Font information should be more accessible inside CharFXTransform

[gruxor]

As it stands, CharFXTransform's Font property is an RID, which means only font-related functionality from TextServer can be used. This disallows the use of any of Font's functions, such as get_string_size, since the RID can't be used to reconstruct the Font from the buffer. The only other way to use Font-exclusive functionality that doesn't exist on TextServer is to get the theme, then get all the fonts, and compare each font's RID until it matches the one inside the CharFXTransform. This makes certain operations inside RichTextEffect cumbersome to perform.

Solutions to this could come in many forms, such as storing the font's string ID (which would make getting it from the theme much easier, i.e. without iterating) or by adding a function to get the used Font (or one of its derivative types) directly. Alternatively, maybe a way to use the font's RID to (re)construct one of the Font classes from the buffer.

[Calinou]

• Related to More advanced text flow manipulation in RichTextEffect/CharFXTransform #3417, Allow RichTextEffects to insert or replace text #6078 and Let RichTextEffect change the font and content #3450.