Qt 枚举比较并输出到 QDebug

发布于 2024-11-28 05:35:53 字数 1675 浏览 6 评论 0原文

我正在将枚举注册到 Qt 元对象系统。我已经仔细检查过所有这些都有一个元类型 ID，一切看起来都很完美。但我对这些的比较有一些未解决的问题。

让我们考虑一下用于填充组合框的代码：

WgtEnumItemEditor::WgtEnumItemEditor (QVariant::Type t, QWidget *p) : QComboBox(p) {
    QMetaObject const &mo = staticMetaObject;
    QString mtName = QMetaType::typeName(t);
    mtName = mtName.mid( mtName.lastIndexOf(':')+1 );
    qint32 const iEnum = mo.indexOfEnumerator( mtName.toLatin1() );
    QMetaEnum const &en = mo.enumerator( iEnum );
    quint32 const cEnum = en.keyCount();

    for (quint32 i=0; i<cEnum; i++){
        const char *key = en.key(i);
        uint const val = en.value(i);
        QVariant const var ( t, &val );
        addItem( classNameToNaturalString(key), var );
        qDebug() << var;
    }
}

它工作得很好，我的列表填充了我的枚举的人类可读文本。

现在，我尝试使用 QVariant 本身包含枚举值来设置列表显示的初始值：

void WgtEnumItemEditor::setValue (const QVariant &v) {
    for (quint32 i=0; i<count(); i++) {
        if (itemData(i)==v.data) {
            setCurrentIndex(i);
            break;
        }
    }
}

这段代码不起作用。我必须将测试替换为：

*(uint*)itemData(i).data()==*(uint*)v.data()

这样它就可以工作。

谁能解释一下如何在 QVariants 中启用自定义枚举的比较？或者我在创建用作列表的用户数据的 QVariant 时做错了什么？

另外，如果我尝试 qDebug() 在循环中创建的 QVariants 来填充列表，我会得到空值输出。例如，第一块代码中生成的输出如下所示：

QVariant(ReadingDirection, ) 
QVariant(ReadingDirection, )
QVariant(ReadingDirection, )
QVariant(ReadingDirection, )
QVariant(ReadingDirection, )
QVariant(BarcodeStandard, )
QVariant(BarcodeStandard, )
QVariant(BarcodeStandard, )

正如您所看到的，该值未正确输出...您能帮我找出原因吗？

谢谢你，皮埃尔.

原文

i am registering enums to the Qt meta-object system. i have double checked that all of those have a meta-type ID, and everything looks perfect. But i have some kind of unresolved issue with the comparison of those.

Let's consider this code for populating a combobox:

WgtEnumItemEditor::WgtEnumItemEditor (QVariant::Type t, QWidget *p) : QComboBox(p) {
    QMetaObject const &mo = staticMetaObject;
    QString mtName = QMetaType::typeName(t);
    mtName = mtName.mid( mtName.lastIndexOf(':')+1 );
    qint32 const iEnum = mo.indexOfEnumerator( mtName.toLatin1() );
    QMetaEnum const &en = mo.enumerator( iEnum );
    quint32 const cEnum = en.keyCount();

    for (quint32 i=0; i<cEnum; i++){
        const char *key = en.key(i);
        uint const val = en.value(i);
        QVariant const var ( t, &val );
        addItem( classNameToNaturalString(key), var );
        qDebug() << var;
    }
}

It works good, my list gets populated with human readable texts for my enums.

Now, i'm trying to set the initial value displayed by the list with a QVariant itself containing a value for the enum:

void WgtEnumItemEditor::setValue (const QVariant &v) {
    for (quint32 i=0; i<count(); i++) {
        if (itemData(i)==v.data) {
            setCurrentIndex(i);
            break;
        }
    }
}

This piece of code doesn't work. i have to replace the test by:

*(uint*)itemData(i).data()==*(uint*)v.data()

This way it works.

Can anyone explain me how to enable comparison of my custom enums in QVariants? Or am i doing something wrong while creating the QVariant being used as userdata for the list maybe?

Also, if i try to qDebug() the QVariants created in loop for populating the list, i get empty values outputs. For instance, the output generated in the first chunk of code looks like this:

QVariant(ReadingDirection, ) 
QVariant(ReadingDirection, )
QVariant(ReadingDirection, )
QVariant(ReadingDirection, )
QVariant(ReadingDirection, )
QVariant(BarcodeStandard, )
QVariant(BarcodeStandard, )
QVariant(BarcodeStandard, )

As you can see, the value isn't outputed correctly... Can you please help me find why?

Thank you,
Pierre.

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