[qt] QLabel: set color of text and background

How do I set color of text and background of a QLabel ?

The ONLY thing that worked for me was html.

And I found it to be the far easier to do than any of the programmatic approaches.

The following code changes the text color based on a parameter passed by a caller.

enum {msg_info, msg_notify, msg_alert};
:
:
void bits::sendMessage(QString& line, int level)
{
    QTextCursor cursor = ui->messages->textCursor();
    QString alertHtml  = "<font color=\"DeepPink\">";
    QString notifyHtml = "<font color=\"Lime\">";
    QString infoHtml   = "<font color=\"Aqua\">";
    QString endHtml    = "</font><br>";

    switch(level)
    {
        case msg_alert:  line = alertHtml % line; break;
        case msg_notify: line = notifyHtml % line; break;
        case msg_info:   line = infoHtml % line; break;
        default:         line = infoHtml % line; break;
    }

    line = line % endHtml;
    ui->messages->insertHtml(line);
    cursor.movePosition(QTextCursor::End);
    ui->messages->setTextCursor(cursor);
}

You can use QPalette, however you must set setAutoFillBackground(true); to enable background color

QPalette sample_palette;
sample_palette.setColor(QPalette::Window, Qt::white);
sample_palette.setColor(QPalette::WindowText, Qt::blue);

sample_label->setAutoFillBackground(true);
sample_label->setPalette(sample_palette);
sample_label->setText("What ever text");

It works fine on Windows and Ubuntu, I haven't played with any other OS.

Note: Please see QPalette, color role section for more details

This one is working perfect

QColorDialog *dialog = new QColorDialog(this);
QColor color=  dialog->getColor();
QVariant variant= color;
QString colcode = variant.toString();
ui->label->setStyleSheet("QLabel { background-color :"+colcode+" ; color : blue; }");

getColor() method returns the selected color. You can change label color using stylesheet

The best way to set any feature regarding the colors of any widget is to use QPalette.

And the easiest way to find what you are looking for is to open Qt Designer and set the palette of a QLabel and check the generated code.

I add this answer because I think it could be useful to anybody.

I step into the problem of setting RGBA colors (that is, RGB color with an Alpha value for transparency) for color display labels in my painting application.

As I came across the first answer, I was unable to set an RGBA color. I have also tried things like:

myLabel.setStyleSheet("QLabel { background-color : %s"%color.name())

where color is an RGBA color.

So, my dirty solution was to extend QLabel and override paintEvent() method filling its bounding rect.

Today, I've open up the qt-assistant and read the style reference properties list. Affortunately, it has an example that states the following:

QLineEdit { background-color: rgb(255, 0, 0) }

Thats open up my mind in doing something like the code below, as an example:

myLabel= QLabel()
myLabel.setAutoFillBackground(True) # This is important!!
color  = QtGui.QColor(233, 10, 150)
alpha  = 140
values = "{r}, {g}, {b}, {a}".format(r = color.red(),
                                     g = color.green(),
                                     b = color.blue(),
                                     a = alpha
                                     )
myLabel.setStyleSheet("QLabel { background-color: rgba("+values+"); }")

Note that setAutoFillBackground() set in False will not make it work.

Regards,