To change the text color and background color of a QLabel, here is what I would do :
QLabel* pLabel = new QLabel;
pLabel->setStyleSheet("QLabel { background-color : red; color : blue; }");
You could also avoid using Qt Style Sheets and change the QPalette colors of your QLabel, but you might get different results on different platforms and/or styles.
As Qt documentation states :
Using a QPalette isn't guaranteed to work for all styles, because style authors are restricted by the different platforms' guidelines and by the native theme engine.
In order to change the label size you can select an appropriate size policy for the label like expanding or minimum expanding.
You can scale the pixmap by keeping its aspect ratio every time it changes:
QPixmap p; // load pixmap
// get label dimensions
int w = label->width();
int h = label->height();
// set a scaled pixmap to a w x h window keeping its aspect ratio
label->setPixmap(p.scaled(w,h,Qt::KeepAspectRatio));
There are two places where you should add this code:
When the pixmap is updated
In the resizeEvent of the widget that contains the label
If I understand you correctly, the simplest thing to do is simply to ignore that label's horizontal size hint.
As long as you have other widgets in there (or force a minimum width manually to the container), this should do what you want:
#include <QtGui>
int main(int argc, char **argv)
{
QApplication app(argc, argv);
QLabel *l1 = new QLabel("This very long text doesn't influence "
"the width of the parent widget");
l1->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Fixed);
// Style just to make it clear that the widget is
// being resized to fit the parent, it doesn't "overflow"
l1->setFrameShape(QFrame::Box);
l1->setFrameShadow(QFrame::Raised);
l1->setAlignment(Qt::AlignHCenter);
QLabel *l2 = new QLabel("This influences the width");
l2->setFrameShape(QFrame::Box);
l2->setFrameShadow(QFrame::Raised);
QWidget w;
QVBoxLayout layout(&w);
layout.addWidget(l1);
layout.addWidget(l2);
w.show();
return app.exec();
}
Best Answer
The best and recommended way is to use Qt Style Sheet.
To change the text color and background color of a
QLabel
, here is what I would do :You could also avoid using Qt Style Sheets and change the
QPalette
colors of yourQLabel
, but you might get different results on different platforms and/or styles.As Qt documentation states :
But you could do something like this :
But as I said, I strongly suggest not to use the palette and go for Qt Style Sheet.