Fix Combo popup size and position

lib/WidgetTypes.lua

@@ -428,6 +428,8 @@ export type Combo = ParentWidget & {
         index: State<any>,
         isOpened: State<boolean>,
     },
+
+    UIListLayout: UIListLayout,
 } & Opened & Closed & Clicked & Hovered
 
 -- Plot

lib/demoWindow.lua

@@ -209,6 +209,12 @@ return function(Iris: Types.Iris)
 
                 Iris.ComboArray({ "Using ComboArray" }, { index = "No Selection" }, { "Red", "Green", "Blue" })
 
+                local heightTestArray = {}
+                for i = 1, 50 do
+                    table.insert(heightTestArray, tostring(i))
+                end
+                Iris.ComboArray({ "Height Test" }, { index = "1" }, heightTestArray)
+
                 local sharedComboIndex2 = Iris.State("7 AM")
 
                 Iris.Combo({ "Combo with Inner widgets" }, { index = sharedComboIndex2 })

lib/widgets/Combo.lua

@@ -130,34 +130,52 @@ return function(Iris: Types.Internal, widgets: Types.WidgetUtility)
     local AnyOpenedCombo: boolean = false
     local ComboOpenedTick: number = -1
     local OpenedCombo: Types.Combo? = nil
+    local CachedContentSize: number = 0
 
     local function UpdateChildContainerTransform(thisWidget: Types.Combo)
         local Combo = thisWidget.Instance :: Frame
         local PreviewContainer = Combo.PreviewContainer :: TextButton
         local ChildContainer = thisWidget.ChildContainer :: ScrollingFrame
 
-        ChildContainer.Size = UDim2.fromOffset(PreviewContainer.AbsoluteSize.X, 0)
-
         local previewPosition: Vector2 = PreviewContainer.AbsolutePosition - widgets.GuiOffset
         local previewSize: Vector2 = PreviewContainer.AbsoluteSize
-        local containerSize: Vector2 = ChildContainer.AbsoluteSize
         local borderSize: number = Iris._config.PopupBorderSize
         local screenSize: Vector2 = ChildContainer.Parent.AbsoluteSize
 
+        local absoluteContentSize = thisWidget.UIListLayout.AbsoluteContentSize.Y
+        CachedContentSize = absoluteContentSize
+
+        local contentsSize: number = absoluteContentSize + 2 * Iris._config.WindowPadding.Y
+
         local x: number = previewPosition.X
-        local y: number
+        local y: number = previewPosition.Y + previewSize.Y + borderSize
         local anchor: Vector2 = Vector2.zero
+        local distanceToScreen: number = screenSize.Y - y
 
-        if previewPosition.Y + containerSize.Y > screenSize.Y then
+        -- Only extend upwards if we cannot fully extend downwards, and we are on the bottom half of the screen.
+        --  i.e. there is more space upwards than there is downwards.
+        if contentsSize > distanceToScreen and y > (screenSize.Y / 2) then
             y = previewPosition.Y - borderSize
             anchor = Vector2.yAxis
-        else
-            y = previewPosition.Y + previewSize.Y + borderSize
+            distanceToScreen = y -- from 0 to the current position
         end
+
         ChildContainer.AnchorPoint = anchor
         ChildContainer.Position = UDim2.fromOffset(x, y)
+
+        local height = math.min(contentsSize, distanceToScreen)
+        ChildContainer.Size = UDim2.fromOffset(PreviewContainer.AbsoluteSize.X, height)
     end
 
+    table.insert(Iris._postCycleCallbacks, function()
+        if AnyOpenedCombo and OpenedCombo then
+            local contentSize = OpenedCombo.UIListLayout.AbsoluteContentSize.Y
+            if contentSize ~= CachedContentSize then
+                UpdateChildContainerTransform(OpenedCombo)
+            end
+        end
+    end)
+
     local function UpdateComboState(input: InputObject)
         if not Iris._started then
             return
@@ -340,7 +358,6 @@ return function(Iris: Types.Internal, widgets: Types.WidgetUtility)
 
             local ChildContainer: ScrollingFrame = Instance.new("ScrollingFrame")
             ChildContainer.Name = "ComboContainer"
-            ChildContainer.AutomaticSize = Enum.AutomaticSize.Y
             ChildContainer.BackgroundColor3 = Iris._config.PopupBgColor
             ChildContainer.BackgroundTransparency = Iris._config.PopupBgTransparency
             ChildContainer.BorderSizePixel = 0
@@ -374,6 +391,7 @@ return function(Iris: Types.Internal, widgets: Types.WidgetUtility)
             ChildContainer.Parent = RootPopupScreenGui
 
             thisWidget.ChildContainer = ChildContainer
+            thisWidget.UIListLayout = ChildContainerUIListLayout
             return Combo
         end,
         Update = function(thisWidget: Types.Combo)