Ligatures support

[rainDiX]

Ligatures do not render when using emacs pgtk

For comparison, here it is how it render using emacs vanilla (a bit blurry because of xwayland's scaling).

How to reproduce

• Set a font with ligature support (e.g. FiraCode or Cascadia Code)
• install ligature.el and configure it (the default config provided in the README should be enough)

My environment

archlinux gtk3 3.24.23 cairo 1.17.2 harfbuzz 2.7.2 sway 1.5.1

[masm11]

I can't enable ligatures on X-build.

0. Install Fira Code font.
1. Build X-emacs.
2. ./src/emacs -Q
3. evaluate (set-fontset-font nil nil "Fira Code").
4. load ligature.el and evaluate it.
5. evaulate commented config snippet.
6. I typed "www" on some buffers. It is not ligatured.

What's wrong?

[rainDiX]

To enable ligatures I do as follows ( Keep steps 0, 1 and 2):

3. evaluate (set-face-attribute 'default nil :font "Fira Code").
4. load ligature.el and evaluate it.
5. evaluate (ligature-set-ligatures 't '("www")) (ligature-mode 1)
6. www should be ligatured

[rainDiX]

Or alternatively, without needing ligature.el at all :

3. evaluate

   
   (set-face-attribute 'default nil :font "Fira Code")
   (let ((ligatures `((?w  . ,(regexp-opt '("www")))
        (?&  . ,(regexp-opt '("&&&" "&&"))))))
   (dolist (char-regexp ligatures)
   (set-char-table-range composition-function-table (car char-regexp)
                         `([,(cdr char-regexp) 0 font-shape-gstring]))))

4. "www" "&&" and "&&&" should be ligatured

[masm11]

thank you. confirmed.

[masm11]

I forgot to register harfbuzz font driver. I registered it, and now ligatures work.

Try latest feature/pgtk on savannah.

[rainDiX]

Tested the newer commit, that fixed it. Thanks.