wpf - 删除最大化 WPF 自定义窗口的 DropShadow

Question

我有一个带有自定义窗口边框的 WPF 应用程序 (.NET Framework 4)。我使用 WPF Shell Integration Library 禁用了玻璃边框, 并绘制我自己的边框。但是，我想在未最大化时在窗口边框周围添加一个 DropShadow。我添加了这样的阴影:

private static bool DropShadow(Window window)
{
    try
    {
        WindowInteropHelper helper = new WindowInteropHelper(window);
        int val = 2;
        int ret1 = DwmSetWindowAttribute(helper.Handle, 2, ref val, 4);

        if (ret1 == 0)
        {
            Margins m = new Margins { Bottom = 0, Left = 0, Right = 0, Top = 0 };
            int ret2 = DwmExtendFrameIntoClientArea(helper.Handle, ref m);
            return ret2 == 0;
        }
        else
        {
            return false;
        }
    }
    catch (Exception ex)
    {
        // Probably dwmapi.dll not found (incompatible OS)
        return false;
    }
}

有关详细信息，请参阅:DropShadow for WPF Borderless Window

此解决方案在使用 WindowState.Normal 时效果很好!然而，当我最大化应用程序并禁用 DWMWA_NCRENDERING_POLICY 时，窗口的背景变得稍微透明，并且我的大多数控件呈现的效果与我以前完​​全不同。

在下图中，您可以看到原始的最大化状态，以及阴影代码。如您所见，它使用阴影代码完全改变了窗口的透明度:o

有什么我想念的吗？我一直在阅读 DWM Function library却找不到答案……

Answer 1

一段时间后，我从另一个角度重新审视了这个问题，并想出了一个更好的解决方案:

public class GlassWindow : Window
{
    [SuppressUnmanagedCodeSecurity]
    internal static class DwmNativeMethods
    {
        [StructLayout(LayoutKind.Sequential)]
        internal struct DwmMargins
        {
            public int cxLeftWidth;
            public int cxRightWidth;
            public int cyTopHeight;
            public int cyBottomHeight;

            public DwmMargins(bool fullWindow)
            {
                this.cxLeftWidth = this.cxRightWidth = this.cyTopHeight = this.cyBottomHeight = fullWindow ? -1 : 0;
            }
        }

        [DllImport("DwmApi.dll")]
        internal static extern int DwmExtendFrameIntoClientArea(IntPtr hwnd, ref DwmMargins m);

        [DllImport("DwmApi.dll")]
        internal static extern int DwmSetWindowAttribute(IntPtr hwnd, int attr, ref int attrValue, int attrSize);
    }

    private IntPtr windowHandle;

    protected override void OnSourceInitialized(EventArgs e)
    {
        base.OnSourceInitialized(e);

        WindowInteropHelper interopHelper = new WindowInteropHelper(this);
        this.windowHandle = interopHelper.Handle;

        this.ToggleAreoGlass(this.WindowState != WindowState.Maximized);

        this.StateChanged += this.GlassWindowStateChanged;
    }

    private void ToggleAreoGlass(bool value)
    {
        // Enable NcRenderingPolicy
        int attrValue = 2;
        int result = DwmNativeMethods.DwmSetWindowAttribute(this.windowHandle, 2, ref attrValue, 4);

        if (result == 0)
        {
            // Extend DwmFrame
            DwmNativeMethods.DwmMargins margins = new DwmNativeMethods.DwmMargins(value);
            DwmNativeMethods.DwmExtendFrameIntoClientArea(this.windowHandle, ref margins);
        }
    }

    private void GlassWindowStateChanged(object sender, EventArgs e)
    {
        this.ToggleAreoGlass(this.WindowState != WindowState.Maximized);
    }
}