Fix 309357

[JiuqingSong]

Bug 309357: HTML emails have inconsistent paragraph spacing when forwarded

It is possible we add some global CSS style after generating HTML from editor. It can cause the HTML style changed by the global CSS. So we need to let editor be aware of such global CSS, so it can generate HTML accordingly.

For example, we can add such CSS to HTML:

<style>
p { margin-top:0; margin-bottom:0}
</style>

And inside editor, if we have a <P> with the same style, there is no problem. However if there is <P> without any style, we expect it to show margins, but the margins will be removed by the CSS above. So in that case we need to explicitly add inline CSS to P to maintain its margins, like:

<p style="margin-top: 1em; margin-bottom: 1em">some text</p>

To achieve this, I'm adding a new option to editor options in defaultModelToDomOptions parameter, for example:

const editor = new Editor(div, {
   ...,
   defaultModelToDomOptions: {
        defaultContentModelFormatOverride: {
            p: {
                marginTop: '0',
                marginBottom: '0',
            },
        },
   }
};

So that when generate HTML, editor knows that default margin for P will be '0' in this context, when a P has other margin value, it will generate explicit inline CSS to keep its style.

[Copilot]

Pull Request Overview

This pull request fixes bug 309357 where HTML emails have inconsistent paragraph spacing when forwarded. The fix enables the editor to be aware of global CSS styles that may override default element formatting, allowing it to generate appropriate inline styles to maintain intended appearance.

Key changes:

• Adds defaultContentModelFormatOverride option to specify default format overrides for HTML tags
• Updates the model-to-DOM context to use these overrides when generating HTML
• Adds demo functionality to test the feature with paragraph margin handling

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
ModelToDomSettings.ts	Adds defaultContentModelFormatMap property to settings interface
ModelToDomOption.ts	Adds defaultContentModelFormatOverride option for tag-specific format overrides
createModelToDomContextTest.ts	Updates tests to verify the new format override functionality
stackFormat.ts	Changes to use context-based format map instead of global default
createModelToDomContext.ts	Implements logic to merge default formats with overrides
paragraphPresets.ts	Adds test preset for HTML paragraphs with margins
allPresets.ts	Includes new paragraph preset in available presets
defaultModelToDomOption.ts	Creates default option with paragraph margin overrides
MainPane.tsx	Integrates the new default model-to-DOM option
MainPane.scss	Adds CSS rule to reset paragraph margins globally
exportContentButton.ts	Updates export functionality to use format overrides and DOMPurify