same event, but has a higher priority.

Both plugins manipulate the event’s data.content object. This is why it is important to register the event listener with lower priority. Otherwise, the PasteFromOffice plugin would just override the data changed in this plugin.

Example: Copy & Paste from Microsoft Word

This plugin was originally created to prevent broken characters to appear when pasting content from an office application document. In this case, characters written in the Symbol font would not be converted correctly during the transfer.

The Font Mapper plugin solves this issue by searching for certain fonts in font-family style properties and replacing them with a Unicode equivalent, which can be displayed in the editor. During this process, the mentioned characters are changed as defined and the font-family style properties are removed.

During the insertion process, the pasted content is converted into a DocumentFragment. The style attribute on this fragment determines the font-family that is taken into account. The font-name will be a full match (i.e., not partial), ignoring the case.

To reduce additional configuration effort, this plugin already comes with a mapping for the Symbol font and therefore supports pasting content from office application documents out of the box.

Plugin Configuration

If the predefined mapping for the Symbol font is insufficient for your use case, you can change the plugin configuration to meet your needs.

1. Change the Symbol font mapping

The following example demonstrates how to add additional mappings for the Symbol font. The map consists of key-value pairs where the keys are the unicode code points to replace and the values are their HTML replacement, which is most likely an entity, but you may also specify any HTML code. By default, the existing Symbol font mapping will remain, only the characters in the map configuration will be overridden.

ClassicEditor.create(document.querySelector('.editor'), {
  plugins: [
    Clipboard,
    FontMapper,
    // ...
  ],
  "coremedia:fontMapper": [
    {
      font: "Symbol",
      map: {
        38: "&",
        39: "ȭ"
        // ...
      },
    },
    // ...
  ],
});

If you want to replace the mapping for all characters in the Symbol font map, you can use the mode property and set it to "replace". The mode is either "append" or "replace", where "append" is the default and fallback for unknown modes. You can even omit the mode option.

In the following example, the existing default character mappings will be removed and only the mapping for character code 38 will be added:

"coremedia:fontMapper": [
    {
        font: "Symbol",
        mode: "replace",
        map: {
            38: "&"
        },
    },
    // ...
],

2. Add additional font mappings

The "coremedia:fontMapper" configuration is declared as an array, that can hold multiple configuration objects for different fonts. You can therefore add additional mappings for other fonts by simply adding more entries.

Please note that the font property must hold the name of the font in oder to work properly. You don’t need to set a mode for new mappings.

Migration from CoreMedia’s CKEditor 4 cmsymbolfontmapper plugin

This plugin is the CKEditor 5 replacement of CoreMedia’s CKEditor 4 cmsymbolfontmapper plugin, which shipped with CoreMedia Studio. If you already have a custom configuration for the old plugin, converting it to a configuration for this Font Mapper plugin is straightforward.

The following example shows a configuration for the cmsymbolfontmapper plugin:

<ui:RichTextArea>
    <ui:plugins exml:mode="append">
        <ui:CustomizeCKEditorPlugin>
            <ui:ckConfig>
                <fx:Object symbolCharacterReplacementMap=""/>
            </ui:ckConfig>
        </ui:CustomizeCKEditorPlugin>
    </ui:plugins>
</ui:RichTextArea>

To add your custom configuration, you will have to add the "coremedia:fontMapper" key with a custom configuration object like shown in the examples above. You will have to explicitly set the font to "Symbol" and can keep the mode as it was (or even remove it). You can then just copy the character mappings from your symbolCharacterReplacementMap into the map property. The migrated configuration would look like this:

"coremedia:fontMapper": [
    {
        font: "Symbol",
        map: {
            37:'‰',
            64:'📧'
        },
    },
    // ...
],

If you did not use a custom configuration for the cmsymbolfontmapper plugin, adding this plugin to your editor will be enough. Both plugins work the same in their default configuration.

As you may have observed, the font parameter is new. Thus, in contrast to cmsymbolfontmapper you can now refer to any font referenced in font-family style attributes.

See Also

• Manual Testing
• CKEditor 5 Paste from Office feature – CKEditor 5 API docs