How to resolve blocking issue with QT modal dialog box?
In Qt, modal dialogs are by default blocking, meaning they block the main thread during display until the dialog is closed to continue executing subsequent code. To run other code while the dialog is displayed, consider the following solutions:
- To use a non-modal dialog box: Use the setModal() function of QDialog to set the dialog box as non-modal, so it will not block the main thread while displaying. However, it is important to note that non-modal dialog boxes cannot prevent users from interacting with other windows, which may lead to some issues.
- Using multi-threading: separating the display of the dialog box from the main thread can be achieved using Qt’s multi-threading mechanism. Create and start a new thread in the main thread, display the dialog box in the new thread, allowing the main thread to continue executing other code.
- Use event loop: Create an event loop in the main thread using the exec() function of QEventLoop, and then display a dialog within the event loop. This way, when the dialog is displayed, the execution of the main thread will not be blocked, allowing other code to continue running.
Here is an example code using an event loop:
QDialog dialog;
// 设置对话框的属性和内容
...
// 创建事件循环
QEventLoop loop;
// 将对话框的finished信号与事件循环的退出槽函数连接
QObject::connect(&dialog, &QDialog::finished, &loop, &QEventLoop::quit);
// 显示对话框
dialog.show();
// 进入事件循环
loop.exec();
// 对话框已关闭，可以继续执行后续代码
Using the above methods, you can resolve the issue of modal dialog blocking in Qt. Choose the appropriate method based on your actual needs and scenarios.
