Draw unit frame bars with the native StatusBar

The custom bar sized its textures in Lua from GetWidth(), so it had to
track how ClassicAPI reports the UI scale (#71), and it stretched the bar
texture instead of cropping it. The engine's StatusBar does that layout
itself.

The background of the missing part is a second StatusBar that fills
from the other end (ClassicAPI's SetReverseFill), one frame level below
the fill, so the incoming-heal texture still draws between the two.
SetFrameLevel moves both, and the health and power bars now sit two
levels above their backdrops. SetStatusBarBackgroundTexture becomes
SetStatusBarBackgroundColor, as it only ever took a color.

api/ui-widgets.lua

@@ -3,15 +3,19 @@ setfenv(1, pfUI:GetEnvironment())
 
 do -- statusbars
   local animations = {}
-  local stepsize, val
-  local width, height, point
+  local stepsize
+
+  -- native StatusBar methods the bar overrides
+  local statusbar = CreateFrame("StatusBar")
+  local SetValue, SetMinMaxValues = statusbar.SetValue, statusbar.SetMinMaxValues
+  local SetOrientation, SetFrameLevel = statusbar.SetOrientation, statusbar.SetFrameLevel
 
   local animate = CreateFrame("Frame", "pfStatusBarAnimation", UIParent)
   animate:SetScript("OnUpdate", function()
     stepsize = tonumber(pfUI_config.unitframes.animation_speed)
 
     for bar in pairs(animations) do
-      if not bar.val_ or abs(bar.val_ - bar.val) < stepsize or bar.instant then
+      if not bar.val_ or abs(bar.val_ - bar.val) < stepsize then
         bar:DisplayValue(bar.val)
       elseif bar.val ~= bar.val_ then
         bar:DisplayValue(bar.val_ + min((bar.val-bar.val_) / stepsize, max(bar.val-bar.val_, 30 / GetFramerate())))
@@ -21,7 +25,8 @@ do -- statusbars
 
   local handlers = {
     ["DisplayValue"] = function(self, val)
-      val = Clamp(val, self.min, self.max)
+      local smin, smax = self:GetMinMaxValues()
+      val = Clamp(val, smin, smax)
 
       -- remove animation queue
       if val == self.val_ then
@@ -30,51 +35,20 @@ do -- statusbars
 
       -- set current visible value
       self.val_ = val
+      SetValue(self, val)
 
-      if self.mode == "vertical" then
-        height = self:GetHeight()
-        point = height / (self.max - self.min) * (val - self.min)
-
-        -- keep values in limits
-        point = Clamp(point, 0, height)
-
-        -- set point to zero if value and max is zero
-        if val == 0 then point = 0 end
-
-        -- set status bar position/size
-        self.bar:SetPoint("TOPLEFT", self, "TOPLEFT", 0, - height + point)
-        self.bar:SetPoint("BOTTOMRIGHT", self, "BOTTOMRIGHT", 0, 0)
-
-        -- set background bar position/size
-        self.bg:SetPoint("TOPLEFT", self, "TOPLEFT", 0, 0)
-        self.bg:SetPoint("BOTTOMRIGHT", self, "BOTTOMRIGHT", 0, point)
-      else
-        width = self:GetWidth()
-        point = width / (self.max - self.min) * (val - self.min)
-
-        -- keep values in limits
-        point = Clamp(point, 0, width)
-
-        -- set point to zero if value and max is zero
-        if val == 0 then point = 0 end
-
-        -- set status bar position/size
-        self.bar:SetPoint("TOPLEFT", self, "TOPLEFT", 0, 0)
-        self.bar:SetPoint("BOTTOMRIGHT", self, "BOTTOMRIGHT", - width + point, 0)
-
-        -- set background bar position/size
-        self.bg:SetPoint("BOTTOMRIGHT", self, "BOTTOMRIGHT", 0, 0)
-        self.bg:SetPoint("TOPLEFT", self, "TOPLEFT", point, 0)
-      end
+      -- the background fills the missing part, all of an empty range
+      self.bg:SetValue(smax > smin and (smax - val) / (smax - smin) or 1)
     end,
 
     ["SetMinMaxValues"] = function(self, smin, smax, smooth)
       -- smoothen the transition by keeping the value at the same percentage as before
-      if smooth and self.max and self.max > 0 and smax > 0 and self.max ~= smax then
-        self.val_ = (self.val_ or self.val) / self.max * smax
+      local _, oldmax = self:GetMinMaxValues()
+      if smooth and oldmax > 0 and smax > 0 and oldmax ~= smax then
+        self.val_ = (self.val_ or self.val) / oldmax * smax
       end
 
-      self.min, self.max = smin, smax
+      SetMinMaxValues(self, smin, smax)
       self:DisplayValue(self.val_ or self.val)
     end,
 
@@ -87,41 +61,35 @@ do -- statusbars
       end
     end,
 
-    ["SetStatusBarTexture"] = function(self, r, g, b, a)
-      self.bar:SetTexture(r, g, b, a)
-    end,
-
-    ["SetStatusBarColor"] = function(self, r, g, b, a)
-      self.bar:SetVertexColor(r, g, b, a)
-    end,
-
-    ["SetStatusBarBackgroundTexture"] = function(self, r, g, b, a)
-      self.bg:SetTexture(r, g, b, a)
-    end,
-
     ["SetStatusBarBackgroundColor"] = function(self, r, g, b, a)
-      self.bg:SetVertexColor(r, g, b, a)
+      self.bg:SetColorFill(r, g, b, a)
     end,
 
