自定义控件-第一个绘制OK，第二个不绘制'；t

我在某个地方找到了一些自定义分组框的代码，用圆角、渐变背景和阴影绘制。我觉得它看起来很不错，所以我用标签控件对它进行了调整。

奇怪的是，当我把其中一个控件放到表单设计器上时，默认属性被设置好了，它画得很好——我在表单上放了多个副本，它们都很好。

然而，当我尝试在运行时添加几个控件时，实际上只有第一个版本绘制正确。其他的都变成了空白的白色盒子。

我真的不知道该怎么办。

标签的代码如下(抱歉-太长了！(

public class LabelEx : Label
{
    private System.Drawing.Color _BorderColor = Color.FromArgb(141, 178, 227);
    private float _BorderWidth = 1;
    private System.Drawing.Color _BackgroundColor = Color.White;
    private System.Drawing.Color _BackgroundColorGradient = Color.FromArgb(227, 235, 246);
    private ControlGradientMode _BackgroundGradientMode = ControlGradientMode.Vertical;
    private int _CornerRadius = 5;
    private RoundedControlCorners _Corners = RoundedControlCorners.All;
    private int _DropShadowThickness = 3;
    private bool _DropShadowVisible = true;
    private System.Drawing.Color _ShadowColor = Color.FromArgb(50, Color.Black);
    private ControlStyles _LabelStyle = ControlStyles.Extended;
    public enum ControlStyles
    {
        Standard,
        Extended
    }
    public LabelEx()
    {
        //InitializeComponent();
    }
    /// <summary>Gets or sets the radius of the corners of the control.</summary>
    //[Category("Appearance"), Description("This feature will round the corners of the control.")]
    public int CornerRadius
    {
        get { return _CornerRadius; }
        set
        {
            if (value > 35)
            {
                _CornerRadius = 35;
            }
            else
            {
                if (value < 1)
                {
                    _CornerRadius = 1;
                }
                else
                {
                    _CornerRadius = value;
                }
            }
            Invalidate();
        }
    }
    /// <summary>Turns on or off the control shadowing.</summary>
    //[Category("Appearance"), Description("This feature will turn on control shadowing.")]
    public bool DropShadowVisible
    {
        get { return _DropShadowVisible; }
        set
        {
            _DropShadowVisible = value;
            Invalidate();
        }
    }
    /// <summary>Gets or sets the color of the control's border.</summary>
    //[Category("Appearance"), Description("This feature will allow you to change the color of the control's border.")]
    public System.Drawing.Color BorderColor
    {
        get { return _BorderColor; }
        set
        {
            _BorderColor = value;
            Invalidate();
        }
    }
    /// <summary>Gets or Sets the control's border size.</summary>
    //[Category("Appearance"), Description("This feature will allow you to set the control's border size.")]
    public float BorderWidth
    {
        get { return _BorderWidth; }
        set
        {
            if (value > 10)
            {
                _BorderWidth = 10;
            }
            else
            {
                if (value < 1)
                {
                    _BorderWidth = 1;
                }
                else
                {
                    _BorderWidth = value;
                }
            }
            Invalidate();
        }
    }
    /// <summary>Gets or sets the size of the shadow border thickness.</summary>
   // [Category("Appearance"), Description("This feature will change the size of the shadow border.")]
    public int DropShadowThickness
    {
        get { return _DropShadowThickness; }
        set
        {
            if (value > 10)
            {
                _DropShadowThickness = 10;
            }
            else
            {
                if (value < 1)
                {
                    _DropShadowThickness = 1;
                }
                else
                {
                    _DropShadowThickness = value;
                }
            }
            Invalidate();
        }
    }
    /// <summary>Gets or sets the background color to use. This color can also be used in combination with BackgroundColorGradient for a gradient paint.</summary>
    // [Category("Appearance"), Description("This feature will change the group control color. This color can also be used in combination with BackgroundColorGradient for a gradient paint.")]
    public System.Drawing.Color BackgroundColor
    {
        get { return _BackgroundColor; }
        set
        {
            _BackgroundColor = value;
            Invalidate();
        }
    }
    /// <summary>Specifies the second color when using the gradient mode.</summary>
    // [Category("Appearance"), Description("This feature can be used in combination with BackgroundColor to create a gradient background.")]
    public System.Drawing.Color BackgroundColorGradient
    {
        get { return _BackgroundColorGradient; }
        set
        {
            _BackgroundColorGradient = value;
            Invalidate();
        }
    }
    /// <summary>This property secifies the type of gradient to use when painting the background.</summary>
    // [Category("Appearance"), Description("This feature turns on background gradient painting.")]
    public ControlGradientMode BackgroundGradientMode
    {
        get { return _BackgroundGradientMode; }
        set
        {
            _BackgroundGradientMode = value;
            Invalidate();
        }
    }
    /// <summary>Specifies which corners to apply rounding for</summary>
    public RoundedControlCorners Corners
    {
        get { return _Corners; }
        set
        {
            _Corners = value;
            Invalidate();
        }
    }
    /// <summary>Gets or sets the Style for the GroupBox.  Standard duplicates the stock groupbox.  Extended allows the customization ability</summary>
    // [Category("Appearance"), Description("Gets or sets the Style for the GroupBox.  Standard duplicates the stock groupbox.  Extended allows the customization ability")]
    // [DefaultValue(ControlStyles.Extended)]
    public ControlStyles LabelStyle
    {
        get { return _LabelStyle; }
        set
        {
            _LabelStyle = value;
            Invalidate();
        }
    }
    /// <summary>
    /// Function to paint the label as per what we want.
    /// </summary>
    /// <param name="e"></param>
    protected override void OnPaint(PaintEventArgs e)
    {
        //Just use a normal label if the "standard" is set.
        if (_LabelStyle == ControlStyles.Standard)
        {
            base.OnPaint(e);
            return;
        }
        //we must set the smoothing mode to anti alias or high quality(They are the same) in order to get the
        //nice rounded corders on our control
        e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
        //first lets set the rectangles we will be drawing in.  If the drop shadow is visible then we need to 
        //reduce the size of the main rectangle and create a second one that is offset by the shadow thickness.
        Rectangle shadowRec = default(Rectangle);
        Rectangle frameRec = default(Rectangle);
        if (DropShadowVisible)
        {
            shadowRec = Rectangle.FromLTRB(DropShadowThickness, DropShadowThickness, this.ClientRectangle.Right - 1, this.ClientRectangle.Bottom - 1);
            frameRec = Rectangle.FromLTRB(0, 0, this.ClientRectangle.Right - DropShadowThickness - 2, this.ClientRectangle.Bottom - DropShadowThickness - 2);
        }
        else
        {
            frameRec = Rectangle.FromLTRB(this.ClientRectangle.Left, this.ClientRectangle.Top, this.ClientRectangle.Right - 1, this.ClientRectangle.Bottom - 1);
        }
        if (frameRec.Height <= 0 | frameRec.Width <= 0)
            return;
        //draw the drop shadow using the shadow path rectangle
        if (DropShadowVisible)
        {
            using (GraphicsPath path = GraphicsFunctions.RoundRectangle(shadowRec, _CornerRadius, _Corners))
            {
                using (SolidBrush b = new SolidBrush(_ShadowColor))
                {
                    e.Graphics.FillPath(b, path);
                }
            }
        }
        //draw the rest of the control in the main frame path
        using (GraphicsPath path = GraphicsFunctions.RoundRectangle(frameRec, _CornerRadius, _Corners))
        {
            //paint the background inside the frame
            if (BackgroundGradientMode == ControlGradientMode.None)
            {
                //solid background
                using (SolidBrush b = new SolidBrush(BackgroundColor))
                {
                    e.Graphics.FillPath(b, path);
                }
            }
            else
            {
                //gradient
                if (BackgroundGradientMode == ControlGradientMode.VerticalGlow)
                {
                    using (LinearGradientBrush b = new LinearGradientBrush(new Point(0, frameRec.Top + (frameRec.Height / 2)), new Point(0, frameRec.Bottom - 1), BackgroundColorGradient, BackgroundColor))
                    {
                        b.WrapMode = WrapMode.TileFlipXY;
                        e.Graphics.FillPath(b, path);
                    }
                }
                else if (BackgroundGradientMode == ControlGradientMode.HorizontalGlow)
                {
                    using (LinearGradientBrush b = new LinearGradientBrush(new Point(frameRec.Left + (frameRec.Width / 2), 0), new Point(frameRec.Right - 1, 0), BackgroundColorGradient, BackgroundColor))
                    {
                        b.WrapMode = WrapMode.TileFlipXY;
                        e.Graphics.FillPath(b, path);
                    }
                }
                else
                {
                    using (LinearGradientBrush br = new LinearGradientBrush(frameRec, BackgroundColor, BackgroundColorGradient, (LinearGradientMode)BackgroundGradientMode))
                    {
                        e.Graphics.FillPath(br, path);
                    }
                }
                //
                using (SolidBrush b = new SolidBrush(ForeColor))
                {
                    StringFormat sf = new StringFormat();
                    //Rectangle textRec = default(Rectangle);

