pub trait PrintOperationPreviewImpl: ObjectImpl {
// Required methods
fn render_page(&self, page_nr: i32);
fn is_selected(&self, page_nr: i32) -> bool;
fn end_preview(&self);
// Provided methods
fn ready(&self, context: &PrintContext) { ... }
fn got_page_size(&self, context: &PrintContext, page_setup: &PageSetup) { ... }
}