Handle touch scrolling in DataGrid

src/Avalonia.Controls.DataGrid/DataGridCell.cs

@@ -173,7 +173,7 @@ namespace Avalonia.Controls
                     }
                     if (OwningRow != null)
                     {
-                        e.Handled = OwningGrid.UpdateStateOnMouseLeftButtonDown(e, ColumnIndex, OwningRow.Slot, !e.Handled);
+                        OwningGrid.UpdateStateOnMouseLeftButtonDown(e, ColumnIndex, OwningRow.Slot, !e.Handled);
                         OwningGrid.UpdatedStateOnMouseLeftButtonDown = true;
                     }
                 }

src/Avalonia.Controls.DataGrid/Primitives/DataGridRowsPresenter.cs

@@ -5,6 +5,9 @@
 
 using System;
 using System.Diagnostics;
+
+using Avalonia.Input;
+using Avalonia.Input.GestureRecognizers;
 using Avalonia.Layout;
 using Avalonia.Media;
 
@@ -16,6 +19,11 @@ namespace Avalonia.Controls.Primitives
     /// </summary>
     public sealed class DataGridRowsPresenter : Panel
     {
+        public DataGridRowsPresenter()
+        {
+            AddHandler(Gestures.ScrollGestureEvent, OnScrollGesture);
+        }
+
         internal DataGrid OwningGrid
         {
             get;
@@ -176,6 +184,11 @@ namespace Avalonia.Controls.Primitives
             return new Size(totalCellsWidth + headerWidth, totalHeight);
         }
 
+        private void OnScrollGesture(object sender, ScrollGestureEventArgs e)
+        {
+            e.Handled = e.Handled || OwningGrid.UpdateScroll(-e.Delta);
+        }
+
 #if DEBUG
         internal void PrintChildren()
         {

src/Avalonia.Controls.DataGrid/Themes/Default.xaml

@@ -247,7 +247,11 @@
             <DataGridColumnHeader Name="PART_TopRightCornerHeader" Grid.Column="2"/>
             <Rectangle Name="PART_ColumnHeadersAndRowsSeparator" Grid.ColumnSpan="3" VerticalAlignment="Bottom" StrokeThickness="1" Height="1" Fill="{DynamicResource ThemeControlMidHighBrush}"/>
 
-            <DataGridRowsPresenter Name="PART_RowsPresenter" Grid.ColumnSpan="2" Grid.Row="1" />
+            <DataGridRowsPresenter Name="PART_RowsPresenter" Grid.ColumnSpan="2" Grid.Row="1">
+              <DataGridRowsPresenter.GestureRecognizers>
+                <ScrollGestureRecognizer CanHorizontallyScroll="True" CanVerticallyScroll="True" />
+              </DataGridRowsPresenter.GestureRecognizers>
+            </DataGridRowsPresenter>
             <Rectangle Name="PART_BottomRightCorner" Fill="{DynamicResource ThemeControlMidHighBrush}" Grid.Column="2" Grid.Row="2" />
             <Rectangle Name="BottomLeftCorner" Fill="{DynamicResource ThemeControlMidHighBrush}" Grid.Row="2" Grid.ColumnSpan="2" />
             <ScrollBar Name="PART_VerticalScrollbar" Orientation="Vertical" Grid.Column="2" Grid.Row="1" Width="{DynamicResource ScrollBarThickness}"/>

src/Avalonia.Controls.DataGrid/Themes/Fluent.xaml

@@ -601,7 +601,11 @@
             <DataGridRowsPresenter Name="PART_RowsPresenter"
                                    Grid.Row="1"
                                    Grid.RowSpan="2"
-                                   Grid.ColumnSpan="3" />
+                                   Grid.ColumnSpan="3">
+              <DataGridRowsPresenter.GestureRecognizers>
+                <ScrollGestureRecognizer CanHorizontallyScroll="True" CanVerticallyScroll="True" />
+              </DataGridRowsPresenter.GestureRecognizers>
+            </DataGridRowsPresenter>
             <Rectangle Name="PART_BottomRightCorner"
                        Fill="{DynamicResource DataGridScrollBarsSeparatorBackground}"
                        Grid.Column="2"