QTreeView 与 QTreeWidget 例子

🕗 发布于 2024-12-12 12:31 qt

1. 先举个例子

1班有3个学生：张三、李四、王五
4个学生属性：语文数学英语性别。
语文数学英语使用QDoubleSpinBox* 编辑，范围为0到100,1位小数
性别使用QComboBox* 编辑，选项为：男、女
实现效果：
在这里插入图片描述

2. 按照例子实现

2.1 自定义一个QStandardItemModel 来存数据

#include <QApplication>
#include <QTreeView>
#include <QStandardItemModel>
#include <QStandardItem>
#include <QDoubleSpinBox>
#include <QComboBox>
#include <QStyledItemDelegate>
#include <QHeaderView>

class CustomStandardItemModel : public QStandardItemModel
{
public:
    CustomStandardItemModel(QObject *parent = nullptr);

    Qt::ItemFlags flags(const QModelIndex &index) const override;
};


class CustomStandardItemModel : public QStandardItemModel
{
public:
    CustomStandardItemModel(QObject *parent = nullptr);

    Qt::ItemFlags flags(const QModelIndex &index) const override;
};


CustomStandardItemModel::CustomStandardItemModel(QObject *parent) : QStandardItemModel(parent)
{
    // Set up the model
    setColumnCount(2);
    setHorizontalHeaderLabels(QStringList()<< "属性" << "值") ;

    // Root item
    QStandardItem *rootItem = invisibleRootItem();
    QStandardItem *classItem = new QStandardItem("1班");
    rootItem->appendRow(classItem);

    // Students
    QStringList students = {"张三", "李四", "王五"};
    for (const QString &student : students)
    {
        QStandardItem *studentItem = new QStandardItem(student);
        classItem->appendRow(studentItem);

        // Subjects
        QStringList subjects = {"语文", "数学", "英语", "性别"};
        for (const QString &subject : subjects)
        {
            QStandardItem *subjectItem = new QStandardItem(subject);
            subjectItem->setEditable(false); // Property column is not editable
            QStandardItem *valueItem = new QStandardItem(subject == "性别"?"女":"100.0");
            valueItem->setEditable(true); // Value column is editable for level 2
            studentItem->appendRow(QList<QStandardItem*>() << subjectItem << valueItem);
        }
    }
}

Qt::ItemFlags CustomStandardItemModel::flags(const QModelIndex &index) const
{
    if (index.column() == 1 && index.parent().isValid()) {
        QStandardItem *item = itemFromIndex(index);
        if (item && item->hasChildren()) {
            // If the item has children, it's a student node, make value column not editable
            return QAbstractItemModel::flags(index) & ~Qt::ItemIsEditable;
        }
    }
    return QStandardItemModel::flags(index);
}

2.2 自定义一个QStyledItemDelegate 来显示不同的QWidget控件

class CustomDelegate : public QStyledItemDelegate
{
public:
    CustomDelegate(QObject *parent = nullptr) ;

    QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override;

};


CustomDelegate::CustomDelegate(QObject *parent) : QStyledItemDelegate(parent)
{

}

QWidget *CustomDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    if (index.column() == 1 && index.parent().isValid())
    {
        QString property = index.sibling(index.row(), 0).data().toString();
        if (property == "语文" || property == "数学" || property == "英语")
        {
            QDoubleSpinBox *spinBox = new QDoubleSpinBox(parent);
            spinBox->setRange(0, 100);
            spinBox->setDecimals(1);
            return spinBox;
        } else if (property == "性别") {
            QComboBox *comboBox = new QComboBox(parent);
            comboBox->addItem("男");
            comboBox->addItem("女");
            return comboBox;
        }
    }
    return QStyledItemDelegate::createEditor(parent, option, index);
}

2.3 使用 QTreeView 来显示

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    CustomStandardItemModel* model;
    CustomDelegate* delegate;

