如何在c＃中初始化折叠的GroupBox？

Question

我已经自定义GroupBox以使其可折叠/可扩展。

代码工作正常。但我想以折叠的形式初始化这个GroupBox而不是消耗品。我试图设置值（m_collapsed = true / false和m_bResizingFromCollapse = true / false）并覆盖OnPaint，但没有任何工作。

  namespace ABC
{
/// <summary>
/// GroupBox control that provides functionality to 
/// allow it to be collapsed.
/// </summary>
[ToolboxBitmap(typeof(CollapsibleGroupBox))]
public partial class CollapsibleGroupBox : GroupBox
{
    #region Fields

    private Rectangle m_toggleRect = new Rectangle(8, 2, 11, 11);
    private Boolean m_collapsed = false;
    private Boolean m_bResizingFromCollapse = false;

    private const int m_collapsedHeight = 20;
    private Size m_FullSize = Size.Empty;

    #endregion

    #region Events & Delegates

    /// <summary>Fired when the Collapse Toggle button is pressed</summary>
    public delegate void CollapseBoxClickedEventHandler(object sender);
    public event CollapseBoxClickedEventHandler CollapseBoxClickedEvent;

    #endregion

    #region Constructor

    public CollapsibleGroupBox()
    {
        InitializeComponent();
    }

    #endregion

    #region Public Properties

    [Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
    public int FullHeight
    {
        get { return m_FullSize.Height; }
    }

    [DefaultValue(false), Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
    public bool IsCollapsed
    {
        get { return m_collapsed; }
        set
        {
            if (value != m_collapsed)
            {
                m_collapsed = value;

                if (!value)
                    // Expand
                    this.Size = m_FullSize;
                else
                {
                    // Collapse
                    m_bResizingFromCollapse = true;
                    this.Height = m_collapsedHeight;
                    m_bResizingFromCollapse = false;
                }

                foreach (Control c in Controls)
                    c.Visible = !value;

                Invalidate();
            }
        }
    }

    [Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
    public int CollapsedHeight
    {
        get { return m_collapsedHeight; }
    }

    #endregion

    #region Overrides

    protected override void OnMouseUp(MouseEventArgs e)
    {
        if (m_toggleRect.Contains(e.Location))
            ToggleCollapsed();
        else
            base.OnMouseUp(e);
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        HandleResize();
        DrawGroupBox(e.Graphics);
        DrawToggleButton(e.Graphics);
    }

    #endregion

    #region Implimentation

    void DrawGroupBox(Graphics g)
    {
        // Get windows to draw the GroupBox
        Rectangle bounds = new Rectangle(ClientRectangle.X, ClientRectangle.Y + 6, ClientRectangle.Width, ClientRectangle.Height - 6);
        GroupBoxRenderer.DrawGroupBox(g, bounds, Enabled ? GroupBoxState.Normal : GroupBoxState.Disabled);

        // Text Formating positioning & Size
        StringFormat sf = new StringFormat();
        int i_textPos = (bounds.X + 8) + m_toggleRect.Width + 2;
        int i_textSize = (int)g.MeasureString(Text, this.Font).Width;
        i_textSize = i_textSize < 1 ? 1 : i_textSize;
        int i_endPos = i_textPos + i_textSize + 1;

        // Draw a line to cover the GroupBox border where the text will sit
        g.DrawLine(SystemPens.Control, i_textPos, bounds.Y, i_endPos, bounds.Y);

        // Draw the GroupBox text
        using (SolidBrush drawBrush = new SolidBrush(Color.FromArgb(0, 70, 213)))
            g.DrawString(Text, this.Font, drawBrush, i_textPos, 0);
    }

    void DrawToggleButton(Graphics g)
    {
        if (IsCollapsed)
        {
            Image plusImage = Image.FromFile(Path.Combine(GameManager.sAssetsDir, "plus.bmp"));
            g.DrawImage(plusImage, m_toggleRect);
        }
        else
        {
            Image minusImage = Image.FromFile(Path.Combine(GameManager.sAssetsDir, "minus.bmp"));
            g.DrawImage(minusImage, m_toggleRect);
        }
    }

    void ToggleCollapsed()
    {
        IsCollapsed = !IsCollapsed;

        if (CollapseBoxClickedEvent != null)
            CollapseBoxClickedEvent(this);
    }

    void HandleResize()
    {
        if (!m_bResizingFromCollapse && !m_collapsed)
            m_FullSize = this.Size;
    }

    #endregion
}

}