XBM

XBM is the X Window System's one-bit bitmap, written as C source: the width and height as #define lines, an optional hotspot, and the bits as an array, black where a bit is set. It reads and writes through the Egami.Formats.Extended package: register it with WithXbm() or WithExtendedFormats() (Extended formats).

Reads	X11 files of bytes and X10 files of 16-bit words, the leftmost pixel in the lowest bit; comments anywhere
Writes	X11, a pixel black when its gray value is below half, with the name and hotspot from XbmDetails
Natural pixel type	Gray8, black 0 and white 255
FormatInfo	XbmFormat.Info: name XBM, extension .xbm, MIME type image/x-xbitmap

XbmDetails keeps the name the C identifiers start with (cursor for cursor_width) and the hotspot.

// What the header said that the pixels do not: PcxDetails, SgiDetails, SunRasterDetails, XbmDetails and XpmDetails.
using Raster image = Raster.Load("arrow.xbm", context);
if (image.Metadata.FormatDetails is XbmDetails xbm)
{
    Console.WriteLine($"{xbm.Name}, hotspot {xbm.Hotspot}");
}

// Writers take the name and hotspot back from the details.
image.Metadata.FormatDetails = new XbmDetails { Name = "pointer", Hotspot = new Point(0, 0) };
image.Save("pointer.xbm");

The file is read whole; a probe reads only the #define lines. A file that ends early keeps the rows it has, with the warning Xbm.RowsMissing.