feat(tracker): tuck the objective marker in beside the quest line

Drops the left-margin reserve the marker used to get: the quest list goes
back to its original indent and the marker tucks in to the left of
whatever owns the head of the line -- the quest item button where there
is one, the collapse button where there is not -- hanging over the
tracker's left edge, and off it entirely at larger sizes. A marker that
reaches past the edge is reparented above the scroll frame, which would
otherwise clip it.

It is also centred on the quest's whole text block rather than on the
title alone. The block is added up from the line heights the tracker
itself sets: measuring the frames with GetTop/GetBottom reads positions
from a half-built tracker on login and flings the marker off it.

Modules/Tracker/TrackerLinePool.lua

@@ -115,19 +115,13 @@ local linePool = {}
 local buttonPool = {}
 local lineMarginLeft = 10
 
--- Gutter given to the supertrack button, which sits flush with the left edge of a quest line. The
--- collapse button, the quest item buttons and the labels are all shifted right by this much, so
--- nothing lands on top of it and nothing hangs over the tracker's left edge. Fed into
--- questMarginLeft, which every width calculation already builds on, so the tracker widens to match.
-function TrackerLinePool.GetSuperTrackMarginReserve()
-    if (not Questie.db.profile.trackerShowSuperTrackButton) or (not TrackerUtils:IsSuperTrackAvailable()) then
-        return 0
-    end
+-- Gap kept between the supertrack button and whatever it is tucked in next to.
+local superTrackButtonGap = 2
 
-    -- Reserved even for quests whose button is hidden, so the list does not shift around as quests
-    -- come in and out of the supertrackable set.
-    return (Questie.db.profile.trackerSuperTrackButtonSize or 25) + 4
-end
+-- Left edge of a quest line's collapse button. QuestieTracker anchors it at questMarginLeft - 8
+-- with a width of trackerFontSizeQuest, and questMarginLeft carries a matching + trackerFontSizeQuest,
+-- so it lands on a flat 18 whatever the font size is.
+local superTrackCollapseButtonLeft = 18
 
 ---@param questFrame Frame
 function TrackerLinePool.Initialize(questFrame)
@@ -529,9 +523,62 @@ function TrackerLinePool.Initialize(questFrame)
 
         superTrackButton.SetSuperTrackButton = function(self, questId)
             self.questId = questId
+            -- Back to the title line on its own: the objective lines below have not been laid out
+            -- yet, so the tracker measures the block and calls SetBlockHeight once they are. Same
+            -- for the quest item button, which is set up further down and owns this slot.
+            self.blockHeight = nil
+            self.itemButtonShown = nil
             self:RefreshSuperTrackButton()
         end
 
+        -- Horizontally: tucked in to the left of whatever else owns the head of the line -- the
+        -- quest item button where there is one, the collapse button where there is not. It hangs
+        -- over the line's left edge, and off the tracker entirely at larger sizes; giving the
+        -- marker a column of its own would mean indenting every quest in the tracker for it.
+        -- Vertically: centred on the quest's whole text block, title plus objectives, the height
+        -- the tracker hands us. Without one, centred on the quest title alone, which is all that
+        -- exists at the point the button is first set up.
+        superTrackButton.AnchorSuperTrackButton = function(self)
+            local buttonSize = Questie.db.profile.trackerSuperTrackButtonSize or 25
+            local blockHeight = self.blockHeight or Questie.db.profile.trackerFontSizeQuest
+            local slotLeft = self.itemButtonShown and 0 or superTrackCollapseButtonLeft
+            local offsetX = slotLeft - superTrackButtonGap - buttonSize
+
+            -- The lines live inside the tracker's scroll frame, which clips anything hanging over
+            -- its edge, so a marker that reaches past it is reparented above the clip. It stays
+            -- anchored to its line either way, and every redraw hides it by hand
+            -- (ResetLinesForChange) before deciding whether to show it again.
+            self:SetParent(((offsetX + lineMarginLeft) < 0) and trackerQuestFrame or line)
+
+            self:ClearAllPoints()
+            self:SetPoint("TOPLEFT", line, "TOPLEFT", offsetX, (buttonSize - blockHeight) / 2 + 1)
+
+            -- Has to sit above the tracker backdrop, which is what swallows a frame left at level 0.
+            -- Strata comes from the line rather than from whichever parent it ended up with, so the
+            -- two cases draw the same.
+            self:SetFrameStrata(line:GetFrameStrata())
+            self:SetFrameLevel(line:GetFrameLevel() + 10)
+        end
+
+        superTrackButton.SetBlockHeight = function(self, blockHeight)
+            if self.blockHeight == blockHeight then
+                return
+            end
+
+            self.blockHeight = blockHeight
+            self:AnchorSuperTrackButton()
+        end
+
+        superTrackButton.SetItemButtonShown = function(self, shown)
+            shown = shown and true or false
+            if (self.itemButtonShown or false) == shown then
+                return
+            end
+
+            self.itemButtonShown = shown
+            self:AnchorSuperTrackButton()
+        end
+
         superTrackButton.RefreshSuperTrackButton = function(self)
             -- No map pin means the client has nothing to point the marker at (quest in another zone,
             -- or a quest without map coordinates), so there is nothing to offer.
@@ -581,12 +628,7 @@ function TrackerLinePool.Initialize(questFrame)
             -- while the mouse is still held down.
             self:SetPressedOffset(false)
 
