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c++qtqcombobox

Remove arrow from disabled QComboBox while respecting style

In the picture below, the first QComboBox is disabled:

enter image description here

I want to emphasize the fact that the value cannot be changed by removing the arrow of disabled QComboBoxes.

I've tried modifying the stylesheet already being used to:

QComboBox::down-arrow:disabled {
  border: 0;
  background: transparent;
  image: none;
  height: 0;
  width: 0;
}

But it doesn't solve the issue and conflicts with my current style (set using qApp->setStyle("fusion")):

enter image description here

How can I get it?

Solution

  • The trick can be done by using a QProxyStyle and returning a null QRect for the arrow subcontrol (QProxyStyle::subControlRect). A QProxyStyle allows you to vary specific behaviours of a style without the need of implementing a whole new one (it wraps the original style).

    class MyProxyStyle : public QProxyStyle {
public:
  MyProxyStyle(const QString& base_style_name) : QProxyStyle(base_style_name) {}

  QRect MyProxyStyle::subControlRect(QStyle::ComplexControl cc,
                                     const QStyleOptionComplex* option,
                                     QStyle::SubControl sc,
                                     const QWidget* widget) const override
  {
    if (cc == CC_ComboBox && sc == SC_ComboBoxArrow && !widget->isEnabled()) return QRect();
    return QProxyStyle::subControlRect(cc, option, sc, widget);
  }
};

// ...

qApp->setStyle(new MyProxyStyle("fusion"));

    Result:

    enter image description here