add fontconfig plugin

1 files changed, 57 insertions, 0 deletions

diff --git a/fontconfig.lua b/fontconfig.lua
new file mode 100644
index 0000000..3ef3de9
--- /dev/null
+++ b/fontconfig.lua
@@ -0,0 +1,57 @@
+-- mod-version:1 -- lite-xl 1.16
+local subprocess = require "process"
+
+local core = require "core"
+local style = require "core.style"
+local config = require "core.config"
+
+--[[
+    Example config (put it in user module):
+    ```
+    local fc = require "plugins.fontconfig"
+    fc(
+        { name = "sans", size = 13 * SCALE },     -- UI font
+        { name = "monospace", size = 13 * SCALE } -- code font
+    )
+    ```
+]]
+
+local function resolve_font(spec)
+    local scan_rate = 1 / config.fps
+    local proc = subprocess.start({ "fc-match", "-s", "-f", "%{file}\n", spec }, {
+        stdin = subprocess.REDIRECT_DISCARD,
+        stdout = subprocess.REDIRECT_PIPE,
+        stderr = subprocess.REDIRECT_STDOUT
+    })
+    local prev, lines = {}, {}
+    while proc:running() do
+        coroutine.yield(scan_rate)
+        local buf = proc:read_stdout()
+        local p, _, n = string.match(buf, "(.+)\n(.+)")
+        if p then
+            prev[#prev + 1] = p
+            lines[#lines + 1] = table.concat(prev, "")
+            prev = { n }
+        else
+            prev[#prev + 1] = buf
+        end
+    end
+    table.insert(lines, table.concat(prev, ""))
+
+    if proc:returncode() ~= 0 or #lines < 1 then
+        error(string.format("Cannot find a font matching the given specs: %q", spec), 0)
+    end
+    -- maybe in the future we can detect and do glyph substitution here...
+    return lines[1]
+end
+
+local function load_system_fonts(font, code_font)
+    core.add_thread(function()
+        local font_file = resolve_font(font.name)
+        local code_font_file = resolve_font(code_font.name)
+        style.font = renderer.font.load(font_file, font.size, font)
+        style.code_font = renderer.font.load(code_font_file, code_font.size, code_font)
+    end)
+end
+
+return load_system_fonts
\ No newline at end of file