fix(shapers): Properly calculate metrics of single characters composed of many glyphs

Author: alerque

shapers/base.lua

@@ -67,9 +67,18 @@ function shaper:measureChar (char)
    local options = SILE.font.loadDefaults({})
    options.tracking = SILE.settings:get("shaper.tracking")
    local items = self:shapeToken(char, options)
-   if items and items[1] then
-      local item = items[1]
-      return item, item.gid ~= 0
+   if items and #items > 0 then
+      local measurements = {
+         width = 0,
+         height = 0,
+         depth = 0,
+      }
+      for _, item in ipairs(items) do
+         measurements.width = measurements.width + item.width
+         measurements.height = math.max(measurements.height, item.height)
+         measurements.depth = math.max(measurements.depth, item.depth)
+      end
+      return measurements, items[1].gid ~= 0
    else
       SU.error("Unable to measure character", char)
    end