---------------------------更新：2014-05-19---------------------------
优化了一下逻辑，就是既然可以通过设置BorderSide=None来不显示边框，那么再设计一个BorderMode.None就显得多余，即BorderMode枚举只需要2个元素即可（Single和ThreeD），而与其弄一个只有2个元素的枚举还不如干脆不要这个枚举，改为给PanelEx加一个布尔属性BorderIsSingleMode（之所以这样命名是考虑把与边框相关的属性都以Border开头，方便在设计器中使用），为true则代表单色模式，否则为三维模式，而显不显示、显示哪些边则完全交给BorderSide控制，同时把BorderSide的默认值设为None，即默认不显示边框。修改后的代码如下：
using System;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms; namespace AhDung.Controls
{
/// <summary>
/// 可设置边框样式的Panel
/// </summary>
public class PanelEx : Panel
{
private Color borderColor;
private Border3DStyle border3DStyle;
private ToolStripStatusLabelBorderSides borderSide;
private bool borderIsSingleMode; [DefaultValue(true), Description("指定边框是否为单色模式。false代表三维模式")]
public bool BorderIsSingleMode
{
get { return borderIsSingleMode; }
set
{
if (borderIsSingleMode == value) { return; }
borderIsSingleMode = value;
this.Invalidate();
}
} [DefaultValue(typeof(Color), "Black"), Description("边框颜色。仅当边框为单色模式时有效")]
public Color BorderColor
{
get { return borderColor; }
set
{
if (borderColor == value) { return; }
borderColor = value;
this.Invalidate();
}
} [DefaultValue(Border3DStyle.Etched), Description("边框三维样式。仅当边框为三维模式时有效")]
public Border3DStyle Border3DStyle
{
get { return border3DStyle; }
set
{
if (border3DStyle == value) { return; }
border3DStyle = value;
this.Invalidate();
}
} //之所以不直接用Border3DSide是因为这货不被设计器支持，没法灵活选择位置组合
[DefaultValue(ToolStripStatusLabelBorderSides.None), Description("边框位置。可*启用各个方位的边框")]
public ToolStripStatusLabelBorderSides BorderSide
{
get { return borderSide; }
set
{
if (borderSide == value) { return; }
borderSide = value;
this.Invalidate();
}
} public PanelEx()
{
this.borderIsSingleMode = true;
this.borderColor = Color.Black;
this.border3DStyle = System.Windows.Forms.Border3DStyle.Etched;
this.borderSide = ToolStripStatusLabelBorderSides.None;
} protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
if (this.BorderStyle != System.Windows.Forms.BorderStyle.None
|| BorderSide == ToolStripStatusLabelBorderSides.None)
{ return; } using (Graphics g = e.Graphics)
{
//单色模式
if (this.BorderIsSingleMode)
{
using (Pen pen = new Pen(BorderColor))
{
//若是四条边都启用，则直接画矩形
if (BorderSide == ToolStripStatusLabelBorderSides.All)
{
g.DrawRectangle(pen, , , this.Width - , this.Height - );
}
else //否则分别绘制线条
{
if ((BorderSide & ToolStripStatusLabelBorderSides.Top) == ToolStripStatusLabelBorderSides.Top)
{
g.DrawLine(pen, , , this.Width - , );
} if ((BorderSide & ToolStripStatusLabelBorderSides.Right) == ToolStripStatusLabelBorderSides.Right)
{
g.DrawLine(pen, this.Width - , , this.Width - , this.Height - );
} if ((BorderSide & ToolStripStatusLabelBorderSides.Bottom) == ToolStripStatusLabelBorderSides.Bottom)
{
g.DrawLine(pen, , this.Height - , this.Width - , this.Height - );
} if ((BorderSide & ToolStripStatusLabelBorderSides.Left) == ToolStripStatusLabelBorderSides.Left)
{
g.DrawLine(pen, , , , this.Height - );
}
}
}
}
else //三维模式
{
ControlPaint.DrawBorder3D(g, this.ClientRectangle, this.Border3DStyle, (Border3DSide) BorderSide); //这儿要将ToolStripStatusLabelBorderSides转换为Border3DSide
}
}
}
}
}
---------------------------原文：2014-05-14---------------------------
注：此乃Winform控件，开发环境为.net 2.0
工作需要，我对自带Panel进行了一下呈现上的扩展，方便设置边框效果。先看效果：
