如何连接两个 QComboBox 以使第二个仅显示某些项目？

Question

我有两个 QComboBox 可以相互连接。

特别是，如果在第一个 QComboBox 中进行缩放，我希望在第二个 QComboBox 中也不会显示，反之亦然..

这是我的代码：

auto lingua_originaleT = new QComboBox();
lingua_originaleT->addItems({"Italiano", "Inglese", "Francese", "Spagnolo", "Portoghese", "Tedesco", "Cinese"});
auto lingua_targetT = new QComboBox();
lingua_targetT->addItems({"Italiano", "Inglese", "Francese", "Spagnolo", "Portoghese", "Tedesco", "Cinese"});

结果应该是这样的：

同样的语言也不应该出现在第二个下拉菜单中

Answer 1

一种可能的解决方案是使用 QSortFilterProxyModel 进行过滤：

#include <QApplication>
#include <QComboBox>
#include <QHBoxLayout>
#include <QSortFilterProxyModel>
#include <QStandardItemModel>
#include <QWidget>

class FilterProxyModel: public QSortFilterProxyModel{
public:
    using QSortFilterProxyModel::QSortFilterProxyModel;
protected:
    bool filterAcceptsRow(int source_row, const QModelIndex &source_parent) const{
        if(filterRegExp().isEmpty())
            return true;
        return !QSortFilterProxyModel::filterAcceptsRow(source_row, source_parent);
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QWidget widget;
    widget.resize(640, 480);
    widget.show();

    QStandardItemModel *model = new QStandardItemModel(&widget);
    const QStringList values{"Italiano", "Inglese", "Francese", "Spagnolo", "Portoghese", "Tedesco", "Cinese"};
    for(const QString & value: values){
        model->appendRow(new QStandardItem(value));
    }
    QComboBox *lingua_originaleT = new QComboBox;
    FilterProxyModel *proxy_originalT = new FilterProxyModel(&widget);
    proxy_originalT->setSourceModel(model);
    lingua_originaleT->setModel(proxy_originalT);

    QComboBox *lingua_targetT = new QComboBox;
    FilterProxyModel *proxy_targetT = new FilterProxyModel(&widget);
    proxy_targetT->setSourceModel(model);
    lingua_targetT->setModel(proxy_targetT);

    QHBoxLayout *lay = new QHBoxLayout(&widget);
    lay->addWidget(lingua_originaleT);
    lay->addWidget(lingua_targetT);

    QObject::connect(lingua_originaleT, &QComboBox::currentTextChanged, proxy_targetT, &FilterProxyModel::setFilterFixedString);
    QObject::connect(lingua_targetT, &QComboBox::currentTextChanged, proxy_originalT, &FilterProxyModel::setFilterFixedString);

    lingua_originaleT->setCurrentIndex(0);
    lingua_targetT->setCurrentIndex(1);

    return a.exec();
}

Answer 2

在内部，QCombobox 使用 QStandardItemModel - 除非您使用 setModel() 提供自定义模型。

这意味着您可以执行以下操作：

// Just some setup
auto combo = new QComboBox(this);
combo->addItems({ "Item0", "Item1", "Item2" });

// Here is the interesting bit
auto model = qobject_cast<QStandardItemModel*>(combo->model());
auto item  = model->item(0); // <-- index in the combobox
item->setEnabled(false); // <-- You can't select it anymore

if(combo->currentIndex() == 0) // Choose another one if it's already selected
    combo->setCurrentIndex(1);

// From now, Item 0 will be visible in the dropdown but not selectable by the user.

我让你找到一种方法让 2 个框相互禁用其他项目（重要的是，如果选择更改，则启用它们一次）。这是一个监听每个盒子的索引变化信号并相应地更新另一个模型的问题。

Answer 3

我解决了，解决方案完美！ 我是这样做的：

lingua_originaleT = new QComboBox();
lingua_targetT = new QComboBox();

    QStringList traduzioneLangList = {"Italiano", "Inglese", "Francese", "Spagnolo", "Portoghese", "Tedesco", "Cinese"};
    lingua_originaleT->clear();
    lingua_originaleT->addItems(traduzioneLangList);
    lingua_originaleT->setCurrentIndex(-1);
    lingua_targetT->clear();
    lingua_targetT->addItems(traduzioneLangList);
    lingua_targetT->setCurrentIndex(-1);

    connect(lingua_originaleT, &QComboBox::currentTextChanged, lingua_targetT, [=](const QString &selection) {
        auto tarLangList = traduzioneLangList;
        lingua_targetT->blockSignals(true);
        tarLangList.removeOne(selection);
        lingua_targetT->clear();
        lingua_targetT->addItems(traduzioneLangList);
        lingua_targetT->blockSignals(false);
    });
    connect(lingua_targetT, &QComboBox::currentTextChanged, lingua_originaleT, [=](const QString &selection) {
        auto tarLangList = traduzioneLangList;
        lingua_originaleT->blockSignals(true);
        tarLangList.removeOne(selection);
        lingua_originaleT->clear();
        lingua_originaleT->addItems(traduzioneLangList);
        lingua_originaleT->blockSignals(false);
    });
    lingua_originaleT->setCurrentIndex(0);

非常感谢 reddit 上的@lifof！