Energy tick: the spark rides a timer-driven fill, drop the OnUpdate

The tick frame is a status bar whose invisible fill sweeps each period
from a duration object, with the spark anchored to the fill's edge
(ClassicAPI v1.19.1). A timer at each period's end rolls the sweep over
by whole periods, paused while hidden and caught up as it shows. The
five-second rule ends on its own timer, and the spark's alpha and the
rule bar update on the events that change them. Full mana now hides the
frame on every event, not just on a power update.

modules/energytick.lua

@@ -84,11 +84,6 @@ pfUI:RegisterModule("energytick", function()
     return
   end
 
-  -- inside the module body on purpose: C is on pfUI.env, not _G
-  local function getBarWidth()
-    return C.unitframes.player.pwidth ~= "-1" and C.unitframes.player.pwidth or C.unitframes.player.width
-  end
-
   local rawborder, default_border = GetBorderSize("unitframes")
   local cbtexture = pfUI.media[C.appearance.castbar.texture]
 
@@ -128,8 +123,13 @@ pfUI:RegisterModule("energytick", function()
     return true
   end
 
-  local energytick = CreateFrame("Frame", nil, pfUI.uf.player.power.bar)
+  -- the bar sweeps its fill over one tick period from a duration object; the
+  -- fill is invisible and carries the spark on its edge
+  local energytick = CreateFrame("StatusBar", nil, pfUI.uf.player.power.bar)
   energytick:SetAllPoints(pfUI.uf.player.power.bar)
+  energytick:SetColorFill(1, 1, 1, 0)
+  energytick.sweep = C_DurationUtil.CreateDuration()
+  energytick:SetTimerDuration(energytick.sweep, Enum.StatusBarInterpolation.Immediate, Enum.StatusBarTimerDirection.ElapsedTime)
   energytick:RegisterEvent("PLAYER_ENTERING_WORLD")
   energytick:RegisterUnitEvent("UNIT_DISPLAYPOWER", "player")
   energytick:RegisterUnitEvent("UNIT_POWER_UPDATE", "player")
@@ -138,21 +138,61 @@ pfUI:RegisterModule("energytick", function()
   energytick:RegisterEvent("SPELLS_CHANGED")
   energytick:RegisterEvent("PLAYER_AURAS_CHANGED")
 
+  -- the spark hides until a tick is seen, and dims while the rule is up and
+  -- nothing has ticked inside it yet
+  local function UpdateRule()
+    local fsrUp = energytick.mode == "MANA" and energytick.fsr:IsActive()
+    energytick.fsrbar:SetShown(fsrUp and energytick:IsShown() and C.unitframes.player.showfsr == "1")
+    energytick.spark:SetAlpha(not energytick.start and 0 or (fsrUp and not energytick.fsrGain) and .4 or 1)
+  end
+
+  -- the window closed without being re-armed
+  local function RuleEnd()
+    energytick.fsrSpell, energytick.fsrGain = nil, nil
+    energytick.fsr:Reset()
+    UpdateRule()
+  end
+
+  local function ArmRule()
+    energytick.fsr:SetTimeFromStart(GetTime(), FIVE_SECOND_RULE)
+    if energytick.ruletimer then energytick.ruletimer:Cancel() end
+    energytick.ruletimer = C_Timer.NewTimer(FIVE_SECOND_RULE, RuleEnd)
+  end
+
+  -- sweeps the period that holds now and wakes at its end. Rolls over by
+  -- whole periods, not from now: restarting bakes timer overshoot into the
+  -- phase as drift the lock then has to chase. Runs only while shown; a
+  -- hidden bar keeps its phase and catches up as it shows.
+  local Sweep
+  local function Wrap() Sweep() end
+  function Sweep()
+    if energytick.wrap then energytick.wrap:Cancel() end
+    if not energytick.start or not energytick:IsShown() then return end
+
+    local now = GetTime()
+    while now - energytick.start >= energytick.max do
+      energytick.start = energytick.start + energytick.max * math.floor((now - energytick.start) / energytick.max)
+      energytick.max = getAdjustedTickTimer()
+    end
+
+    energytick.sweep:SetTimeFromStart(energytick.start, energytick.max)
+    energytick.wrap = C_Timer.NewTimer(energytick.start + energytick.max - now, Wrap)
+  end
+
   energytick:SetScript("OnEvent", function()
     if UnitPowerType("player") == Enum.PowerType.Mana and C.unitframes.player.manatick == "1" then
       this.mode = "MANA"
-      this:Show()
     elseif UnitPowerType("player") == Enum.PowerType.Energy and C.unitframes.player.energy == "1" then
       this.mode = "ENERGY"
-      this:Show()
     else
       this.mode = nil
-      this:Hide()
     end
 
