Mainpulating a QObject created from a button press

问题

I am making an application, and at some point, the user will be creating some sort of from/survey. When creating, the user selects the various question types etc. by pressing a button and a new object will be created.

To create a new section, for example:

void CreateSurvey::question_section()
{
 QLabel *sectionTitle = new QLabel();
 sectionTitle->setText("New Section");
 layout->addWidget(sectionTitle);

 QLabel *titleLabel = new QLabel("Title");
 QLineEdit *titleEdit = new QLineEdit("New Section");

 QHBoxLayout *hLayout = new QHBoxLayout;
 hLayout->addWidget(titleLabel);
 hLayout->addWidget(titleEdit);

 layout->addLayout(hLayout);

 sectionCount++;
 qDebug() << "sections: " << sectionCount;
}

When the application is running, the text 'TitleEdit' will be edited by the user for the title of the section. Say this has been called 3 times, so there are 3 sections. How do I get the strings entered for the title for each section?, or how do i get the string entered for a particular section?

Thanks

回答1:

You can use a container like QVector to store your QLineEdit objects. Use this container to access the text of each QLineEdit object.

#include <QApplication>
#include <QtWidgets>

class Survey : public QWidget
{
    Q_OBJECT
public:
    Survey(QWidget *parent = Q_NULLPTR) : QWidget(parent)
    {
        resize(600, 400);
        setLayout(new QVBoxLayout);
        layout()->setAlignment(Qt::AlignTop);
        QPushButton *button = new QPushButton("Add line edit");
        connect(button, &QPushButton::clicked, this, &Survey::addLineEdit);
        layout()->addWidget(button);    
        QPushButton *print_button = new QPushButton("Print all text");    
        connect(print_button, &QPushButton::clicked, this, [=]
        {
            for(int i = 0; i < line_edit_vector.size(); i++)
                qDebug() << getText(i);
        });    
        layout()->addWidget(print_button);
    }

    QString getText(int index) const
    {
        if(line_edit_vector.size() > index)
            return line_edit_vector[index]->text();
        return QString();
    }

private slots:
    void addLineEdit()
    {
        QLineEdit *edit = new QLineEdit("Line edit");
        layout()->addWidget(edit);
        line_edit_vector.append(edit);
    }

private:
    QVector<QLineEdit*> line_edit_vector;
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Survey survey;
    survey.show();
    return a.exec();
}

#include "main.moc"

回答2:

in your CreateSurvey header add a

public slot:
    void title_changed();

in your question_section method, add a connection:

connect(titleEdit,SIGNAL(editingFinished()),this,SLOT(title_changed()));

and add the title_changed slot:

void CreateSurvey::title_changed()
{
    QLineEdit *titleEdit=qobject_cast<QLineEdit*>(sender());
    if (titleEdit) {
      qDebug() << titleEdit->text();
    }
}

In this way every time the line gets edited the slot title_changed will be triggered.

if you want to know all the titles once just one has been edited, use this slot:

void CreateSurvey::title_changed()
{
     for (int i = 0; i < layout->count(); ++i) {
         QLineEdit *titleEdit=qobject_cast<QLineEdit*>(layout->itemAt(i));
         if (titleEdit) {
             qDebug() << titleEdit->text();
         }
     }
}

来源：https://stackoverflow.com/questions/41098139/mainpulating-a-qobject-created-from-a-button-press

标签

c++

string

qobject