Question

On a dialog I have a QLineEdit and a button. I want to enable a tool tip for the QLineEdit(in it or under it) when I press the button. Please give me a code snippet.

Answer 1

Here is a simple example:

class MyWidget : public QWidget
{
        Q_OBJECT

    public:

        MyWidget(QWidget* parent = 0) : QWidget(parent)
        {
            QVBoxLayout* layout = new QVBoxLayout(this);
            edit = new QLineEdit(this);
            layout->addWidget(edit);
            showButton = new QPushButton("Show tool tip", this);
            layout->addWidget(showButton);
            hideButton = new QPushButton("Hide tool tip", this);
            layout->addWidget(hideButton);

            connect(showButton, SIGNAL(clicked(bool)), this, SLOT(showToolTip()));
            connect(hideButton, SIGNAL(clicked(bool)), this, SLOT(hideToolTip()));
        }

    public slots:

        void showToolTip()
        {
            QToolTip::showText(edit->mapToGlobal(QPoint()), "A tool tip");
        }

        void hideToolTip()
        {
            QToolTip::hideText();
        }

    private:

        QLineEdit* edit;
        QPushButton* showButton;
        QPushButton* hideButton;
};

As you can see, there is no easy way to just enable the tool tip of some widget. You have to provide global coordinates to QToolTip::showText.

Another way to do this is to create a QHelpEvent yourself and post this event using QCoreApplication::postEvent. This way, you can specify the text to be shown in your widget using QWidget::setToolTip. You still have to provide global coordinates, though.

I am really interested in why you want to do this since tool tips are intended to be shown only when you hover your mouse or when you ask for the “What’s this” information. It looks like bad design to use it for something else. If you want to give a message to the user, why don’t you use QMessageBox?