                    switch (this.TextAlign)
                    {
                        case ContentAlignment.BottomCenter:
                            sf.Alignment = StringAlignment.Center;
                            sf.LineAlignment = StringAlignment.Far;
                            break;
                        case ContentAlignment.BottomLeft:
                            sf.Alignment = StringAlignment.Near;
                            sf.LineAlignment = StringAlignment.Far;
                            break;
                        case ContentAlignment.BottomRight:
                            sf.Alignment = StringAlignment.Far;
                            sf.LineAlignment = StringAlignment.Far;
                            break;
                        case ContentAlignment.MiddleCenter:
                            sf.Alignment = StringAlignment.Center;
                            sf.LineAlignment = StringAlignment.Center;
                            break;
                        case ContentAlignment.MiddleLeft:
                            sf.Alignment = StringAlignment.Near;
                            sf.LineAlignment = StringAlignment.Center;
                            break;
                        case ContentAlignment.MiddleRight:
                            sf.Alignment = StringAlignment.Far;
                            sf.LineAlignment = StringAlignment.Center;
                            break;
                        case ContentAlignment.TopCenter:
                            sf.Alignment = StringAlignment.Center;
                            sf.LineAlignment = StringAlignment.Near;
                            break;
                        case ContentAlignment.TopLeft:
                            sf.Alignment = StringAlignment.Near;
                            sf.LineAlignment = StringAlignment.Near;
                            break;
                        case ContentAlignment.TopRight:
                            sf.Alignment = StringAlignment.Far;
                            sf.LineAlignment = StringAlignment.Near;
                            break;
                    }

