Show loot history and the icon picker in ClassicAPI ScrollBoxes

pfUIScrollBoxListTemplate (api/ui-widgets.xml) is a WowScrollBoxList with
pfUIScrollBarTemplate beside it, 5px inside the frame, so a list's
backdrop goes on the frame itself. The addon list moves onto it and drops
the sibling backdrop frame.

Loot history builds a flat list of item rows and, under an expanded item,
player rows; the view sizes and indents them. The item frame array, the
player pool, the hand-placed rows and the scroll child re-attach are gone,
and the scroll position holds across roll updates.

The icon picker's FauxScrollFrame and 80 fixed buttons become a grid view
over the provider's icon indices. Picking an icon reinitializes the shown
buttons instead of redrawing the grid, and closing the popup drops the
grid's entries along with the provider.

api/ui-widgets.lua

@@ -1252,7 +1252,7 @@ end
 -- survives filter changes -- a spell icon you picked still saves after you
 -- switch the filter to "Items" and it drops out of the visible grid.
 --
---   name          global-name prefix for the scroll frame and editboxes
+--   name          global-name prefix for the icon grid and editboxes
 --   parent        the popup frame to attach the widgets to
 --   extraType     IconDataProviderExtraType.* seed (Spellbook / Equipment)
 --   nameLabelText header shown above the name field
@@ -1322,17 +1322,13 @@ function pfUI.api.CreateIconPicker(name, parent, extraType, nameLabelText)
   parent.iconLabel:SetPoint("TOPLEFT", parent, "TOPLEFT", 14, -86)
   parent.iconLabel:SetText(MACRO_POPUP_CHOOSE_ICON)
 
-  -- Icon grid + scroll
-  local iconScroll = CreateFrame("ScrollFrame", name.."Scroll", parent, "FauxScrollFrameTemplate")
-  iconScroll:SetPoint("TOPLEFT", parent, "TOPLEFT", 14, -116)
-  iconScroll:SetWidth(ICON_GRID_COLS * (ICON_BTN_SIZE + ICON_BTN_PAD) - ICON_BTN_PAD)
-  iconScroll:SetHeight(ICON_GRID_ROWS * (ICON_BTN_SIZE + ICON_BTN_PAD) - ICON_BTN_PAD)
-
-  local scrollbar = _G[name.."ScrollScrollBar"]
-  scrollbar:ClearAllPoints()
-  scrollbar:SetPoint("TOPLEFT", iconScroll, "TOPRIGHT", 8, -16)
-  scrollbar:SetPoint("BOTTOMLEFT", iconScroll, "BOTTOMRIGHT", 8, 16)
-  SkinScrollbar(scrollbar)
+  -- Icon grid: the template keeps 5px around the grid and its 7px scroll bar,
+  -- and the grid leaves 4px before the bar
+  local gridWidth = ICON_GRID_COLS * (ICON_BTN_SIZE + ICON_BTN_PAD) - ICON_BTN_PAD
+  local gridHeight = ICON_GRID_ROWS * (ICON_BTN_SIZE + ICON_BTN_PAD) - ICON_BTN_PAD
+  local grid = CreateFrame("Frame", name.."Icons", parent, "pfUIScrollBoxListTemplate")
+  grid:SetPoint("TOPLEFT", parent, "TOPLEFT", 9, -111)
+  grid:SetSize(gridWidth + 4 + 7 + 10, gridHeight + 10)
 
   -- Filter dropdown: All / Spells / Items
   local filterDropdown = CreateFrame("Frame", name.."Filter", parent, "UIDropDownMenuTemplate")
@@ -1367,38 +1363,54 @@ function pfUI.api.CreateIconPicker(name, parent, extraType, nameLabelText)
   UIDropDownMenu_SetSelectedValue(filterDropdown, "all")
   SkinDropDown(filterDropdown)
 
