WINAPI / DWMAPI具有不规则形状的模糊窗口

Question

注意：这不是无边框窗口的问题。

因此，前几天在Windows 7上浏览“开始”菜单时，我偶然发现了该程序：

这是一个本地Windows程序，称为“数学输入面板”。现在，我对窗口形状感到好奇。我知道它不是完全由DWM绘制的，因为边框和“关闭”按钮看起来像是腥的，并且窗口没有阴影（我启用了阴影）。关于如何进行此操作，我的第一个猜测是使用DwmEnableBlurBehindWindow，但我无法想象它可用于不规则的窗口形状，对吗？（或者还有另一种方法可以做到这一点，或者完全是微软的巫术？）

Answer 1

这是一个快速被黑客入侵的WPF解决方案。它采用hRgnBlur的的DWM_BLURBEHIND结构，以及一些互操作。

本示例将在窗口上应用椭圆形的背景模糊。

您可以轻松地将其转换为附加属性或行为，以实现MVVM友好性。收听WM_DWMCOMPOSITIONCHANGED消息并根据需要重新应用模糊效果也是一个好主意。

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        WindowStyle = WindowStyle.None;
        AllowsTransparency = true;

        SourceInitialized += OnSourceInitialized;
    }

    private void OnSourceInitialized(object sender, EventArgs eventArgs)
    {
        if (!NativeMethods.DwmIsCompositionEnabled())
            return;

        var hwnd = new WindowInteropHelper(this).Handle;

        var hwndSource = HwndSource.FromHwnd(hwnd);
        var sizeFactor = hwndSource.CompositionTarget.TransformToDevice.Transform(new Vector(1.0, 1.0));

        Background = System.Windows.Media.Brushes.Transparent;
        hwndSource.CompositionTarget.BackgroundColor = Colors.Transparent;

        using (var path = new GraphicsPath())
        {
            path.AddEllipse(0, 0, (int)(ActualWidth * sizeFactor.X), (int)(ActualHeight * sizeFactor.Y));

            using (var region = new Region(path))
            using (var graphics = Graphics.FromHwnd(hwnd))
            {
                var hRgn = region.GetHrgn(graphics);

                var blur = new NativeMethods.DWM_BLURBEHIND
                {
                    dwFlags = NativeMethods.DWM_BB.DWM_BB_ENABLE | NativeMethods.DWM_BB.DWM_BB_BLURREGION | NativeMethods.DWM_BB.DWM_BB_TRANSITIONONMAXIMIZED,
                    fEnable = true,
                    hRgnBlur = hRgn,
                    fTransitionOnMaximized = true
                };

                NativeMethods.DwmEnableBlurBehindWindow(hwnd, ref blur);

                region.ReleaseHrgn(hRgn);
            }
        }
    }

    [SuppressUnmanagedCodeSecurity]
    private static class NativeMethods
    {
        [StructLayout(LayoutKind.Sequential)]
        public struct DWM_BLURBEHIND
        {
            public DWM_BB dwFlags;
            public bool fEnable;
            public IntPtr hRgnBlur;
            public bool fTransitionOnMaximized;
        }

        [Flags]
        public enum DWM_BB
        {
            DWM_BB_ENABLE = 1,
            DWM_BB_BLURREGION = 2,
            DWM_BB_TRANSITIONONMAXIMIZED = 4
        }

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

        [DllImport("dwmapi.dll", PreserveSig = false)]
        public static extern void DwmEnableBlurBehindWindow(IntPtr hwnd, ref DWM_BLURBEHIND blurBehind);
    }
}

与以下XAML一起使用：

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        WindowStyle = WindowStyle.None;
        AllowsTransparency = true;

        SourceInitialized += OnSourceInitialized;
    }

    private void OnSourceInitialized(object sender, EventArgs eventArgs)
    {
        if (!NativeMethods.DwmIsCompositionEnabled())
            return;

        var hwnd = new WindowInteropHelper(this).Handle;

        var hwndSource = HwndSource.FromHwnd(hwnd);
        var sizeFactor = hwndSource.CompositionTarget.TransformToDevice.Transform(new Vector(1.0, 1.0));

        Background = System.Windows.Media.Brushes.Transparent;
        hwndSource.CompositionTarget.BackgroundColor = Colors.Transparent;

        using (var path = new GraphicsPath())
        {
            path.AddEllipse(0, 0, (int)(ActualWidth * sizeFactor.X), (int)(ActualHeight * sizeFactor.Y));

            using (var region = new Region(path))
            using (var graphics = Graphics.FromHwnd(hwnd))
            {
                var hRgn = region.GetHrgn(graphics);

                var blur = new NativeMethods.DWM_BLURBEHIND
                {
                    dwFlags = NativeMethods.DWM_BB.DWM_BB_ENABLE | NativeMethods.DWM_BB.DWM_BB_BLURREGION | NativeMethods.DWM_BB.DWM_BB_TRANSITIONONMAXIMIZED,
                    fEnable = true,
                    hRgnBlur = hRgn,
                    fTransitionOnMaximized = true
                };

