C#滑鼠拖動表單代碼

private Point mouseOffset; //記錄滑鼠指標的座標
private bool isMouseDown = false; //記錄滑鼠按鍵是否按下

/// <summary>
/// 遞迴得到指定控制項位移量X值
/// </summary>
/// <param name="sender">指定的控制項</param>
/// <returns></returns>
private int GetOffsetX(Control sender)
{
    if (sender == this)
    {
        return 0;
    }
    if (sender.Parent != this)
    {
        return sender.Left + GetOffsetX(sender.Parent);
    }
    else
    {
        return 0;
    }
}

/// <summary>
/// 遞迴得到指定控制項位移量Y值
/// </summary>
/// <param name="sender">指定的控制項</param>
/// <returns></returns>
private int GetOffsetY(Control sender)
{
    if (sender == this)
    {
        return 0;
    }
    if (sender.Parent != this)
    {
        return sender.Top + GetOffsetY(sender.Parent);
    }
    else
    {
        return 0;
    }

}

/// <summary>
/// MouseDown
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void FormTitle_MouseDown(object sender, MouseEventArgs e)
{
    int xOffset;
    int yOffset;
    if (e.Button == MouseButtons.Left)
    {
        xOffset = -(e.X + GetOffsetX((Control)sender));
        yOffset = -(e.Y + GetOffsetY((Control)sender));
        mouseOffset = new Point(xOffset, yOffset);
        isMouseDown = true;
    }
}

/// <summary>
/// MouseMove
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void FormTitle_MouseMove(object sender, MouseEventArgs e)
{
    if (isMouseDown)
    {
        Point mousePos = Control.MousePosition;
        mousePos.Offset(mouseOffset.X, mouseOffset.Y);
        Location = mousePos;
    }
}

/// <summary>
/// MouseUp
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void FormTitle_MouseUp(object sender, MouseEventArgs e)
{
    // 修改滑鼠狀態isMouseDown的值
    // 確保只有滑鼠左鍵按下並移動時，才移動表單
    if (e.Button == MouseButtons.Left)
    {
        isMouseDown = false;
    }

}