ICO libraries for C/C++

• Magick++, the C++ API of ImageMagick, reads every entry of an ICO or CUR file (BMP and PNG) and writes multi-size icons. It’s the practical choice when you need full ICO support in C or C++ (use MagickWand for plain C).

The single-header decoders (stb_image, LodePNG) don’t read ICO. The format is simple enough that many programs parse ICONDIR themselves and hand each entry to a PNG or BMP decoder; on Windows, LoadImage and CreateIconFromResourceEx load icons through the OS.

• Magick++ Read and write Windows ICO icons in C++ with Magick++, the ImageMagick C++ API: list all icon sizes, convert ICO to PNG, build multi-size favicon.ico files.