[docs] Improve Tree View selection doc

docs/data/tree-view/accessibility/accessibility.md

@@ -61,6 +61,11 @@ When a single-select tree receives focus:
 - If none of the items are selected when the tree receives focus, focus is set on the first item.
 - If an item is selected before the tree receives focus, focus is set on the selected item.
 
+|                         Keys | Description                                                  |
+| ---------------------------: | :----------------------------------------------------------- |
+| <kbd class="key">Space</kbd> | Selects the focused item.                                    |
+| <kbd class="key">Enter</kbd> | Selects the focused item if the item does not have children. |
+
 ### On multi-select trees
 
 When a multi-select tree receives focus:

docs/data/tree-view/rich-tree-view/selection/ParentChildrenSelectionRelationship.js

@@ -0,0 +1,99 @@
+import * as React from 'react';
+import Box from '@mui/material/Box';
+import { RichTreeView } from '@mui/x-tree-view/RichTreeView';
+
+import { useTreeViewApiRef } from '@mui/x-tree-view/hooks';
+
+const MUI_X_PRODUCTS = [
+  {
+    id: 'grid',
+    label: 'Data Grid',
+    children: [
+      { id: 'grid-community', label: '@mui/x-data-grid' },
+      { id: 'grid-pro', label: '@mui/x-data-grid-pro' },
+      { id: 'grid-premium', label: '@mui/x-data-grid-premium' },
+    ],
+  },
+  {
+    id: 'pickers',
+    label: 'Date and Time Pickers',
+    children: [
+      { id: 'pickers-community', label: '@mui/x-date-pickers' },
+      { id: 'pickers-pro', label: '@mui/x-date-pickers-pro' },
+    ],
+  },
+  {
+    id: 'charts',
+    label: 'Charts',
+    children: [{ id: 'charts-community', label: '@mui/x-charts' }],
+  },
+  {
+    id: 'tree-view',
+    label: 'Tree View',
+    children: [{ id: 'tree-view-community', label: '@mui/x-tree-view' }],
+  },
+];
+
+function getItemDescendantsIds(item) {
+  const ids = [];
+  item.children?.forEach((child) => {
+    ids.push(child.id);
+    ids.push(...getItemDescendantsIds(child));
+  });
+
+  return ids;
+}
+
+export default function ParentChildrenSelectionRelationship() {
+  const [selectedItems, setSelectedItems] = React.useState([]);
+  const toggledItemRef = React.useRef({});
+  const apiRef = useTreeViewApiRef();
+
+  const handleItemSelectionToggle = (event, itemId, isSelected) => {
+    toggledItemRef.current[itemId] = isSelected;
+  };
+
+  const handleSelectedItemsChange = (event, newSelectedItems) => {
+    setSelectedItems(newSelectedItems);
+
+    // Select / unselect the children of the toggled item
+    const itemsToSelect = [];
+    const itemsToUnSelect = {};
+    Object.entries(toggledItemRef.current).forEach(([itemId, isSelected]) => {
+      const item = apiRef.current.getItem(itemId);
+      if (isSelected) {
+        itemsToSelect.push(...getItemDescendantsIds(item));
+      } else {
+        getItemDescendantsIds(item).forEach((descendantId) => {
+          itemsToUnSelect[descendantId] = true;
+        });
+      }
+    });
+
+    const newSelectedItemsWithChildren = Array.from(
+      new Set(
+        [...newSelectedItems, ...itemsToSelect].filter(
+          (itemId) => !itemsToUnSelect[itemId],
+        ),
+      ),
+    );
+
+    setSelectedItems(newSelectedItemsWithChildren);
+
+    toggledItemRef.current = {};
+  };
+
+  return (
+    <Box sx={{ height: 264, flexGrow: 1, maxWidth: 400 }}>
+      <RichTreeView
+        multiSelect
+        checkboxSelection
+        apiRef={apiRef}
+        items={MUI_X_PRODUCTS}
+        selectedItems={selectedItems}
+        onSelectedItemsChange={handleSelectedItemsChange}
+        onItemSelectionToggle={handleItemSelectionToggle}
+      />
+    </Box>
+  );
+}

docs/data/tree-view/rich-tree-view/selection/ParentChildrenSelectionRelationship.tsx

