选择时DataGrid自动滚动

Question

我有一个自定义数据网格，在该数据网格中我改变了我们选择元素的方式。
我在选择中添加了一些功能，例如：

• 当我们选择元素时，就像按下了“Ctrl”键。
• 当我们单击选定的行时，该行将变为未选中状态。
• 当我们进行多项选择时，所有行都会将 selectedValue 更改为第一行将拥有的那个。
• 当我们通过右键单击进行多项选择（鼠标向下、移动，然后鼠标向上）时，它会反转所选行的值。

这是一个 DataGrid 扩展，所以我只用 C# 编码。

为此，我在 PreviewMouseDown 和 MouseUp 上为 datagridrow 添加了事件句柄。

    private enum ButtonClicked {Left, Middle, Right};
    private ButtonClicked m_oMouseButtonClicked;
    private void PreviewMouseDownHandler(object sender, MouseButtonEventArgs e)
    {
        DataGridRow row = sender as DataGridRow;

        if (e.LeftButton == MouseButtonState.Pressed)
        {
            row.IsSelected = !row.IsSelected;
            m_oMouseButtonClicked = ButtonClicked.Left;
        }
        else if (e.RightButton == MouseButtonState.Pressed)
        {
            //row.IsSelected = !row.IsSelected;
            m_oMouseButtonClicked = ButtonClicked.Right;
        }

        row.CaptureMouse();
        row.MouseMove += row_MouseMove;

        e.Handled = true;
    }

    void row_MouseMove(object sender, MouseEventArgs e)
    {
        Point oPosFromThis = e.GetPosition(this);

        if (oPosFromThis.Y > this.ActualHeight)
        {
        }
        else if (oPosFromThis.Y < 0)
        {
        }
    }

    void Row_MouseUp(object sender, MouseButtonEventArgs e)
    {
        int nStart;
        int nEnd;

        DataGridRow row = sender as DataGridRow;
        row.ReleaseMouseCapture();
        row.MouseMove -= row_MouseMove;

        int nStartRowIndex = ItemContainerGenerator.IndexFromContainer(row);


        Point oPosFromRow = e.MouseDevice.GetPosition(row);
        int nEndRowIndex = nStartRowIndex + (int)Math.Floor(oPosFromRow.Y / row.ActualHeight);


        if (nStartRowIndex < nEndRowIndex)
        {
            nStart = Math.Max(nStartRowIndex, 0);
            nEnd = Math.Min(nEndRowIndex, Items.Count - 1);
        }
        else 
        {
            nStart = Math.Max(nEndRowIndex, 0);
            nEnd = Math.Min(nStartRowIndex, Items.Count - 1);
        }

        for (; nStart <= nEnd; ++nStart)
        {
            DataGridRow oTmp = ((DataGridRow)ItemContainerGenerator.ContainerFromIndex(nStart));
            if (m_oMouseButtonClicked == ButtonClicked.Left)
            {
                oTmp.IsSelected = row.IsSelected;
            }
            else if (m_oMouseButtonClicked == ButtonClicked.Right)
            {
                oTmp.IsSelected = !oTmp.IsSelected;
            }
        }

        e.Handled = true;
    }

我将鼠标捕捉到我单击的行，以便即使我离开数据网格也能捕捉到 mouseUp。

但是使用我的代码，我失去了我想要拥有的功能。当我进行多项选择并且我在数据网格下方或上方时自动滚动。我知道我必须添加 MouseMove 处理程序才能做到这一点，但现在我被卡住了，因为我不知道该怎么做。

