异步操作
在默认情况下,PrintOperation::run()在打印操作完成时返回。如果你需要运行非阻塞的打印操作,请调用PrintOperation::set_allow_async()。请注意,并非所有平台都支持set_allow_async(),但done信号仍然会被发出。
run()可能会返回PrintOperation::Result::IN_PROGRESS。要跟踪状态并处理结果或错误,你需要实现done和status_changed信号的信号处理函数。
例如:
// in class ExampleWindow's method... auto op = PrintOperation::create(); // ...set up op... op->signal_done().connect(sigc::bind(sigc::mem_fun( *this, &ExampleWindow::on_printoperation_done), op)); // run the op
然后,检查错误并连接到status_changed信号,例如:
void ExampleWindow::on_printoperation_done(Gtk::PrintOperationResult result, const Glib::RefPtr<PrintOperation>& op) { if (result == Gtk::PrintOperation::Result::ERROR) //notify user else if (result == Gtk::PrintOperation::Result::APPLY) //Update PrintSettings with the ones used in this PrintOperation if (! op->is_finished()) op->signal_status_changed().connect(sigc::bind(sigc::mem_fun( *this, &ExampleWindow::on_printoperation_status_changed), op)); }
最后检查状态。例如:
void ExampleWindow::on_printoperation_status_changed(const Glib::RefPtr<PrintOperation>& op) { if (op->is_finished()) //the print job is finished else //get the status with get_status() or get_status_string() //update UI }