Add TemplatePart attributes for DataGrid controls

src/Avalonia.Controls.DataGrid/DataGrid.cs

@@ -32,6 +32,14 @@ namespace Avalonia.Controls
     /// <summary>
     /// Displays data in a customizable grid.
     /// </summary>
+    [TemplatePart(DATAGRID_elementBottomRightCornerHeaderName,     typeof(IVisual))]
+    [TemplatePart(DATAGRID_elementColumnHeadersPresenterName,      typeof(DataGridColumnHeadersPresenter))]
+    [TemplatePart(DATAGRID_elementFrozenColumnScrollBarSpacerName, typeof(Control))]
+    [TemplatePart(DATAGRID_elementHorizontalScrollbarName,         typeof(ScrollBar))]
+    [TemplatePart(DATAGRID_elementRowsPresenterName,               typeof(DataGridRowsPresenter))]
+    [TemplatePart(DATAGRID_elementTopLeftCornerHeaderName,         typeof(ContentControl))]
+    [TemplatePart(DATAGRID_elementTopRightCornerHeaderName,        typeof(ContentControl))]
+    [TemplatePart(DATAGRID_elementVerticalScrollbarName,           typeof(ScrollBar))]
     [PseudoClasses(":invalid", ":empty-rows", ":empty-columns")]
     public partial class DataGrid : TemplatedControl
     {

src/Avalonia.Controls.DataGrid/DataGridCell.cs

@@ -13,6 +13,7 @@ namespace Avalonia.Controls
     /// <summary>
     /// Represents an individual <see cref="T:Avalonia.Controls.DataGrid" /> cell.
     /// </summary>
+    [TemplatePart(DATAGRIDCELL_elementRightGridLine, typeof(Rectangle))]
     [PseudoClasses(":selected", ":current", ":edited", ":invalid")]
     public class DataGridCell : ContentControl
     {

src/Avalonia.Controls.DataGrid/DataGridRow.cs

@@ -21,6 +21,11 @@ namespace Avalonia.Controls
     /// <summary>
     /// Represents a <see cref="T:Avalonia.Controls.DataGrid" /> row.
     /// </summary>
+    [TemplatePart(DATAGRIDROW_elementBottomGridLine, typeof(Rectangle))]
+    [TemplatePart(DATAGRIDROW_elementCells,          typeof(DataGridCellsPresenter))]
+    [TemplatePart(DATAGRIDROW_elementDetails,        typeof(DataGridDetailsPresenter))]
+    [TemplatePart(DATAGRIDROW_elementRoot,           typeof(Panel))]
+    [TemplatePart(DATAGRIDROW_elementRowHeader,      typeof(DataGridRowHeader))]
     [PseudoClasses(":selected", ":editing", ":invalid")]
     public class DataGridRow : TemplatedControl
     {

src/Avalonia.Controls.DataGrid/DataGridRowGroupHeader.cs

@@ -14,6 +14,12 @@ using System.Reactive.Linq;
 
 namespace Avalonia.Controls
 {
+    [TemplatePart(DATAGRIDROWGROUPHEADER_expanderButton,      typeof(ToggleButton))]
+    [TemplatePart(DATAGRIDROWGROUPHEADER_indentSpacer,        typeof(Control))]
+    [TemplatePart(DATAGRIDROWGROUPHEADER_itemCountElement,    typeof(TextBlock))]
+    [TemplatePart(DATAGRIDROWGROUPHEADER_propertyNameElement, typeof(TextBlock))]
+    [TemplatePart(DataGridRow.DATAGRIDROW_elementRoot,        typeof(Panel))]
+    [TemplatePart(DataGridRow.DATAGRIDROW_elementRowHeader,   typeof(DataGridRowHeader))]
     [PseudoClasses(":pressed", ":current", ":expanded")]
     public class DataGridRowGroupHeader : TemplatedControl
     {

src/Avalonia.Controls.DataGrid/DataGridRowHeader.cs

@@ -13,6 +13,7 @@ namespace Avalonia.Controls.Primitives
     /// <summary>
     /// Represents an individual <see cref="T:Avalonia.Controls.DataGrid" /> row header. 
     /// </summary>
+    [TemplatePart(DATAGRIDROWHEADER_elementRootName, typeof(Control))]
     [PseudoClasses(":invalid", ":selected", ":editing", ":current")]
     public class DataGridRowHeader : ContentControl
     {