Test Lib Camera Rust

Main.cs

using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;

namespace ConsoleApp3
{
    class Program
    {
        const string dllPath = @"C:\DEV\Escapi\escapi\target\debug\escapi_rust.dll";

        [STAThread]
        static int Main(string[] args)
        {
            Int64 device_ptr;
            uint camera_index = 0;
            uint width = 320;
            uint height = 240;
            float framerate = 30.0f;
            var result = init(camera_index, width, height, framerate, out device_ptr);
            if (result != 0)
            {
                Int64 str_ptr;
                result = get_device_name(device_ptr, out str_ptr);
                if (result != 0)
                {
                    byte[] bytes = new byte[result];
                    Marshal.Copy(new IntPtr(str_ptr), bytes, 0, result);
                    var deviceName = Encoding.UTF8.GetString(bytes);
                    Console.WriteLine("device name is " + deviceName);
                    free_string(str_ptr);
                }

                Int64 bufferPtr;
                Int64 bufferLength;
                result = get_capture_buffer(device_ptr, out bufferPtr, out bufferLength);

                if (result != 0)
                {
                    byte[] imageBytes = new byte[bufferLength * 4];
                    Marshal.Copy(new IntPtr(bufferPtr), imageBytes, 0, (int) (bufferLength * 4));
                    SavePPM(width, height ,imageBytes);
                }

                free_device(device_ptr);
            }
            Console.WriteLine("Program ended. Press a key to exit.");
            Console.ReadLine();
            return 0;
        }

        private static void SavePPM(uint width, uint height, byte[] imageBytes)
        {
            var imageBytesLength = imageBytes.Length;
            using (var writer = new StreamWriter("image.ppm"))
            {
                writer.WriteLine("P3");
                writer.WriteLine("" + width + " " + height);
                writer.WriteLine("255");
                for (int j = 0; j < height; j++)
                {
                    for (int i = 0; i < width ; i++)
                    {
                        for (int channel = 0; channel < 4; channel++)
                        {
                            if (channel < 3)
                            {
                                var baseIndex = j * width * 4 + i * 4;
                                var swapedChannelIndx = SwapChannelIndex(channel);
                                var index = baseIndex + swapedChannelIndx;
                                writer.Write("" + imageBytes[index] + " ");
                            }
                        }
                    }
                    writer.WriteLine("");
                }
            }
        }

        private static int SwapChannelIndex(int channel)
        {
            if (channel == 0)
            {
                return 2;
            }
            if (channel == 2)
            {
                return 0;
            }
            return channel;
        }

        [DllImport(dllPath, CharSet = CharSet.Auto)]
        public static extern Int32 init
        (
            UInt32 camIndex,
            UInt32 width,
            UInt32 height,
            float desired_fps,
            out Int64 intPtr
        );

        [DllImport(dllPath, CharSet = CharSet.Auto)]
        public static extern Int32 num_devices();
        
        [DllImport(dllPath, CharSet = CharSet.Auto)]
        public static extern Int32 get_device_name(Int64 device_ptr, out Int64 str_ptr_out);
        
        [DllImport(dllPath, CharSet = CharSet.Auto)]
        public static extern void free_string(Int64 str_ptr);

        [DllImport(dllPath, CharSet = CharSet.Auto)]
        public static extern void free_device(Int64 str_ptr);

        [DllImport(dllPath, CharSet = CharSet.Auto)]
        public static extern Int32 get_capture_buffer(Int64 device_ptr, out Int64 buffer_ptr_out, out Int64 buffer_length);


    }
}