QlineEdit in focus

gabor53

Hi,
I would like to change the background color of QLineEdit when it is in focus. Can somebody please show me which is the best way of doing it?

Thank you.

jsulm

You can use setStyleSheet(const QString & styleSheet), for a style sheet description see: http://doc.qt.io/qt-5/stylesheet.html

Ratzz

@gabor53
You may also try

    QPalette palette;
    palette.setColor(QPalette::Base,Qt::black);
    palette.setColor(QPalette::Text,Qt::white);
    ui->lineEdit->setPalette(palette);

gabor53

How can I know that lineEdit is in focus?
Thnks.

ValentinMichelet

Hi,

Either connect the QApplication signal focusChanged() to your slot:
http://doc.qt.io/qt-5/qapplication.html#focusChanged

Or reimplement the focusInEvent() method in a custom MyLineEdit, that inherits from QLineEdit, and promote your QLineEdit in QtDesigner using MyLineEdit.
http://doc.qt.io/qt-5/qwidget.html#focusInEvent

Or you can use style sheet as @jsulm suggested:
setStyleSheet("QLineEdit:focus {...}");

If you want only one QLineEdit to have a specific behavior, then give it a name with setObjectName() or through QtDesigner, and use it in the style sheet string:
setStyleSheet("QLineEdit:focus#myLineEdit {...}");

But I realize that I'm giving you different options without telling you what's the best one. I'd say style sheet, but only because it seems easier. I don't really know the mechanisms behind every solution.

gabor53

Thank you, it worked with LineEdit. Should this work with QComboBox too? I tried

setStyleSheet("QComboBox:focus#comboBox{background-color: rgb(170, 255, 127)}");

but nothing happened.
Thank you for all your help.

ValentinMichelet

Each time I need to apply a style sheet, I read the documentation first.

Here is the list of pseudo states:
http://doc.qt.io/qt-5/stylesheet-reference.html#list-of-pseudo-states
And it is said:

:focus The item has input focus.

I don't really know what "input focus" means for QCombBox, maybe it's when it's editable and its line edit has the focus. So then I'd go see how they style a QComboBox in examples:
http://doc.qt.io/qt-5/stylesheet-examples.html#customizing-qcombobox

I recommend you to read carefully these topics:
http://doc.qt.io/qt-5/stylesheet.html
http://doc.qt.io/qt-5/stylesheet-syntax.html
http://doc.qt.io/qt-5/stylesheet-designer.html (optional)
http://doc.qt.io/qt-5/stylesheet-customizing.html
http://doc.qt.io/qt-5/stylesheet-reference.html
http://doc.qt.io/qt-5/stylesheet-examples.html

After reading them, you'll have a global sight of what are style sheets in Qt, how to use them properly, and what can be done and can't.

gabor53

Thank you.