将鼠标固定在单元格上时，如何在DataGridView中维护选定的行？

Question

我正在尝试在DataGridView中实现行移动。我希望能够选择多个行，然后单击所选行的任何单元格以开始拖动操作。问题在于，当我将鼠标固定在单元格上时，行会取消选择。我如何防止这种情况发生？

Answer 1

从快速的Google搜索中 这 似乎是一种解决行拖放行的解决方案。请注意，我刚刚从链接页面上撕下了以下代码，我无法保证其有效性。

private Rectangle dragBoxFromMouseDown;
private int rowIndexFromMouseDown;
private int rowIndexOfItemUnderMouseToDrop;

private void dataGridView1_MouseMove(object sender, MouseEventArgs e)
{
    if ((e.Button & MouseButtons.Left) == MouseButtons.Left)
    {
        // If the mouse moves outside the rectangle, start the drag.
        if (dragBoxFromMouseDown != Rectangle.Empty &&
            !dragBoxFromMouseDown.Contains(e.X, e.Y))
        {
            // Proceed with the drag and drop, passing in the list item.                    
            DragDropEffects dropEffect = dataGridView1.DoDragDrop(dataGridView1.Rows[rowIndexFromMouseDown], DragDropEffects.Move);
        }
    }
}

private void dataGridView1_MouseDown(object sender, MouseEventArgs e)
{
    // Get the index of the item the mouse is below.
    rowIndexFromMouseDown = dataGridView1.HitTest(e.X, e.Y).RowIndex;

    if (rowIndexFromMouseDown != -1)
    {
        // Remember the point where the mouse down occurred. 
        // The DragSize indicates the size that the mouse can move 
        // before a drag event should be started.                
        Size dragSize = SystemInformation.DragSize;
        // Create a rectangle using the DragSize, with the mouse position being
        // at the center of the rectangle.
        dragBoxFromMouseDown = new Rectangle(new Point(e.X - (dragSize.Width / 2), e.Y - (dragSize.Height / 2)), dragSize);
    }
    else
    {
        // Reset the rectangle if the mouse is not over an item in the ListBox.
        dragBoxFromMouseDown = Rectangle.Empty;
    }
}

private void dataGridView1_DragOver(object sender, DragEventArgs e)
{
    e.Effect = DragDropEffects.Move;
}

private void dataGridView1_DragDrop(object sender, DragEventArgs e)
{
    // The mouse locations are relative to the screen, so they must be 
    // converted to client coordinates.
    Point clientPoint = dataGridView1.PointToClient(new Point(e.X, e.Y));
    // Get the row index of the item the mouse is below. 
    rowIndexOfItemUnderMouseToDrop = dataGridView1.HitTest(clientPoint.X, clientPoint.Y).RowIndex;
    // If the drag operation was a move then remove and insert the row.
    if (e.Effect== DragDropEffects.Move)
    {
        DataGridViewRow rowToMove = e.Data.GetData(typeof(DataGridViewRow)) as DataGridViewRow;
        dataGridView1.Rows.RemoveAt(rowIndexFromMouseDown);
        dataGridView1.Rows.Insert(rowIndexOfItemUnderMouseToDrop, rowToMove);
    }
}

Answer 2

子类别分类datagridview可帮助您以有条件的方式做到这一点：

class SimpleDataGridView : DataGridView {

    public Action<DataGridViewCellMouseEventArgs> BeforeCellMouseDown;
    public Action<DataGridViewCellMouseEventArgs> AfterCellMouseDown;

    protected override void OnCellMouseDown(DataGridViewCellMouseEventArgs e) {
        if(BeforeCellMouseDown != null)
            BeforeCellMouseDown(e);

        base.OnCellMouseDown(e);

        if(AfterCellMouseDown != null)
            AfterCellMouseDown(e);
    }
}

然后，您可以在构造函数中以这种方式使用它：

IEnumerable<DataGridViewRow> sel = null;

dataGridView1.BeforeCellMouseDown = 
    e => {
        if (yourCondition)
            // Save the selection
            sel = dataGridView1.SelectedRows.OfType<DataGridViewRow>();
        else
            sel = null;
    };

dataGridView1.AfterCellMouseDown = 
    e => {
        if(sel != null) {
            // Restore the selection
            foreach(var row in sel)
                row.Selected = true;
        }
    };

Answer 3

我个人不确定如何更改您所谈论的问题的默认行为，但我确实知道，默认情况下，右键单击在DataGridView上没有任何操作。话虽如此，可能确实可以实现我以前做过的事情：自定义上下文menustrip允许用户通过选择行来复制/粘贴行，右键单击以打开上下文菜单，复制行，然后正确 - 单击行标头以打开上下文菜单和粘贴。 CellClick和Rowheadermouseclick事件应该使这更容易。