Unable to set geometry in Qt

问题:

I get an error with setGeometry in a very simple program in Qt5.

int main(int argc, char *argv[])
{

    QApplication a(argc, argv);

    QLabel* m_photo = new QLabel;
    m_photo->setPixmap(QPixmap("test.jpg"));
    m_photo->show();

    return a.exec();
}

Error: setGeometry: Unable to set geometry 6x16+640+300 on QWidgetWindow/'QLabelClassWindow'. Resulting geometry: 160x16+640+300 (frame: 9, 38, 9, 9, custom margin: 0, 0, 0, 0, minimum size: 0x0, maximum size: 16777215x16777215).

I see Qt adding custom widget to a layout, but I did not understand the comment.
What am I doing wrong?

回答1:

Probably you get this error because you don't use setGeometry(), you should set geometry yourself. Try this:

       

m_photo->setGeometry(200,200,200,200);

Better way: label should have same size as picture. To do this you can use QPixmap method width() and height

    QLabel* m_photo = new QLabel;
    QPixmap px("G:/2/qt.jpg");
    m_photo->setPixmap(px);
    m_photo->setGeometry(200,200,px.width(),px.height());
    m_photo->show();

Edit.

I understood why you get this error. It is very simple, your picture doesn't load! Why? Very simple too: probably your picture(test.jpg) was putted near exe file, but Qt doesn't see this file(because Qt use another build directory)

Solution: put test.jpg in correct directory or set pixmap full path(ad I do "G:/2/test.jpg" for example). Also use this code: check is your picture load successfully.

    QLabel* m_photo = new QLabel;
    QPixmap px("G:/2/qt.jpg");
    if(!px.isNull())
    {
    m_photo->setPixmap(px);
    m_photo->show();
    }
    else
        qDebug() << "Cannot find picture";

Is it work now?