-    ["SetOrientation"] = function(self, mode)
-      self.mode = strlower(mode)
+    ["SetOrientation"] = function(self, orientation)
+      SetOrientation(self, orientation)
+      self.bg:SetOrientation(orientation)
+    end,
+
+    -- the background stays one level below the fill, under anything else
+    -- drawn on the fill's frame
+    ["SetFrameLevel"] = function(self, level)
+      SetFrameLevel(self, level)
+      self.bg:SetFrameLevel(level - 1)
     end,
   }
 
   function pfUI.api.CreateStatusBar(name, parent)
-    local f = CreateFrame("Button", name, parent)
-    f:EnableMouse(false)
+    local f = CreateFrame("StatusBar", name, parent)
+    SetMinMaxValues(f, 0, 100)
+    SetValue(f, 0)
+    f.val = 0
 
-    f.bar = f:CreateTexture(nil, "NORMAL")
-    f.bar:SetPoint("TOPLEFT", f, "TOPLEFT", 0, 0)
-    f.bar:SetPoint("BOTTOMRIGHT", f, "BOTTOMRIGHT", 0, 0)
-
-    f.bg = f:CreateTexture(nil, "BACKGROUND")
-    f.bg:SetPoint("TOPLEFT", f, "TOPLEFT", 0, 0)
-    f.bg:SetPoint("BOTTOMRIGHT", f, "BOTTOMRIGHT", 0, 0)
-
-    -- set some default values
-    f.min, f.max, f.val = 0, 100, 0
+    f.bg = CreateFrame("StatusBar", nil, f)
+    f.bg:SetFrameLevel(f:GetFrameLevel() - 1)
+    f.bg:SetAllPoints(f)
+    f.bg:SetReverseFill(true)
+    f.bg:SetMinMaxValues(0, 1)
+    f.bg:SetValue(1)
 
     -- add all handler functions to the object
     for name, func in pairs(handlers) do

api/unitframes.lua

@@ -508,6 +508,8 @@ function pfUI.uf:UpdateConfig()
   if tonumber(f.config.height) < 0 then f.hp:Hide() end
   pfUI.api.CreateBackdrop(f.hp, default_border)
 
+  -- one level above the backdrop for the bar's background, one more for its fill
+  f.hp.bar:SetFrameLevel(f.hp.backdrop:GetFrameLevel() + 2)
   f.hp.bar:SetStatusBarTexture(pfUI.media[f.config.bartexture])
   f.hp.bar:SetAllPoints(f.hp)
   if f.config.verticalbar == "1" then
@@ -522,7 +524,7 @@ function pfUI.uf:UpdateConfig()
   if custombg == "1" then
     local cr, cg, cb, ca = GetStringColor(custombgcolor)
     cr, cg, cb, ca = tonumber(cr), tonumber(cg), tonumber(cb), tonumber(ca)
-    f.hp.bar:SetStatusBarBackgroundTexture(cr,cg,cb,ca)
+    f.hp.bar:SetStatusBarBackgroundColor(cr,cg,cb,ca)
   end
 
   f.power:ClearAllPoints()
@@ -531,7 +533,7 @@ function pfUI.uf:UpdateConfig()
   if tonumber(f.config.pheight) < 0 then f.power:Hide() end
 
   pfUI.api.CreateBackdrop(f.power, default_border)
-  f.power.bar:SetFrameLevel(f.power.backdrop:GetFrameLevel() + 1)
+  f.power.bar:SetFrameLevel(f.power.backdrop:GetFrameLevel() + 2)
   f.power.bar:SetStatusBarTexture(pfUI.media[f.config.pbartexture])
   f.power.bar:SetAllPoints(f.power)
 
@@ -541,7 +543,7 @@ function pfUI.uf:UpdateConfig()
   if custompbg == "1" then
     local cr, cg, cb, ca = GetStringColor(custompbgcolor)
     cr, cg, cb, ca = tonumber(cr), tonumber(cg), tonumber(cb), tonumber(ca)
-    f.power.bar:SetStatusBarBackgroundTexture(cr,cg,cb,ca)
+    f.power.bar:SetStatusBarBackgroundColor(cr,cg,cb,ca)
   end
 
   local fontname, fontsize, fontstyle
@@ -1490,7 +1492,7 @@ function pfUI.uf:CreateUnitFrame(unit, id, config, tick)
 
   f.incHeal = CreateFrame("Frame", nil, f.hp)
   -- Texture lives on hp.bar for correct draw order:
-  -- hp.bar.bg (BACKGROUND) < incHeal (BORDER) < hp.bar.bar (NORMAL)
+  -- hp.bar.bg (a level below) < incHeal (BORDER) < hp.bar's fill (ARTWORK)
   f.incHeal.texture = f.hp.bar:CreateTexture(nil, "BORDER")
   f.incHeal.texture:SetAllPoints(f.incHeal)
   -- Override Show/Hide since texture lives on hp.bar, not incHeal