    QTreeView *treeView;
    treeView = new QTreeView();
    treeView->setObjectName(QString::fromUtf8("treeView"));
    treeView->setGeometry(QRect(40, 30, 241, 501));


    model = new CustomStandardItemModel();
    delegate = new CustomDelegate();

    treeView->setModel(model);
    treeView->setItemDelegate(delegate);
    treeView->header()->setSectionResizeMode(QHeaderView::ResizeToContents);
    treeView->expandAll();
    treeView->show();

    bool ret = a.exec();

    delete model;
    delete delegate;
    delete treeView;

    return ret;
}

2.4 运行效果

在这里插入图片描述

修改语文、数学、英语时，双击后，变成QDoubleSpinBox 控件
在这里插入图片描述

修改性别时，双击后，变成QComboBox控件

3. 增加修改的信号

要在 CustomDelegate 中实现值修改时发送信号，通知告知是哪个学生的哪个属性的值变成了多少，可以按照以下步骤进行修改：

定义信号：在 CustomDelegate 类中添加一个信号，用于在值修改时发送。
捕获编辑器值的变化：在 setModelData 方法中捕获编辑器的值变化，并发出信号。

修改代码：


class CustomDelegate : public QStyledItemDelegate
{
    Q_OBJECT
public:
    CustomDelegate(QObject *parent = nullptr) ;

    QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override;


    void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const override;

signals:
    void valueChanged( QString &student,  QString &property, QVariant value) const;
};


CustomDelegate::CustomDelegate(QObject *parent) : QStyledItemDelegate(parent)
{

}

QWidget *CustomDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    if (index.column() == 1 && index.parent().isValid()) {
        QString property = index.sibling(index.row(), 0).data().toString();
        if (property == "语文" || property == "数学" || property == "英语") {
            QDoubleSpinBox *spinBox = new QDoubleSpinBox(parent);
            spinBox->setRange(0, 100);
            spinBox->setDecimals(1);
            return spinBox;
        } else if (property == "性别") {
            QComboBox *comboBox = new QComboBox(parent);
            comboBox->addItem("男");
            comboBox->addItem("女");
            return comboBox;
        }
    }
    return QStyledItemDelegate::createEditor(parent, option, index);
}

void CustomDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
    if (index.column() == 1 && index.parent().isValid()) {
        QString property = index.sibling(index.row(), 0).data().toString();
        QString student = index.parent().data().toString();

        if (QDoubleSpinBox *spinBox = qobject_cast<QDoubleSpinBox*>(editor))
        {
            double value = spinBox->value();
            model->setData(index, value);
            emit valueChanged(student, property, QVariant::fromValue(value));
        }
        else if (QComboBox *comboBox = qobject_cast<QComboBox*>(editor))
        {
            QString value = comboBox->currentText();
            model->setData(index, value);
            emit valueChanged(student, property, QVariant::fromValue(value));
        }
    }
    else
    {
        QStyledItemDelegate::setModelData(editor, model, index);
    }
}

连接信号和槽

    // 连接信号槽
    QObject::connect(delegate, &CustomDelegate::valueChanged, [&](const QString &student, const QString &property, QVariant value) 
    {
        if (property == "性别")
        {
            qDebug() << "学生:" << student << "属性:" << property << "值:" << value.toString();
        }
        else
        {
            qDebug() << "学生:" << student << "属性:" << property << "值:" << value.toDouble();
        }
    });

4. 上面例子改为QTreeWidget 实现

基本步骤也差不多，就是少了QStandardItemModel


#include <QApplication>
#include <QTreeWidget>
#include <QTreeWidgetItem>
#include <QHeaderView>
#include <QLineEdit>
#include <QDoubleSpinBox>
#include <QComboBox>
#include <QAbstractItemView>
#include <QEvent>
#include <QMouseEvent>
#include <QItemDelegate>
#include <QDebug>
#include <cmath> // 用于std::fabs函数
#include <iostream>

class MyTreeWidgetDelegate : public QItemDelegate {
    Q_OBJECT

public:
    MyTreeWidgetDelegate(QObject* parent = nullptr) : QItemDelegate(parent) {}

    QWidget* createEditor(QWidget* parent, const QStyleOptionViewItem& option, const QModelIndex& index) const override 
    {
        if (index.column() == 1)
        {
            QTreeWidgetItem* item = static_cast<QTreeWidgetItem*>(index.internalPointer());
            if (item && item->parent() && item->parent()->parent()) {
                const QString attr = item->text(0);
                if (attr == "语文" || attr == "数学" || attr == "英语") {
                    QDoubleSpinBox* spinBox = new QDoubleSpinBox(parent);
                    spinBox->setRange(0, 100);
                    spinBox->setDecimals(1);
                    spinBox->setSingleStep(0.1);
                    return spinBox;
                }
                else if (attr == "性别") 
                {
                    QComboBox* comboBox = new QComboBox(parent);
                    comboBox->addItems({ "男", "女" });
                    return comboBox;
                }
            }
        }
        return QItemDelegate::createEditor(parent, option, index);
    }

