How to get WPF DataGridCell visual horizontal (X-axis) position?

I need to get the position of a WPF DataGridCell, obtained in a DataGrid cell changed event, but only can get the vertical (Y-axis). The horizontal remains the same, despite a different column is pointed.

Here is the almost working code. Test by clicking on different cells.

/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
    List<Person> Persons = new List<Person>();

    public MainWindow()
    {
        InitializeComponent();

        Persons.Add(new Person { Id = 1, Name = "John", City = "London" });
        Persons.Add(new Person { Id = 2, Name = "Charles", City = "Rome" });
        Persons.Add(new Person { Id = 3, Name = "Paul", City = "Chicago" });

        this.EditingDataGrid.ItemsSource = Persons;
        this.EditingDataGrid.CurrentCellChanged += new EventHandler<EventArgs>(EditingDataGrid_CurrentCellChanged);
    }

    void EditingDataGrid_CurrentCellChanged(object sender, EventArgs e)
    {
        DataGridCell Cell = GetCurrentCell(this.EditingDataGrid);
        var Position = Cell.PointToScreen(new Point(0, 0));
        // WHY X NEVER CHANGES??!!
        MessageBox.Show("X=" + Position.X.ToString() + ", Y=" + Position.Y.ToString(), "Position");
    }

    /// <summary>
    /// Returns, for this supplied Source Data-Grid, the current Data-Grid-Cell.
    /// May return null if no associated Cell is found.
    /// </summary>
    public static DataGridCell GetCurrentCell(DataGrid SourceDataGrid)
    {
        if (SourceDataGrid.CurrentCell == null)
            return null;

        var RowContainer = SourceDataGrid.ItemContainerGenerator.ContainerFromItem(SourceDataGrid.CurrentCell.Item);
        if (RowContainer == null)
            return null;

        var RowPresenter = GetVisualChild<System.Windows.Controls.Primitives.DataGridCellsPresenter>(RowContainer);
        if (RowPresenter == null)
            return null;

        var Container = RowPresenter.ItemContainerGenerator.ContainerFromItem(SourceDataGrid.CurrentCell.Item);
        var Cell = Container as DataGridCell;

        // Try to get the cell if null, because maybe the cell is virtualized
        if (Cell == null)
        {
            SourceDataGrid.ScrollIntoView(RowContainer, SourceDataGrid.CurrentCell.Column);
            Container = RowPresenter.ItemContainerGenerator.ContainerFromItem(SourceDataGrid.CurrentCell.Item);
            Cell = Container as DataGridCell;
        }

   开发者_运维技巧     return Cell;
    }

    /// <summary>
    /// Returns the nearest child having the specified TRet type for the supplied Target.
    /// </summary>
    public static TRet GetVisualChild<TRet>(DependencyObject Target) where TRet : DependencyObject
    {
        if (Target == null)
            return null;

        for (int ChildIndex = 0; ChildIndex < VisualTreeHelper.GetChildrenCount(Target); ChildIndex++)
        {
            var Child = VisualTreeHelper.GetChild(Target, ChildIndex);

            if (Child != null && Child is TRet)
                return (TRet)Child;
            else
            {
                TRet childOfChild = GetVisualChild<TRet>(Child);

                if (childOfChild != null)
                    return childOfChild;
            }
        }

        return null;
    }
}

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string City { get; set; }
}

The DataGrid is just defined by... <DataGrid x:Name="EditingDataGrid"/>

Maybe exists there an alternative to get that DataGridCell position?

---

You can get the DataGridCell from CurrentCell like this

void EditingDataGrid_CurrentCellChanged(object sender, EventArgs e)
{
    DataGridCell Cell = GetDataGridCell(EditingDataGrid.CurrentCell);
    var Position = Cell.PointToScreen(new Point(0, 0));
    MessageBox.Show("X=" + Position.X.ToString() + ", Y=" + Position.Y.ToString(), "Position");
}
public static DataGridCell GetDataGridCell(DataGridCellInfo cellInfo)
{
    if (cellInfo.IsValid == false)
    {
        return null;
    }
    var cellContent = cellInfo.Column.GetCellContent(cellInfo.Item);
    if (cellContent == null)
    {
        return null;
    }
    return cellContent.Parent as DataGridCell;
}

You could also create an extension method on the DataGrid to do this

DataGridExtensions.cs

public static class DataGridExtensions
{
    public static DataGridCell GetCurrentDataGridCell(this DataGrid dataGrid)
    {
        DataGridCellInfo cellInfo = dataGrid.CurrentCell;
        if (cellInfo.IsValid == false)
        {
            return null;
        }
        var cellContent = cellInfo.Column.GetCellContent(cellInfo.Item);
        if (cellContent == null)
        {
            return null;
        }
        return cellContent.Parent as DataGridCell;
    }
}

Which you can use like this everytime you want to get the current DataGridCell

DataGridCell Cell = EditingDataGrid.GetCurrentDataGridCell();

---

I guess what's going on is that your grid's default selection mode is full row, the code you're using to get the DataGridCell is getting the first selected cell which holds the "Id" column value.

What you can try to do is changing the grid's selection mode to "Cell" and this trigger the message box with correct coordinates.

<DataGrid x:Name="EditingDataGrid" SelectionUnit="Cell"/>

Also I've changed your code a bit, see if it would work for you:

void EditingDataGrid_CurrentCellChanged(object sender, EventArgs e)
{
    // this will iterate through all selected cell of the datagrid
    foreach (DataGridCellInfo cellInfo in this.EditingDataGrid.SelectedCells)
    {
        DataGridCell Cell = GetCurrentCell(this.EditingDataGrid, cellInfo);
        if (Cell != null)
        {
            var Position = Cell.PointToScreen(new Point(0, 0));
            MessageBox.Show("X=" + Position.X.ToString() + 
                            ", Y=" + Position.Y.ToString() + 
                            " Content = " + ((TextBlock)Cell.Content).Text.ToString(), "Position");
        }
    }
}

/// <summary>
/// Returns, for this supplied Source Data-Grid, the current Data-Grid-Cell.
/// May return null if no associated Cell is found.
/// </summary>
public static DataGridCell GetCurrentCell(DataGrid grid, DataGridCellInfo cellInfo)
{
    DataGridCell result = null;
    DataGridRow row = (DataGridRow)grid.ItemContainerGenerator.ContainerFromItem(cellInfo.Item);
    if (row != null)
    {
        int columnIndex = grid.Columns.IndexOf(cellInfo.Column);
        if (columnIndex > -1)
        {
            DataGridCellsPresenter presenter = GetVisualChild<DataGridCellsPresenter>(row);
            result = presenter.ItemContainerGenerator.ContainerFromIndex(columnIndex) as DataGridCell;
        }
    }
    return result;
}

/// <summary>
/// Returns the nearest child having the specified TRet type for the supplied Target.
/// </summary>
static T GetVisualChild<T>(Visual parent) where T : Visual
{
    T child = default(T);
    int numVisuals = VisualTreeHelper.GetChildrenCount(parent);
    for (int i = 0; i < numVisuals; i++)
    {
        Visual v = (Visual)VisualTreeHelper.GetChild(parent, i);
        child = v as T;
        if (child == null)
        {
            child = GetVisualChild<T>(v);
        }
        if (child != null)
        {
            break;
        }
    }
    return child;
}

hope this helps, regards