Winfrom 中 ListBox如何实现上移下移，置顶 置底的功能

private void button1_Click(object sender, EventArgs e)
{
    // 上移
    if (this.listBox1.SelectedIndices.Count > 0 &&
        this.listBox1.SelectedIndices[0] > 0)
    {
        int[] newIndices =
            this.listBox1.SelectedIndices.Cast<int>()
            .Select(index => index - 1).ToArray();

        this.listBox1.SelectedItems.Clear();

        for (int i = 0; i < newIndices.Length; i++)
        {
            object obj = this.listBox1.Items[newIndices[i]];
            this.listBox1.Items[newIndices[i]] = this.listBox1.Items[newIndices[i] + 1];
            this.listBox1.Items[newIndices[i] + 1] = obj;
            this.listBox1.SelectedItems.Add(this.listBox1.Items[newIndices[i]]);
        }
    }
}

private void button2_Click(object sender, EventArgs e)
{
    // 下移
    if (this.listBox1.SelectedIndices.Count > 0 &&
        this.listBox1.SelectedIndices[this.listBox1.SelectedIndices.Count - 1] <
        this.listBox1.Items.Count - 1)
    {
        int[] newIndices =
            this.listBox1.SelectedIndices.Cast<int>()
            .Select(index => index + 1).ToArray();

        this.listBox1.SelectedItems.Clear();

        for (int i = newIndices.Length; i > 0; i--)
        {
            object obj = this.listBox1.Items[newIndices[i - 1]];
            this.listBox1.Items[newIndices[i - 1]] = this.listBox1.Items[newIndices[i - 1] - 1];
            this.listBox1.Items[newIndices[i - 1] - 1] = obj;
            this.listBox1.SelectedItems.Add(this.listBox1.Items[newIndices[i - 1]]);
        }
    }
}

private void button3_Click(object sender, EventArgs e)
{
    // 置顶
    if (this.listBox1.SelectedIndices.Count > 0 &&
        this.listBox1.SelectedIndices[0] > 0)
    {
        int[] oldIndices =
            this.listBox1.SelectedIndices.Cast<int>().ToArray();

        int[] newIndices =
            this.listBox1.SelectedIndices.Cast<int>()
            .Select(index => index - 1).ToArray();

        int offest = oldIndices[0];

        while (offest-- > 0)
        {
            this.listBox1.SelectedItems.Clear();

            for (int i = 0; i < newIndices.Length; i++)
            {
                object obj = this.listBox1.Items[newIndices[i]];
                this.listBox1.Items[newIndices[i]] = this.listBox1.Items[newIndices[i] + 1];
                this.listBox1.Items[newIndices[i] + 1] = obj;
                this.listBox1.SelectedItems.Add(this.listBox1.Items[newIndices[i]]);
            }

            newIndices = newIndices.Select(index => index - 1).ToArray();
        }
    }
}

private void button4_Click(object sender, EventArgs e)
{
    // 置末
    if (this.listBox1.SelectedIndices.Count > 0 &&
        this.listBox1.SelectedIndices[this.listBox1.SelectedIndices.Count - 1] <
        this.listBox1.Items.Count - 1)
    {
        int[] oldIndices =
            this.listBox1.SelectedIndices.Cast<int>().ToArray();

        int[] newIndices =
            this.listBox1.SelectedIndices.Cast<int>()
            .Select(index => index + 1).ToArray();

        int offest = oldIndices[oldIndices.Length - 1];

        while (offest++ < this.listBox1.Items.Count - 1)
        {
            this.listBox1.SelectedItems.Clear();

            for (int i = newIndices.Length; i > 0; i--)
            {
                object obj = this.listBox1.Items[newIndices[i - 1]];
                this.listBox1.Items[newIndices[i - 1]] = this.listBox1.Items[newIndices[i - 1] - 1];
                this.listBox1.Items[newIndices[i - 1] - 1] = obj;
                this.listBox1.SelectedItems.Add(this.listBox1.Items[newIndices[i - 1]]);
            }

            newIndices = newIndices.Select(index => index + 1).ToArray();
        }
    }
}