Add TreeView.LeadingAction sub-component

.changeset/tame-nails-live.md

@@ -0,0 +1,5 @@
+---
+"@primer/react": minor
+---
+
+TreeView: Add support for `TreeView.LeadingAction`

e2e/components/TreeView.test.ts

@@ -138,4 +138,37 @@ test.describe('TreeView', () => {
       })
     }
   })
+
+  test.describe('Leading Action', () => {
+    for (const theme of themes) {
+      test.describe(theme, () => {
+        test('default @vrt', async ({page}) => {
+          await visit(page, {
+            id: 'components-treeview-features--leading-action',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+
+          expect(await page.screenshot()).toMatchSnapshot(`TreeView.Leading Action.${theme}.png`)
+        })
+
+        test('axe @aat', async ({page}) => {
+          await visit(page, {
+            id: 'components-treeview-features--leading-action',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+          await expect(page).toHaveNoViolations({
+            rules: {
+              'color-contrast': {
+                enabled: theme !== 'dark_dimmed',
+              },
+            },
+          })
+        })
+      })
+    }
+  })
 })

packages/react/src/TreeView/TreeView.docs.json

@@ -105,6 +105,16 @@
         }
       ]
     },
+    {
+      "name": "TreeView.LeadingAction",
+      "props": [
+        {
+          "name": "children",
+          "required": true,
+          "type": "React.ReactNode"
+        }
+      ]
+    },
     {
       "name": "TreeView.DirectoryIcon",
       "props": []

packages/react/src/TreeView/TreeView.examples.stories.tsx

@@ -0,0 +1,76 @@
+import {GrabberIcon} from '@primer/octicons-react'
+import type {Meta, Story} from '@storybook/react'
+import React from 'react'
+import Box from '../Box'
+import {TreeView} from './TreeView'
+import {IconButton} from '../Button'
+
+const meta: Meta = {
+  title: 'Components/TreeView/Examples',
+  component: TreeView,
+  decorators: [
+    Story => {
+      return (
+        // Prevent TreeView from expanding to the full width of the screen
+        <Box sx={{maxWidth: 400}}>
+          <Story />
+        </Box>
+      )
+    },
+  ],
+}
+
+export const DraggableListItem: Story = () => {
+  return (
+    <Box
+      sx={{
+        // using Box for css, this could be in a css file as well
+        '.treeview-item': {
+          '.treeview-leading-action': {visibility: 'hidden'},
+          '&:hover, &:focus': {
+            '.treeview-leading-action': {visibility: 'visible'},
+          },
+        },
+      }}
+    >
+      <TreeView aria-label="Issues">
+        <ControlledDraggableItem id="item-1">Item 1</ControlledDraggableItem>
+        <ControlledDraggableItem id="item-2">
+          Item 2
+          <TreeView.SubTree>
+            <TreeView.Item id="item-2-sub-task-1">sub task 1</TreeView.Item>
+            <TreeView.Item id="item-2-sub-task-2">sub task 2</TreeView.Item>
+          </TreeView.SubTree>
+        </ControlledDraggableItem>
+        <ControlledDraggableItem id="item-3">Item 3</ControlledDraggableItem>
+      </TreeView>
+    </Box>
+  )
+}
+
+const ControlledDraggableItem: React.FC<{id: string; children: React.ReactNode}> = ({id, children}) => {
+  const [expanded, setExpanded] = React.useState(false)
+
+  return (
+    <>
+      <TreeView.Item id={id} className="treeview-item" expanded={expanded} onExpandedChange={setExpanded}>
+        <TreeView.LeadingAction>
+          <IconButton
+            icon={GrabberIcon}
+            variant="invisible"
+            aria-label="Reorder item"
+            className="treeview-leading-action"
+            draggable="true"
+            onDragStart={() => {
+              setExpanded(false)
+              // other drag logic to follow
+            }}
+          />
+        </TreeView.LeadingAction>
+        {children}
+      </TreeView.Item>
+    </>
+  )
+}
+
+export default meta

