Qt: using enums with QComboBox

Question

I have a set of parameters that I need to edit, some of which are enums.

As of today, I use the raw value of the enum in a QSpinBox, which is not friendly at all. You have to remember the values by yourself and set the good one:

For instance, E_Range could be presenting a combobox with these:

typedef enum {
    ERANGE_2_5  = 0, /*!< +/- 2.5 V */
    ERANGE_5    = 1, /*!< +/- 5 V */
    ERANGE_10   = 2, /*!< +/- 10 V */
    ERANGE_AUTO = 3  /*!< Auto range */
} TVoltageRange_e;

I didn't find anything about using an enum in a QComboBox. Is it possible?
If yes, what are the steps?

I mean, I guess I'll have to declare the enum through Qt so that it is "enumerable" with the Qt metaobject. But from there, I'm not sure.

Answer 1

Of course you can always hardcode the values, but as soon as you modify that enum you have to rememeber to change the code that populates your combobox.

I mean, I guess I'll have to declare the enum through Qt so that it is "enumerable" with the Qt metaobject. But from there, I'm not sure.

Exactly, using introspection is a smart move. Mark the enum with Q_ENUMS and add the Q_OBJECT macro. Then:

• Grab your class' metaobject via Class::staticMetaObject()
• Get the QMetaEnum for your enum via QMetaObject::indexOfEnumerator() + QMetaObject::enumerator()
• Get the number of keys via QMetaEnum::keyCount(), and iterate getting the key names and their corresponding values (QMetaEnum::key(), QMetaEnum::keyToValue()).

With this you'll be able to populate your combobox programmatically (the typical pattern is to add the enum key as the user-visible string and the corresponding value as its "item data", cf. QComboBox's documentation.)