Answer 1

我终于通过尝试错误尝试找到了解决方案。我添加了获取 scrollviewer 元素的方法，然后我启动了一个 Timer 来单独执行滚动。

public claa AAA
{
    private enum ButtonClicked {Left, Middle, Right};

    private ButtonClicked m_oMouseButtonClicked;

    private DispatcherTimer m_oTimer;

    private double m_nScrollOffset;

    private ScrollViewer m_oScrollBar;



    public IcuAlertGrid()
    {
        this.Initialized += IcuAlertGrid_Initialized;
        this.Loaded += IcuAlertGrid_Loaded;

        m_oTimer = new DispatcherTimer();
        m_oTimer.Tick += m_oTimer_Tick;
        m_oTimer.Interval = new TimeSpan(2500000);
    }

    void IcuAlertGrid_Initialized(object sender, EventArgs e)
    {
        setStyle0(true);
        //throw new NotImplementedException();
    }

    void IcuAlertGrid_Loaded(object sender, RoutedEventArgs e)
    {
        m_oScrollBar = GetScrollViewer(this);
    }

    void m_oTimer_Tick(object sender, EventArgs e)
    {
        if (m_oScrollBar != null)
        {
            m_oScrollBar.ScrollToVerticalOffset(m_oScrollBar.VerticalOffset + m_nScrollOffset);
        }
    }

    private void PreviewMouseDownHandler(object sender, MouseButtonEventArgs e)
    {
        DataGridRow row = sender as DataGridRow;

        if (e.LeftButton == MouseButtonState.Pressed)
        {
            row.IsSelected = !row.IsSelected;
            m_oMouseButtonClicked = ButtonClicked.Left;
        }
        else if (e.RightButton == MouseButtonState.Pressed)
        {
            //row.IsSelected = !row.IsSelected;
            m_oMouseButtonClicked = ButtonClicked.Right;
        }

        row.CaptureMouse();
        row.MouseMove += row_MouseMove;

        e.Handled = true;
    }

    private void row_MouseMove(object sender, MouseEventArgs e)
    {
        DataGridRow oRow = sender as DataGridRow;
        Point oPosFromThis = e.GetPosition(this);

        if (oPosFromThis.Y < 0)
        {
            m_nScrollOffset = -1.0;
            m_oTimer.Start();
        } 
        else if (this.ActualHeight < oPosFromThis.Y)
        {
            m_nScrollOffset = 1.0;
            m_oTimer.Start();
        } 
        else
        {
            m_oTimer.Stop();
        }
    }

    private void Row_MouseUp(object sender, MouseButtonEventArgs e)
    {
        int nStart;
        int nEnd;

        m_oTimer.Stop();

        DataGridRow row = sender as DataGridRow;
        row.ReleaseMouseCapture();
        row.MouseMove -= row_MouseMove;

        int nStartRowIndex = ItemContainerGenerator.IndexFromContainer(row);
        Point oPosFromRow = e.MouseDevice.GetPosition(row); 
        int nEndRowIndex = nStartRowIndex + (int)Math.Floor(oPosFromRow.Y / row.ActualHeight);


        if (nStartRowIndex < nEndRowIndex)
        {
            nStart = Math.Max(nStartRowIndex, 0);
            nEnd = Math.Min(nEndRowIndex, Items.Count - 1);
        }
        else
        {
            nStart = Math.Max(nEndRowIndex, 0);
            nEnd = Math.Min(nStartRowIndex, Items.Count - 1);
        }

        for (; nStart <= nEnd; ++nStart)
        {
            DataGridRow oTmp = ((DataGridRow)ItemContainerGenerator.ContainerFromIndex(nStart));
            if (m_oMouseButtonClicked == ButtonClicked.Left)
            {
                oTmp.IsSelected = row.IsSelected;
            }
            else if (m_oMouseButtonClicked == ButtonClicked.Right)
            {
                oTmp.IsSelected = !oTmp.IsSelected;
            }
        }
        e.Handled = true;
    }

    private static ScrollViewer GetScrollViewer(DependencyObject p_oParent) 
    {
        ScrollViewer child = default(ScrollViewer);

        int numVisuals = VisualTreeHelper.GetChildrenCount(p_oParent);

        for (int i = 0; i < numVisuals; i++)
        {
            Visual v = (Visual)VisualTreeHelper.GetChild(p_oParent, i);
            child = v as ScrollViewer;

            if (child == null)
            {
                child = GetScrollViewer(v);
            }

            if (child != null)
            {
                break;
            }
        }

        return child;
    }
}