power: Add support for atlas textures (#694)

elements/power.lua

@@ -32,6 +32,9 @@ The following options are listed by priority. The first check that returns true
 .colorTapping      - Use `self.colors.tapping` to color the bar if the unit isn't tapped by the player (boolean)
 .colorThreat       - Use `self.colors.threat[threat]` to color the bar based on the unit's threat status. `threat` is
                      defined by the first return of [UnitThreatSituation](https://warcraft.wiki.gg/wiki/API_UnitThreatSituation) (boolean)
+.colorPowerAtlas   - Use `self.colors.power[token].atlas` to replace the texture whenever it's available. The previously
+                     defined texture (if any) will be restored if the color changes to one that doesn't have an atlas
+                     (boolean)
 .colorPower        - Use `self.colors.power[token]` to color the bar based on the unit's power type. This method will
                      fall-back to `:GetAlternativeColor()` if it can't find a color matching the token. If this function
                      isn't defined, then it will attempt to color based upon the alternative power colors returned by
@@ -120,7 +123,7 @@ local function UpdateColor(self, event, unit)
 
 	local pType, pToken, altR, altG, altB = UnitPowerType(unit)
 
-	local r, g, b, color
+	local r, g, b, color, atlas
 	if(element.colorDisconnected and not UnitIsConnected(unit)) then
 		color = self.colors.disconnected
 	elseif(element.colorTapping and not UnitPlayerControlled(unit) and UnitIsTapDenied(unit)) then
@@ -146,6 +149,10 @@ local function UpdateColor(self, event, unit)
 		else
 			color = self.colors.power[ALTERNATE_POWER_INDEX]
 		end
+
+		if(element.colorPowerAtlas and color) then
+			atlas = color.atlas
+		end
 	elseif(element.colorClass and (UnitIsPlayer(unit) or UnitInPartyIsAI(unit)))
 		or (element.colorClassNPC and not (UnitIsPlayer(unit) or UnitInPartyIsAI(unit)))
 		or (element.colorClassPet and UnitPlayerControlled(unit) and not UnitIsPlayer(unit)) then
@@ -160,31 +167,41 @@ local function UpdateColor(self, event, unit)
 		r, g, b = self:ColorGradient((element.cur or 1) + adjust, (element.max or 1) + adjust, unpack(element.smoothGradient or self.colors.smooth))
 	end
 
-	if(color) then
-		r, g, b = color[1], color[2], color[3]
-	end
+	if(atlas) then
+		element:SetStatusBarTexture(atlas)
+		element:SetStatusBarColor(1, 1, 1)
+	else
+		if(color) then
+			r, g, b = color[1], color[2], color[3]
+		end
 
-	if(b) then
-		element:SetStatusBarColor(r, g, b)
+		if(b) then
+			if(element.__texture) then
+				element:SetStatusBarTexture(element.__texture)
+			end
 
-		local bg = element.bg
-		if(bg) then
-			local mu = bg.multiplier or 1
-			bg:SetVertexColor(r * mu, g * mu, b * mu)
+			element:SetStatusBarColor(r, g, b)
+
+			local bg = element.bg
+			if(bg) then
+				local mu = bg.multiplier or 1
+				bg:SetVertexColor(r * mu, g * mu, b * mu)
+			end
 		end
 	end
 
 	--[[ Callback: Power:PostUpdateColor(unit, r, g, b)
 	Called after the element color has been updated.
 
-	* self - the Power element
-	* unit - the unit for which the update has been triggered (string)
-	* r    - the red component of the used color (number)[0-1]
-	* g    - the green component of the used color (number)[0-1]
-	* b    - the blue component of the used color (number)[0-1]
+	* self  - the Power element
+	* unit  - the unit for which the update has been triggered (string)
+	* r     - the red component of the used color (number?)[0-1]
+	* g     - the green component of the used color (number?)[0-1]
+	* b     - the blue component of the used color (number?)[0-1]
+	* atlas - the atlas used instead of color (string?)
 	--]]
 	if(element.PostUpdateColor) then
-		element:PostUpdateColor(unit, r, g, b)
+		element:PostUpdateColor(unit, r, g, b, atlas)
 	end
 end
 
@@ -399,6 +416,10 @@ local function Enable(self)
 			element:SetStatusBarTexture([[Interface\TargetingFrame\UI-StatusBar]])
 		end
 
+		if(element.colorPowerAtlas) then
+			element.__texture = element.__texture or element:GetStatusBarTexture():GetTexture()
+		end
+
 		if(not element.GetDisplayPower) then
 			element.GetDisplayPower = GetDisplayPower
 		end