@@ -0,0 +1,106 @@
+import * as React from 'react';
+import Box from '@mui/material/Box';
+import { RichTreeView } from '@mui/x-tree-view/RichTreeView';
+import { TreeViewBaseItem } from '@mui/x-tree-view/models';
+import { useTreeViewApiRef } from '@mui/x-tree-view/hooks';
+
+const MUI_X_PRODUCTS: TreeViewBaseItem[] = [
+  {
+    id: 'grid',
+    label: 'Data Grid',
+    children: [
+      { id: 'grid-community', label: '@mui/x-data-grid' },
+      { id: 'grid-pro', label: '@mui/x-data-grid-pro' },
+      { id: 'grid-premium', label: '@mui/x-data-grid-premium' },
+    ],
+  },
+  {
+    id: 'pickers',
+    label: 'Date and Time Pickers',
+    children: [
+      { id: 'pickers-community', label: '@mui/x-date-pickers' },
+      { id: 'pickers-pro', label: '@mui/x-date-pickers-pro' },
+    ],
+  },
+  {
+    id: 'charts',
+    label: 'Charts',
+    children: [{ id: 'charts-community', label: '@mui/x-charts' }],
+  },
+  {
+    id: 'tree-view',
+    label: 'Tree View',
+    children: [{ id: 'tree-view-community', label: '@mui/x-tree-view' }],
+  },
+];
+
+function getItemDescendantsIds(item: TreeViewBaseItem) {
+  const ids: string[] = [];
+  item.children?.forEach((child) => {
+    ids.push(child.id);
+    ids.push(...getItemDescendantsIds(child));
+  });
+
+  return ids;
+}
+
+export default function ParentChildrenSelectionRelationship() {
+  const [selectedItems, setSelectedItems] = React.useState<string[]>([]);
+  const toggledItemRef = React.useRef<{ [itemId: string]: boolean }>({});
+  const apiRef = useTreeViewApiRef();
+
+  const handleItemSelectionToggle = (
+    event: React.SyntheticEvent,
+    itemId: string,
+    isSelected: boolean,
+  ) => {
+    toggledItemRef.current[itemId] = isSelected;
+  };
+
+  const handleSelectedItemsChange = (
+    event: React.SyntheticEvent,
+    newSelectedItems: string[],
+  ) => {
+    setSelectedItems(newSelectedItems);
+
+    // Select / unselect the children of the toggled item
+    const itemsToSelect: string[] = [];
+    const itemsToUnSelect: { [itemId: string]: boolean } = {};
+    Object.entries(toggledItemRef.current).forEach(([itemId, isSelected]) => {
+      const item = apiRef.current!.getItem(itemId);
+      if (isSelected) {
+        itemsToSelect.push(...getItemDescendantsIds(item));
+      } else {
+        getItemDescendantsIds(item).forEach((descendantId) => {
+          itemsToUnSelect[descendantId] = true;
+        });
+      }
+    });
+
+    const newSelectedItemsWithChildren = Array.from(
+      new Set(
+        [...newSelectedItems, ...itemsToSelect].filter(
+          (itemId) => !itemsToUnSelect[itemId],
+        ),
+      ),
+    );
+
+    setSelectedItems(newSelectedItemsWithChildren);
+
+    toggledItemRef.current = {};
+  };
+
+  return (
+    <Box sx={{ height: 264, flexGrow: 1, maxWidth: 400 }}>
+      <RichTreeView
+        multiSelect
+        checkboxSelection
+        apiRef={apiRef}
+        items={MUI_X_PRODUCTS}
+        selectedItems={selectedItems}
+        onSelectedItemsChange={handleSelectedItemsChange}
+        onItemSelectionToggle={handleItemSelectionToggle}
+      />
+    </Box>
+  );
+}

docs/data/tree-view/rich-tree-view/selection/ParentChildrenSelectionRelationship.tsx.preview

@@ -0,0 +1,9 @@
+<RichTreeView
+  multiSelect
+  checkboxSelection
+  apiRef={apiRef}
+  items={MUI_X_PRODUCTS}
+  selectedItems={selectedItems}
+  onSelectedItemsChange={handleSelectedItemsChange}
+  onItemSelectionToggle={handleItemSelectionToggle}
+/>

docs/data/tree-view/rich-tree-view/selection/SingleSelectTreeView.js

@@ -0,0 +1,41 @@
+import * as React from 'react';
+import Box from '@mui/material/Box';
+import { RichTreeView } from '@mui/x-tree-view/RichTreeView';
+
+const MUI_X_PRODUCTS = [
+  {
+    id: 'grid',
+    label: 'Data Grid',
+    children: [
+      { id: 'grid-community', label: '@mui/x-data-grid' },
+      { id: 'grid-pro', label: '@mui/x-data-grid-pro' },
+      { id: 'grid-premium', label: '@mui/x-data-grid-premium' },
+    ],
+  },
+  {
+    id: 'pickers',
+    label: 'Date and Time Pickers',
+    children: [
+      { id: 'pickers-community', label: '@mui/x-date-pickers' },
+      { id: 'pickers-pro', label: '@mui/x-date-pickers-pro' },
+    ],
+  },
+  {
+    id: 'charts',
+    label: 'Charts',
+    children: [{ id: 'charts-community', label: '@mui/x-charts' }],
+  },
+  {
+    id: 'tree-view',
+    label: 'Tree View',
+    children: [{ id: 'tree-view-community', label: '@mui/x-tree-view' }],
+  },
+];
+
+export default function SingleSelectTreeView() {
+  return (
+    <Box sx={{ minHeight: 200, flexGrow: 1, maxWidth: 400 }}>
+      <RichTreeView items={MUI_X_PRODUCTS} />
+    </Box>
+  );
+}