-            -- Flush with the left edge of the line, in the gutter GetSuperTrackMarginReserve keeps
-            -- clear. Anchored to the top rather than centred on the line so the button stays level
-            -- with the first row of a quest title that wraps, matching the collapse button.
-            local fontSizeQuest = Questie.db.profile.trackerFontSizeQuest
-            self:ClearAllPoints()
-            self:SetPoint("TOPLEFT", line, "TOPLEFT", 0, (buttonSize - fontSizeQuest) / 2 + 1)
+            self:AnchorSuperTrackButton()
 
             -- The icon carries the selected variant itself; the glow is the one part the pin draws
             -- as a separate texture.
@@ -596,8 +638,6 @@ function TrackerLinePool.Initialize(questFrame)
                 self.glow:Hide()
             end
 
-            -- Has to sit above the tracker backdrop, which is what swallows a frame left at level 0.
-            self:SetFrameLevel(line:GetFrameLevel() + 10)
             self:Show()
         end
 
@@ -701,6 +741,9 @@ function TrackerLinePool.Initialize(questFrame)
 
         line.expandQuest = expandQuest
 
+        -- Its own slot in the pool, so a run of lines drawn for one quest can be walked back over.
+        line.lineIndex = i
+
         linePool[i] = line
         nextFrame = line
     end
@@ -1060,6 +1103,49 @@ function TrackerLinePool.GetCurrentButton()
     return buttonPool[buttonIndex]
 end
 
+-- Height of the block of lines a single quest was drawn into, title line through last objective.
+-- Added up from the heights the tracker itself set rather than measured off the frames: on login
+-- the tracker has not been laid out yet, and GetTop/GetBottom then report positions from a
+-- half-built frame, which is enough to fling a marker centred on the result off the tracker.
+---@return number|nil blockHeight
+function TrackerLinePool.GetQuestBlockHeight(firstLine, lastLine)
+    if (not firstLine) or (not lastLine) or (not firstLine.lineIndex) or (not lastLine.lineIndex) then
+        return nil
+    end
+
+    if lastLine.lineIndex < firstLine.lineIndex then
+        return nil
+    end
+
+    local blockHeight = 0
+    for i = firstLine.lineIndex, lastLine.lineIndex do
+        local line = linePool[i]
+        if not line then
+            return nil
+        end
+
+        blockHeight = blockHeight + line:GetHeight()
+    end
+
+    -- The last line of a quest carries the padding to the next one. That is empty space below the
+    -- text, so it plays no part in where the block's centre is. A quest collapsed down to its title
+    -- is the exception: that single line is the whole quest, and neither reference reads right on
+    -- its own -- against the text alone the marker rides high over the row's empty half, against
+    -- the whole row it sits low under the title it belongs to -- so it splits the difference.
+    local trailingPadding = Questie.db.profile.trackerQuestPadding + 2
+    if lastLine.lineIndex == firstLine.lineIndex then
+        trailingPadding = trailingPadding / 2
+    end
+
+    blockHeight = blockHeight - trailingPadding
+
+    if blockHeight <= 0 then
+        return nil
+    end
+
+    return blockHeight
+end
+
 ---@return table|nil lineIndex linePool[lineIndex - 1]
 function TrackerLinePool.GetPreviousLine()
     lineIndex = lineIndex - 1
@@ -1109,6 +1195,10 @@ function TrackerLinePool.HideUnusedLines()
             line.expandZone.zoneId = nil
             line.criteriaMark.mode = nil
             line.playButton.mode = nil
+            -- Hidden by hand: a marker that overflows to the left of its line is parented above the
+            -- scroll frame's clip, so hiding the line no longer hides it.
+            line.superTrackButton.questId = nil
+            line.superTrackButton:Hide()
         end
     end
 end