packages/react/src/TreeView/TreeView.features.stories.tsx

@@ -4,7 +4,10 @@ import {
   DiffRemovedIcon,
   DiffRenamedIcon,
   FileIcon,
+  GrabberIcon,
   KebabHorizontalIcon,
+  IssueClosedIcon,
+  IssueOpenedIcon,
 } from '@primer/octicons-react'
 import type {Meta, Story} from '@storybook/react'
 import React from 'react'
@@ -989,4 +992,52 @@ export const WithoutIndentation: Story = () => (
   </nav>
 )
 
+export const LeadingAction: Story = () => {
+  return (
+    <TreeView aria-label="Issues">
+      <TreeView.Item id="item-0">
+        <TreeView.LeadingAction>
+          <IconButton icon={GrabberIcon} aria-label="Reorder item 1" variant="invisible" />
+        </TreeView.LeadingAction>
+        <TreeView.LeadingVisual>
+          <Octicon icon={IssueClosedIcon} sx={{color: 'done.fg'}} />
+        </TreeView.LeadingVisual>
+        Item 1
+      </TreeView.Item>
+      <TreeView.Item id="item-2">
+        <TreeView.LeadingAction>
+          <IconButton icon={GrabberIcon} aria-label="Reorder item 2" variant="invisible" />
+        </TreeView.LeadingAction>
+        <TreeView.LeadingVisual>
+          <Octicon icon={IssueOpenedIcon} sx={{color: 'open.fg'}} />
+        </TreeView.LeadingVisual>
+        Item 2
+        <TreeView.SubTree>
+          <TreeView.Item id="item-2-sub-task-1">
+            <TreeView.LeadingVisual>
+              <Octicon icon={IssueOpenedIcon} sx={{color: 'open.fg'}} />
+            </TreeView.LeadingVisual>
+            sub task 1
+          </TreeView.Item>
+          <TreeView.Item id="item-2-sub-task-2">
+            <TreeView.LeadingVisual>
+              <Octicon icon={IssueOpenedIcon} sx={{color: 'open.fg'}} />
+            </TreeView.LeadingVisual>
+            sub task 2
+          </TreeView.Item>
+        </TreeView.SubTree>
+      </TreeView.Item>
+      <TreeView.Item id="item-3">
+        <TreeView.LeadingAction>
+          <IconButton icon={GrabberIcon} aria-label="Reorder item 3" variant="invisible" />
+        </TreeView.LeadingAction>
+        <TreeView.LeadingVisual>
+          <Octicon icon={IssueOpenedIcon} sx={{color: 'open.fg'}} />
+        </TreeView.LeadingVisual>
+        Item 3
+      </TreeView.Item>
+    </TreeView>
+  )
+}
+
 export default meta

packages/react/src/TreeView/TreeView.tsx

@@ -97,15 +97,20 @@ const UlBox = styled.ul<SxProp>`
         outline-offset: -2;
       }
     }
+    &[data-has-leading-action] {
+      --has-leading-action: 1;
+    }
   }
 
   .PRIVATE_TreeView-item-container {
     --level: 1; /* default level */
     --toggle-width: 1rem; /* 16px */
     position: relative;
     display: grid;
-    grid-template-columns: calc(calc(var(--level) - 1) * (var(--toggle-width) / 2)) var(--toggle-width) 1fr;
-    grid-template-areas: 'spacer toggle content';
+    --leading-action-width: calc(var(--has-leading-action, 0) * 1.5rem);
+    --spacer-width: calc(calc(var(--level) - 1) * (var(--toggle-width) / 2));
+    grid-template-columns: var(--spacer-width) var(--leading-action-width) var(--toggle-width) 1fr;
+    grid-template-areas: 'spacer leadingAction toggle content';
     width: 100%;
     min-height: 2rem; /* 32px */
     font-size: ${get('fontSizes.1')};
@@ -138,7 +143,7 @@ const UlBox = styled.ul<SxProp>`
   }
 
