docs: explain how to implement Grid range selection

articles/components/grid/selection.adoc

@@ -68,11 +68,40 @@ include::{root}/frontend/demo/component/grid/react/grid-multi-select-mode.tsx[re
 endif::[]
 --
 
-In addition to selecting rows individually, a range of rows can be selected by dragging from one selection checkbox to another, if enabled:
+=== Range Selection
+
+In addition to selecting rows individually, you may want to enable users to select or deselect a range of rows using kbd:[Shift] + Click. Since there is a variety of possible behaviors for range selection, Grid provides the necessary event, `item-toggle`, to create your own implementation. This event provides information about the toggled row, its selection state, and whether the user was holding kbd:[Shift] during the toggle.
+
+The example below demonstrates a possible implementation of range selection using that event. In this implementation, the first clicked row is stored as an anchor point. When the user holds kbd:[Shift] and clicks another row, the selection state of all rows between the anchor and the newly clicked row is updated to match the clicked row's state. The clicked row then becomes the new anchor point for future selections.
 
 [.example]
 --
+ifdef::lit[]
+[source,typescript]
+----
+include::{root}/frontend/demo/component/grid/grid-range-selection.ts[render,tags=snippet,indent=0,group=Lit]
+----
+endif::[]
+
+ifdef::flow[]
+[source,java]
+----
+include::{root}/src/main/java/com/vaadin/demo/component/grid/GridRangeSelection.java[render,tags=snippet,indent=0,group=Flow]
+----
+endif::[]
 
+ifdef::react[]
+[source,tsx]
+----
+include::{root}/frontend/demo/component/grid/react/grid-range-selection.tsx[render,tags=snippet,indent=0,group=React]
+----
+endif::[]
+--
+
+A range of rows can also be selected by dragging from one selection checkbox to another, if enabled:
+
+[.example]
+--
 [source,typescript]
 ----
 <source-info group="Lit"></source-info>
@@ -97,9 +126,9 @@ selectionModel.setDragSelect(true);
   ...
 </Grid>
 ----
-
 --
 
+
 == Selection Modes in Flow
 
 Each selection mode is represented by a [classname]`GridSelectionModel`, accessible through the [methodname]`getSelectionModel()` method, which can be cast that to the specific selection model type, [classname]`SingleSelectionModel` or [classname]`MultiSelectionModel`. These interfaces provide selection mode specific APIs for configuration and selection events.

frontend/demo/component/grid/grid-range-selection.ts

@@ -0,0 +1,80 @@
+import 'Frontend/demo/init'; // hidden-source-line
+import '@vaadin/grid';
+import '@vaadin/grid/vaadin-grid-selection-column.js';
+import { html, LitElement } from 'lit';
+import { customElement, state } from 'lit/decorators.js';
+import type { GridItemToggleEvent } from '@vaadin/grid';
+import { getPeople } from 'Frontend/demo/domain/DataService';
+import type Person from 'Frontend/generated/com/vaadin/demo/domain/Person';
+import { applyTheme } from 'Frontend/generated/theme';
+
+// tag::snippet[]
+@customElement('grid-range-selection')
+export class Example extends LitElement {
+  protected override createRenderRoot() {
+    const root = super.createRenderRoot();
+    // Apply custom theme (only supported if your app uses one)
+    applyTheme(root);
+    return root;
+  }
+
+  @state()
+  private items: Person[] = [];
+
+  @state()
+  private selectedItems: Person[] = [];
+
+  private rangeStartItem?: Person;
+
+  protected override async firstUpdated() {
+    const { people } = await getPeople();
+    this.items = people;
+  }
+
+  handleItemToggle(event: GridItemToggleEvent<Person>) {
+    const { item, selected, shiftKey } = event.detail;
+
+    // If the anchor point isn't set, set it to the current item
+    this.rangeStartItem ??= item;
+
+    if (shiftKey) {
+      // Calculcate the range of items between the anchor point and
+      // the current item
+      const [rangeStart, rangeEnd] = [this.rangeStartItem, item]
+        .map((i) => this.items.indexOf(i))
+        .sort((a, b) => a - b);
+      const rangeItems = this.items.slice(rangeStart, rangeEnd + 1);
+
+      // Update the selection state of items within the range
+      // based on the state of the current item
+      const newSelectedItems = new Set(this.selectedItems);
+      rangeItems.forEach((rangeItem) => {
+        if (selected) {
+          newSelectedItems.add(rangeItem);
+        } else {
+          newSelectedItems.delete(rangeItem);
+        }
+      });
+      this.selectedItems = [...newSelectedItems];
+    }
+
+    // Update the anchor point to the current item
+    this.rangeStartItem = item;
+  }
+
+  protected override render() {
+    return html`
+      <vaadin-grid
+        .items="${this.items}"
+        .selectedItems="${this.selectedItems}"
+        @item-toggle="${this.handleItemToggle}"
+      >
+        <vaadin-grid-selection-column></vaadin-grid-selection-column>
+        <vaadin-grid-column path="firstName"></vaadin-grid-column>
+        <vaadin-grid-column path="lastName"></vaadin-grid-column>
+        <vaadin-grid-column path="email"></vaadin-grid-column>
+      </vaadin-grid>
+    `;
+  }
+}
+// end::snippet[]