-  local iconButtons = {}
-  for r = 1, ICON_GRID_ROWS do
-    for c = 1, ICON_GRID_COLS do
-      local i = (r - 1) * ICON_GRID_COLS + c
-      local btn = CreateFrame("Button", nil, parent)
-      btn:SetSize(ICON_BTN_SIZE, ICON_BTN_SIZE)
-      btn:SetPoint("TOPLEFT", iconScroll, "TOPLEFT", (c-1) * (ICON_BTN_SIZE + ICON_BTN_PAD), -(r-1) * (ICON_BTN_SIZE + ICON_BTN_PAD))
+  -- the selected icon gets a gold border in the grid and shows in the preview
+  local function UpdateSelection()
+    grid.ScrollBox:ReinitializeFrames()
+    parent.selectedPreview.tex:SetTexture(selectedIconPath)
+  end
+
+  local function IconOnClick()
+    local path = provider:GetIconByIndex(this.iconIndex)
+    if path then selectedIconPath = path end
+    UpdateSelection()
+  end
+
+  local function IconOnEnter()
+    local path = provider:GetIconByIndex(this.iconIndex)
+    if type(path) == "string" then
+      GameTooltip:SetOwner(this, "ANCHOR_RIGHT")
+      GameTooltip:SetText(IconKey(path), 1, 1, 1)
+      GameTooltip:Show()
+    end
+  end
+
+  local function InitIconButton(btn, icon)
+    -- one-time setup of a pooled button
+    if not btn.texture then
       CreateBackdrop(btn)
       btn.texture = btn:CreateTexture(nil, "ARTWORK")
       btn.texture:SetAllPoints(btn)
       btn.texture:SetTexCoord(.08, .92, .08, .92)
-      btn:SetScript("OnClick", function()
-        if this.iconIndex and provider then
-          local path = provider:GetIconByIndex(this.iconIndex)
-          if path then selectedIconPath = path end
-          RefreshIconGrid()
-        end
-      end)
-      btn:SetScript("OnEnter", function()
-        if not this.iconIndex or not provider then return end
-        local path = provider:GetIconByIndex(this.iconIndex)
-        if type(path) == "string" then
-          GameTooltip:SetOwner(this, "ANCHOR_RIGHT")
-          GameTooltip:SetText(IconKey(path), 1, 1, 1)
-          GameTooltip:Show()
-        end
-      end)
+      btn:SetScript("OnClick", IconOnClick)
+      btn:SetScript("OnEnter", IconOnEnter)
       btn:SetScript("OnLeave", GameTooltip_Hide)
-      iconButtons[i] = btn
+    end
+
+    btn.iconIndex = icon.index
+    local path = provider:GetIconByIndex(icon.index)
+    btn.texture:SetTexture(path)
+    if IconKey(path) == IconKey(selectedIconPath) then
+      btn.backdrop:SetBackdropBorderColor(1, 0.82, 0, 1)
+    else
+      btn.backdrop:SetBackdropBorderColor(pfUI.cache.er, pfUI.cache.eg, pfUI.cache.eb, pfUI.cache.ea)
     end
   end
 
+  local view = CreateScrollBoxListGridView(ICON_GRID_COLS, 0, 0, 0, 4, ICON_BTN_PAD, ICON_BTN_PAD)
+  view:SetElementSize(ICON_BTN_SIZE, ICON_BTN_SIZE)
+  view:SetElementInitializer("Button", InitIconButton)
+  ScrollUtil.InitScrollBoxListWithScrollBar(grid.ScrollBox, grid.ScrollBar, view)
+
   -- Rebuild the search-filtered index list (provider indices whose icon
   -- basename contains the search text); nil when the search box is empty.
   function RebuildFilter()
@@ -1416,38 +1428,17 @@ function pfUI.api.CreateIconPicker(name, parent, extraType, nameLabelText)
     end
   end
 
