How do I set the background color of a widget like combobox or double spin box?

Question

I am trying to set the background color for a double spin box, and I am not sure what function I should use.

I saw some function called SetBackgroundRole which accepts a Qt::ColorRole, but I am not sure how to use this one as well.

Kindly let me know, what's the simple way to change the background color of a QComboBox or QDoubleSpinBox?

Answer 1

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.

To make sure your background color will be correct, I would suggest to use the Qt Style Sheet. Here is what I did to change the background color of a QComboBox:

myComboBox->setStyleSheet("QComboBox { background-color: blue; }");

I haven't specifically tried for a QSpinBox, but I guess it'll work the same !

Answer 2

fhe is generally correct, but doesn't account for the widgets (like spin boxes and buttons/comboboxes) that use a different background role in the palette. A more general solution would be something like this:

QPalette pal = widget.palette();
pal.setColor(widget.backgroundRole(), Qt::blue);
widget.setPalette(pal);

Alternatively, you could look into the descriptions of the various palette roles and figure out the one you want, then apply it to the widget containing the others you want changed. The palette changes should propagate to the children widgets.

Answer 3

Actually, if you look at the Qt docs for QPalette in the case of a QComboBox the background role is probably not what you want. What you want is:

QPalette::Base Used mostly as the background color for text entry widgets, but can also be used for other painting - such as the background of combobox drop down lists and toolbar handles. It is usually white or another light color.

So here is the code I am using to set the background color of a combo box I am using to match the color of the widget it is on:

QPalette pal = myComboBox->palette();
pal.setColor(QPalette::Base, pal.color(QPalette::Window));
myComboBox->setPalette(pal);

Answer 4

Apparently in Qt 4.1 and onwards, you need to set this->setAutoFillBackground( true ); for the palette to apply the background color.

Answer 5

While the previous answers may set the background color for a non-editable QComboBox, they do not work for an editable QComboBox. For that case, you need to derive the QLineEdit widget used for the editing and reset its background.

Here is how I got it to work:

    QComboBox *myComboBox = new QComboBox();
    myComboBox->setEditable(true);
    QColor backColor = QColor(246, 230, 230);
    QLineEdit *lineEditor = myComboBox->lineEdit();
    QPalette pal = lineEditor->palette();
    pal.setColor(QPalette::Base, backColor);
    lineEditor->setPalette(pal);

Answer 6

Construct a palette that is blue no matter what the actual widget:

comboBox->setPalette( QPalette( Qt::blue ) );

Answer 7

I'd try something like

QPalette pal = widget.palette();
pal.setColor(QPalette::Window, Qt::blue);
widget.setPalette(pal);

Answer 8

comboBox->setPalette( QPalette( Qt::blue ) );

Works fine for me!

Answer 9

No previously answers worked for me, but I made a mix of all responses and finally worked on Qt 5.12:

QPalette pal = ui.widget->palette();
pal.setColor(QPalette::Base, Qt::red);
ui.widget->setPalette(pal);