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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
namespace Windows.Win32;
internal static partial class PInvokeCore
{
public delegate BOOL EnumChildWindowsCallback(HWND hWnd);
public static unsafe BOOL EnumChildWindows<T>(T hwndParent, EnumChildWindowsCallback callback)
where T : IHandle<HWND>
{
// We pass a function pointer to the native function and supply the callback as
// reference data, so that the CLR doesn't need to generate a native code block for
// each callback delegate instance (for storing the closure pointer).
GCHandle gcHandle = GCHandle.Alloc(callback);
try
{
return EnumChildWindows(hwndParent.Handle, &EnumChildWindowsNativeCallback, (LPARAM)(nint)gcHandle);
}
finally
{
gcHandle.Free();
GC.KeepAlive(hwndParent.Wrapper);
}
}
[UnmanagedCallersOnly(CallConvs = [typeof(CallConvStdcall)])]
private static BOOL EnumChildWindowsNativeCallback(HWND hWnd, LPARAM lParam)
{
return ((EnumChildWindowsCallback)((GCHandle)(nint)lParam).Target!)(hWnd);
}
}
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