说明：
* 只有当原有属性BorderStyle为None时才能应用样式，此时可通过BorderMode设置【不显示、单色、三维】三种边框模式；这是因为BorderStyle为FixedSingle或Fixed3D时，自带边框似乎不属于Panel的一部分，不能控制或清除，我猜应该是底层API负责绘制的，所以唯有在None时才能*发挥；
* 无论单色或是三维模式，均可通过BorderSide*启用/禁用各个方位的边框；
* 在单色模式下，可通过BorderColor设置边框颜色，此时设置三维样式（Border3DStyle）无效；
* 在三维模式下，可通过Border3DStyle设置三维样式，此时设置边框颜色（BorderColor）无效；
代码在此：
using System;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms; namespace AhDung.Controls
{
/// <summary>
/// 边框模式（无、单色、三维）
/// </summary>
public enum BorderMode { None, Single, ThreeD } /// <summary>
/// 可设置边框样式的Panel
/// </summary>
public class PanelEx : Panel
{
private Color borderColor;
private Border3DStyle border3DStyle;
private ToolStripStatusLabelBorderSides borderSide;
private BorderMode borderMode; [DefaultValue(BorderMode.None), Description("边框模式。可设置单色模式或三维模式")]
public BorderMode BorderMode
{
get { return borderMode; }
set
{
if (borderMode == value) { return; }
borderMode = value;
this.Invalidate();
}
} [DefaultValue(typeof(Color), "Black"), Description("边框颜色。仅当边框为单色模式时有效")]
public Color BorderColor
{
get { return borderColor; }
set
{
if (borderColor == value) { return; }
borderColor = value;
this.Invalidate();
}
} [DefaultValue(Border3DStyle.Etched), Description("边框三维样式。仅当边框为三维模式时有效")]
public Border3DStyle Border3DStyle
{
get { return border3DStyle; }
set
{
if (border3DStyle == value) { return; }
border3DStyle = value;
this.Invalidate();
}
} //之所以不直接用Border3DSide是因为这货不被设计器支持，没法灵活选择位置组合
[DefaultValue(ToolStripStatusLabelBorderSides.All), Description("边框位置。可*启用各个方位的边框")]
public ToolStripStatusLabelBorderSides BorderSide
{
get { return borderSide; }
set
{
if (borderSide == value) { return; }
borderSide = value;
this.Invalidate();
}
} public PanelEx()
{
this.borderMode = BorderMode.None;
this.borderColor = Color.Black;
this.border3DStyle = System.Windows.Forms.Border3DStyle.Etched;
this.borderSide = ToolStripStatusLabelBorderSides.All;
} protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
if (this.BorderStyle != System.Windows.Forms.BorderStyle.None
|| BorderMode == BorderMode.None
|| BorderSide == ToolStripStatusLabelBorderSides.None)
{ return; } using (Graphics g = e.Graphics)
{
//三维模式
if (this.BorderMode == BorderMode.ThreeD)
{
ControlPaint.DrawBorder3D(g, this.ClientRectangle, this.Border3DStyle, (Border3DSide)BorderSide);//这儿要将ToolStripStatusLabelBorderSides转换为Border3DSide
}
else //单色模式
{
using (Pen pen = new Pen(BorderColor))
{
//若是四条边都启用，则直接画矩形
if (BorderSide == ToolStripStatusLabelBorderSides.All)
{
g.DrawRectangle(pen, , , this.Width - , this.Height - );
}
else //否则分别绘制线条
{
if ((BorderSide & ToolStripStatusLabelBorderSides.Top) == ToolStripStatusLabelBorderSides.Top)
{ g.DrawLine(pen, , , this.Width - , ); } if ((BorderSide & ToolStripStatusLabelBorderSides.Right) == ToolStripStatusLabelBorderSides.Right)
{ g.DrawLine(pen, this.Width - , , this.Width - , this.Height - ); } if ((BorderSide & ToolStripStatusLabelBorderSides.Bottom) == ToolStripStatusLabelBorderSides.Bottom)
{ g.DrawLine(pen, , this.Height - , this.Width - , this.Height - ); } if ((BorderSide & ToolStripStatusLabelBorderSides.Left) == ToolStripStatusLabelBorderSides.Left)
{ g.DrawLine(pen, , , , this.Height - ); }
}
}
}
}
}
}
}
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