                    sf.Alignment = StringAlignment.Center;
                    e.Graphics.DrawString(this.Text, this.Font, b, (RectangleF)frameRec, sf);
                    Invalidate();
                }
                Invalidate();
            }
            e.Graphics.ResetTransform();
            //draw the border
            using (Pen p = new Pen(BorderColor, BorderWidth))
            {
                e.Graphics.DrawPath(p, path);
            }
        }
    }
}

它依赖于此：

[Flags()]
public enum RoundedControlCorners
{
    None = 0,
    NorthWest = 2,
    NorthEast = 4,
    SouthEast = 8,
    SouthWest = 16,
    All = NorthWest | NorthEast | SouthEast | SouthWest,
    North = NorthWest | NorthEast,
    South = SouthEast | SouthWest,
    East = NorthEast | SouthEast,
    West = NorthWest | SouthWest
}
public enum ControlGradientMode
{
    /// <summary>Specifies no gradient mode.</summary>
    None = 4,
    /// <summary>Specifies a gradient from upper right to lower left.</summary>
    BackwardDiagonal = LinearGradientMode.BackwardDiagonal,
    /// <summary>Specifies a gradient from upper left to lower right.</summary>
    ForwardDiagonal = LinearGradientMode.ForwardDiagonal,
    /// <summary>Specifies a gradient from left to right.</summary>
    Horizontal = LinearGradientMode.Horizontal,
    /// <summary>Specifies a gradient from top to bottom.</summary>
    Vertical = LinearGradientMode.Vertical,
    VerticalGlow = 5,
    HorizontalGlow = 6
}
public static class GraphicsFunctions
{
    public static GraphicsPath RoundRectangle(Rectangle r, int radius, RoundedControlCorners corners)
    {
        GraphicsPath path = new GraphicsPath();
        if (r.Width <= 0 | r.Height <= 0)
            return path;
        int d = radius * 2;
        int nw = ((corners & RoundedControlCorners.NorthWest) == RoundedControlCorners.NorthWest ? d : 0);
        int ne = ((corners & RoundedControlCorners.NorthEast) == RoundedControlCorners.NorthEast ? d : 0);
        int se = ((corners & RoundedControlCorners.SouthEast) == RoundedControlCorners.SouthEast ? d : 0);
        int sw = ((corners & RoundedControlCorners.SouthWest) == RoundedControlCorners.SouthWest ? d : 0);
        //path.AddLine(r.Left + nw, r.Top, r.Right - ne, r.Top);
        path.AddLine(r.Left + nw, r.Top, r.Right - ne, r.Top);
        if (ne > 0)
        {
            path.AddArc(Rectangle.FromLTRB(r.Right - ne, r.Top, r.Right, r.Top + ne), -90, 90);
        }
        path.AddLine(r.Right, r.Top + ne, r.Right, r.Bottom - se);
        if (se > 0)
        {
            path.AddArc(Rectangle.FromLTRB(r.Right - se, r.Bottom - se, r.Right, r.Bottom), 0, 90);
        }
        path.AddLine(r.Right - se, r.Bottom, r.Left + sw, r.Bottom);
        if (sw > 0)
        {
            path.AddArc(Rectangle.FromLTRB(r.Left, r.Bottom - sw, r.Left + sw, r.Bottom), 90, 90);
        }
        path.AddLine(r.Left, r.Bottom - sw, r.Left, r.Top + nw);
        if (nw > 0)
        {
            path.AddArc(Rectangle.FromLTRB(r.Left, r.Top, r.Left + nw, r.Top + nw), 180, 90);
        }
        path.CloseFigure();
        return path;
    }
}

我用来将其添加到表单的代码：

LabelEx oLabel1 = new LabelEx();
LabelEx oLabel2 = new LabelEx();
LabelEx oLabel3 = new LabelEx();
oLabel1.Top = 50;
oLabel2.Top = 100;
oLabel3.Top = 150;
oLabel1.Height = 25;
oLabel2.Height = 25;
oLabel1.Text = "Hello";
oLabel2.Text = "There";
scBase.Panel2.Controls.Add(oLabel1);
scBase.Panel2.Controls.Add(oLabel2);

protected override void OnPaint(PaintEventArgs e)
{
   //...
            Invalidate();
}