Access C# method from a C++ project located in the same solution

Question

Hi,
I am building a solution that contains two projects (one is C# class library and one other a C++ static library). I added the C# project to the C++ project as reference and also i checked the register as interop COM and make Assembly COM-Visible checkbox in C# project. But i ca't see the neither namespace nor the class or methods of C# project in the C++ project.

Please help me

Answer 1

C#

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Media.Imaging;
using System.Runtime.InteropServices;
using WIA;
namespace MyLib1
{
public class MySharpClass1
{
const string wiaFormatBMP = "{B96B3CAB-0728-11D3-9D7B-0000F81EF32E}";

    public static string convertBitmapToBase64(BitmapImage bi)
    {
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        PngBitmapEncoder encoder = new PngBitmapEncoder();
        encoder.Frames.Add(BitmapFrame.Create(bi));
        encoder.Save(ms);
        byte[] bitmapdata = ms.ToArray();
        return Convert.ToBase64String(bitmapdata);
    }

    public static string convBmpToBase64Strings(Bitmap bmp, ImageFormat imageFormat)
    {
        System.IO.MemoryStream stream = new System.IO.MemoryStream();
        bmp.Save(stream, System.Drawing.Imaging.ImageFormat.Bmp);
        byte[] imageBytes = stream.ToArray();
        string base64String = Convert.ToBase64String(imageBytes);
        return base64String;
    }
    void SharpScanDocument()
    {
        DeviceManager deviceManager;
        DeviceInfos devices;
        deviceManager = new DeviceManager();
        devices = deviceManager.DeviceInfos;
        DeviceInfo selectedDevice;
        Device ourdevice;
        int selectedScanIndex = 0;
        string base64String = "";
        for (int i = 1; i <= devices.Count; i++)
        {
            DeviceInfo device;
            device = devices[i];
            if (device.Type == WiaDeviceType.ScannerDeviceType)
            {
                selectedScanIndex = i;
            }
        }
        if (selectedScanIndex > 0)
        {
            selectedDevice = devices[selectedScanIndex];
            ourdevice = selectedDevice.Connect();
            Items items;

            items = ourdevice.Items;
            WIA.Item item = ourdevice.Items[1] as WIA.Item;
            WIA.ICommonDialog wiaCommonDialog = new WIA.CommonDialog();
            WIA.ImageFile img = (WIA.ImageFile)wiaCommonDialog.ShowTransfer(item, wiaFormatBMP, false);
            byte[] buffer = (byte[])img.FileData.get_BinaryData();
            MemoryStream ms = new MemoryStream(buffer);
            Bitmap bmp = new Bitmap(Image.FromStream(ms));
            base64String = convBmpToBase64Strings(bmp, bmp.RawFormat);

        }
        Console.WriteLine($"Scan done");
        Console.ReadLine();
    }
}

}

C++

include "pch.h"

include "CppLib1.h"

namespace MyCppSpace {
class CppLib1 {
void testSharpCall() {
MyLib1::MySharpClass1::SharpScanDocument();
}
};
}

Answer 2

Hi,

But i ca't see the neither namespace nor the class or methods of C# project in the C++ project.

I suggest you could refer to the answer:

COM itself does not have a concept of namespace (which is language-specific).

RegAsm.exe uses the assembly name as the name of the library statement in the IDL. It does not care which namespace your COMVisible class is in.

By default the C++ compiler imports a type library into a namespace with its name specified by the library statement in the IDL. Use the assembly name as the namespace name (or rename the namespace in the import statement) in your C++ code.

If you want to use COM. As far as I'm concerned you should make your C# class exposed to COM and then you can use it in C++. For more details I suggest you could refer to the thread: https://stackoverflow.com/a/29988737/11872808

Best Regards,

Jeanine

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