Show the addon list in a ClassicAPI ScrollBox

The list built one row per addon in a ScrollFrame, hid the rows out of
view by hand and drove pfUI's own slider. A WowScrollBoxList keeps rows
only for the addons in view and recycles them while scrolling.

pfUIScrollBarTemplate (api/ui-widgets.xml) is a ScrollBarMixin bar with
the old slider's look: a thin track and a flat teal thumb that hides when
nothing scrolls. Its steppers exist for the mixin but stay hidden.

Rows read the addon's enabled state, so profiles enable and disable
addons directly instead of clicking every row's checkbox. A checkbox
now shows whether an addon is enabled; it showed whether it was loaded.

api/ui-widgets.xml

@@ -0,0 +1,31 @@
+<Ui xmlns="http://www.blizzard.com/wow/ui/">
+  <!--
+  pfUI's scroll bar for ClassicAPI's ScrollBox: a thin track with a flat
+  thumb. ScrollBarMixin needs Back and Forward steppers, so they exist but
+  stay hidden. Hook it up with ScrollUtil.InitScrollBoxListWithScrollBar.
+  -->
+  <EventFrame name="pfUIScrollBarTemplate" inherits="VerticalScrollBarTemplate" virtual="true">
+    <Size x="7"/>
+    <KeyValues>
+      <KeyValue key="hideIfUnscrollable" value="true" type="boolean"/>
+    </KeyValues>
+    <Frames>
+      <Frame parentKey="Track" setAllPoints="true" enableMouse="true">
+        <Frames>
+          <EventButton parentKey="Thumb">
+            <Size x="7"/>
+            <Layers>
+              <Layer level="ARTWORK">
+                <Texture setAllPoints="true">
+                  <Color r=".3" g="1" b=".8" a=".5"/>
+                </Texture>
+              </Layer>
+            </Layers>
+          </EventButton>
+        </Frames>
+      </Frame>
+      <EventButton parentKey="Back" hidden="true"/>
+      <EventButton parentKey="Forward" hidden="true"/>
+    </Frames>
+  </EventFrame>
+</Ui>

init/api.xml

@@ -1,6 +1,7 @@
 <Ui xmlns="http://www.blizzard.com/wow/ui/">
   <Include file="..\api\api.lua"/>
   <Include file="..\api\config.lua"/>
+  <Include file="..\api\ui-widgets.xml"/>
   <Include file="..\api\ui-widgets.lua"/>
   <Include file="..\api\unitframes.lua"/>
 </Ui>

modules/addons.lua

@@ -69,12 +69,42 @@ pfUI:RegisterModule("addons", function ()
     pfUI.addons:Hide()
   end)
 
+  -- installed addons, one entry per row of the addon list
+  local addons = {}
+  for i = 1, GetNumAddOns() do
+    local name, title, notes = GetAddOnInfo(i)
+    addons[i] = {
+      index = i,
+      name = name,
+      title = title,
+      notes = notes,
+      author = GetAddOnMetadata(name, "Author"),
+      version = GetAddOnMetadata(name, "Version"),
+      deps = { GetAddOnDependencies(i) },                         -- required (.toc Dependencies)
+      optdeps = { C_AddOns.GetAddOnOptionalDependencies(i) },     -- optional (.toc OptionalDeps)
+    }
+  end
+
+  local function IsAddonEnabled(index)
+    local _, _, _, enabled = GetAddOnInfo(index)
+    return enabled
+  end
+
+  local function SetAddonEnabled(index, enabled)
+    if enabled then
+      EnableAddOn(index)
+    else
+      DisableAddOn(index)
+    end
+    pfUI.addons.hasChanged = true
+  end
+
   -- addons profile
   local function GetSelectedAddonsList()
     local selected_addons = {}
-    for i, frame in ipairs(pfUI.addons.list) do
-      if frame.input:GetChecked() then
-        table.insert(selected_addons, frame.aname)
+    for i, addon in ipairs(addons) do
+      if IsAddonEnabled(i) then
+        table.insert(selected_addons, addon.name)
       end
     end
     return selected_addons
@@ -90,28 +120,20 @@ pfUI:RegisterModule("addons", function ()
     pfUI.addons.profile.dropdown:SetSelectionByText(profile)
 
