Question

我刚刚为CheckedListBox实现了拖放重新排序功能。现在我希望它向下滚动，如果在底部拖动，反之亦然在顶部（普通的拖动自动滚动）

我发现了很多WPF信息，但我看不出如何将这些解决方案应用到我的winform ChekedListBox。

这是我的代码：

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

            Point point = myListBox.PointToClient(new Point(e.X, e.Y));

            int index = myListBox.IndexFromPoint(point);
            int selectedIndex = myListBox.SelectedIndex;

            if (index < 0)
            {
                index = selectedIndex;
            }

            if (index != selectedIndex)
            {
                myListBox.SwapItems(selectedIndex, index);
                myListBox.SelectedIndex = index;
            }
         }

Answer 1

您可以更新CheckedListBox.TopIndex事件处理程序中的Timer.Tick属性以实现自动滚动功能。要启动和停止计时器，请使用CheckedListBox.DragLeave和CheckedListBox.DragEnter事件。这是一段代码：

private void checkedListBox1_DragEnter(object sender, DragEventArgs e) {
    scrollTimer.Stop();
}

private void checkedListBox1_DragLeave(object sender, EventArgs e) {
    scrollTimer.Start();
}

private void scrollTimer_Tick(object sender, EventArgs e) {
    Point cursor = PointToClient(MousePosition);
    if (cursor.Y < checkedListBox1.Bounds.Top)
        checkedListBox1.TopIndex -= 1;
    else if (cursor.Y > checkedListBox1.Bounds.Bottom)
        checkedListBox1.TopIndex += 1;
}

Answer 2

我实际上最终将此添加到我的DragOver事件处理程序中。也许不像光滑，但它对我来说效果更好。

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

        Point point = myListBox.PointToClient(new Point(e.X, e.Y));

        int index = myListBox.IndexFromPoint(point);
        int selectedIndex = myListBox.SelectedIndex;

        if (index < 0)
        {
            index = selectedIndex;
        }

        if (index != selectedIndex)
        {
            myListBox.SwapItems(selectedIndex, index);
            myListBox.SelectedIndex = index;
        }

        if (point.Y <= (Font.Height*2))
        {
            myListBox.TopIndex -= 1;
        }
        else if (point.Y >= myListBox.Height - (Font.Height*2))
        {
            myListBox.TopIndex += 1;
        }
    }

使用DragDrop重新排序自动滚动CheckedListBox

2 个答案: