QTreeWidget backgroundcolor

[vmferreira]

Hi,
I'm trying to change the background color of a qtreewidget without sucess:

QApplication *qa = new QApplication(argc, argv);
QWidget *qw = new QWidget();
QTreeWidget *tw = new QTreeWidget(qw);
QStringList lst;
lst.append(QString("testing"));
QTreeWidgetItem *test = new QTreeWidgetItem(tw, lst);
tw->setBackgroundColor(Qt::blue);
What's wrong? I'm using qt 4.2

In fact, I'm trying to change the color of a QGraphicsView (implemented in 4.2) ..
Thanks in advance

[jacek]

What's wrong?

QTreeWidgetItem::setBackgroundColor() takes two parameters.

If you want to change the whole QTreeWidget background, try:

QPalette p( treeWidget->palette() );
p.setColor( QPalette::Base, Qt::blue );
treeWidget->setPalette( p );

QPalette p( treeWidget->palette() );
p.setColor( QPalette::Base, Qt::blue );
treeWidget->setPalette( p );

To copy to clipboard, switch view to plain text mode 

In fact, I'm trying to change the color of a QGraphicsView (implemented in 4.2)

Then why you are bothering with QTreeWidgetItem? Try QGraphicsView::setBackgroundBrush().

[vmferreira]

Thanks a lot jacek, your answer helped a lot.
Now, I'm trying to get the view of the graphic transparent, in order to see a pixmap that is loaded from the widget parent, above is how I'm doing:

QApplication *qa = new QApplication(argc, argv);
QWidget *qd = new QWidget();
QPixmap pix(":/images/bola_verde.png");
qd->setBackgroundPixmap(pix);

QGraphicsScene *scene = new QGraphicsScene(qd);
QGraphicsView *view = new QGraphicsView ( scene, qd );
view->setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
QBrush alphaBrush = view->palette().brush(QPalette::Base);
QColor alphaColor(Qt::transparent);
alphaBrush.setColor(alphaColor);
//view->setBackgroundBrush(alphaBrush);
view->setWindowOpacity(0.3);
scene->setBackgroundBrush(alphaBrush);

It does not work. This can be done? I don't think that mask() can solve my problem..

Thanks

[jacek]

This can be done?

Of course:

QGraphicsScene *scene = new QGraphicsScene(qd);
QGraphicsView *view = new QGraphicsView ( scene, qd );
view->setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
 
QPalette p( view->palette() );
p.setBrush( QPalette::Base, Qt::NoBrush );
view->setPalette( p );

QGraphicsScene *scene = new QGraphicsScene(qd);
QGraphicsView *view = new QGraphicsView ( scene, qd );
view->setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);

QPalette p( view->palette() );
p.setBrush( QPalette::Base, Qt::NoBrush );
view->setPalette( p );

To copy to clipboard, switch view to plain text mode 

I don't think that mask() can solve my problem..

No, setMask() is for making "holes" in widgets.

[vmferreira]

Thanks again jacek, but now it didn't work
My code:
QApplication *qa = new QApplication(argc, argv);
QWidget *qd = new QWidget();
QPixmap pix(":/images/bola_verde.png");
qd->setBackgroundPixmap(pix);

QGraphicsScene *scene = new QGraphicsScene(qd);
QGraphicsView *view = new QGraphicsView ( scene, qd );
QPalette p( view->palette() );
p.setBrush( QPalette::Base, Qt::NoBrush );
view->setPalette( p );
//scene->setBackgroundBrush(p.brush(QPalette::Base));
This is my result:
imagem.PNG

Looks like there is another background before the widget's background. I've already tried removing scene's background, but it didn't work either..

[jacek]

Looks like there is another background before the widget's background.

It's hard to tell what's wrong without seeing the code, but setPalette() worked for me. Maybe you change the background afterwards? Or it's not a background, but part of the item?