     -- load profile
-    local selected_list = pfUI_addon_profiles[profile]
-    for i=1, GetNumAddOns() do
-      local active = false
-      local f = pfUI.addons.list[i]
+    local selected = {}
+    for _, name in ipairs(pfUI_addon_profiles[profile]) do
+      selected[name] = true
+    end
 
-      for i_i, n in ipairs(selected_list) do
-        if f.aname == n then
-          active = true
-          break
-        end
-      end
-
-      if active then
-        if not f.input:GetChecked() then
-          f.input:Click()
-        end
-      else
-        if f.input:GetChecked() then
-          f.input:Click()
-        end
+    for i, addon in ipairs(addons) do
+      if selected[addon.name] and not IsAddonEnabled(i) then
+        SetAddonEnabled(i, true)
+      elseif not selected[addon.name] and IsAddonEnabled(i) then
+        SetAddonEnabled(i, false)
       end
     end
+
+    pfUI.addons.scroll:ReinitializeFrames()
   end
 
   -- addon profiles
@@ -193,23 +215,6 @@ pfUI:RegisterModule("addons", function ()
     return menu
   end)
 
-  -- addon list: scroll frame
-  pfUI.addons.scroll = CreateScrollFrame("pfAddonListScroll", pfUI.addons)
-  pfUI.addons.scroll:SetSize(360, 410)
-  pfUI.addons.scroll:SetPoint("BOTTOM", 0, 10)
-
-  pfUI.addons.scroll.backdrop = CreateFrame("Frame", nil, pfUI.addons.scroll)
-  pfUI.addons.scroll.backdrop:SetFrameLevel(1)
-  pfUI.addons.scroll.backdrop:SetPoint("TOPLEFT", pfUI.addons.scroll, "TOPLEFT", -5, 5)
-  pfUI.addons.scroll.backdrop:SetPoint("BOTTOMRIGHT", pfUI.addons.scroll, "BOTTOMRIGHT", 5, -5)
-  CreateBackdrop(pfUI.addons.scroll.backdrop, nil, true)
-
-  -- addon list: scroll parent
-  pfUI.addons.list = CreateScrollChild("pfAddonList", pfUI.addons.scroll)
-  pfUI.addons.list:RegisterEvent("ADDON_LOADED")
-  pfUI.addons.list:RegisterEvent("PLAYER_ENTERING_WORLD")
-  pfUI.addons.list:SetHeight(GetNumAddOns() * 25 + 26)
-
   local function AddDependencyLines(header, deps)
     if not deps or table.getn(deps) == 0 then return end
     GameTooltip:AddLine(" ")
@@ -225,137 +230,105 @@ pfUI:RegisterModule("addons", function ()
     end
   end
 
-  local function AddonOnEnter()
-    this:SetBackdropBorderColor(1,1,1,.08)
+  local function RowOnEnter(self)
+    local addon = self.addon
+    self:SetBackdropBorderColor(1,1,1,.08)
 
-    GameTooltip:SetOwner(this, "ANCHOR_RIGHT")
-    GameTooltip:SetText(this.atitle)
-    if this.aversion then
-      GameTooltip:AddDoubleLine(T["Version"], this.aversion, 1,1,1, .2,1,.8)
+    GameTooltip:SetOwner(self, "ANCHOR_RIGHT")
+    GameTooltip:SetText(addon.title)
+    if addon.version then
+      GameTooltip:AddDoubleLine(T["Version"], addon.version, 1,1,1, .2,1,.8)
     end
 
-    if this.aauthor then
-      GameTooltip:AddDoubleLine(T["Author"], this.aauthor, 1,1,1, .2,1,.8)
+    if addon.author then
+      GameTooltip:AddDoubleLine(T["Author"], addon.author, 1,1,1, .2,1,.8)
     end
 
-    GameTooltip:AddLine(this.anote, .75,.75,.75,1)
-    AddDependencyLines(T["Dependencies"], this.adeps)
-    AddDependencyLines(T["Optional Dependencies"], this.aoptdeps)
+    GameTooltip:AddLine(addon.notes, .75,.75,.75,1)
+    AddDependencyLines(T["Dependencies"], addon.deps)
+    AddDependencyLines(T["Optional Dependencies"], addon.optdeps)
     GameTooltip:SetWidth(180)
     GameTooltip:Show()
   end
 
-  local function AddonOnLeave()
-    this:SetBackdropBorderColor(1,1,1,.04)
+  local function RowOnLeave(self)
+    self:SetBackdropBorderColor(1,1,1,.04)
     GameTooltip:Hide()
   end
 