docs/data/tree-view/rich-tree-view/selection/SingleSelectTreeView.tsx

@@ -0,0 +1,42 @@
+import * as React from 'react';
+import Box from '@mui/material/Box';
+import { RichTreeView } from '@mui/x-tree-view/RichTreeView';
+import { TreeViewBaseItem } from '@mui/x-tree-view/models';
+
+const MUI_X_PRODUCTS: TreeViewBaseItem[] = [
+  {
+    id: 'grid',
+    label: 'Data Grid',
+    children: [
+      { id: 'grid-community', label: '@mui/x-data-grid' },
+      { id: 'grid-pro', label: '@mui/x-data-grid-pro' },
+      { id: 'grid-premium', label: '@mui/x-data-grid-premium' },
+    ],
+  },
+  {
+    id: 'pickers',
+    label: 'Date and Time Pickers',
+    children: [
+      { id: 'pickers-community', label: '@mui/x-date-pickers' },
+      { id: 'pickers-pro', label: '@mui/x-date-pickers-pro' },
+    ],
+  },
+  {
+    id: 'charts',
+    label: 'Charts',
+    children: [{ id: 'charts-community', label: '@mui/x-charts' }],
+  },
+  {
+    id: 'tree-view',
+    label: 'Tree View',
+    children: [{ id: 'tree-view-community', label: '@mui/x-tree-view' }],
+  },
+];
+
+export default function SingleSelectTreeView() {
+  return (
+    <Box sx={{ minHeight: 200, flexGrow: 1, maxWidth: 400 }}>
+      <RichTreeView items={MUI_X_PRODUCTS} />
+    </Box>
+  );
+}

docs/data/tree-view/rich-tree-view/selection/SingleSelectTreeView.tsx.preview

@@ -0,0 +1 @@
+<RichTreeView items={MUI_X_PRODUCTS} />

docs/data/tree-view/rich-tree-view/selection/selection.md

@@ -11,12 +11,32 @@ waiAria: https://www.w3.org/WAI/ARIA/apg/patterns/treeview/
 
 <p class="description">Handle how users can select items.</p>
 
+## Single selection
+
+By default, the Tree View allows selecting a single item.
+
+{{"demo": "SingleSelectTreeView.js"}}
+
+:::success
+When the Tree View uses single selection, you can select an item by clicking it,
+or using the [keyboard shortcuts](/x/react-tree-view/accessibility/#on-single-select-trees).
+:::
+
 ## Multi selection
 
-The Tree View also supports multi-selection:
+Use the `multiSelect` prop to enable multi-selection.
 
 {{"demo": "MultiSelectTreeView.js"}}
 
+:::success
+When the Tree View uses multi selection, you can select multiple items using the mouse in two ways:
+
+- To select multiple independent items, hold <kbd class="key">Ctrl</kbd> (or <kbd class="key">⌘ Command</kbd> on macOS) and click the items.
+- To select a range of items, click on the first item of the range, then hold the <kbd class="key">Shift</kbd> key while clicking on the last item of the range.
+
+You can also use the [keyboard shortcuts](/x/react-tree-view/accessibility/#on-multi-select-trees) to select items.
+:::
+
 ## Disable selection
 
 Use the `disableSelection` prop if you don't want your items to be selectable:
@@ -54,3 +74,23 @@ Learn more about the _Controlled and uncontrolled_ pattern in the [React documen
 Use the `onItemSelectionToggle` prop if you want to react to an item selection change:
 
 {{"demo": "TrackItemSelectionToggle.js"}}
+
+## Parent / children selection relationship
+
+Automatically select an item when all of its children are selected and automatically select all children when the parent is selected.
+
+:::warning
+This feature isn't implemented yet. It's coming.
+
+👍 Upvote [issue #12883](https://github.com/mui/mui-x/issues/4821) if you want to see it land faster.
+
+Don't hesitate to leave a comment on the same issue to influence what gets built.
+Especially if you already have a use case for this component,
+or if you are facing a pain point with your current solution.
+:::
+
+If you cannot wait for the official implementation,
+you can create your own custom solution using the `selectedItems`,
+`onSelectedItemsChange` and `onItemSelectionToggle` props:
+
+{{"demo": "ParentChildrenSelectionRelationship.js"}}