GenIco.dib

#!meta

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#!markdown

Writes the Logo.png image into a .ico file. Since .ico can store a set of .png at different resolutions directly this basically just creates the required header stuff.

#!csharp

using System.Runtime.InteropServices;

struct Header {
    Int16 Reserved = 0;
    Int16 Format = 1;
    public Int16 NumImages = 1;
    public Header(int numImages) {
        NumImages = (Int16)numImages;
    }
}

struct ImageEntry {
    public byte Width = 0;
    public byte Height = 0;
    public byte NumPaletteColors = 0;
    byte Reserved = 0;
    Int16 ColorPlane = 0;
    Int16 BitsPerPixel = 0;
    public UInt32 Size;
    public UInt32 Offset;

    public ImageEntry(byte resolution, uint size, uint offset) {
        Width = Height = resolution;
        Size = size;
        Offset = offset;
    }
}

byte[] StructToBytes<T>(T data) {
    int size = Marshal.SizeOf(data);
    byte[] bytes = new byte[size];
    IntPtr ptr = IntPtr.Zero;
    try {
        ptr = Marshal.AllocHGlobal(size);
        Marshal.StructureToPtr(data, ptr, true);
        Marshal.Copy(ptr, bytes, 0, size);
    } finally {
        Marshal.FreeHGlobal(ptr);
    }
    return bytes;
}

#!csharp

List<byte> resolutions = [ 16, 24, 32, 48, 20, 30, 40, 0 ];

List<byte[]> images = new();
foreach (byte r in resolutions)
    images.Add(System.IO.File.ReadAllBytes($"Assets/{(r == 0 ? 256 : r)}x{(r == 0 ? 256 : r)}.png"));

#!csharp

{
    using var stream = new System.IO.FileStream("Assets/Logo.ico", System.IO.FileMode.Create);
    using var writer = new System.IO.BinaryWriter(stream);

    writer.Write(StructToBytes(new Header(images.Count)));

    // Write image directory
    uint offset = (uint)(Marshal.SizeOf(typeof(Header)) + images.Count * Marshal.SizeOf(typeof(ImageEntry)));
    for (int i = 0; i < resolutions.Count; ++i)
    {
        writer.Write(StructToBytes(new ImageEntry(resolutions[i], (uint)images[i].Length, offset)));
        offset += (uint)images[i].Length;
    }

    // Write the actual images
    foreach (var b in images)
        writer.Write(b);
}