   &[data-omit-spacer='true'] .PRIVATE_TreeView-item-container {
-    grid-template-columns: 0 0 1fr;
+    grid-template-columns: 0 0 0 1fr;
   }
 
   .PRIVATE_TreeView-item[aria-current='true'] > .PRIVATE_TreeView-item-container {
@@ -202,6 +207,12 @@ const UlBox = styled.ul<SxProp>`
     color: ${get('colors.fg.muted')};
   }
 
+  .PRIVATE_TreeView-item-leading-action {
+    display: flex;
+    color: ${get('colors.fg.muted')};
+    grid-area: leadingAction;
+  }
+
   .PRIVATE_TreeView-item-level-line {
     width: 100%;
     height: 100%;
@@ -354,11 +365,16 @@ const Item = React.forwardRef<HTMLElement, TreeViewItemProps>(
     },
     ref,
   ) => {
-    const [slots, rest] = useSlots(children, {leadingVisual: LeadingVisual, trailingVisual: TrailingVisual})
+    const [slots, rest] = useSlots(children, {
+      leadingAction: LeadingAction,
+      leadingVisual: LeadingVisual,
+      trailingVisual: TrailingVisual,
+    })
     const {expandedStateCache} = React.useContext(RootContext)
     const labelId = useId()
     const leadingVisualId = useId()
     const trailingVisualId = useId()
+
     const [isExpanded, setIsExpanded] = useControllableState({
       name: itemId,
       // If the item was previously mounted, it's expanded state might be cached.
@@ -449,6 +465,7 @@ const Item = React.forwardRef<HTMLElement, TreeViewItemProps>(
           aria-expanded={isSubTreeEmpty ? undefined : isExpanded}
           aria-current={isCurrentItem ? 'true' : undefined}
           aria-selected={isFocused ? 'true' : 'false'}
+          data-has-leading-action={slots.leadingAction ? true : undefined}
           onKeyDown={handleKeyDown}
           onFocus={event => {
             // Scroll the first child into view when the item receives focus
@@ -488,6 +505,7 @@ const Item = React.forwardRef<HTMLElement, TreeViewItemProps>(
             <div style={{gridArea: 'spacer', display: 'flex'}}>
               <LevelIndicatorLines level={level} />
             </div>
+            {slots.leadingAction}
             {hasSubTree ? (
               // This lint rule is disabled due to the guidelines in the `TreeView` api docs.
               // https://github.com/github/primer/blob/main/apis/tree-view-api.md#the-expandcollapse-chevron-toggle
@@ -829,6 +847,25 @@ const TrailingVisual: React.FC<TreeViewVisualProps> = props => {
 
 TrailingVisual.displayName = 'TreeView.TrailingVisual'
 
+// ----------------------------------------------------------------------------
+// TreeView.LeadingAction
+
+const LeadingAction: React.FC<TreeViewVisualProps> = props => {
+  const {isExpanded} = React.useContext(ItemContext)
+  const children = typeof props.children === 'function' ? props.children({isExpanded}) : props.children
+  return (
+    <>
+      <div className="PRIVATE_VisuallyHidden" aria-hidden={true}>
+        {props.label}
+      </div>
+      <div className="PRIVATE_TreeView-item-leading-action" aria-hidden={true}>
+        {children}
+      </div>
+    </>
+  )
+}
+
+LeadingAction.displayName = 'TreeView.LeadingAction'
 // ----------------------------------------------------------------------------
 // TreeView.DirectoryIcon
 
@@ -898,6 +935,7 @@ ErrorDialog.displayName = 'TreeView.ErrorDialog'
 export const TreeView = Object.assign(Root, {
   Item,
   SubTree,
+  LeadingAction,
   LeadingVisual,
   TrailingVisual,
   DirectoryIcon,