-  local function AddonOnClick()
-    this.input:Click()
+  local function RowOnClick(self)
+    self.input:Click()
   end
 
-  local function InputOnClick()
-    if this:GetChecked() then
-      EnableAddOn(this:GetID())
-    else
-      DisableAddOn(this:GetID())
-    end
-    pfUI.addons.hasChanged = true
+  local function InputOnClick(self)
+    SetAddonEnabled(self:GetParent().addon.index, self:GetChecked())
 
-    local id, name = pfUI.addons.profile.dropdown:GetSelection()
+    local _, name = pfUI.addons.profile.dropdown:GetSelection()
     name = name or T["Current"]
     pfUI_addon_profiles[name] = GetSelectedAddonsList()
   end
 
-  pfUI.addons.list:SetScript("OnEvent", function()
-    for i=1, GetNumAddOns() do
-      local aname, atitle, anote = GetAddOnInfo(i)
-      local aauthor = GetAddOnMetadata(aname, "Author")
-      local aversion = GetAddOnMetadata(aname, "Version")
+  local function InitRow(row, addon)
+    -- one-time setup of a pooled row
+    if not row.input then
+      row:SetBackdrop(pfUI.backdrop_hover)
+      row:SetBackdropBorderColor(1,1,1,.04)
 
-      -- basic frame
-      if not pfUI.addons.list[i] then
-        pfUI.addons.list[i] = CreateFrame("Button", nil, pfUI.addons.list)
-        local frame = pfUI.addons.list[i]
-        frame.aname = aname
-        frame.atitle = atitle
-        frame.anote = anote
-        frame.aauthor = aauthor
-        frame.aversion = aversion
-        frame.adeps = { GetAddOnDependencies(i) }                          -- required (.toc Dependencies)
-        frame.aoptdeps = { C_AddOns.GetAddOnOptionalDependencies(i) }      -- optional (.toc OptionalDeps)
+      row:EnableMouse(true)
+      row:SetScript("OnEnter", RowOnEnter)
+      row:SetScript("OnLeave", RowOnLeave)
+      row:SetScript("OnClick", RowOnClick)
 
-        frame:SetSize(340, 25)
-        frame:SetPoint("TOPLEFT", 5, i * -25 + 20)
+      -- caption
+      row.caption = row:CreateFontString(nil, "LOW", "GameFontNormal")
+      row.caption:SetFont(pfUI.font_default, C.global.font_size + 2, "OUTLINE")
+      row.caption:SetPoint("LEFT", row, "LEFT", 2, 0)
+      row.caption:SetFontObject(GameFontWhite)
+      row.caption:SetJustifyH("LEFT")
 
-        frame:SetBackdrop(pfUI.backdrop_hover)
-        frame:SetBackdropBorderColor(1,1,1,.04)
-
-        frame:EnableMouse(1)
-        frame:SetScript("OnEnter", AddonOnEnter)
-        frame:SetScript("OnLeave", AddonOnLeave)
-        frame:SetScript("OnClick", AddonOnClick)
-
-        -- caption
-        frame.caption = frame:CreateFontString("Status", "LOW", "GameFontNormal")
-        frame.caption:SetFont(pfUI.font_default, C.global.font_size + 2, "OUTLINE")
-        frame.caption:SetPoint("LEFT", frame, "LEFT", 2, 0)
-        frame.caption:SetFontObject(GameFontWhite)
-        frame.caption:SetJustifyH("LEFT")
-        frame.caption:SetText(atitle)
-
-        -- input field
-        frame.input = CreateFrame("CheckButton", nil, frame, "UICheckButtonTemplate")
-        frame.input:SetFrameLevel(3)
-        frame.input:SetNormalTexture("")
-        frame.input:SetPushedTexture("")
-        frame.input:SetHighlightTexture("")
-        CreateBackdrop(frame.input, nil, true)
-        frame.input:SetBackdropBorderColor(.3,.3,.3,1)
-        frame.input:SetWidth(14)
-        frame.input:SetHeight(14)
-        frame.input:SetPoint("RIGHT" , -5, 1)
-        frame.input:SetID(i)
-        frame.input:SetScript("OnClick", InputOnClick)
-      end
-
-      if IsAddOnLoaded(i) then
-        pfUI.addons.list[i].input:SetChecked()
-        pfUI.addons.list[i].caption:SetAlpha(1)
-      else
-        pfUI.addons.list[i].caption:SetAlpha(.5)
-      end
+      -- input field
+      row.input = CreateFrame("CheckButton", nil, row, "UICheckButtonTemplate")
+      row.input:SetNormalTexture("")
+      row.input:SetPushedTexture("")
+      row.input:SetHighlightTexture("")
+      CreateBackdrop(row.input, nil, true)
+      row.input:SetBackdropBorderColor(.3,.3,.3,1)
+      row.input:SetSize(14, 14)
+      row.input:SetPoint("RIGHT" , -5, 1)
+      row.input:SetScript("OnClick", InputOnClick)
     end
-  end)
 