+    -- mana regen stops showing at full mana
+    this:SetShown(this.mode and not (this.mode == "MANA" and UnitPower("player") >= UnitPowerMax("player")))
+
     if event == "SPELLS_CHANGED" or event == "PLAYER_AURAS_CHANGED" then
       energyRegenTimeMod = nil
-      return
     end
 
     -- a shift swaps the power the gains are measured on
@@ -167,18 +207,16 @@ pfUI:RegisterModule("energytick", function()
       cost = cost and cost[1]
       if cost and cost.type == Enum.PowerType.Mana and cost.cost > 0 then
         this.fsrSpell, this.fsrGain = arg3, nil
-        this.fsr:SetTimeFromStart(GetTime(), FIVE_SECOND_RULE)
+        ArmRule()
       end
-      return
     end
 
     -- Unit::Update won't expire the rule while the spending spell still channels
     if event == "UNIT_SPELLCAST_CHANNEL_STOP" and arg1 == "player" then
       if this.fsrSpell and this.fsrSpell == arg3 then
         this.fsrGain = nil
-        this.fsr:SetTimeFromStart(GetTime(), FIVE_SECOND_RULE)
+        ArmRule()
       end
-      return
     end
 
     -- only the shown power: a cat druid's mana regen is not an energy gain
@@ -193,61 +231,11 @@ pfUI:RegisterModule("energytick", function()
         if this.fsr:IsActive() then
           this.fsrGain = true
         end
-      end
-
-      -- phase is kept while hidden; OnUpdate catches up by whole periods
-      if this.mode == "MANA" and power >= UnitPowerMax("player") then
-        this:Hide()
+        Sweep()
       end
     end
-  end)
 
-  energytick:SetScript("OnUpdate", function()
-    -- Throttle for performance
-    if (this.tick or 0) > GetTime() then
-      return
-    end
-    this.tick = GetTime() + 0.020  -- ~50 FPS
-
-    -- five-second rule: fsrbar drains from this.fsr by itself. The display is
-    -- cosmetic and can be hidden on its own; the window itself (fsr/fsrGain)
-    -- keeps running either way -- it still dims the sweep spark below.
-    local fsrUp = this.mode == "MANA" and this.fsr:IsActive()
-    if not fsrUp and this.fsrSpell then
-      this.fsrSpell, this.fsrGain = nil, nil
-      this.fsr:Reset()
-    end
-    this.fsrbar:SetShown(fsrUp and C.unitframes.player.showfsr == "1")
-
-    if not this.start then
-      this.spark:SetAlpha(0)
-      return
-    end
-
-    if this.mode == "MANA" and UnitPower("player") >= UnitPowerMax("player") then
-      this.spark:SetAlpha(0)
-      return
-    end
-
-    this.current = GetTime() - this.start
-
-    -- roll over by whole periods, not from now: restarting bakes frame
-    -- overshoot into the phase as drift the lock then has to chase
-    if this.current > this.max then
-      this.start = this.start + this.max * math.floor(this.current / this.max)
-      this.max = getAdjustedTickTimer()
-      this.current = GetTime() - this.start
-    end
-
-    -- dim while the rule is up and nothing has ticked inside it yet
-    this.spark:SetAlpha((fsrUp and not this.fsrGain) and .4 or 1)
-
-    if not C.unitframes.player.pheight then
-      return
-    end
-
-    local pos = getBarWidth() * (this.current / this.max)
-    this.spark:SetPoint("LEFT", pos - ((C.unitframes.player.pheight + 5) / 2), 0)
+    UpdateRule()
   end)
 
   energytick.fsr = C_DurationUtil.CreateDuration()
@@ -275,8 +263,14 @@ pfUI:RegisterModule("energytick", function()
   energytick.fsrbar:SetTimerDuration(energytick.fsr, Enum.StatusBarInterpolation.Immediate, Enum.StatusBarTimerDirection.RemainingTime)
   energytick.fsrbar:Hide()
 
-  -- the bar isn't parented to energytick, and OnUpdate stops with it
+  -- the bar isn't parented to energytick, so it follows it by hand
+  energytick:SetScript("OnShow", function()
+    Sweep()
+    UpdateRule()
+  end)
+
   energytick:SetScript("OnHide", function()
+    Sweep()
     this.fsrbar:Hide()
   end)
 
@@ -285,6 +279,8 @@ pfUI:RegisterModule("energytick", function()
   energytick.spark:SetHeight(C.unitframes.player.pheight + 15)
   energytick.spark:SetWidth(C.unitframes.player.pheight + 5)
   energytick.spark:SetBlendMode("ADD")
+  energytick.spark:SetPoint("CENTER", energytick:GetStatusBarTexture(), "RIGHT")
+  energytick.spark:SetAlpha(0)
 
   local hookUpdateConfig = pfUI.uf.player.UpdateConfig
   function pfUI.uf.player.UpdateConfig()