                NativeMethods.DwmEnableBlurBehindWindow(hwnd, ref blur);

                region.ReleaseHrgn(hRgn);
            }
        }
    }

    [SuppressUnmanagedCodeSecurity]
    private static class NativeMethods
    {
        [StructLayout(LayoutKind.Sequential)]
        public struct DWM_BLURBEHIND
        {
            public DWM_BB dwFlags;
            public bool fEnable;
            public IntPtr hRgnBlur;
            public bool fTransitionOnMaximized;
        }

        [Flags]
        public enum DWM_BB
        {
            DWM_BB_ENABLE = 1,
            DWM_BB_BLURREGION = 2,
            DWM_BB_TRANSITIONONMAXIMIZED = 4
        }

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

        [DllImport("dwmapi.dll", PreserveSig = false)]
        public static extern void DwmEnableBlurBehindWindow(IntPtr hwnd, ref DWM_BLURBEHIND blurBehind);
    }
}

结果是：

Answer 2

因此，在我不知道的情况下，hRgn可以采用不规则形状（并且DwmEnableBlurBehindWindow采用hRgn，但我知道）。因此，这是我的解决方案（或多或少）与 WPF 兼容：

...和源代码：

主窗口.xaml：

<Window x:Class="IrregularGlassWindow.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow"
        Height="500"
        Width="500"
        Background="#01FFFFFF"
        AllowsTransparency="True"
        WindowStyle="None"
        ResizeMode="NoResize">
  <Window.Clip>
    <PathGeometry>
      <PathFigure StartPoint="250,0">
        <ArcSegment Point="250,500"
                    RotationAngle="180"
                    Size="250,250"
                    SweepDirection="Clockwise" />
        <ArcSegment Point="250,0"
                    RotationAngle="180"
                    Size="250,250"
                    SweepDirection="Clockwise" />
      </PathFigure>
    </PathGeometry>
  </Window.Clip>
  <Grid>
    <Ellipse Margin="1"
             Width="498"
             Height="498"
             Stroke="#8FFF"
             StrokeThickness="1.25" />
    <Ellipse Width="500"
             Height="500"
             Stroke="#C000"
             StrokeThickness="1"/>
  </Grid>
</Window>

MainWindow.xaml.cs：

public partial class MainWindow : Window {
  public MainWindow() {
    InitializeComponent();

    this.SourceInitialized += MainWindow_SourceInitialized;
    this.KeyDown += MainWindow_KeyDown;
  }

  void MainWindow_KeyDown(object sender, KeyEventArgs e) {
    if (e.Key == Key.Escape) this.Close();
  }

  void MainWindow_SourceInitialized(object sender, EventArgs e) {
    var helper = new WindowInteropHelper(this);
    var hwnd = helper.Handle;
    var src = HwndSource.FromHwnd(hwnd);

    src.CompositionTarget.BackgroundColor = Colors.Transparent;

    WindowChrome.SetWindowChrome(this, new WindowChrome {
      CaptionHeight = 500,
      CornerRadius = new CornerRadius(0),
      GlassFrameThickness = new Thickness(0),
      NonClientFrameEdges = NonClientFrameEdges.None,
      ResizeBorderThickness = new Thickness(0),
      UseAeroCaptionButtons = false
    });

    GraphicsPath path = new GraphicsPath(FillMode.Alternate);
    path.StartFigure();
    path.AddArc(new RectangleF(0, 0, 500, 500), 0, 360);
    path.CloseFigure();

    var dbb = new DwmBlurBehind(true);
    dbb.SetRegion(Graphics.FromHwnd(hwnd), new Region(path));
    DwmApi.DwmEnableBlurBehindWindow(hwnd, ref dbb);
  }
}

我认为其他人打败了我，但我的解决方案是这样的：

当窗口的SourceInitialized事件被触发时，这意味着我们有了窗口的句柄。所以在这个函数的处理程序中，我得到了窗口句柄。然后我调用从 dwmapi.dll 导入的名为 的函数DwmEnableBlurBehindWindow。这基本上将窗户的透明区域变成了特定区域的玻璃。我从 pinvoke.net 获得的结构DwmBlurBehind，它将 GDI+ 转换System.Drawing.Region为hRgn. 被hRgn传递到DwmEnableBlurBehindWindow，它将透明部分剪辑到Region。在本例中，我使用了一个圆圈。那么 XAML 只是重音边框。值得注意的是，由于某种原因，设置Window.Background为在此处为 trueTransparent时不会启用命中测试AllowsTransparency。不知道为什么，但这可能与隐藏代码有关。