fix(SelectPanel): auto scroll when list overflows

.changeset/soft-schools-nail.md

@@ -0,0 +1,5 @@
+---
+"@primer/components": patch
+---
+
+Handle overflow and active-descendant scrolling within `SelectPanel`

docs/content/SelectPanel.mdx

@@ -7,4 +7,50 @@ A `SelectPanel` provides an anchor that will open an overlay with a list of sele
 
 ## Example
 
+```javascript live noinline
+function getColorCircle(color) {
+  return function () {
+    return <BorderBox bg={color} borderColor={color} width={14} height={14} borderRadius={10} margin="auto" />
+  }
+}
+
+const items = [
+  {leadingVisual: getColorCircle('#a2eeef'), text: 'enhancement', id: 1},
+  {leadingVisual: getColorCircle('#d73a4a'), text: 'bug', id: 2},
+  {leadingVisual: getColorCircle('#0cf478'), text: 'good first issue', id: 3},
+  {leadingVisual: getColorCircle('#ffd78e'), text: 'design', id: 4},
+  {leadingVisual: getColorCircle('#ff0000'), text: 'blocker', id: 5},
+  {leadingVisual: getColorCircle('#a4f287'), text: 'backend', id: 6},
+  {leadingVisual: getColorCircle('#8dc6fc'), text: 'frontend', id: 7}
+]
+
+function DemoComponent() {
+const [selected, setSelected] = React.useState([items[0], items[1]])
+  const [filter, setFilter] = React.useState('')
+  const filteredItems = items.filter(item => item.text.toLowerCase().startsWith(filter.toLowerCase()))
+  const [open, setOpen] = React.useState(false)
+
+  return (
+    <SelectPanel
+      renderAnchor={({children, 'aria-labelledby': ariaLabelledBy, ...anchorProps}) => (
+        <DropdownButton aria-labelledby={` ${ariaLabelledBy}`} {...anchorProps}>
+          {children || 'Select Labels'}
+        </DropdownButton>
+      )}
+      placeholderText="Filter Labels"
+      open={open}
+      onOpenChange={setOpen}
+      items={filteredItems}
+      selected={selected}
+      onSelectedChange={setSelected}
+      onFilterChange={setFilter}
+      showItemDividers={true}
+      overlayProps={{width: 'small', height: 'xsmall'}}
+    />
+  )
+}
+
+render(<DemoComponent />)
+```
+
 ## Component props

docs/src/@primer/gatsby-theme-doctocat/live-code-scope.js

@@ -23,6 +23,7 @@ import State from '../../../components/State'
 import {Dialog as Dialog2} from '../../../../src/Dialog/Dialog'
 import {AnchoredOverlay} from '../../../../src/AnchoredOverlay'
 import {ConfirmationDialog, useConfirm} from '../../../../src/Dialog/ConfirmationDialog'
+import {SelectPanel} from '../../../../src/SelectPanel/SelectPanel'
 
 export default {
   ...doctocatComponents,
@@ -48,5 +49,6 @@ export default {
   Dialog2,
   ConfirmationDialog,
   useConfirm,
-  AnchoredOverlay
+  AnchoredOverlay,
+  SelectPanel
 }

src/FilteredActionList/FilteredActionList.tsx

@@ -1,13 +1,16 @@
-import React, {KeyboardEventHandler, useCallback, useMemo, useRef} from 'react'
+import React, {KeyboardEventHandler, useCallback, useEffect, useMemo, useRef} from 'react'
 import {GroupedListProps, ListPropsBase} from '../ActionList/List'
 import TextInput, {TextInputProps} from '../TextInput'
 import Box from '../Box'
+import Flex from '../Flex'
 import {ActionList} from '../ActionList'
 import Spinner from '../Spinner'
 import {useFocusZone} from '../hooks/useFocusZone'
 import {uniqueId} from '../utils/uniqueId'
 import {itemActiveDescendantClass} from '../ActionList/Item'
 import {useProvidedStateOrCreate} from '../hooks/useProvidedStateOrCreate'
+import styled from 'styled-components'
+import {get} from '../constants'
 
 export interface FilteredActionListProps extends Partial<Omit<GroupedListProps, keyof ListPropsBase>>, ListPropsBase {
   loading?: boolean
@@ -17,6 +20,34 @@ export interface FilteredActionListProps extends Partial<Omit<GroupedListProps,
   textInputProps?: Partial<Omit<TextInputProps, 'onChange'>>
 }
 
