On Windows, there are two possible ways to access scanners: WIA2 and TWAIN. In Libinsane, the goal is to keep things as cross-platform as possible, so we have to hide them.

The API multiplexer takes 2 or more implementations and wraps them to show them as a single one.

When listing devices, the device identifiers are prefixed with the name of each wrapped implementation. This way, when we try to open a device, it can find back the corresponding implementation quickly and easily.

See multiplexer.h.