how to set QDialog width and height and allow automatic window placement

问题

Is there a way to just initialize a QDialog's width and height and not change the x and y coordinates without using a ui file? I just have a simple QDialog and want to set only the width and height, and have the x and y automatically set to the center of the parent, but when I try setGeometry, the inherited geometry's x and y are 0. How does the x and y get set when the dialog is created using a ui file?

class MyDialog : public QDialog
{
    MyDialog::MyDialog(QWidget *parent) :
        QDialog(parent)
    {
        setGeometry(geometry().x(), geometry().y(), 200, 400);
    }
}

回答1:

Use with resize instead of setGeometry, it should work as you expected.

回答2:

I'd like to extend your solution to work also on systems with a second monitor (even if this is an old thread...):

...
if (parent != NULL)
    QPoint parentPos = parent->mapToGlobal(parent->pos());
    setGeometry(parentPos.x() + parent->width()/2 - nWidth/2,
                parentPos.y() + parent->height()/2 - nHeight/2,
                nWidth, nHeight);
else
...

Marcel

回答3:

I have better solution:

class MyDialog : public QDialog
{
    MyDialog::MyDialog(QWidget *parent) :
        QDialog(parent)
    {
        int nWidth = 300;
        int nHeight = 400;
        if (parent != NULL)
            setGeometry(parent->x() + parent->width()/2 - nWidth/2,
                parent->y() + parent->height()/2 - nHeight/2,
                nWidth, nHeight);
        else
            resize(nWidth, nHeight);
    }
}

来源：https://stackoverflow.com/questions/21635427/how-to-set-qdialog-width-and-height-and-allow-automatic-window-placement