如何在QGraphicsScene中更改QLineEdit的背景色

Question

I have a QGraphicsScene and add a QlineEdit but changing color just doesn't work.

QGridLayout *layout = new QGridLayout(this);
QGraphicsView *view = new QGraphicsView(this);
QGraphicsScene *scene = new QGraphicsScene(this);

QWidget *widget = new QWidget();
QGridLayout *widgetLayout = new QGridLayout(this);
QLineEdit *le1 = new QLineEdit(widget);
QLineEdit *le2 = new QLineEdit(widget);
widgetLayout->addWidget(le1,1,0);
widgetLayout->addWidget(le2,2,0);
widget->setLayout(widgetLayout);



QPalette paletteRed = le1->palette();
paletteRed.setColor(QPalette::Background,Qt::red);

QPalette paletteGreen = le1->palette();
paletteGreen.setColor(QPalette::Background,Qt::green);


le1->setAutoFillBackground(true);
le1->setPalette(paletteRed); // not working
widget->setPalette(paletteGreen); // working


view->setScene(scene);
scene->addWidget(widget);

ui->centralWidget->setLayout(layout);
layout->addWidget(view);

Do I have to trigger something like update() ( which is not working either to get another color ) if the widget is in a scene?

EDIT:

created new example Code.

I know this works in a normal QWidget . Actually the code works fine if i place the QLineEdit in a normal QFrame etc but its in a QGraphicsScene . And in this special case its not working. Text and highlight color etc is also working fine. But backgroud/base/etc ist not.

Answer 1

Setting background color via QPalette does not for my widget, why?

Usually it is autoFillBackground property not set to true to allow setting background on its own.

QPalette palette = pWidget->palette(); // fixed it (need to initialize)
palette.setColor(pWidget->backgroundRole(), bkgndColor); // for background (fixed)
palette.setColor(pWidget->foregroundRole(), fgrndColor); // for foreground
pWidget->setAutoFillBackground(true); // to allow to fill the background
pWidget->setPalette(palette);

Setting the background via stylesheet may also work because it forces autoFillBackground == true mode.

Answer 2

I would like to suggest a slight modification on AlexanderVX's answer. In the first line I would write:

QPalette palette = pWidget->palette();

Just to make sure you tune just what you need of the base object palette.

Regards.

Answer 3

I had an similar issue where the background-color just colored the outline:

the problem was that there was an border-image set. After setting border-image: none; the background color showed up