Deux ligne

  using System.Net;
  using System.Net.Sockets;
  using System.Text;
  
  var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
  await socket.ConnectAsync(IPAddress.Parse("192.168.1.78"), 1234);
  Console.WriteLine("Connected!");
  for (var j = 0; j < 10; j = (j + 1) % 10)
  {
      for (var i = 0; i < 100; i++)
      {
          var color = $"{(i + 10 * j) % 256:X2}{((i + 10 * j) * 2) % 256:X2}{((i + 10 * j) * 3) % 256:X2}";
          var cmd1 = Encoding.Latin1.GetBytes($"PX {140 - i} {i + 10} {color}\n");
          await socket.SendAsync(new ArraySegment<byte>(cmd1, 0, cmd1.Length));
          var cmd2 = Encoding.Latin1.GetBytes($"PX {i + 10} {i + 10} {color}\n");
          await socket.SendAsync(new ArraySegment<byte>(cmd2, 0, cmd2.Length));
      }
  }

2

  using System.Net;
  using System.Net.Sockets;
  using System.Text;
  
  var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
  await socket.ConnectAsync(IPAddress.Parse("192.168.1.78"), 1234);
  Console.WriteLine("Connected!");
  for (var j = 0; j < 80; j = (j + 1))
  {
      for (var i = 0; i < 3; i++)
      {
          var color = (i + j) % 2 == 0 ? "000000" : $"{(i + 10 * j) % 256:X2}{((i + 10 * j) * 2) % 256:X2}{((i + 10 * j) * 3) % 256:X2}";
          var cmd1 = Encoding.Latin1.GetBytes($"PX {2 * i} {2 * j} {color}\n");
          var cmd2 = Encoding.Latin1.GetBytes($"PX {2 * i + 1} {2 * j} {color}\n");
          var cmd3 = Encoding.Latin1.GetBytes($"PX {2 * i} {2 * j + 1} {color}\n");
          var cmd4 = Encoding.Latin1.GetBytes($"PX {2 * i + 1} {2 * j + 1} {color}\n");
          await socket.SendAsync(new ArraySegment<byte>(cmd1, 0, cmd1.Length));
          await socket.SendAsync(new ArraySegment<byte>(cmd2, 0, cmd2.Length));
          await socket.SendAsync(new ArraySegment<byte>(cmd3, 0, cmd3.Length));
          await socket.SendAsync(new ArraySegment<byte>(cmd4, 0, cmd4.Length));
      }
  }

3

  using System.Net;
  using System.Net.Sockets;
  using System.Text;
  
  var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
  await socket.ConnectAsync(IPAddress.Parse("192.168.1.78"), 1234);
  Console.WriteLine("Connected!");
  for (var j = 0; j < 100; j = (j + 1) % 100)
  {
      for (var i = 0; i < 100; i++)
      {
          var baseColor = 0xFF - 10 * Math.Abs(i - 10);
          var second = 10 * Math.Abs(i - 10);
          var color = $"{second:X2}{second:X2}{baseColor:X2}";
          var cmd1 = Encoding.Latin1.GetBytes($"PX {(i + j) % 100 + 10} {158} {color}\n");
          await socket.SendAsync(new ArraySegment<byte>(cmd1, 0, cmd1.Length));
      }
  }