ObjectListView忽略了拖动效果

Question

您好我正在为我的应用程序使用ObjectListView。我尝试制作一个花哨的拖拽效果，因为原来的蓝色效果并不是那么好。这就像我拖动时突出显示第一列。我在正常的listview上使用它

        private void lvPlaylist_DragOver(object sender, DragEventArgs e)
        {
            Point mLoc = lvPlaylist.PointToClient(Cursor.Position);
            var hitt = lvPlaylist.HitTest(mLoc);
            if (hitt.Item == null) return;

            int idx = hitt.Item.Index;
            if (idx == prevItem) return;

            lvPlaylist.Refresh();
            using (Graphics g = lvPlaylist.CreateGraphics())
            {
                Rectangle rect = lvPlaylist.GetItemRect(idx);
                Pen MyPen = new Pen(Color.OrangeRed, 3);
                g.DrawLine(MyPen, rect.Left, rect.Top, rect.Right, rect.Top);
            }
            prevItem = idx;
        }

但它不适用于ObjectListView。实际上确实如此，但当我停止拖动而不释放拖动物体时，它会向我显示蓝色默认拖动效果，而我一直在移动，我看到了自己的拖动效果。有没有办法禁用OLV拖动效果？

Answer 1

您的解决方案是否在所选项目的上方/下方绘制一条线？

您可以允许在使用之间删除：

lvPlaylist.IsSimpleDropSink = true;
((SimpleDropSink)lvPlaylist.DropSink).CanDropBetween = true;

如果这还不够好，你可以回复ModelCanDrop，例如

//((SimpleDropSink)lvPlaylist.DropSink).ModelCanDrop+= ModelCanDrop;

 private void ModelCanDrop(object sender, ModelDropEventArgs e)
 {
     e.DropSink.Billboard.BackColor = Color.GreenYellow;
     e.DropSink.FeedbackColor = Color.GreenYellow;
     e.InfoMessage = "Hey there";
     e.Handled = true;
     e.Effect = DragDropEffects.Move;
 }

如果你真的讨厌那么多你甚至可以：

e.DropSink.EnableFeedback = false;

ObjectListView站点有一个关于拖放的深入的深入教程：

http://objectlistview.sourceforge.net/cs/blog4.html#blog-rearrangingtreelistview

如果你想寻找真正想要的东西，你可以为SimpleDropSink编写自己的子类：

lvPlaylist.IsSimpleDragSource = true;
lvPlaylist.DropSink = new MyDropSink();

private class MyDropSink : SimpleDropSink
{
    public override void DrawFeedback(Graphics g, Rectangle bounds)
    {
        if(DropTargetLocation != DropTargetLocation.None)
            g.DrawString("Heyyy stuffs happening",new Font(FontFamily.GenericMonospace, 10),new SolidBrush(Color.Magenta),bounds.X,bounds.Y );
    }
}

为了你想要的行为，你应该尝试这样的事情：

private class MyDropSink : SimpleDropSink
{
    private ObjectListView _olv;

    public MyDropSink(ObjectListView olv)
    {
        _olv = olv;
    }

    public override void DrawFeedback(Graphics g, Rectangle bounds)
    {
        if(DropTargetLocation != DropTargetLocation.None)
        {
            Point mLoc = _olv.PointToClient(Cursor.Position);
            var hitt = _olv.HitTest(mLoc);
            if (hitt.Item == null) return;

            int idx = hitt.Item.Index;
            Rectangle rect = _olv.GetItemRect(idx);
            Pen MyPen = new Pen(Color.OrangeRed, 3);
            g.DrawLine(MyPen, rect.Left, rect.Top, rect.Right, rect.Top);
        }
    }
}