我有一个 WPF 窗口,WindowStyle 设置为 none。有什么方法可以强制这个窗口留下阴影(就像 WindowStyle 不是 none 时得到的阴影一样)?我不想将AllowTransparency 设置为true,因为它会影响性能。而且我也不想禁用硬件渲染(我在某处读到禁用它时透明度效果更好)。
我编写了一个小实用程序类,它能够完全满足您的要求:在无边框上放置标准阴影Window
但有AllowsTransparency
set to false
.
你只需调用DropShadowToWindow(Window window)
方法。最好在窗口的构造函数之后进行此调用InitializeComponent()
,但即使您在窗口显示后调用它,它也会起作用。
using System;
using System.Drawing.Printing;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;
public static class DwmDropShadow
{
[DllImport("dwmapi.dll", PreserveSig = true)]
private static extern int DwmSetWindowAttribute(IntPtr hwnd, int attr, ref int attrValue, int attrSize);
[DllImport("dwmapi.dll")]
private static extern int DwmExtendFrameIntoClientArea(IntPtr hWnd, ref Margins pMarInset);
/// <summary>
/// Drops a standard shadow to a WPF Window, even if the window is borderless. Only works with DWM (Windows Vista or newer).
/// This method is much more efficient than setting AllowsTransparency to true and using the DropShadow effect,
/// as AllowsTransparency involves a huge performance issue (hardware acceleration is turned off for all the window).
/// </summary>
/// <param name="window">Window to which the shadow will be applied</param>
public static void DropShadowToWindow(Window window)
{
if (!DropShadow(window))
{
window.SourceInitialized += new EventHandler(window_SourceInitialized);
}
}
private static void window_SourceInitialized(object sender, EventArgs e)
{
Window window = (Window)sender;
DropShadow(window);
window.SourceInitialized -= new EventHandler(window_SourceInitialized);
}
/// <summary>
/// The actual method that makes API calls to drop the shadow to the window
/// </summary>
/// <param name="window">Window to which the shadow will be applied</param>
/// <returns>True if the method succeeded, false if not</returns>
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;
}
}
}
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