-  -- show only frames in visible range
-  function pfUI.addons.scroll:ShowVisibleRange()
-    local top_index, bottom_index, range
-    range = floor(pfUI.addons.scroll:GetHeight() / 25) + 1
-    top_index = floor(pfUI.addons.scroll:GetVerticalScroll() / 25) > 0 and floor(pfUI.addons.scroll:GetVerticalScroll() / 25) or 1
-    bottom_index = top_index + range
-    for i=1, GetNumAddOns() do
-      if i >= top_index and i <= bottom_index then
-        pfUI.addons.list[i]:Show()
-      else
-        pfUI.addons.list[i]:Hide()
-      end
-    end
+    row.addon = addon
+    row.caption:SetText(addon.title)
+    row.caption:SetAlpha(IsAddOnLoaded(addon.index) and 1 or .5)
+    row.input:SetChecked(IsAddonEnabled(addon.index))
   end
 
-  pfUI.addons.scroll.slider:SetScript("OnValueChanged", function()
-    this:GetParent():SetVerticalScroll(this:GetValue())
-  end)
-  pfUI.addons.scroll:SetScript("OnScrollRangeChanged", function()
-    this.slider:SetMinMaxValues(1, floor(this:GetVerticalScrollRange() + 25))
-  end)
-  pfUI.addons.scroll:SetScript("OnShow", function()
-    this.slider:SetValue(floor(this:GetVerticalScroll()))
-    pfUI.addons.scroll:ShowVisibleRange()
-  end)
-  pfUI.addons.scroll:SetScript("OnVerticalScroll", function()
-    pfUI.addons.scroll:ShowVisibleRange()
-    this.slider:SetValue(floor(this:GetVerticalScroll()))
+  -- addon list: a ScrollBox keeps rows only for the addons in view
+  pfUI.addons.scroll = CreateFrame("Frame", "pfAddonListScroll", pfUI.addons, "WowScrollBoxList")
+  pfUI.addons.scroll:SetSize(360, 410)
+  pfUI.addons.scroll:SetPoint("BOTTOM", 0, 10)
+
+  -- the ScrollBox clips its children, so the backdrop is a sibling
+  pfUI.addons.scroll.backdrop = CreateFrame("Frame", nil, pfUI.addons)
+  pfUI.addons.scroll.backdrop:SetPoint("TOPLEFT", pfUI.addons.scroll, "TOPLEFT", -5, 5)
+  pfUI.addons.scroll.backdrop:SetPoint("BOTTOMRIGHT", pfUI.addons.scroll, "BOTTOMRIGHT", 5, -5)
+  CreateBackdrop(pfUI.addons.scroll.backdrop, nil, true)
+
+  local scrollbar = CreateFrame("EventFrame", nil, pfUI.addons, "pfUIScrollBarTemplate")
+  scrollbar:SetPoint("TOPRIGHT", pfUI.addons.scroll, "TOPRIGHT")
+  scrollbar:SetPoint("BOTTOMRIGHT", pfUI.addons.scroll, "BOTTOMRIGHT")
+
+  local view = CreateScrollBoxListLinearView(5, 5, 5, 15)
+  view:SetElementExtent(25)
+  view:SetElementInitializer("Button", InitRow)
+  ScrollUtil.InitScrollBoxListWithScrollBar(pfUI.addons.scroll, scrollbar, view)
+  pfUI.addons.scroll:SetDataProvider(CreateDataProvider(addons))
+
+  -- a load-on-demand addon that loads brightens its row
+  pfUI.addons.scroll:RegisterEvent("ADDON_LOADED")
+  pfUI.addons.scroll:SetScript("OnEvent", function(self)
+    self:ReinitializeFrames()
   end)
 
 end)