frontend/demo/component/grid/react/grid-range-selection.tsx

@@ -0,0 +1,66 @@
+import { reactExample } from 'Frontend/demo/react-example'; // hidden-source-line
+import React, { useCallback, useEffect, useRef } from 'react';
+import { useSignals } from '@preact/signals-react/runtime'; // hidden-source-line
+import { useSignal } from '@vaadin/hilla-react-signals';
+import { Grid, GridItemToggleEvent } from '@vaadin/react-components/Grid.js';
+import { GridColumn } from '@vaadin/react-components/GridColumn.js';
+import { GridSelectionColumn } from '@vaadin/react-components/GridSelectionColumn.js';
+import { getPeople } from 'Frontend/demo/domain/DataService';
+import type Person from 'Frontend/generated/com/vaadin/demo/domain/Person';
+
+function Example() {
+  useSignals(); // hidden-source-line
+  const items = useSignal<Person[]>([]);
+  const selectedItems = useSignal<Person[]>([]);
+  const rangeStartItem = useRef<Person>();
+
+  useEffect(() => {
+    getPeople().then(({ people }) => {
+      items.value = people;
+    });
+  }, []);
+
+  const handleItemToggle = (event: GridItemToggleEvent<Person>) => {
+    const { item, selected, shiftKey } = event.detail;
+
+    // If the anchor point isn't set, set it to the current item
+    rangeStartItem.current ??= item;
+
+    if (shiftKey) {
+      // Calculcate the range of items between the anchor point and
+      // the current item
+      const [rangeStart, rangeEnd] = [rangeStartItem.current, item]
+        .map((i) => items.value.indexOf(i))
+        .sort((a, b) => a - b);
+      const rangeItems = items.value.slice(rangeStart, rangeEnd + 1);
+
+      // Update the selection state of items within the range
+      // based on the state of the current item
+      const newSelectedItems = new Set(selectedItems.value);
+      rangeItems.forEach((rangeItem) => {
+        if (selected) {
+          newSelectedItems.add(rangeItem);
+        } else {
+          newSelectedItems.delete(rangeItem);
+        }
+      });
+      selectedItems.value = [...newSelectedItems];
+    }
+
+    // Update the anchor point to the current item
+    rangeStartItem.current = item;
+  };
+
+  return (
+    // tag::snippet[]
+    <Grid items={items.value} selectedItems={selectedItems.value} onItemToggle={handleItemToggle}>
+      <GridSelectionColumn />
+      <GridColumn path="firstName" />
+      <GridColumn path="lastName" />
+      <GridColumn path="email" />
+    </Grid>
+    // end::snippet[]
+  );
+}
+
+export default reactExample(Example); // hidden-source-line

src/main/java/com/vaadin/demo/component/grid/GridRangeSelection.java

@@ -0,0 +1,74 @@
+package com.vaadin.demo.component.grid;
+
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import com.vaadin.demo.domain.Person;
+import com.vaadin.flow.component.grid.Grid;
+import com.vaadin.flow.component.grid.GridMultiSelectionModel;
+import com.vaadin.flow.component.grid.dataview.GridListDataView;
+import com.vaadin.flow.component.html.Div;
+import com.vaadin.flow.router.Route;
+import com.vaadin.demo.DemoExporter; // hidden-source-line
+import com.vaadin.demo.domain.DataService;
+
+@Route("grid-range-selection")
+public class GridRangeSelection extends Div {
+
+    private Person rangeStartItem;
+
+    public GridRangeSelection() {
+        // tag::snippet[]
+        Grid<Person> grid = new Grid<>(Person.class, false);
+        grid.setSelectionMode(Grid.SelectionMode.MULTI);
+        grid.addColumn(Person::getFirstName).setHeader("First name");
+        grid.addColumn(Person::getLastName).setHeader("Last name");
+        grid.addColumn(Person::getEmail).setHeader("Email");
+
+        List<Person> people = DataService.getPeople();
+        grid.setItems(people);
+
+        ((GridMultiSelectionModel<Person>) grid.getSelectionModel())
+                .addClientItemToggleListener(event -> {
+                    Person item = event.getItem();
+
+                    // If the anchor point isn't set, set it to the current item
+                    if (rangeStartItem == null) {
+                        rangeStartItem = item;
+                    }
+
+                    if (event.isShiftKey()) {
+                        // Calculcate the range of items between the anchor
+                        // point and the current item
+                        GridListDataView<Person> dataView = grid
+                                .getListDataView();
+                        int rangeStart = dataView.getItemIndex(rangeStartItem)
+                                .get();
+                        int rangeEnd = dataView.getItemIndex(item).get();
+                        Set<Person> rangeItems = dataView.getItems()
+                                .skip(Math.min(rangeStart, rangeEnd))
+                                .limit(Math.abs(rangeStart - rangeEnd) + 1)
+                                .collect(Collectors.toSet());
+
+                        // Update the selection state of items within the range
+                        // based on the state of the current item
+                        if (event.isSelected()) {
+                            grid.asMultiSelect().select(rangeItems);
+                        } else {
+                            grid.asMultiSelect().deselect(rangeItems);
+                        }
+                    }
+
+                    // Update the anchor point to the current item
+                    rangeStartItem = item;
+                });
+        // end::snippet[]
+
+        add(grid);
+    }
+
+    public static class Exporter // hidden-source-line
+            extends DemoExporter<GridRangeSelection> { // hidden-source-line
+    } // hidden-source-line
+}