Partially fix unicode name truncation.

This fix ensures that name truncation always happens on codepoint
boundaries and that a name has exactly 5 visible codepoints. This should
cover all possible cases unless names can have grapheme clusters, afaik
this is not the case.

src/types/unitframe.lua

@@ -35,24 +35,39 @@ types.UnitFrame = UnitFrame
 
 
 local colors = {
-    hostile = {0.5, 0.0, 0.0},
-    neutral = {0.7, 0.7, 0.0},
-    healthy = {0, 0.1, 0},
-    high = {0, 1.0, 0},
-    mid = {1.0, 1.0, 0},
-    low = {1.0, 0.0, 0},
-    offline = {0.7, 0.7, 0.7},
-    dead = {0.7, 0.7, 0.7},
-    magic = {0.4, 0.4, 1.0},
-    disease = {0.4, 0.2, 0.0},
-    poison = {0.0, 0.7, 0.7},
-    curse = {0.7, 0.0, 0.7},
-    immune = {0.0, 0.2, 0.4},
-    bomb = {1.0, 0.7, 0.7},
-    cyan = {0.0, 0.8, 0.8},
-    white = {1.0, 1.0, 1.0}
+    hostile = { 0.5, 0.0, 0.0 },
+    neutral = { 0.7, 0.7, 0.0 },
+    healthy = { 0, 0.1, 0 },
+    high = { 0, 1.0, 0 },
+    mid = { 1.0, 1.0, 0 },
+    low = { 1.0, 0.0, 0 },
+    offline = { 0.7, 0.7, 0.7 },
+    dead = { 0.7, 0.7, 0.7 },
+    magic = { 0.4, 0.4, 1.0 },
+    disease = { 0.4, 0.2, 0.0 },
+    poison = { 0.0, 0.7, 0.7 },
+    curse = { 0.7, 0.0, 0.7 },
+    immune = { 0.0, 0.2, 0.4 },
+    bomb = { 1.0, 0.7, 0.7 },
+    cyan = { 0.0, 0.8, 0.8 },
+    white = { 1.0, 1.0, 1.0 }
 }
 
+-- This trucates _codepoints_ not graphemes. If combination codepoints are
+-- contained in the string, it will not properly truncate and may return
+-- incorrect graphemes
+local function utf8_truncate(s, n)
+    local init = 0
+    for _ = 1, n do
+        local _, last = string.find(s, ".[\128-\191]*", init + 1)
+        if not last then
+            return s
+        end
+        init = last
+    end
+    return string.sub(s, 1, init)
+end
+
 ---@param unit string
 ---@param config table
 function UnitFrame:Init(unit, config)
@@ -127,7 +142,7 @@ function UnitFrame:StartRangeTicker()
     if self.rangeTicker then
         return
     end
-    local delta = 0.45 + (fastrandom(0, 100)/1000)
+    local delta = 0.45 + (fastrandom(0, 100) / 1000)
     self.rangeTicker = C_Timer.NewTicker(delta, function()
         self:UpdateRange()
     end)
@@ -563,7 +578,7 @@ function UnitFrame:UpdateHealthColor()
     elseif isFriend and pct >= 0.90 then
         self.hp:SetColor(unpack(colors.healthy))
     elseif isFriend and pct >= 0.75 then
-        local progress = (pct - 0.75) / (0.90-0.75)
+        local progress = (pct - 0.75) / (0.90 - 0.75)
         self.hp:SetInterpolatedColor(colors.mid, colors.high, progress)
     else
         local progress = pct / 0.75
@@ -580,25 +595,10 @@ function UnitFrame:UpdateName()
         -- TODO: UnitClass can return Unknown and the color can be nil. Having
         -- the unit exist but not fully loaded is possibly a state we want to
         -- handle more generally
-        local color = RAID_CLASS_COLORS[class] or {r=1, g=1, b=1}
+        local color = RAID_CLASS_COLORS[class] or { r = 1, g = 1, b = 1 }
         self.name:SetTextColor(color.r, color.g, color.b)
     else
         self.name:SetTextColor(1, 1, 1)
     end
-    self.name:SetText(UnitName(self.unit):sub(1, 5))
+    self.name:SetText(utf8_truncate((UnitName(self.unit)), 5))
 end
-
---[[
-    -- UNIT_AURA
-    -- UNIT_CLASSIFICATION_CHANGED
-    -- UNIT_COMBAT
-    -- UNIT_CONNECTION
-    -- UNIT_DISPLAYPOWER
-    -- UNIT_FACTION
-    -- UNIT_FLAGS
-    -- UNIT_LEVEL
-    -- UNIT_MANA
-    -- UNIT_HEALTH_PREDICTION
-    -- UNIT_PHASE
-]]--
-