Constant xcb::ffi::xproto::XCB_GC_PLANE_MASK

pub const XCB_GC_PLANE_MASK: xcb_gc_t = 2

In graphics operations, given a source and destination pixel, the result is computed bitwise on corresponding bits of the pixels; that is, a Boolean operation is performed in each bit plane. The plane-mask restricts the operation to a subset of planes, so the result is:

((src FUNC dst) AND plane-mask) OR (dst AND (NOT plane-mask))