[flutter_markdown] Pass parent TextStyle down to MarkdownElementBuilder.visitElementAfter

[IchordeDionysos]

The parent TextStyle should be passed down to the MarkdownElementBuilder.visitElementAfter method to allow custom markdown tags to override only part of the text style, e.g. the color, but keep all the rest of the styles the same.

This is especially useful when trying to color markdown headers in a certain color, as the parent font size, font family, etc. all are passed down and can be kept, while only the color is overridden.

This will unfortunately lead to a breaking change, due to the nature of how the class is typically used. As all usages of the class are sub-classes any change to the method schema will result in a breaking change!

Enables the following https://github.com/flutter/flutter/issues/105571

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[IchordeDionysos]

@domesticmouse, how do we deal with the breaking change of the PR? Can I just bump the version to the next breaking version, or do you want to consolidate multiple breaking changes into one major release?

[domesticmouse]

@domesticmouse, how do we deal with the breaking change of the PR?

Can I just bump the version to the next breaking version, or do you want to consolidate multiple breaking changes into one major release?

@stuartmorgan thoughts?

[IchordeDionysos]

I've also exposed now the BuildContext in the visitElementAfter method if you need to access the context for some reason, you no longer have to fallback to workarounds like this:

Which is a very hacky workaround and has it's own drawbacks 🙈

  @override
  Widget visitElementAfter(md.Element element, TextStyle? preferredStyle) {
    return RichText(
      text: TextSpan(
        children: [
          WidgetSpan(
            child: Builder(
              builder: (context) {
                return Text(
                  innerText,
                  style: preferredStyle
                );
              },
            ),
          ),
        ],
      ),
    );
  }

Feels free to leave any suggestions/feedback/change requests!

[stuartmorgan-g]

@domesticmouse, how do we deal with the breaking change of the PR? Can I just bump the version to the next breaking version, or do you want to consolidate multiple breaking changes into one major release?

@stuartmorgan thoughts?

Does it have to be a breaking change? What about a new method with a default implementation that calls the existing method (discarding the extra parameters)?

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[IchordeDionysos]

@stuartmorgan thanks for the hint, I've just implemented it, not sure yet about the name of the new function 🤔

/cc @domesticmouse

[IchordeDionysos]

@domesticmouse if you find the time to give this a review here that would be awesome :)

It's no longer a breaking change so should be easier to merge

[stuartmorgan-g]

@IchordeDionysos Are you still planning on updating this based on the last round of feedback?

[stuartmorgan-g]

I'm making this a draft just to get it off of the review queue; please mark it as ready for review once you've had a chance to update. Thanks!

[stuartmorgan-g]

@tarrinneal to adopt, per triage meeting.

[tarrinneal]

Closing and moving changes over to https://github.com/flutter/packages/pull/4393 as I cannot make changes to this pr.