【C#】分享一个可灵活设置边框的Panel

---------------------------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。可自由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, 0, 0, this.Width - 1, this.Height - 1);
                        }
                        else //否则分别绘制线条
                        {
                            if ((BorderSide & ToolStripStatusLabelBorderSides.Top) == ToolStripStatusLabelBorderSides.Top)
                            {
                                g.DrawLine(pen, 0, 0, this.Width - 1, 0);
                            }

                            if ((BorderSide & ToolStripStatusLabelBorderSides.Right) == ToolStripStatusLabelBorderSides.Right)
                            {
                                g.DrawLine(pen, this.Width - 1, 0, this.Width - 1, this.Height - 1);
                            }

                            if ((BorderSide & ToolStripStatusLabelBorderSides.Bottom) == ToolStripStatusLabelBorderSides.Bottom)
                            {
                                g.DrawLine(pen, 0, this.Height - 1, this.Width - 1, this.Height - 1);
                            }

                            if ((BorderSide & ToolStripStatusLabelBorderSides.Left) == ToolStripStatusLabelBorderSides.Left)
                            {
                                g.DrawLine(pen, 0, 0, 0, this.Height - 1);
                            }
                        }
                    }
                }
                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时才能自由发挥；

* 无论单色或是三维模式，均可通过BorderSide自由启用/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。可自由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, 0, 0, this.Width - 1, this.Height - 1);
                        }
                        else //否则分别绘制线条
                        {
                            if ((BorderSide & ToolStripStatusLabelBorderSides.Top) == ToolStripStatusLabelBorderSides.Top)
                            { g.DrawLine(pen, 0, 0, this.Width - 1, 0); }

                            if ((BorderSide & ToolStripStatusLabelBorderSides.Right) == ToolStripStatusLabelBorderSides.Right)
                            { g.DrawLine(pen, this.Width - 1, 0, this.Width - 1, this.Height - 1); }

                            if ((BorderSide & ToolStripStatusLabelBorderSides.Bottom) == ToolStripStatusLabelBorderSides.Bottom)
                            { g.DrawLine(pen, 0, this.Height - 1, this.Width - 1, this.Height - 1); }

                            if ((BorderSide & ToolStripStatusLabelBorderSides.Left) == ToolStripStatusLabelBorderSides.Left)
                            { g.DrawLine(pen, 0, 0, 0, this.Height - 1); }
                        }
                    }
                }
            }
        }
    }
}

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