deepakjois / luatex-harfbuzz Goto Github PK

One of the problems with using LuaRocks for developing LuaTeX related packages is that the default package loader in LuaTeX uses kpse. kpse overrides the standard Lua package loading behavior that LuaRocks relies on.

It is possible to get around it by overriding the LuaTeX package loader, to revert it to the standard Lua behavior. We already have that functionality in ufy. But ufy itself is a LuaRocks package and needs to be loaded before anything else, and hence we have a bootstrapping problem when we invoke LuaTeX.

Currently, we get around it by using LuaTeX’s --lua flag to load a pre-init file that executes before LuaTeX is fully initialized (and hence retains the default package loading behavior), and loads ufy in the global environment. Then we invoke the relevant functions in the TeX file, once LuaTeX is fully initialized. This method however relies on the user invoking LuaTeX with the --lua flag and having a pre-init file located somewhere.

A more elegant solution to this problem might be to create a CTAN module (maybe something called luapackageloader) that can encapsulate the package loading functionality. Assuming this CTAN module is properly installed inside the TeX distribution, we can invoke it as:

\input luapackageloader

% Now it should be possible to load a LuaRocks package
\directlua{require("luabidi")}

and then continue loading the rocks.

This is an issue to track enhancements to the LuaTeX example code that uses Harfbuzz to shape text.

Paragraph Handling

• Fix widths of spacing glue in font loader
• Refactor upem to sp scaling code
• Add Devanagari example
• Add Latin example
• Set cluster level to HB_BUFFER_CLUSTER_LEVEL_CHARACTERS
• Add sample PDFs
• Handle penalty nodes
• Handle different kinds of glue nodes
• Handle direction nodes
• Add ability to load packages using a PATH of some kind
• Handle font switching (includes switching the font style – like roman to italic or bold)
• Handle BiDi (look into libraqm and FriBidi code to get a better understanding)
• Alignment
• Handle hyphenation and corresponding change to shaping.

Font Loading Callback

• Add support for handling features

Testing and Control

• Can we turn Harfbuzz shaping on/off (using an attribute or something)
• Can we test code with busted or something?

HBox Handling

TODO