Specifies the type of the function passed to
Pixbuf.saveToCallback. It is called once for each block of
bytes that is "written" by Pixbuf.saveToCallback. If
successful it should return TRUE. If an error occurs it should set
error and return FALSE, in which case Pixbuf.saveToCallback
will fail with the same error.
Specifies the type of the function passed to Pixbuf.saveToCallback. It is called once for each block of bytes that is "written" by Pixbuf.saveToCallback. If successful it should return TRUE. If an error occurs it should set error and return FALSE, in which case Pixbuf.saveToCallback will fail with the same error.