CODEWITHSUNDEEP
c#windowswinapi
Preston
Preston

Reputation: 1346

Getting back bad strings from user32.dll EnumDisplayDevices

I am trying to get the names of my monitors from user32. With what I have so far all I get returned is in Chinese characters. I'm not sure why, any help would be appreciated.

    public static SafeNativeMethods.DISPLAY_DEVICE GetDevices()
    {
        SafeNativeMethods.DISPLAY_DEVICE d = new SafeNativeMethods.DISPLAY_DEVICE();
        d.Initialize();
        if (SafeNativeMethods.EnumDisplayDevices(null, 1, ref d, 0))
            return d;
        else
            throw new InvalidOperationException(GetLastError());
    }

public static class SafeNativeMethods
{
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public struct DISPLAY_DEVICE
    {
        [MarshalAs(UnmanagedType.U4)]
        public int cb;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
        public string DeviceName;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
        public string DeviceString;
        [MarshalAs(UnmanagedType.U4)]
        public int StateFlags;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
        public string DeviceID;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
        public string DeviceKey;
        public void Initialize()
        {
            this.DeviceName = new string(new char[32]);
            this.DeviceString = new string(new char[128]);
            this.DeviceID = new string(new char[128]);
            this.DeviceKey = new string(new char[128]);
            this.cb = (ushort)Marshal.SizeOf(this);
        }
    }



        [DllImport("User32.dll", SetLastError = true, BestFitMapping = false, ThrowOnUnmappableChar = true)]
        public static extern Boolean EnumDisplayDevices(
            [param: MarshalAs(UnmanagedType.LPTStr)]
            String lpDevice,
            [param: MarshalAs(UnmanagedType.U4)]
            Int32 iDevNum,
            [In, Out]
            ref DISPLAY_DEVICE lpDisplayDevice,
            [param: MarshalAs(UnmanagedType.U4)]
            Int32 iHaveNoIdea
        );
}

This code returns a device name of 屜尮䥄偓䅌㉙ could anyone please explain why and how to get the normal name from this?

Upvotes: 1

Views: 255

Answers (1)

Anders
Anders

Reputation: 101626

"Chinese characters" usually means you tried to interpret a ASCII string as Unicode (UTF-16).

Try adding a CharSet property to your EnumDisplayDevices declaration.

Upvotes: 3

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