nativefiledialog.cs

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using System;
using System.Runtime.InteropServices;
using System.Text;
 
public static class nativefiledialog
{
    public enum nfdresult_t
    {
        NFD_ERROR,
        NFD_OKAY,
        NFD_CANCEL
    }
 
    public struct nfdpathset_t
    {
        private IntPtr buf;
 
        private IntPtr indices;
 
        private IntPtr count;
    }
 
    private const string nativeLibName = "nfd";
 
    private static int Utf8Size(string str)
    {
        return str.Length * 4 + 1;
    }
 
    private unsafe static byte* Utf8EncodeNullable(string str)
    {
        if (str == null)
        {
            return null;
        }
        int num = Utf8Size(str);
        byte* ptr = (byte*)(void*)Marshal.AllocHGlobal(num);
        fixed (char* chars = str)
        {
            Encoding.UTF8.GetBytes(chars, (str != null) ? (str.Length + 1) : 0, ptr, num);
        }
        return ptr;
    }
 
    private unsafe static string UTF8_ToManaged(IntPtr s, bool freePtr = false)
    {
        if (s == IntPtr.Zero)
        {
            return null;
        }
        byte* ptr;
        for (ptr = (byte*)(void*)s; *ptr != 0; ptr++)
        {
        }
        int num = (int)(ptr - (byte*)(void*)s);
        if (num == 0)
        {
            return string.Empty;
        }
        char* ptr2 = stackalloc char[num];
        int chars = Encoding.UTF8.GetChars((byte*)(void*)s, num, ptr2, num);
        string result = new string(ptr2, 0, chars);
        if (freePtr)
        {
            free(s);
        }
        return result;
    }
 
    [DllImport("msvcrt", CallingConvention = CallingConvention.Cdecl)]
    private static extern void free(IntPtr ptr);
 
    [DllImport("nfd", CallingConvention = CallingConvention.Cdecl, EntryPoint = "NFD_OpenDialog")]
    private unsafe static extern nfdresult_t INTERNAL_NFD_OpenDialog(byte* filterList, byte* defaultPath, out IntPtr outPath);
 
    public unsafe static nfdresult_t NFD_OpenDialog(string filterList, string defaultPath, out string outPath)
    {
        byte* intPtr = Utf8EncodeNullable(filterList);
        byte* ptr = Utf8EncodeNullable(defaultPath);
        IntPtr outPath2;
        nfdresult_t result = INTERNAL_NFD_OpenDialog(intPtr, ptr, out outPath2);
        Marshal.FreeHGlobal((IntPtr)intPtr);
        Marshal.FreeHGlobal((IntPtr)ptr);
        outPath = UTF8_ToManaged(outPath2, freePtr: true);
        return result;
    }
 
    [DllImport("nfd", CallingConvention = CallingConvention.Cdecl, EntryPoint = "NFD_OpenDialogMultiple")]
    private unsafe static extern nfdresult_t INTERNAL_NFD_OpenDialogMultiple(byte* filterList, byte* defaultPath, out nfdpathset_t outPaths);
 
    public unsafe static nfdresult_t NFD_OpenDialogMultiple(string filterList, string defaultPath, out nfdpathset_t outPaths)
    {
        byte* intPtr = Utf8EncodeNullable(filterList);
        byte* ptr = Utf8EncodeNullable(defaultPath);
        nfdresult_t result = INTERNAL_NFD_OpenDialogMultiple(intPtr, ptr, out outPaths);
        Marshal.FreeHGlobal((IntPtr)intPtr);
        Marshal.FreeHGlobal((IntPtr)ptr);
        return result;
    }
 
    [DllImport("nfd", CallingConvention = CallingConvention.Cdecl, EntryPoint = "NFD_SaveDialog")]
    private unsafe static extern nfdresult_t INTERNAL_NFD_SaveDialog(byte* filterList, byte* defaultPath, out IntPtr outPath);
 
    public unsafe static nfdresult_t NFD_SaveDialog(string filterList, string defaultPath, out string outPath)
    {
        byte* intPtr = Utf8EncodeNullable(filterList);
        byte* ptr = Utf8EncodeNullable(defaultPath);
        IntPtr outPath2;
        nfdresult_t result = INTERNAL_NFD_SaveDialog(intPtr, ptr, out outPath2);
        Marshal.FreeHGlobal((IntPtr)intPtr);
        Marshal.FreeHGlobal((IntPtr)ptr);
        outPath = UTF8_ToManaged(outPath2, freePtr: true);
        return result;
    }
 
    [DllImport("nfd", CallingConvention = CallingConvention.Cdecl, EntryPoint = "NFD_PickFolder")]
    private unsafe static extern nfdresult_t INTERNAL_NFD_PickFolder(byte* defaultPath, out IntPtr outPath);
 
    public unsafe static nfdresult_t NFD_PickFolder(string defaultPath, out string outPath)
    {
        byte* intPtr = Utf8EncodeNullable(defaultPath);
        IntPtr outPath2;
        nfdresult_t result = INTERNAL_NFD_PickFolder(intPtr, out outPath2);
        Marshal.FreeHGlobal((IntPtr)intPtr);
        outPath = UTF8_ToManaged(outPath2, freePtr: true);
        return result;
    }
 
    [DllImport("nfd", CallingConvention = CallingConvention.Cdecl, EntryPoint = "NFD_GetError")]
    private static extern IntPtr INTERNAL_NFD_GetError();
 
    public static string NFD_GetError()
    {
        return UTF8_ToManaged(INTERNAL_NFD_GetError());
    }
 
    [DllImport("nfd", CallingConvention = CallingConvention.Cdecl)]
    public static extern IntPtr NFD_PathSet_GetCount(ref nfdpathset_t pathset);
 
    [DllImport("nfd", CallingConvention = CallingConvention.Cdecl, EntryPoint = "NFD_PathSet_GetPath")]
    private static extern IntPtr INTERNAL_NFD_PathSet_GetPath(ref nfdpathset_t pathset, IntPtr index);
 
    public static string NFD_PathSet_GetPath(ref nfdpathset_t pathset, IntPtr index)
    {
        return UTF8_ToManaged(INTERNAL_NFD_PathSet_GetPath(ref pathset, index));
    }
 
    [DllImport("nfd", CallingConvention = CallingConvention.Cdecl)]
    public static extern void NFD_PathSet_Free(ref nfdpathset_t pathset);
}