File: Windows\Win32\PInvoke.SendMessage.cs
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Project: src\src\System.Windows.Forms.Primitives\src\System.Windows.Forms.Primitives.csproj (System.Windows.Forms.Primitives)
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
namespace Windows.Win32;
 
internal static partial class PInvoke
{
    /// <inheritdoc cref="SendMessage(HWND, uint, WPARAM, LPARAM)"/>
    public static LRESULT SendMessage<T>(
        T hWnd,
        MessageId Msg,
        WPARAM wParam = default,
        LPARAM lParam = default) where T : IHandle<HWND>
    {
        LRESULT result = SendMessage(hWnd.Handle, (uint)Msg, wParam, lParam);
        GC.KeepAlive(hWnd.Wrapper);
        return result;
    }
 
    /// <inheritdoc cref="SendMessage(HWND, uint, WPARAM, LPARAM)"/>
    public static LRESULT SendMessage<THwnd, TWParam>(
        THwnd hWnd,
        MessageId Msg,
        TWParam wParam,
        LPARAM lParam = default) where THwnd : IHandle<HWND> where TWParam : IHandle<HWND>
    {
        LRESULT result = SendMessage(hWnd.Handle, (uint)Msg, (WPARAM)wParam.Handle, lParam);
        GC.KeepAlive(wParam.Wrapper);
        return result;
    }
 
    /// <inheritdoc cref="SendMessage(HWND, uint, WPARAM, LPARAM)"/>
    public static unsafe LRESULT SendMessage<T>(
        T hWnd,
        MessageId Msg,
        WPARAM wParam,
        string? lParam) where T : IHandle<HWND>
    {
        fixed (char* c = lParam)
        {
            return SendMessage(hWnd, Msg, wParam, (LPARAM)c);
        }
    }
 
    /// <inheritdoc cref="SendMessage(HWND, uint, WPARAM, LPARAM)"/>
    public static unsafe nint SendMessage<THwnd, TLParam>(
        THwnd hWnd,
        MessageId Msg,
        WPARAM wParam,
        ref TLParam lParam)
        where THwnd : IHandle<HWND>
        where TLParam : unmanaged
    {
        fixed (void* l = &lParam)
        {
            return SendMessage(hWnd, Msg, wParam, (LPARAM)l);
        }
    }
 
    /// <inheritdoc cref="SendMessage(HWND, uint, WPARAM, LPARAM)"/>
    public static unsafe nint SendMessage<THwnd, TWParam, TLParam>(
        THwnd hWnd,
        MessageId Msg,
        ref TWParam wParam,
        ref TLParam lParam)
        where THwnd : IHandle<HWND>
        where TWParam : unmanaged
        where TLParam : unmanaged
    {
        fixed (void* w = &wParam, l = &lParam)
        {
            return SendMessage(hWnd, Msg, (WPARAM)(nuint)w, (LPARAM)(nint)l);
        }
    }
}