Reduce class portrait work and use GUID changes for ToT

mods/unitframes-classportrait.lua

@@ -1,5 +1,6 @@
 local _G = ShaguTweaks.GetGlobalEnv()
 local T = ShaguTweaks.T
+local API = ShaguTweaks.API or {}
 
 local addonpath
 local tocs = { "", "-master", "-tbc", "-wotlk" }
@@ -34,16 +35,24 @@ local module = ShaguTweaks:register({
 })
 
 local function UpdatePortraits(frame)
+  if not frame or not frame.unit or not frame.portrait then return end
+
   -- detect unit class or remove for non-player units
   local _, class = UnitClass(frame.unit)
   class = UnitIsPlayer(frame.unit) and class or nil
 
-  -- update class icon if possible
-  if class and frame.portrait then
+  -- Don't reapply the exact same class texture on every UnitFrame_Update.
+  local state = class or false
+  if frame.ShaguTweaksPortraitClass == state then return end
+  frame.ShaguTweaksPortraitClass = state
+
+  if class then
     local iconCoords = CLASS_ICON_TCOORDS[class]
-    frame.portrait:SetTexture(addonpath .. "\\img\\UI-Classes-Circles")
-    frame.portrait:SetTexCoord(unpack(iconCoords))
-  elseif not class and frame.portrait then
+    if iconCoords then
+      frame.portrait:SetTexture(addonpath .. "\\img\\UI-Classes-Circles")
+      frame.portrait:SetTexCoord(unpack(iconCoords))
+    end
+  else
     frame.portrait:SetTexCoord(0, 1, 0, 1)
   end
 end
@@ -61,20 +70,38 @@ module.enable = function(self)
   events:RegisterEvent("PLAYER_ENTERING_WORLD")
   events:RegisterEvent("UNIT_PORTRAIT_UPDATE")
   events:SetScript("OnEvent", function()
-    -- reload player portrait
+    -- force a state refresh because Blizzard may have replaced the texture
+    PlayerFrame.ShaguTweaksPortraitClass = nil
+    TargetFrame.ShaguTweaksPortraitClass = nil
+    PartyMemberFrame1.ShaguTweaksPortraitClass = nil
+    PartyMemberFrame2.ShaguTweaksPortraitClass = nil
+    PartyMemberFrame3.ShaguTweaksPortraitClass = nil
+    PartyMemberFrame4.ShaguTweaksPortraitClass = nil
+
     UpdatePortraits(PlayerFrame)
     UpdatePortraits(TargetFrame)
-
-    -- reload party portraits
     UpdatePortraits(PartyMemberFrame1)
     UpdatePortraits(PartyMemberFrame2)
     UpdatePortraits(PartyMemberFrame3)
     UpdatePortraits(PartyMemberFrame4)
   end)
 
-  -- update target of target
+  -- Target-of-target has no reliable vanilla portrait event. The old module
+  -- refreshed it every rendered frame. With ClassicAPI we can cheaply watch
+  -- its GUID and only touch the portrait when the unit actually changes.
   local tot = CreateFrame("Frame", nil, TargetFrame)
+  tot.elapsed = 0
+  tot.lastguid = nil
   tot:SetScript("OnUpdate", function()
-    UpdatePortraits(TargetofTargetFrame)
+    this.elapsed = this.elapsed + arg1
+    if this.elapsed < .2 then return end
+    this.elapsed = 0
+
+    local guid = API.UnitGUID and API.UnitGUID("targettarget") or UnitName("targettarget")
+    if guid ~= this.lastguid then
+      this.lastguid = guid
+      TargetofTargetFrame.ShaguTweaksPortraitClass = nil
+      UpdatePortraits(TargetofTargetFrame)
+    end
   end)
 end