Function WebPPictureInit 

pub unsafe extern "C" fn WebPPictureInit(
    picture: *mut WebPPicture,
) -> c_int

Should always be called, to initialize the structure. Returns false in case of version mismatch. WebPPictureInit() must have succeeded before using the picture object. Note that, by default, use_argb is false and colorspace is WEBP_YUV420.