From 1a440e1ee7cf5ce284237b08cf275a06802d2bcb Mon Sep 17 00:00:00 2001
From: Jordan Pittman <jordan@cryptica.me>
Date: Wed, 1 May 2024 15:57:28 -0400
Subject: [PATCH] Fix issues with scrolling in a virtual combobox (#3163)

* Scrolling to active option in combobox after opening when last option was selected with the mouse

* Allow virtual combobox to scroll freely with mouse wheel after changing options with keyboard

* Update changelog
---
 packages/@headlessui-react/CHANGELOG.md            |  1 +
 .../src/components/combobox/combobox.tsx           | 14 ++++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/packages/@headlessui-react/CHANGELOG.md b/packages/@headlessui-react/CHANGELOG.md
index f8b612ca43..72c81c4918 100644
--- a/packages/@headlessui-react/CHANGELOG.md
+++ b/packages/@headlessui-react/CHANGELOG.md
@@ -33,6 +33,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix anchored elements not flipping when there is padding ([#3157](https://github.com/tailwindlabs/headlessui/pull/3157))
 - Render virtual items during an exiting transition ([#3160](https://github.com/tailwindlabs/headlessui/pull/3160))
 - Only render virtual options wrapper when there are items to show ([#3161](https://github.com/tailwindlabs/headlessui/pull/3161))
+- Fix issues with scrolling to / around the active option in a virtual combobox ([#3163](https://github.com/tailwindlabs/headlessui/pull/3163))
 
 ### Changed
 
diff --git a/packages/@headlessui-react/src/components/combobox/combobox.tsx b/packages/@headlessui-react/src/components/combobox/combobox.tsx
index 0286b41887..24dcf5a1ff 100644
--- a/packages/@headlessui-react/src/components/combobox/combobox.tsx
+++ b/packages/@headlessui-react/src/components/combobox/combobox.tsx
@@ -196,6 +196,13 @@ let reducers: {
       ...state,
       activeOptionIndex: null,
       comboboxState: ComboboxState.Closed,
+
+      // Clear the last known activation trigger
+      // This is because if a user interacts with the combobox using a mouse
+      // resulting in it closing we might incorrectly handle the next interaction
+      // for example, not scrolling to the active option in a virtual list
+      activationTrigger: ActivationTrigger.Other,
+
       __demoMode: false,
     }
   },
@@ -1651,6 +1658,12 @@ function OptionsFn<TTag extends ElementType = typeof DEFAULT_OPTIONS_TAG>(
     } satisfies OptionsRenderPropArg
   }, [data])
 
+  // When the user scrolls **using the mouse** (so scroll event isn't appropriate)
+  // we want to make sure that the current activation trigger is set to pointer
+  let handleWheel = useEvent(() => {
+    actions.setActivationTrigger(ActivationTrigger.Pointer)
+  })
+
   let ourProps = mergeProps(anchor ? getFloatingPanelProps() : {}, {
     'aria-labelledby': labelledBy,
     role: 'listbox',
@@ -1662,6 +1675,7 @@ function OptionsFn<TTag extends ElementType = typeof DEFAULT_OPTIONS_TAG>(
       '--input-width': useElementSize(data.inputRef, true).width,
       '--button-width': useElementSize(data.buttonRef, true).width,
     } as CSSProperties,
+    onWheel: handleWheel,
   })
 
   // Map the children in a scrollable container when virtualization is enabled