C#重繪windows窗體標題欄和邊框

摘要
windows桌面應用程序都有標准的標題欄和邊框，大部分程序也默認使用這些樣式，一些對視覺效果要求較高的程序，如QQ, MSN，迅雷等聊天工具的樣式則與傳統的windows程序大不相同，其中迅雷還將他們的BOLT界面引擎開放，使得大家也可以創建類似迅雷一樣的界面。那麼這些軟件的界面是怎樣實現的呢，使用C#是否也可以實現類似界面？

重繪方式
常見的自定義標題欄和邊框的方式有兩種，一種是隱藏標題欄和邊框（稱為非客戶區），然後在客戶區（可以放置控件的空間）使用一些常用的控件和圖片來表示邊框，這種方式較簡單而麻煩，但如標題欄的拖動，邊框的拖拽來改變窗體大小等效果，則有需要重新實現，另外有些客戶區的鼠標事件，控件布局等也需要注意調整；另一種則是大部分軟件實現方式，也較難一些；它利用windows的消息機制，截獲windows消息，從而改變消息的行為。即windows的一些消息，會引起窗體繪制或重繪標題欄和邊框的行為，因此只要結果這部分消息，然後開發人員自己處理繪制過程，並忽略默認行為，從而達到自定義的目的。

C#繪制接口
windows消息對於C#開發新手來說較生疏，原因是.net已經將windows消息機制進行了封裝，使得我們很難發現windows消息的蹤跡，其實它是以另一個身份存在著--事件。如控件的OnClick，Mouse等事件，都是對windows消息的封裝，這樣的目的更容易理解，和運用。.net提供了處理消息的接口，常用的方法為Control控件的void WndProc(ref Message m)方法，該方法用於接收任何發送到該控件的windows消息。那麼我們就可以通過重寫該方法來截獲繪制窗體標題欄和邊框的消息了。

找到了截獲windows消息的接口，那麼就需要知道哪些windows消息會引起窗體標題欄和邊框的重繪。使用工具SPY++查看消息，發現windows消息WM_NCPAINT(0x85)和WM_NCACTIVATE(0x86)，WM_NCRBUTTONDOWN(0x00A4)，WM_SETCURSOR(0x0020)，WM_NCLBUTTONUP(0x00A2)，WM_NCLBUTTONDOWN(0xA1)等會重繪標題欄和邊框。其中WM_NCPAINT和WM_NCACTIVATE會引起重繪標題欄和邊框，消息WM_NCRBUTTONDOWN會觸發標題欄的右鍵菜單，截獲該消息可以自定義標題欄的右鍵菜單；其他消息會引起ConrtolBox(最小化，最大化，關閉按鈕區域)的重繪。因此我們可以從截獲這些消息入手。如下為WndProc方法的結構：

using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Runtime.InteropServices;
using System.Diagnostics;

namespace CaptionBox {
    public class ThemeForm : Form {
        #region private structs

        struct _NonClientSizeInfo {
            public Size CaptionButtonSize;
            public Size BorderSize;
            public int CaptionHeight;
            public Rectangle CaptionRect;
            public Rectangle Rect;
            public Rectangle ClientRect;
            public int Width;
            public int Height;
        };

        #endregion

        #region constants

        const int WM_NCACTIVATE = 0x86;
        const int WM_NCPAINT = 0x85;
        const int WM_NCLBUTTONDOWN = 0xA1;
        const int WM_NCRBUTTONDOWN = 0x00A4;
        const int WM_NCRBUTTONUP = 0x00A5;
        const int WM_NCMOUSEMOVE = 0x00A0;
        const int WM_NCLBUTTONUP = 0x00A2;
        const int WM_NCCALCSIZE = 0x0083;
        const int WM_NCMOUSEHOVER = 0x02A0;
        const int WM_NCMOUSELEAVE = 0x02A2;
        const int WM_NCHITTEST = 0x0084;
        const int WM_NCCREATE = 0x0081;
        //const int WM_RBUTTONUP = 0x0205;

        const int WM_LBUTTONDOWN = 0x0201;
        const int WM_CAPTURECHANGED = 0x0215;
        const int WM_LBUTTONUP = 0x0202;
        const int WM_SETCURSOR = 0x0020;
        const int WM_CLOSE = 0x0010;
        const int WM_SYSCOMMAND = 0x0112;
        const int WM_MOUSEMOVE = 0x0200;
        const int WM_SIZE = 0x0005;
        const int WM_SIZING = 0x0214;
        const int WM_GETMINMAXINFO = 0x0024;
        const int WM_ENTERSIZEMOVE = 0x0231;
        const int WM_WINDOWPOSCHANGING = 0x0046;

        // FOR WM_SIZING MSG WPARAM
        const int WMSZ_BOTTOM = 6;
        const int WMSZ_BOTTOMLEFT = 7;
        const int WMSZ_BOTTOMRIGHT = 8;
        const int WMSZ_LEFT = 1;
        const int WMSZ_RIGHT = 2;
        const int WMSZ_TOP = 3;
        const int WMSZ_TOPLEFT = 4;
        const int WMSZ_TOPRIGHT = 5;

        // left mouse button is down.
        const int MK_LBUTTON = 0x0001;

        const int SC_CLOSE = 0xF060;
        const int SC_MAXIMIZE = 0xF030;
        const int SC_MINIMIZE = 0xF020;
        const int SC_RESTORE = 0xF120;
        const int SC_CONTEXTHELP = 0xF180;

        const int HTCAPTION = 2;
        const int HTCLOSE = 20;
        const int HTHELP = 21;
        const int HTMAXBUTTON = 9;
        const int HTMINBUTTON = 8;
        const int HTTOP = 12;

        const int SM_CYBORDER = 6;
        const int SM_CXBORDER = 5;
        const int SM_CYCAPTION = 4;

        const int CS_DropSHADOW = 0x20000;
        const int GCL_STYLE = (-26);

        #endregion

        #region windows api

        [DllImport("User32.dll")]
        private static extern IntPtr GetWindowDC(IntPtr hwnd);
        [DllImport("User32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool GetWindowRect(IntPtr hwnd, ref _RECT rect);
        [DllImport("User32.dll")]
        private static extern int ReleaseDC(IntPtr hwnd, IntPtr hdc);

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        public static extern int SetClassLong(IntPtr hwnd, int nIndex, int dwNewLong);
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        public static extern int GetClassLong(IntPtr hwnd, int nIndex);

        #endregion

        #region default constructor

        public ThemeForm() {
            Text = "ThemeForm1";
            CloseButtonImage = Properties.Resources.close.ToBitmap();
            CloseButtonHoverImage = Properties.Resources.close2.ToBitmap();
            CloseButtonPressDownImage = Properties.Resources.close2.ToBitmap();

            MaximumButtonImage = Properties.Resources.max.ToBitmap();
            MaximumButtonHoverImage = Properties.Resources.max2.ToBitmap();
            MaximumButtonPressDownImage = Properties.Resources.max2.ToBitmap();

            MaximumNormalButtonImage = Properties.Resources.maxnorm.ToBitmap();
            MaximumNormalButtonHoverImage = Properties.Resources.maxnorm2.ToBitmap();
            MaximumNormalButtonPressDownImage = Properties.Resources.maxnorm2.ToBitmap();

            MinimumButtonImage = Properties.Resources.min.ToBitmap();
            MinimumButtonHoverImage = Properties.Resources.min2.ToBitmap();
            MinimumButtonPressDownImage = Properties.Resources.min2.ToBitmap();

            HelpButtonImage = Properties.Resources.help.ToBitmap();
            HelpButtonHoverImage = Properties.Resources.help2.ToBitmap();
            HelpButtonPressDownImage = Properties.Resources.help2.ToBitmap();
            CaptionColor = Brushes.White;
            CaptionBackgroundColor = Color.DimGray;

            SetClassLong(this.Handle, GCL_STYLE, GetClassLong(this.Handle, GCL_STYLE) | CS_DropSHADOW); //API函數加載，實現窗體邊框陰影效果
        }

        #endregion

        [DefaultValue("")]
        [Browsable(true)]
        [Category("ControlBox")]
        public virtual ContextMenuStrip CaptionContextMenu { get; set; }

        protected virtual void OnCaptionContextMenu(int x, int y) {
            if (this.CaptionContextMenu != null)
                this.CaptionContextMenu.Show(x, y);
        }
       
        #region properties

        [Category("ControlBox")]
        [Description("Close button image in control box.")]
        [DisplayName("CloseButtonImage")]
        [DesignOnly(true)]
        public Image CloseButtonImage { get; set; }

        [Category("ControlBox")]
        [Description("Close button image pressed down in control box.")]
        [DisplayName("CloseButtonPressDownImage")]
        [DesignOnly(true)]
        public Image CloseButtonPressDownImage { get; set; }

        [Category("ControlBox")]
        [Description("Close button image hover in control box.")]
        [DisplayName("CloseButtonHoverImage")]
        [DesignOnly(true)]
        public Image CloseButtonHoverImage { get; set; }

        [Category("ControlBox")]
        [Description("Maximum button image in control box.")]
        [DisplayName("MaximumButtonImage")]
        [DesignOnly(true)]
        public Image MaximumButtonImage { get; set; }

        [Category("ControlBox")]
        [Description("Maximum button hover image in control box.")]
        [DisplayName("MaximumButtonHoverImage")]
        [DesignOnly(true)]
        public Image MaximumButtonHoverImage { get; set; }

        [Category("ControlBox")]
        [Description("Maximum button pressed down image in control box.")]
        [DisplayName("MaximumButtonPressDownImage")]
        [DesignOnly(true)]
        public Image MaximumButtonPressDownImage { get; set; }

        [Category("ControlBox")]
        [Description("Maximum Normal button image in control box.")]
        [DisplayName("MaximumNormalButtonImage")]
        [DesignOnly(true)]
        public Image MaximumNormalButtonImage { get; set; }

        [Category("ControlBox")]
        [Description("Maximum Normal button hover image in control box.")]
        [DisplayName("MaximumNormalButtonHoverImage")]
        [DesignOnly(true)]
        public Image MaximumNormalButtonHoverImage { get; set; }

        [Category("ControlBox")]
        [Description("Maximum Normal button pressed down image in control box.")]
        [DisplayName("MaximumNormalButtonPressDownImage")]
        [DesignOnly(true)]
        public Image MaximumNormalButtonPressDownImage { get; set; }

        [Category("ControlBox")]
        [Description("Minimum button image in control box.")]
        [DisplayName("MinimumButtonImage")]
        [DesignOnly(true)]
        public Image MinimumButtonImage { get; set; }

        [Category("ControlBox")]
        [Description("Minimum button hover image in control box.")]
        [DisplayName("MinimumButtonHoverImage")]
        [DesignOnly(true)]
        public Image MinimumButtonHoverImage { get; set; }

        [Category("ControlBox")]
        [Description("Minimum button pressed down image in control box.")]
        [DisplayName("MinimumButtonPressDownImage")]
        [DesignOnly(true)]
        public Image MinimumButtonPressDownImage { get; set; }

        [Category("ControlBox")]
        [Description("Help button image in control box.")]
        [DisplayName("HelpButtonImage")]
        [DesignOnly(true)]
        public Image HelpButtonImage { get; set; }

        [Category("ControlBox")]
        [Description("Help button hover image in control box.")]
        [DisplayName("HelpButtonHoverImage")]
        [DesignOnly(true)]
        public Image HelpButtonHoverImage { get; set; }

        [Category("ControlBox")]
        [Description("Help button pressed down image in control box.")]
        [DisplayName("HelpButtonPressDownImage")]
        [DesignOnly(true)]
        public Image HelpButtonPressDownImage { get; set; }

        [Category("CaptionColor")]
        [Description("The color of caption.")]
        [DisplayName("CaptionColor")]
        [DesignOnly(true)]
        public Brush CaptionColor { get; set; }

        [Category("CaptionColor")]
        [Description("The color of caption.")]
        [DisplayName("CaptionBackgroundColor")]
        [DefaultValue(typeof(Color), "Black")]
        [DesignOnly(true)]
        public Color CaptionBackgroundColor { get; set; }

        #endregion

        #region help methods

        private _NonClientSizeInfo GetNonClientInfo(IntPtr hwnd) {
            _NonClientSizeInfo info = new _NonClientSizeInfo();
            info.CaptionButtonSize = SystemInformation.CaptionButtonSize;
            info.CaptionHeight = SystemInformation.CaptionHeight;

            switch (this.FormBorderStyle) {
                case System.Windows.Forms.FormBorderStyle.Fixed3D:
                    info.BorderSize = SystemInformation.FixedFrameBorderSize;
                    break;
                case System.Windows.Forms.FormBorderStyle.FixedDialog:
                    info.BorderSize = SystemInformation.FixedFrameBorderSize;
                    break;
                case System.Windows.Forms.FormBorderStyle.FixedSingle:
                    info.BorderSize = SystemInformation.FixedFrameBorderSize;
                    break;
                case System.Windows.Forms.FormBorderStyle.FixedToolWindow:
                    info.BorderSize = SystemInformation.FixedFrameBorderSize;
                    info.CaptionButtonSize = SystemInformation.ToolWindowCaptionButtonSize;
                    info.CaptionHeight = SystemInformation.ToolWindowCaptionHeight;
                    break;
                case System.Windows.Forms.FormBorderStyle.Sizable:
                    info.BorderSize = SystemInformation.FrameBorderSize;
                    break;
                case System.Windows.Forms.FormBorderStyle.SizableToolWindow:
                    info.CaptionButtonSize = SystemInformation.ToolWindowCaptionButtonSize;
                    info.BorderSize = SystemInformation.FrameBorderSize;
                    info.CaptionHeight = SystemInformation.ToolWindowCaptionHeight;
                    break;
                default:
                    info.BorderSize = SystemInformation.BorderSize;
                    break;
            }

            _RECT areatRect = new _RECT();
            GetWindowRect(hwnd, ref areatRect);

            int width = areatRect.right - areatRect.left;
            int height = areatRect.bottom - areatRect.top;

            info.Width = width;
            info.Height = height;

            Point xy = new Point(areatRect.left, areatRect.top);
            xy.Offset(-areatRect.left, -areatRect.top);

            info.CaptionRect = new Rectangle(xy.X, xy.Y + info.BorderSize.Height, width, info.CaptionHeight);
            info.Rect = new Rectangle(xy.X, xy.Y, width, height);
            info.ClientRect = new Rectangle(xy.X + info.BorderSize.Width,
                xy.Y + info.CaptionHeight + info.BorderSize.Height,
                width - info.BorderSize.Width * 2,
                height - info.CaptionHeight - info.BorderSize.Height * 2);

            return info;
        }

        private void DrawTitle(Graphics g, _NonClientSizeInfo ncInfo, bool active) {
            int titleX;

            if (this.ShowIcon &&
                this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.FixedToolWindow &&
                this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.SizableToolWindow) {
                Size iconSize = SystemInformation.SmallIconSize;
                g.DrawIcon(this.Icon, new Rectangle(new Point(ncInfo.BorderSize.Width, ncInfo.BorderSize.Height + (ncInfo.CaptionHeight - iconSize.Height) / 2), iconSize));
                titleX = ncInfo.BorderSize.Width + iconSize.Width + ncInfo.BorderSize.Width;
            } else {
                titleX = ncInfo.BorderSize.Width;
            }

            SizeF captionTitleSize = g.MeasureString(this.Text, SystemFonts.CaptionFont);
            g.DrawString(this.Text, SystemFonts.CaptionFont, CaptionColor,
                    new RectangleF(titleX,
                        (ncInfo.BorderSize.Height + ncInfo.CaptionHeight - captionTitleSize.Height) / 2,
                        ncInfo.CaptionRect.Width - ncInfo.BorderSize.Width * 2 - SystemInformation.MinimumWindowSize.Width,
                        ncInfo.CaptionRect.Height), StringFormat.GenericTypographic);
        }

        private void DrawBorder(Graphics g, _NonClientSizeInfo ncInfo, Brush background, bool active) {
            Rectangle borderTop = new Rectangle(ncInfo.Rect.Left,
                    ncInfo.Rect.Top,
                    ncInfo.Rect.Left + ncInfo.Rect.Width,
                    ncInfo.Rect.Top + ncInfo.BorderSize.Height);
            Rectangle borderLeft = new Rectangle(
                    new Point(ncInfo.Rect.Location.X, ncInfo.Rect.Location.Y + ncInfo.BorderSize.Height),
                    new Size(ncInfo.BorderSize.Width, ncInfo.ClientRect.Height + ncInfo.CaptionHeight + ncInfo.BorderSize.Height));
            Rectangle borderRight = new Rectangle(ncInfo.Rect.Left + ncInfo.Rect.Width - ncInfo.BorderSize.Width,
                    ncInfo.Rect.Top + ncInfo.BorderSize.Height,
                    ncInfo.BorderSize.Width,
                    ncInfo.ClientRect.Height + ncInfo.CaptionHeight + ncInfo.BorderSize.Height);
            Rectangle borderBottom = new Rectangle(ncInfo.Rect.Left + ncInfo.BorderSize.Width,
                    ncInfo.Rect.Top + ncInfo.Rect.Height - ncInfo.BorderSize.Height,
                    ncInfo.Rect.Width - ncInfo.BorderSize.Width * 2,
                    ncInfo.Rect.Height);

            //Rectangle leftbottom = new Rectangle(new Point(ncInfo.Rect.Location.X, ncInfo.Rect.Height - ncInfo.BorderSize.Width * 2),
            //    new Size(ncInfo.BorderSize.Width * 2, ncInfo.BorderSize.Width * 2));

            //g.FillPie(Brushes.Red, leftbottom, 90, 180);
            //g.FillRectangle(Brushes.Red, leftbottom);
            // top border
            g.FillRectangle(background, borderTop);
            // left border
            g.FillRectangle(background, borderLeft);
            // right border
            g.FillRectangle(background, borderRight);
            // bottom border
            g.FillRectangle(background, borderBottom);
        }

        private void DrawCaption(IntPtr hwnd, bool active) {
            IntPtr dc;
            Graphics g;
            Size iconSize;
            _NonClientSizeInfo ncInfo;
            Brush backgroundColor = new SolidBrush(CaptionBackgroundColor);
            Brush foregroundColor = CaptionColor;

            iconSize = SystemInformation.SmallIconSize;

            dc = GetWindowDC(hwnd);
            ncInfo = GetNonClientInfo(hwnd);
            g = Graphics.FromHdc(dc);

            g.FillRectangle(backgroundColor, ncInfo.CaptionRect);

            DrawBorder(g, ncInfo, backgroundColor, active);
            DrawTitle(g, ncInfo, active);
            DrawControlBox(g, ncInfo, backgroundColor, this.ControlBox, this.MaximizeBox, this.MinimizeBox, this.HelpButton);
       
            g.Dispose();
            ReleaseDC(hwnd, dc);
        }

        private void DrawControlBox(Graphics g, _NonClientSizeInfo info, Brush background, bool closeBtn, bool maxBtn, bool minBtn, bool helpBtn) {
            if (this.ControlBox) {
                int closeBtnPosX = info.CaptionRect.Left + info.CaptionRect.Width - info.BorderSize.Width - info.CaptionButtonSize.Width;
                int maxBtnPosX = closeBtnPosX - info.CaptionButtonSize.Width;
                int minBtnPosX = maxBtnPosX - info.CaptionButtonSize.Width;
                int btnPosY = info.BorderSize.Height + (info.CaptionHeight - info.CaptionButtonSize.Height) / 2;

                Rectangle btnRect = new Rectangle(new Point(closeBtnPosX, btnPosY), info.CaptionButtonSize);
                Rectangle maxRect = new Rectangle(new Point(maxBtnPosX, btnPosY), info.CaptionButtonSize);
                Rectangle minRect = new Rectangle(new Point(minBtnPosX, btnPosY), info.CaptionButtonSize);

                Brush backgroundColor = new SolidBrush(CaptionBackgroundColor);

                g.FillRectangle(backgroundColor, btnRect);
                g.FillRectangle(backgroundColor, maxRect);
                g.FillRectangle(backgroundColor, minRect);

                g.DrawImage(CloseButtonImage, btnRect);

                if (this.MaximizeBox || this.MinimizeBox) {
                    if (this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.FixedToolWindow &&
                        this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.SizableToolWindow) {
                        if (this.WindowState == FormWindowState.Maximized) {
                            g.DrawImage(MaximumNormalButtonImage, maxRect);
                        } else {
                            g.DrawImage(MaximumButtonImage, maxRect);
                        }
                        g.DrawImage(MinimumButtonImage, minRect);
                    }
                } else if (this.HelpButton) {
                    if (this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.FixedToolWindow &&
                        this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.SizableToolWindow) {
                        g.DrawImage(HelpButtonImage, maxRect);
                    }
                }
            }
        }

        #endregion

        #region Major method WndProc

        private int LOBYTE(long p) { return (int)(p & 0x0000FFFF); }
        private int HIBYTE(long p) { return (int)(p >> 16); }

        protected override void WndProc(ref Message m) {
            if (this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.None) {
                switch (m.Msg) {
                    case WM_NCPAINT:
                        DrawCaption(m.HWnd, Form.ActiveForm == this);
                        return;
                    case WM_NCACTIVATE:
                        DrawCaption(m.HWnd, m.WParam.ToInt32() > 0);
                        return;
                    case WM_NCRBUTTONDOWN: {
                            int posX, posY;
                            int wp = m.WParam.ToInt32();
                            long lp = m.LParam.ToInt64();
                            posX = LOBYTE(lp);
                            posY = HIBYTE(lp);

                            if (wp == HTCAPTION) {
                                Point pt = this.PointToClient(new Point(posX, posY));
                                if (this.CaptionContextMenu != null) {
                                    this.CaptionContextMenu.Show(posX, posY);
                                    return;
                                }
                            }
                            break;
                        }
                    case WM_SETCURSOR:
                        if (this.ControlBox) {
                            int posX, posY;
                            int wp = m.WParam.ToInt32();
                            long lp = m.LParam.ToInt64();
                            posX = LOBYTE(lp);
                            posY = HIBYTE(lp);

                            Brush backgroundColor = new SolidBrush(CaptionBackgroundColor);
                            _NonClientSizeInfo ncInfo = GetNonClientInfo(m.HWnd);
                            IntPtr dc = GetWindowDC(m.HWnd);

                            Graphics g = Graphics.FromHdc(dc);
                            int closeBtnPosX = ncInfo.CaptionRect.Left + ncInfo.CaptionRect.Width - ncInfo.BorderSize.Width - ncInfo.CaptionButtonSize.Width;
                            int maxBtnPosX, minBtnPosX;
                            maxBtnPosX = closeBtnPosX - ncInfo.CaptionButtonSize.Width;
                            minBtnPosX = maxBtnPosX - ncInfo.CaptionButtonSize.Width;

                            int btnPosY = ncInfo.BorderSize.Height + (ncInfo.CaptionHeight - ncInfo.CaptionButtonSize.Height) / 2;

                            Rectangle btnRect = new Rectangle(new Point(closeBtnPosX, btnPosY), ncInfo.CaptionButtonSize);
                            Rectangle maxRect = new Rectangle(new Point(maxBtnPosX, btnPosY), ncInfo.CaptionButtonSize);
                            Rectangle minRect = new Rectangle(new Point(minBtnPosX, btnPosY), ncInfo.CaptionButtonSize);

                            g.FillRectangle(backgroundColor, btnRect);
                            g.FillRectangle(backgroundColor, maxRect);
                            g.FillRectangle(backgroundColor, minRect);

                            if (posX != HTCLOSE) {
                                g.DrawImage(CloseButtonImage, btnRect);
                            } else if (MouseButtons != System.Windows.Forms.MouseButtons.Left) {
                                g.DrawImage(CloseButtonHoverImage, btnRect);
                            } else {
                                g.DrawImage(CloseButtonPressDownImage, btnRect);
                            }

                            if (this.MaximizeBox || this.MinimizeBox) {
                                if (this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.FixedToolWindow &&
                                    this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.SizableToolWindow) {
                                    if (this.WindowState == FormWindowState.Maximized) {
                                        if (this.MaximizeBox) {
                                            if (posX != HTMAXBUTTON) {
                                                g.DrawImage(MaximumNormalButtonImage, maxRect);
                                            } else if (MouseButtons != System.Windows.Forms.MouseButtons.Left) {
                                                g.DrawImage(MaximumNormalButtonHoverImage, maxRect);
                                            } else {
                                                g.DrawImage(MaximumNormalButtonPressDownImage, maxRect);
                                            }
                                        } else {
                                            g.DrawImage(MaximumNormalButtonImage, maxRect);
                                        }
                                    } else {
                                        if (this.MaximizeBox) {
                                            if (posX != HTMAXBUTTON) {
                                                g.DrawImage(MaximumButtonImage, maxRect);
                                            } else if (MouseButtons != System.Windows.Forms.MouseButtons.Left) {
                                                g.DrawImage(MaximumButtonHoverImage, maxRect);
                                            } else {
                                                g.DrawImage(MaximumButtonPressDownImage, maxRect);
                                            }
                                        } else {
                                            g.DrawImage(MaximumButtonImage, maxRect);
                                        }
                                    }

                                    if (this.MinimizeBox) {
                                        if (posX != HTMINBUTTON) {
                                            g.DrawImage(MinimumButtonImage, minRect);
                                        } else if (MouseButtons != System.Windows.Forms.MouseButtons.Left) {
                                            g.DrawImage(MinimumButtonHoverImage, minRect);
                                        } else {
                                            g.DrawImage(MinimumButtonPressDownImage, minRect);
                                        }
                                    } else {
                                        g.DrawImage(MinimumButtonImage, minRect);
                                    }
                                }
                            } else if (this.HelpButton) {
                                if (this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.FixedToolWindow &&
                                    this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.SizableToolWindow) {
                                    if (posX != HTHELP) {
                                        g.DrawImage(HelpButtonImage, maxRect);
                                    } else if (MouseButtons != System.Windows.Forms.MouseButtons.Left) {
                                        g.DrawImage(HelpButtonHoverImage, maxRect);
                                    } else {
                                        g.DrawImage(HelpButtonPressDownImage, maxRect);
                                    }
                                }
                            }

                            g.Dispose();
                            ReleaseDC(m.HWnd, dc);
                        }
                        break;
                    case WM_NCLBUTTONUP: {
                            int wp = m.WParam.ToInt32();
                            switch (wp) {
                                case HTCLOSE:
                                    m.Msg = WM_SYSCOMMAND;
                                    m.WParam = new IntPtr(SC_CLOSE);
                                    break;
                                case HTMAXBUTTON:
                                    if (this.MaximizeBox) {
                                        m.Msg = WM_SYSCOMMAND;
                                        if (this.WindowState == FormWindowState.Maximized) {
                                            m.WParam = new IntPtr(SC_RESTORE);
                                        } else {
                                            m.WParam = new IntPtr(SC_MAXIMIZE);
                                        }
                                    }
                                    break;
                                case HTMINBUTTON:
                                    if (this.MinimizeBox) {
                                        m.Msg = WM_SYSCOMMAND;
                                        m.WParam = new IntPtr(SC_MINIMIZE);
                                    }
                                    break;
                                case HTHELP:
                                    m.Msg = WM_SYSCOMMAND;
                                    m.WParam = new IntPtr(SC_CONTEXTHELP);
                                    break;
                                default:
                                    break;
                            }
                            break;
                        }

                    case WM_NCLBUTTONDOWN:
                        if (this.ControlBox) {
                            bool ret = false;
                            int posX, posY;
                            int wp = m.WParam.ToInt32();
                            long lp = m.LParam.ToInt64();
                            posX = LOBYTE(lp);
                            posY = HIBYTE(lp);

                            _NonClientSizeInfo ncInfo = GetNonClientInfo(m.HWnd);
                            IntPtr dc = GetWindowDC(m.HWnd);
                            Brush backgroundColor = new SolidBrush(CaptionBackgroundColor);

                            Graphics g = Graphics.FromHdc(dc);
                            int closeBtnPosX = ncInfo.CaptionRect.Left + ncInfo.CaptionRect.Width - ncInfo.BorderSize.Width - ncInfo.CaptionButtonSize.Width;
                            int maxBtnPosX, minBtnPosX;
                            int btnPosY = ncInfo.BorderSize.Height + (ncInfo.CaptionHeight - ncInfo.CaptionButtonSize.Height) / 2;
                            maxBtnPosX = closeBtnPosX - ncInfo.CaptionButtonSize.Width;
                            minBtnPosX = maxBtnPosX - ncInfo.CaptionButtonSize.Width;

                            Rectangle btnRect = new Rectangle(new Point(closeBtnPosX, btnPosY), ncInfo.CaptionButtonSize);
                            Rectangle maxRect = new Rectangle(new Point(maxBtnPosX, btnPosY), ncInfo.CaptionButtonSize);
                            Rectangle minRect = new Rectangle(new Point(minBtnPosX, btnPosY), ncInfo.CaptionButtonSize);

                            g.FillRectangle(backgroundColor, btnRect);
                            g.FillRectangle(backgroundColor, maxRect);
                            g.FillRectangle(backgroundColor, minRect);

                            if (wp == HTCLOSE) {
                                g.DrawImage(CloseButtonPressDownImage, btnRect);
                                ret = true;
                            } else {
                                g.DrawImage(CloseButtonImage, btnRect);
                            }

                            if (this.MaximizeBox || this.MinimizeBox) {
                                if (this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.SizableToolWindow &&
                                    this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.FixedToolWindow) {
                                    if (this.WindowState == FormWindowState.Maximized) {
                                        if (wp == HTMAXBUTTON && this.MaximizeBox) {
                                            minBtnPosX = maxBtnPosX - ncInfo.CaptionButtonSize.Width;
                                            g.DrawImage(MaximumNormalButtonPressDownImage, maxRect);
                                            ret = true;
                                        } else {
                                            g.DrawImage(MaximumNormalButtonImage, maxRect);
                                        }
                                    } else {
                                        if (wp == HTMAXBUTTON && this.MaximizeBox) {
                                            minBtnPosX = maxBtnPosX - ncInfo.CaptionButtonSize.Width;
                                            g.DrawImage(MaximumButtonPressDownImage, maxRect);
                                            ret = true;
                                        } else {
                                            g.DrawImage(MaximumButtonImage, maxRect);
                                        }
                                    }
                                    if (wp == HTMINBUTTON && this.MinimizeBox) {
                                        g.DrawImage(MinimumButtonPressDownImage, minRect);
                                        ret = true;
                                    } else {
                                        g.DrawImage(MinimumButtonImage, minRect);
                                    }
                                }
                            } else if (this.HelpButton) {
                                if (this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.FixedToolWindow &&
                                    this.FormBorderStyle != System.Windows.Forms.FormBorderStyle.SizableToolWindow) {
                                    if (wp == HTHELP) {
                                        g.DrawImage(HelpButtonPressDownImage, maxRect);
                                        ret = true;
                                    } else {
                                        g.DrawImage(HelpButtonImage, maxRect);
                                    }
                                }
                            }

                            g.Dispose();
                            ReleaseDC(m.HWnd, dc);

                            if (ret)
                                return;
                        }
                        break;
                }
            }

            base.WndProc(ref m);
        }

        #endregion
    }
}
 

運行效果：