Support transparent colors

[khaledhosny]

Issues #14 and #15 implemented support for color options and fonts, but transparency (alpha) is currently ignored because it needs cooperation between various LaTeX package. We need to figure what should be done here.

[emojifreak]

beamer.cls transparency does not work for COLR/CPAL nor CBDT/CBLC font as expected 😭

\documentclass{beamer}
\usepackage{harfload}
\usepackage{fontspec}
\setsansfont{Segoe UI Emoji}[
  RawFeature={mode=harf;+dist;+ccmp}]

\usetheme{Madrid}

\begin{document}
\begin{frame}{text 😂 text after emoji}
\setbeamercovered{transparent=30}
   \begin{itemize}
  \item <+-> Apple 🍎{\fontspec[RawFeature={mode=harf}]{Noto Color Emoji} 🍎}
  \item <+-> Peach 🍑{\fontspec[RawFeature={mode=harf}]{Noto Color Emoji} 🍑}
  \item <+-> Orange 🍊{\fontspec[RawFeature={mode=harf}]{Noto Color Emoji} 🍊}
 \end{itemize}
\end{frame}
\end{document}

harftex-transparent.pdf

[khaledhosny]

That is a different issue, though. My issue is about when the font palette uses transparent color. Your issue is about respecting transparent text color.

I don’t think bitmap fonts can be easily made transparent. Layer fonts should be doable, but that requires more deeper knowledge of LaTeX, PDF and LuaTeX than I do.

[khaledhosny]

Will be fixed when integrated with luaotfload.