LibVNCServer
LibVNCServer/LibVNCClient are cross-platform C libraries
LibVNCServer, a library for easy implementation of a VNC server. VNC is a set of programs using the RFB (Remote Frame Buffer) protocol. They are designed to "export" a frame buffer via net: you set up a server and can connect to it via VNC viewers. If the server supports WebSockets (which LibVNCServer does), you can also connect using an in-browser VNC viewer like noVNC. LibVNCServer/LibVNCClient are cross-platform C libraries that allow you to easily implement VNC server or client functionality in your program.