Merge pull request #560 from yepeng2002/feature/WPFDropdownCell

Add WPF Dropdown Window Control Class for Cells

Author: jingwood

DemoWPF/MainWindow.xaml.cs

@@ -1,7 +1,10 @@
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
+using System.Linq;
 using System.Windows;
+using System.Windows.Controls;
 using System.Windows.Media;
 using System.Windows.Shapes;
 using unvell.ReoGrid.CellTypes;
@@ -279,16 +282,196 @@ private void AddDemoSheet3()
 
 			// information cell
 			worksheet.SetRangeBorders(19, 0, 1, 10, BorderPositions.Top, RangeBorderStyle.GraySolid);
-		}
+
+      // dropdown cell
+      worksheet["B18"] = "Dropdown ListView:";
+      worksheet["D18"] = "Choose...";
+      worksheet["D18"] = new ListViewDropdownCell();
+      worksheet.Ranges["D18"].BorderOutside = RangeBorderStyle.GraySolid;
+    }
 
 		private void ShowText(Worksheet sheet, string text)
 		{
 			sheet[19, 0] = text;
 		}
-		#endregion // Demo Sheet 3 : Built-in Cell Types
 
-		#region Menu - File
-		private void File_New_Click(object sender, RoutedEventArgs e)
+
+    class ListViewDropdownCell : DropdownCell
+    {
+      private readonly ListView listView;
+
+      public ListViewDropdownCell()
+      {
+        listView = new ListView
+        {
+          BorderThickness = new Thickness(0),
+          SelectionMode = SelectionMode.Single,
+          View = new GridView()
+        };
+
+        this.DropdownControl = listView;
+
+        var gridView = (GridView)listView.View;
+        gridView.Columns.Add(new GridViewColumn
+        {
+          Header = "Name",
+          Width = 120,
+          DisplayMemberBinding = new System.Windows.Data.Binding(nameof(ListViewItemData.Text))
+        });
+        gridView.Columns.Add(new GridViewColumn
+        {
+          Header = "Description",
+          Width = 120,
+          DisplayMemberBinding = new System.Windows.Data.Binding(nameof(ListViewItemData.SubText))
+        });
+
+        // Create data items
+        var items = new List<ListViewItemData>
+        {
+            new ListViewItemData { Group = "A", Text = "Apple", SubText = "Red fruit" },
+            new ListViewItemData { Group = "A", Text = "Banana", SubText = "Yellow fruit" },
+            new ListViewItemData { Group = "B", Text = "Watermelon", SubText = "Green fruit" },
+            new ListViewItemData { Group = "B", Text = "Grape", SubText = "Purple fruit" }
+        };
+
+        listView.ItemsSource = items;
+        this.MinimumDropdownWidth = 300;
+
+        listView.PreviewMouseDoubleClick += ListView_MouseDoubleClick;
+        listView.PreviewKeyDown += ListView_PreviewKeyDown;
+      }
+
+      private void ListView_MouseDoubleClick(object sender, System.Windows.Input.MouseButtonEventArgs e)
+      {
+        var listView = sender as ListView;
+        var depObj = e.OriginalSource as DependencyObject;
+        while (depObj != null && !(depObj is ListViewItem))
+          depObj = VisualTreeHelper.GetParent(depObj);
+
+        if (depObj is ListViewItem listViewItem)
+        {
+          listView.SelectedItem = listView.ItemContainerGenerator.ItemFromContainer(listViewItem);
+        }
+
+        CommitSelection();
+      }
+
+      private void ListView_PreviewKeyDown(object sender, System.Windows.Input.KeyEventArgs e)
+      {
+        var listView = sender as ListView;
+
+        if (e.Key == System.Windows.Input.Key.Enter)
+        {
+          CommitSelection();
+          e.Handled = true;
+        }
+        else if (e.Key == System.Windows.Input.Key.Escape)
+        {
+          PullUp();
+          e.Handled = true;
+        }
+        else if (e.Key == System.Windows.Input.Key.Up || e.Key == System.Windows.Input.Key.Down)
+        {
+          // Handle up/down key selection 
+          int currentIndex = listView.SelectedIndex;
+          int itemCount = listView.Items.Count;
+
+          if (itemCount > 0)
+          {
+            if (e.Key == System.Windows.Input.Key.Up)
+            {
+              // Up key: select previous item
+              if (currentIndex > 0)
+              {
+                listView.SelectedIndex = currentIndex - 1;
+                var item = listView.ItemContainerGenerator.ContainerFromIndex(currentIndex - 1) as ListViewItem;
+                item?.Focus();
+              }
+              else
+              {
+                // If on first item, cycle to last item 
+                listView.SelectedIndex = itemCount - 1;
+                var item = listView.ItemContainerGenerator.ContainerFromIndex(itemCount - 1) as ListViewItem;
+                item?.Focus();
+              }
+            }
+            else if (e.Key == System.Windows.Input.Key.Down)
+            {
+              // Down key: select next item 
+              if (currentIndex < itemCount - 1)
+              {
+                listView.SelectedIndex = currentIndex + 1;
+                var item = listView.ItemContainerGenerator.ContainerFromIndex(currentIndex + 1) as ListViewItem;
+                item?.Focus();
+              }
+              else
+              {
+                // If on last item, cycle to first item
+                listView.SelectedIndex = 0;
+                var item = listView.ItemContainerGenerator.ContainerFromIndex(0) as ListViewItem;
+                item?.Focus();
+              }
+            }
+
+            // Ensure selected item is visible
+            if (listView.SelectedItem != null)
+            {
+              listView.ScrollIntoView(listView.SelectedItem);
+            }
+
+            e.Handled = true;
+          }
+        }
+        else if (e.Key == System.Windows.Input.Key.Tab)
+        {
+          // Handle Tab key 
+          CommitSelection();
+          e.Handled = true;
+        }
+      }
+
+      protected override void OnDropdownControlLostFocus()
+      {
+        PullUp();
+      }
+
+      public override void PushDown()
+      {
+        base.PushDown();
+
+        // When dropdown panel opens, automatically select the item matching current cell content
+        if (this.Cell?.Data is string text && listView.ItemsSource is IEnumerable<ListViewItemData> items)
+        {
+          var itemToSelect = items.FirstOrDefault(i => i.Text == text);
+          if (itemToSelect != null)
+          {
+            listView.SelectedItem = itemToSelect;
+            listView.ScrollIntoView(itemToSelect);
+          }
+        }
+      }
+
+      private void CommitSelection()
+      {
+        if (listView.SelectedItem is ListViewItemData selectedItem)
+        {
+          this.Cell.Data = selectedItem.Text;
+          PullUp();
+        }
+      }
+
+      // Data item class
+      private class ListViewItemData
+      {
+        public string Group { get; set; }
+        public string Text { get; set; }
+        public string SubText { get; set; }
+      }
+    }
+    #endregion // Demo Sheet 3 : Built-in Cell Types
+
+    #region Menu - File
+    private void File_New_Click(object sender, RoutedEventArgs e)
 		{
 			grid.Reset();
 		}