BitmapInfoHeader.cs

using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace SL3Reader;

[StructLayout(LayoutKind.Sequential, Size = Size), SkipLocalsInit]
internal struct BitmapInfoHeader
{
    internal const int Size = 40;

    private uint StructureSize;
    private int Width;
    private int Height;
    private ushort Planes;
    private ushort BitCount;
    private BitmapCompressionMode Compression;
    private uint ImageSize;
    private int XPixelsPerMeter;
    private int YPixelsPerMeter;
    private uint NumberOfUsedColors;
    private uint NumberOfImportantColors;

    internal BitmapInfoHeader(int width,
                              int height,
                              ushort bitCount = 8,
                              int xPixelsPerMeter = 0,
                              int yPixelsPerMeter = 0) =>
        Update(width, height, bitCount, xPixelsPerMeter, yPixelsPerMeter);

    internal void Update(int width,
                         int height,
                         ushort bitCount = 8,
                         int xPixelsPerMeter = 0,
                         int yPixelsPerMeter = 0)
    {
        const ushort ByteSize = 8;
        StructureSize = Size;
        Width = width;
        Height = height;
        Planes = 1;
        BitCount = bitCount;
        Compression = BitmapCompressionMode.BI_RGB;
        ImageSize = (uint)(bitCount / ByteSize * height * width); // (width + (4 - width % 4))
        XPixelsPerMeter = xPixelsPerMeter;
        YPixelsPerMeter = yPixelsPerMeter;
        NumberOfUsedColors = 256;
        NumberOfImportantColors = 256;
    }
}