+  -- one grid entry per provider index the filter lets through, scrolled to the top
   function RefreshIconGrid()
     EnsureProvider()
-    local numIcons = filtered and table.getn(filtered) or provider:GetNumIcons()
-    local numRows = math.ceil(numIcons / ICON_GRID_COLS)
-    FauxScrollFrame_Update(iconScroll, numRows, ICON_GRID_ROWS, ICON_BTN_SIZE + ICON_BTN_PAD)
-    local offset = FauxScrollFrame_GetOffset(iconScroll)
-    for i = 1, ICON_GRID_ROWS * ICON_GRID_COLS do
-      local listIdx = i + offset * ICON_GRID_COLS
-      local btn = iconButtons[i]
-      if listIdx <= numIcons then
-        btn:Show()
-        local providerIdx = filtered and filtered[listIdx] or listIdx
-        btn.iconIndex = providerIdx
-        local path = provider:GetIconByIndex(providerIdx)
-        btn.texture:SetTexture(path)
-        if IconKey(path) == IconKey(selectedIconPath) then
-          btn.backdrop:SetBackdropBorderColor(1, 0.82, 0, 1)
-        else
-          btn.backdrop:SetBackdropBorderColor(pfUI.cache.er, pfUI.cache.eg, pfUI.cache.eb, pfUI.cache.ea)
-        end
-      else
-        btn:Hide()
-        btn.iconIndex = nil
-      end
+    if filtered then
+      grid.ScrollBox:SetDataProvider(CreateDataProviderWithAssignedKey(filtered, "index"))
+    else
+      grid.ScrollBox:SetDataProvider(CreateDataProviderByIndexCount(provider:GetNumIcons()))
     end
     parent.selectedPreview.tex:SetTexture(selectedIconPath)
   end
 
-  iconScroll:SetScript("OnVerticalScroll", function()
-    FauxScrollFrame_OnVerticalScroll(ICON_BTN_SIZE + ICON_BTN_PAD, function() RefreshIconGrid() end)
-  end)
-
   -- Search box (bottom-left) filters the grid by icon name.
   parent.searchLabel = parent:CreateFontString(nil, "OVERLAY", "GameFontNormal")
   parent.searchLabel:SetPoint("BOTTOMLEFT", parent, "BOTTOMLEFT", 16, 18)
@@ -1462,13 +1453,14 @@ function pfUI.api.CreateIconPicker(name, parent, extraType, nameLabelText)
   parent.search:SetScript("OnTextChanged", function()
     searchText = strupper(strtrim(this:GetText()))
     RebuildFilter()
-    scrollbar:SetValue(0)
     RefreshIconGrid()
   end)
 
-  -- Release the provider when the popup closes so its icon cache GCs.
+  -- Release the provider when the popup closes so its icon cache GCs, and
+  -- the grid's entries that index into it.
   parent:HookScript("OnHide", function()
     if provider then provider:Release(); provider = nil end
+    grid.ScrollBox:RemoveDataProvider()
   end)
 
   local handle = { editbox = parent.editbox, search = parent.search }
@@ -1476,15 +1468,13 @@ function pfUI.api.CreateIconPicker(name, parent, extraType, nameLabelText)
   function handle.SetIcon(path) selectedIconPath = path or QUESTION_MARK end
   function handle.Refresh() RefreshIconGrid() end
   function handle.SetIconAreaShown(shown)
-    local method = shown and "Show" or "Hide"
-    iconScroll[method](iconScroll)
-    for _, b in ipairs(iconButtons) do b[method](b) end
-    parent.iconLabel[method](parent.iconLabel)
-    parent.selectedLabel[method](parent.selectedLabel)
-    parent.selectedPreview[method](parent.selectedPreview)
-    filterDropdown[method](filterDropdown)
-    parent.searchLabel[method](parent.searchLabel)
-    parent.search[method](parent.search)
+    grid:SetShown(shown)
+    parent.iconLabel:SetShown(shown)
+    parent.selectedLabel:SetShown(shown)
+    parent.selectedPreview:SetShown(shown)
+    filterDropdown:SetShown(shown)
+    parent.searchLabel:SetShown(shown)
+    parent.search:SetShown(shown)
   end
   return handle
 end