Qt：在发出信号之前发出消息(Qt: Issuing a message before emitting a signal)

Qt：在发出信号之前发出消息(Qt: Issuing a message before emitting a signal)

我的申请和我的问题的简要说明：

在QTabWidget中，我有几个包含每个2个QRadioButtons的groupBox。 例如，选择菜单（groupBox）:( RadioButton :) A（RadioButton :) B

在某个时间点，只有一个菜单可以处于活动状态。 两个radioButton都连接到其他 - >当我点击radioButton A并将其设置为true时，radioButton B会自动设置为false - 反之亦然。

在尝试更改菜单设置时，在发出单击信号之前，我想发出一个QMessageBox警告“您确定要更改菜单吗？这可能会对您的设备造成严重损坏。” - 是/否。

单击是时，我想更改菜单设置。 点击“否”时，我希望一切都像以前一样。

我唯一的问题是：在on_radio_button_toggled插槽中发出QMessageBox时，radioButton状态已经更改为true。 即使我再次更改插槽中的状态并更正它们，当弹出消息显示时，状态似乎已经改变。 我不希望这样，因为这意味着menue的状态已经改变了。

在发出实际信号槽之前，如何或如何让QMessageBox弹出 - 单击单选按钮？

非常感谢您的帮助。

更新：我现在已经按照建议实现了eventFilter。 这是我的源代码：

ui->radioButtonMenu1->installEventFilter(this); ui->radioButtonMenu2->installEventFilter(this);

SubmenuOne是一个QWidget。 它通过QTabWidget（通过占位符）集成到MainWindow中。

bool SubmenuOne::eventFilter(QObject *obj, QEvent *event) { if(event->type() == QEvent::MouseButtonPress) { QMessageBox::StandardButton reply; reply= QMessageBox::question(this,tr("WARNING"),tr("Changing the settings may cause severe damage to your device! Please confirm your decision."),QMessageBox::Yes|QMessageBox::No); if (reply == QMessageBox::Yes) { //QMouseEvent *mouseEvent = static_cast<QMouseEvent *>(event); //keyEvent->accept(); //event->accept(); qDebug("Yes."); return false; } else { qDebug("No."); return true; } } }

Brief description of my application and my question:

In a QTabWidget I have several groupBoxes containing each 2 QRadioButtons. E.g. Select Menu (groupBox): (RadioButton:) A (RadioButton:) B

At one point of time, only one Menu can be active. Both radioButtons are connected to each othe -> When I click radioButton A and set it true, radioButton B is automatically set false - and the other way round.

When trying to change the menu setting, before a click signal is emitted, I would like to issue a QMessageBox Warning "Are you sure you want to change the menu? This can cause severe damage to your device." -Yes/No.

When clicking Yes, I would like to change the menue setting. When clicking No, I would like everything to remain as before.

The only problem I have is: When issuing the QMessageBox in the on_radio_button_toggled slot, the radioButton state has already changed to true. Even if I change the state in the slot again and correct them, it looks like the state has already changed when the pop up message shows up. I don't want that because that implies that the state of the menue has already changed.

Where or How can I let a QMessageBox pop up before emitting the actual signal slot - when clicking the radio Button?

Thank you very much for your help.

Update: I have now implemented an eventFilter as recommended. Here is my source code:

ui->radioButtonMenu1->installEventFilter(this); ui->radioButtonMenu2->installEventFilter(this);

SubmenuOne is a QWidget. It is integrated into the MainWindow by a QTabWidget (via placeholder).

bool SubmenuOne::eventFilter(QObject *obj, QEvent *event) { if(event->type() == QEvent::MouseButtonPress) { QMessageBox::StandardButton reply; reply= QMessageBox::question(this,tr("WARNING"),tr("Changing the settings may cause severe damage to your device! Please confirm your decision."),QMessageBox::Yes|QMessageBox::No); if (reply == QMessageBox::Yes) { //QMouseEvent *mouseEvent = static_cast<QMouseEvent *>(event); //keyEvent->accept(); //event->accept(); qDebug("Yes."); return false; } else { qDebug("No."); return true; } } }

最满意答案

你必须使用bool eventFilter(QObject *obj, QEvent *event); 在窗口中声明事件过滤器，然后将事件过滤器安装到每个radiobutton，如下所示： radioButton1->installEventFilter(this); 。 然后在eventFilter检查事件类型： if (event->type() == QEvent::MouseButtonPress)并显示您的QMessageBox 。 然后您可以接受事件并根据用户选择返回true或false 。

bool SubmenuOne::eventFilter(QObject *obj, QEvent *event) { if(event->type() == QEvent::MouseButtonPress) { QMessageBox::StandardButton reply; reply= QMessageBox::question(this,tr("WARNING"),tr("Changing the settings may cause severe damage to your device! Please confirm your decision."),QMessageBox::Yes|QMessageBox::No); if (reply == QMessageBox::Yes) { static_cast<QRadioButton*>(obj)->setChecked(True); } event->accepted(); return true; } return QMainWindow::eventFilter(obj, event); //you forget this. QMainWindow is just base class of your SubmenuOne. }

You have to use bool eventFilter(QObject *obj, QEvent *event); Declare event filter in your window, then instal event filter to every radiobutton like this: radioButton1->installEventFilter(this);. Then at eventFilter check event type: if (event->type() == QEvent::MouseButtonPress) and show your QMessageBox. Then you can accept event and return true or false depending on user choise.

bool SubmenuOne::eventFilter(QObject *obj, QEvent *event) { if(event->type() == QEvent::MouseButtonPress) { QMessageBox::StandardButton reply; reply= QMessageBox::question(this,tr("WARNING"),tr("Changing the settings may cause severe damage to your device! Please confirm your decision."),QMessageBox::Yes|QMessageBox::No); if (reply == QMessageBox::Yes) { static_cast<QRadioButton*>(obj)->setChecked(True); } event->accepted(); return true; } return QMainWindow::eventFilter(obj, event); //you forget this. QMainWindow is just base class of your SubmenuOne. }