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

Question

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);
    }
}

Try with resize instead of setGeometry, resize should work as you expected: https://qt-project.org/doc/qt-5/qwidget.html#size-prop — Zlatomir, Feb 07 '14 at 18:50
ok, that kind of works, but the x and y are not centered based on the new width and height. — Alex, Feb 07 '14 at 18:58

score 7 · Answer 1 · answered Feb 07 '14 at 19:15

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);
    }
}

score 5 · Answer 2 · answered Feb 07 '14 at 18:59

5

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

answered Feb 07 '14 at 18:59

Zlatomir

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right, but the dialog now looks like it was opened and someone resized it. it's not centered as it would be if it was created using the ui gui designer – Alex Feb 07 '14 at 19:03

score 4 · Answer 3 · answered Jun 03 '16 at 07:56

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

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

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