Function gifski::c_api::gifski_set_error_message_callback

#[no_mangle]
pub unsafe extern "C" fn gifski_set_error_message_callback(
    handle: *const GifskiHandle,
    cb: unsafe extern "C" fn(_: *const c_char, _: *mut c_void),
    user_data: *mut c_void
) -> GifskiError

Get a callback when an error occurs. This is intended mostly for logging and debugging, not for user interface.

The callback function has the following arguments:

• A \0-terminated C string in UTF-8 encoding. The string is only valid for the duration of the call. Make a copy if you need to keep it.
• An arbitrary pointer (user_data). user_data can be NULL.

The callback must be thread-safe (it will be called from another thread). It must remain valid at all times, until gifski_finish completes.

If the callback is not set, errors will be printed to stderr.

This function must be called before gifski_set_file_output() to take effect.