VCS/bmpmem - Sample is best!

開発環境	Microsoft Visual Studio Community 2017
実行環境	Microsoft Windows 10 Home (64-bit)
プロジェクトの種類	Visual C# / Windows フォーム アプリケーション (.NET Framework)
プロジェクト名	bmp

Form1.cs

using System;
using System.Drawing;
using System.IO;
using System.Windows.Forms;
 
namespace bmp
{
    public partial class Form1 : Form
    {
        private byte[] buf;
 
        public Form1()
        {
            InitializeComponent();
        }
 
        private void button1_Click(object sender, EventArgs e)
        {
            //var image = Image.FromFile(@"C:\tmp\pcg.bmp");
            //var stream = new FileStream(@"C:\tmp\pcg.bmp", FileMode.Open);
            uint biWidth = 256;
            uint biHeight = 128;
            uint biSizeImage = ((biWidth + 7) / 8) * biHeight;
            uint bfOffBits = 14 + 40 + 8;
            uint bfSize = bfOffBits + biSizeImage;
            buf = new byte[bfSize];
 
            // BITMAPFILEHEADER
            WriteBuf2(0, 0x4d42);   // "BM"
            WriteBuf4(2, bfSize);
            WriteBuf4(10, bfOffBits);
 
            // BITMAPINFOHEADER
            WriteBuf4(14, 40);   // biSize
            WriteBuf4(18, biWidth);
            WriteBuf4(22, biHeight);
            WriteBuf2(26, 1);   // biPlanes
            WriteBuf2(28, 1);   // biBitCount
            WriteBuf4(34, biSizeImage);
 
            // RGBQUAD
            WriteBuf4(54, 0x00000000);
            WriteBuf4(58, 0x00ffffff);
 
            var i = bfOffBits;
            for(var y = 0; y < 128; y++)
            {
                for (var x = 0; x < 256; x += 8)
                {
                    buf[i++] = (byte)y;
                }
            }
 
            var stream = new MemoryStream(buf);
            var image = Image.FromStream(stream);
            pictureBox1.Width = (int)biWidth;
            pictureBox1.Image = image;
        }
 
        private void WriteBuf2(int offset, ushort value)
        {
            var tmp = BitConverter.GetBytes(value);
            Array.Copy(tmp, 0, buf, offset, 2);
        }
 
        private void WriteBuf4(int offset, uint value)
        {
            var tmp = BitConverter.GetBytes(value);
            Array.Copy(tmp, 0, buf, offset, 4);
        }
    }
}