QWidget::setLayout: Attempting to set QLayout "" on Widget "", which already has a layout
Solution 1
So I believe your problem is in this line:
QHBoxLayout *hlayout = new QHBoxLayout(this);
In particular, I think the problem is passing this
into the QHBoxLayout
. Because you intend for this QHBoxLayout
to NOT be the top level layout of this
, you should not pass this
into the constructor.
Here's my re-write that I hacked into a test app locally and seems to work great:
Widget::Widget(QWidget *parent) :
QWidget(parent)
{
QLabel *label = new QLabel("Test");
QHBoxLayout *hlayout = new QHBoxLayout();
QVBoxLayout *vlayout = new QVBoxLayout();
QSpacerItem *spacer = new QSpacerItem(40, 20, QSizePolicy::Fixed);
QLineEdit *lineEdit = new QLineEdit();
hlayout->addItem(spacer);
hlayout->addWidget(lineEdit);
vlayout->addLayout(hlayout);
vlayout->addWidget(label);
setLayout(vlayout);
}
Solution 2
The problem is that you are creating layouts with a parent of this
. When you do that, it sets the layout to be the main layout of this
. Thus, it is redundant to call setMainLayout()
.
user1369511
Updated on April 15, 2020Comments
-
user1369511 about 4 years
I'm trying to set the layout of a widget manually through code (not in Designer), but I'm doing something wrong, because I get this warning:
QWidget::setLayout: Attempting to set QLayout "" on Widget "", which already has a layout
And also the layout is messed up (the label is at the top, instead of the bottom).
This is an example code that reproduces the problem:
Widget::Widget(QWidget *parent) : QWidget(parent) { QLabel *label = new QLabel("Test", this); QHBoxLayout *hlayout = new QHBoxLayout(this); QVBoxLayout *vlayout = new QVBoxLayout(this); QSpacerItem *spacer = new QSpacerItem(40, 20, QSizePolicy::Fixed); QLineEdit *lineEdit = new QLineEdit(this); hlayout->addItem(spacer); hlayout->addWidget(lineEdit); vlayout->addLayout(hlayout); vlayout->addWidget(label); setLayout(vlayout); }