Question

.Net 4 WPF DataGrid MVVM

用户点击添加按钮，触发viewmodel上的命令。在viewmodel命令执行中，我将一个新对象添加到网格绑定到的viewmodel的viewcollection中。新行确实出现在我的网格中。但是，我还想将焦点发送到该新行中的第一个可编辑单元格。

我甚至“欺骗”了mvvm，在我的viewmodel上添加了一个视图监听的事件，知道何时聚焦新行。

我搜索过但没有运气。当我遇到这个时，我很有希望：

Datagrid Set focus on newly added row

导致

http://social.msdn.microsoft.com/forums/en-US/wpf/thread/63974f4f-d9ee-45af-8499-42f29cbc22ae

但其他人报告的问题并没有人回答，问题是如何处理网格的虚拟化行为。尚未创建新添加的行。因此GetCells调用经常失败。如果需要ScrollIntoView，则更有可能失败。

我已经吸引了大量的事件，包括LoadingRow和RequestBringIntoView而没有运气。根据我挂钩的事件，我已经设法能够获得对单元格的引用。但后来我收到错误“内容生成正在进行时无法调用StartAt”。但是当我调用单元格的BeginEdit时，我检查了ItemContainerGenerator的状态，它是ContainersGenerated。

Answer 1

以下是一种以编程方式将焦点设置到特定单元格的方法：

DataGridCell cell = GetCell(rowIndex, colIndex);
cell.Focus;

有关GetCell（）的更多信息，请参阅以下article。

Answer 2

这似乎对我有用：

    using System.Windows.Controls;
    using System.Windows.Controls.Primitives;
    using System.Windows.Media;

    private void SetFocusOnNewRow(DataGrid theDataGrid, Int32 columnIndex)
    {
        theDataGrid.UnselectAll();
        theDataGrid.UpdateLayout();

        Int32 newRowIndex = theDataGrid.Items.Count - 1;
        theDataGrid.ScrollIntoView(theDataGrid.Items[newRowIndex]);
        DataGridRow newDataGridRow = theDataGrid.ItemContainerGenerator.ContainerFromIndex(newRowIndex) as DataGridRow;

        DataGridCellsPresenter newDataGridCellsPresenter = GetVisualChild<DataGridCellsPresenter>(newDataGridRow);
        if (newDataGridCellsPresenter != null)
        {
            DataGridCell newDataGridCell = newDataGridCellsPresenter.ItemContainerGenerator.ContainerFromIndex(columnIndex) as DataGridCell;
            if (newDataGridCell != null)
                newDataGridCell.Focus();
        }
    }

    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;
    }

Answer 3

这对我有用：

private void button_Click(object sender, RoutedEventArgs e)
{
    //Scroll to the last row
    var border = VisualTreeHelper.GetChild(dataGrid, 0) as Decorator;
    if (border != null)
    {
        var scroll = border.Child as ScrollViewer;
        if (scroll != null) scroll.ScrollToEnd();
    }

    //Edit the first cell of the last row
    int lastRow = dataGrid.Items.Count - 1;
    DataGridCell cell = GetCell(lastRow, 0);
    cell.Focus();
    dataGrid.BeginEdit();
}


public DataGridCell GetCell(int row, int column)
{
    DataGridRow rowContainer = GetRow(row);

    if (rowContainer != null)
    {
        DataGridCellsPresenter presenter = GetVisualChild<DataGridCellsPresenter>(rowContainer);

        // try to get the cell but it may possibly be virtualized
        DataGridCell cell = (DataGridCell)presenter.ItemContainerGenerator.ContainerFromIndex(column);
        if (cell == null)
        {
            // now try to bring into view and retreive the cell
            dataGrid.ScrollIntoView(rowContainer, dataGrid.Columns[column]);
            cell = (DataGridCell)presenter.ItemContainerGenerator.ContainerFromIndex(column);
        }
        return cell;
    }
    return null;
}

public DataGridRow GetRow(int index)
{
    DataGridRow row = (DataGridRow)dataGrid.ItemContainerGenerator.ContainerFromIndex(index);
    if (row == null)
    {
        // may be virtualized, bring into view and try again
        dataGrid.ScrollIntoView(dataGrid.Items[index]);
        row = (DataGridRow)dataGrid.ItemContainerGenerator.ContainerFromIndex(index);
    }
    return row;
}

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;
}

如何将单元格集中在WPF DataGrid中的新行上

3 个答案: