给WPF程序增加玻璃效果

在Vista中增加了一种Aero新界面，也就是我们所说的玻璃效果，这种效果比较酷，我也常常喜欢在自己写的小程序中加入这种效果。

　　　　

实现这种效果并不难，也就是两个API，MSDN的文章将玻璃框扩展到 WPF 应用程序详细介绍了如何实现这种效果。在google上拿"C# DwmExtendFrameIntoClientArea"做关键字，也能搜到一大把。

我一般是用的CodeProject的文章Adding Glass Effect to WPF using Attached Properties上所述的那样，通过依赖属性注入这种效果，只要在窗口中加一句话src:GlassEffect.IsEnabled="True"即可使能这种效果，用起来非常方便。通过这种方式实现起来的效果如下：

　　　　

看起来一起都非常简单，但这种方法只是仅仅实现了玻璃效果，还有几个不完善的地方：

1. 这种方法只能实现全屏玻璃效果，不能实现部分玻璃效果。
2. 实现玻璃效果后，我们往往还需要隐藏标题栏中的图标和文字。
3. 那些玻璃化的部分不能像标题栏那样通过鼠标拖动窗口。

因此，我将那个代码改动了一下，增加了上述功能，代码如下：  

    public class GlassInfo: System.Windows.Markup.MarkupExtension
    {
        public int TopMargin { get; set; }
        public bool ShowIcon { get; set; }
        public bool ShowTitle { get; set; }

        public GlassInfo()
        {
            TopMargin = -1;
            ShowIcon = true;
            ShowTitle = true;
        }

        public override object ProvideValue(IServiceProvider serviceProvider)
        {
            return this;
        }
    }
    
    public class GlassEffect
    {
        public static GlassInfo GetInfo(DependencyObject obj)
        {
            return (GlassInfo)obj.GetValue(InfoProperty);
        }

        public static void SetInfo(DependencyObject obj, GlassInfo value)
        {
            obj.SetValue(InfoProperty, value);
        }

        public static readonly DependencyProperty InfoProperty =
            DependencyProperty.RegisterAttached("Info", typeof(GlassInfo), typeof(GlassEffect), new FrameworkPropertyMetadata(OnIsEnabledChanged));


        public static void OnIsEnabledChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args)
        {
            if (System.ComponentModel.DesignerProperties.GetIsInDesignMode(obj))
                return;
            
            (obj as Window).Loaded += (s, e) => ApplyGlassEffect(obj as Window, args.NewValue as GlassInfo);

            EnableMouseDrag(obj as Window,(args.NewValue as GlassInfo).TopMargin);
        }

        static void ApplyGlassEffect(Window window, GlassInfo info)
        {
            if (!DwmIsCompositionEnabled())
                return;

            var originalBackground = window.Background;
            window.Background = Brushes.Transparent;

            try
            {
                IntPtr mainWindowPtr = new WindowInteropHelper(window).Handle;
                HwndSource mainWindowSrc = HwndSource.FromHwnd(mainWindowPtr);
                mainWindowSrc.CompositionTarget.BackgroundColor = Color.FromArgb(0, 0, 0, 0);

                var margins = info.TopMargin == -1 ? new MARGINS(-1, -1, -1, -1) : new MARGINS { Top = info.TopMargin };
                DwmExtendFrameIntoClientArea(mainWindowPtr, ref margins);

                ApplyWindowThemeAttribute(info, mainWindowPtr);
            }
            catch (DllNotFoundException)
            {
                window.Background = originalBackground;
            }
        }

        static void ApplyWindowThemeAttribute(GlassInfo info, IntPtr mainWindowPtr)
        {
            WTA_OPTIONS ops = new WTA_OPTIONS();

            // We Want To Hide the Caption and the Icon
            ops.Flags = WTNCA_NODRAWCAPTION | WTNCA_NODRAWICON | WTNCA_NOSYSMENU;

            // If we set the Mask to the same value as the Flags, the Flags are Added. If Not They are Removed
            if (!info.ShowTitle)
            {
                ops.Mask |= WTNCA_NODRAWCAPTION;
            }
            if (!info.ShowIcon)
            {
                ops.Mask |= WTNCA_NODRAWICON | WTNCA_NOSYSMENU;
            }

            // Set It, The Marshal.Sizeof() stuff is to get the right size of the custom struct, and in UINT/DWORD Form
            SetWindowThemeAttribute(mainWindowPtr, WindowThemeAttributeType.WTA_NONCLIENT,
                ref ops, (uint)Marshal.SizeOf(typeof(WTA_OPTIONS)));
        }

        #region 设置任意位置拖动效果API
        const int WM_NCLBUTTONDOWN = 0xA1;
        const int HT_CAPTION = 0x2;

        [DllImportAttribute("user32.dll")]
        static extern int SendMessage(IntPtr hWnd,
                         int Msg, int wParam, int lParam);
        [DllImportAttribute("user32.dll")]
        static extern bool ReleaseCapture();

        static void EnableMouseDrag(Window window,int topMargin)
        {
            window.MouseLeftButtonDown += (s, e) =>
            {
                var win = s as Window;

                var point = e.GetPosition(win);
                if (point.Y > topMargin)
                    return;
            
                Console.WriteLine(e.OriginalSource);
                var mainWindowPtr = new WindowInteropHelper(win).Handle;
                ReleaseCapture();
                SendMessage(mainWindowPtr, WM_NCLBUTTONDOWN, HT_CAPTION, 0);
            };
        }
        #endregion

        #region 设置玻璃效果API
        [StructLayout(LayoutKind.Sequential)]
        struct MARGINS
        {
            public int Left;
            public int Right;
            public int Top;
            public int Bottom;

            public MARGINS(int left,int right,int top,int bottom)
            {
                this.Left = left;
                this.Right = right;
                this.Top = top;
                this.Bottom = bottom;
            }

            public MARGINS(Thickness margin)
            {
                this.Left = (int)margin.Left;
                this.Right = (int)margin.Right;
                this.Top = (int)margin.Top;
                this.Bottom = (int)margin.Bottom;
            }
        };


        [DllImport("DwmApi.dll")]
        static extern int DwmExtendFrameIntoClientArea(IntPtr hwnd, ref MARGINS pMarInset);

        [DllImport("dwmapi.dll", PreserveSig = false)]
        static extern bool DwmIsCompositionEnabled();

        public static readonly DependencyProperty IsEnabledProperty =
            DependencyProperty.RegisterAttached("IsEnabled",
                typeof(Boolean),
                typeof(GlassEffect),
                new FrameworkPropertyMetadata(OnIsEnabledChanged)); 
        #endregion

        #region 设置标题栏属性

        /// <summary>
        /// Do Not Draw The Caption (Text)
        /// </summary>
        public static uint WTNCA_NODRAWCAPTION = 0x00000001;
        /// <summary>
        /// Do Not Draw the Icon
        /// </summary>
        public static uint WTNCA_NODRAWICON = 0x00000002;
        /// <summary>
        /// Do Not Show the System Menu
        /// </summary>
        public static uint WTNCA_NOSYSMENU = 0x00000004;
        /// <summary>
        /// Do Not Mirror the Question mark Symbol
        /// </summary>
        public static uint WTNCA_NOMIRRORHELP = 0x00000008;

        /// <summary>
        /// The Options of What Attributes to Add/Remove
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        struct WTA_OPTIONS
        {
            public uint Flags;
            public uint Mask;
        }

        /// <summary>
        /// What Type of Attributes? (Only One is Currently Defined)
        /// </summary>
        enum WindowThemeAttributeType
        {
            WTA_NONCLIENT = 1,
        };

        /// <summary>
        /// Set The Window's Theme Attributes
        /// </summary>
        /// <param name="hWnd">The Handle to the Window</param>
        /// <param name="wtype">What Type of Attributes</param>
        /// <param name="attributes">The Attributes to Add/Remove</param>
        /// <param name="size">The Size of the Attributes Struct</param>
        /// <returns>If The Call Was Successful or Not</returns>
        [DllImport("UxTheme.dll")]
        static extern int SetWindowThemeAttribute(IntPtr hWnd, WindowThemeAttributeType wtype, ref WTA_OPTIONS attributes, uint size); 
        #endregion

    }

使用示例如下：

<Window x:Class="WpfApplication.MainWindow"
    … …
    src:GlassEffect.Info="{util:GlassInfo TopMargin=32, ShowIcon=False, ShowTitle=False}">

最终效果如下：