+function scrollIntoViewingArea(
+  child: HTMLElement,
+  container: HTMLElement,
+  margin = 8,
+  behavior: ScrollBehavior = 'smooth'
+) {
+  const {top: childTop, bottom: childBottom} = child.getBoundingClientRect()
+  const {top: containerTop, bottom: containerBottom} = container.getBoundingClientRect()
+
+  const isChildTopAboveViewingArea = childTop < containerTop + margin
+  const isChildBottomBelowViewingArea = childBottom > containerBottom - margin
+
+  if (isChildTopAboveViewingArea) {
+    const scrollHeightToChildTop = childTop - containerTop + container.scrollTop
+    container.scrollTo({behavior, top: scrollHeightToChildTop - margin})
+  } else if (isChildBottomBelowViewingArea) {
+    const scrollHeightToChildBottom = childBottom - containerBottom + container.scrollTop
+    container.scrollTo({behavior, top: scrollHeightToChildBottom + margin})
+  }
+
+  // either completely in view or outside viewing area on both ends, don't scroll
+}
+
+const StyledHeader = styled.div`
+  box-shadow: 0 1px 0 ${get('colors.border.primary')};
+  z-index: 1;
+`
+
 export function FilteredActionList({
   loading = false,
   placeholderText,
@@ -37,6 +68,7 @@ export function FilteredActionList({
   )
 
   const containerRef = useRef<HTMLInputElement>(null)
+  const scrollContainerRef = useRef<HTMLDivElement>(null)
   const inputRef = useRef<HTMLInputElement>(null)
   const activeDescendantRef = useRef<HTMLElement>()
   const listId = useMemo(uniqueId, [])
@@ -74,26 +106,39 @@ export function FilteredActionList({
 
       if (current) {
         current.classList.add(itemActiveDescendantClass)
+
+        if (scrollContainerRef.current) {
+          scrollIntoViewingArea(current, scrollContainerRef.current)
+        }
       }
     }
   })
 
+  useEffect(() => {
+    // if items changed, we want to instantly move active descendant into view
+    if (activeDescendantRef.current && scrollContainerRef.current) {
+      scrollIntoViewingArea(activeDescendantRef.current, scrollContainerRef.current, undefined, 'auto')
+    }
+  }, [items])
+
   return (
-    <Box ref={containerRef} flexGrow={1} flexDirection="column">
-      <TextInput
-        ref={inputRef}
-        block
-        width="auto"
-        color="text.primary"
-        value={filterValue}
-        onChange={onInputChange}
-        onKeyPress={onInputKeyPress}
-        placeholder={placeholderText}
-        aria-label={placeholderText}
-        aria-controls={listId}
-        {...textInputProps}
-      />
-      <Box flexGrow={1} overflow="auto">
+    <Flex ref={containerRef} flexDirection="column" overflow="hidden">
+      <StyledHeader>
+        <TextInput
+          ref={inputRef}
+          block
+          width="auto"
+          color="text.primary"
+          value={filterValue}
+          onChange={onInputChange}
+          onKeyPress={onInputKeyPress}
+          placeholder={placeholderText}
+          aria-label={placeholderText}
+          aria-controls={listId}
+          {...textInputProps}
+        />
+      </StyledHeader>
+      <Box ref={scrollContainerRef} overflow="auto">
         {loading ? (
           <Box width="100%" display="flex" flexDirection="row" justifyContent="center" pt={6} pb={7}>
             <Spinner />
@@ -102,7 +147,7 @@ export function FilteredActionList({
           <ActionList items={items} {...listProps} role="listbox" id={listId} />
         )}
       </Box>
-    </Box>
+    </Flex>
   )
 }
 

src/stories/SelectPanel.stories.tsx

@@ -31,15 +31,18 @@ export default meta
 
 function getColorCircle(color: string) {
   return function () {
-    return <BorderBox bg={color} borderColor={color} padding={2} borderRadius={10} />
+    return <BorderBox bg={color} borderColor={color} width={14} height={14} borderRadius={10} margin="auto" />
   }
 }
 
 const items = [
   {leadingVisual: getColorCircle('#a2eeef'), text: 'enhancement', id: 1},
   {leadingVisual: getColorCircle('#d73a4a'), text: 'bug', id: 2},
   {leadingVisual: getColorCircle('#0cf478'), text: 'good first issue', id: 3},
-  {leadingVisual: getColorCircle('#8dc6fc'), text: 'design', id: 4}
+  {leadingVisual: getColorCircle('#ffd78e'), text: 'design', id: 4},
+  {leadingVisual: getColorCircle('#ff0000'), text: 'blocker', id: 5},
+  {leadingVisual: getColorCircle('#a4f287'), text: 'backend', id: 6},
+  {leadingVisual: getColorCircle('#8dc6fc'), text: 'frontend', id: 7}
 ]
 
 export function MultiSelectStory(): JSX.Element {
@@ -66,6 +69,7 @@ export function MultiSelectStory(): JSX.Element {
         onSelectedChange={setSelected}
         onFilterChange={setFilter}
         showItemDividers={true}
+        overlayProps={{width: 'small', height: 'xsmall'}}
       />
     </>
   )
@@ -96,6 +100,7 @@ export function SingleSelectStory(): JSX.Element {
         onSelectedChange={setSelected}
         onFilterChange={setFilter}
         showItemDividers={true}
+        overlayProps={{width: 'small', height: 'xsmall'}}
       />
     </>
   )