    void setEditorData(QWidget* editor, const QModelIndex& index) const override 
    {
        if (index.column() == 1) 
        {
            QTreeWidgetItem* item = static_cast<QTreeWidgetItem*>(index.internalPointer());
            if (item && item->parent() && item->parent()->parent()) {
                const QString attr = item->text(0);
                if (attr == "语文" || attr == "数学" || attr == "英语") {
                    QDoubleSpinBox* spinBox = qobject_cast<QDoubleSpinBox*>(editor);
                    if (spinBox) 
                    {
                        spinBox->setValue(item->text(1).toDouble());
                    }
                }
                else if (attr == "性别") 
                {
                    QComboBox* comboBox = qobject_cast<QComboBox*>(editor);
                    if (comboBox) 
                    {
                        comboBox->setCurrentText(item->text(1));
                    }
                }
            }
        }
        else 
        {
            QItemDelegate::setEditorData(editor, index);
        }
    }

    void setModelData(QWidget* editor, QAbstractItemModel* model, const QModelIndex& index) const override 
    {
        if (index.column() == 1) 
        {
            QString property = index.sibling(index.row(), 0).data().toString();
            QString student = index.parent().data().toString();

            if (QDoubleSpinBox* spinBox = qobject_cast<QDoubleSpinBox*>(editor))
            {
                double oldValue = index.sibling(index.row(), 1).data().toDouble();
                double value = spinBox->value();
                if (std::fabs(oldValue - value) > 1e-6)
                {
                    model->setData(index, value, Qt::EditRole);
                    emit valueChanged(student, property, QVariant::fromValue(value));
                }
            }
            else if (QComboBox* comboBox = qobject_cast<QComboBox*>(editor))
            {
                QString oldValue = index.sibling(index.row(), 1).data().toString();
                QString value = comboBox->currentText();
                if (oldValue != value)
                {
                    model->setData(index, value, Qt::EditRole);
                    emit valueChanged(student, property, QVariant::fromValue(value));
                }
            }
        }
        else 
        {
            QItemDelegate::setModelData(editor, model, index);
        }
    }

    void updateEditorGeometry(QWidget* editor, const QStyleOptionViewItem& option, const QModelIndex& index) const override 
    {
        editor->setGeometry(option.rect);
    }
signals:
    void valueChanged(QString& student, QString& property, QVariant value) const;
};

class CustomTreeWidget : public QTreeWidget {
    Q_OBJECT

public:
    CustomTreeWidget(QWidget* parent = nullptr) : QTreeWidget(parent) {
        setColumnCount(2);
        setHeaderLabels({ "属性", "值" });

        // 设置属性列不可编辑
        header()->setSectionResizeMode(0, QHeaderView::Stretch);
        header()->setSectionResizeMode(1, QHeaderView::Stretch);

        // 创建班级节点
        QTreeWidgetItem* classItem = new QTreeWidgetItem(this);
        classItem->setText(0, "1班");
        classItem->setFlags(classItem->flags() & ~Qt::ItemIsEditable);

        // 创建学生节点
        QStringList students = { "张三", "李四", "王五" };
        for (const QString& student : students) {
            QTreeWidgetItem* studentItem = new QTreeWidgetItem(classItem);
            studentItem->setText(0, student);
            studentItem->setFlags(studentItem->flags() & ~Qt::ItemIsEditable);

            // 创建学生属性节点
            QStringList attributes = { "语文", "数学", "英语", "性别" };
            for (const QString& attr : attributes) 
            {
                QTreeWidgetItem* attrItem = new QTreeWidgetItem(studentItem);
                attrItem->setText(0, attr);
                if (attr == "语文" || attr == "数学" || attr == "英语")
                {
                    attrItem->setText(1, "100");
                }
                else
                {
                    attrItem->setText(1, "男");
                }
                attrItem->setFlags(attrItem->flags() & ~Qt::ItemIsEditable);

                if (attr == "语文" || attr == "数学" || attr == "英语" || attr == "性别") 
                {
                    attrItem->setFlags(attrItem->flags() | Qt::ItemIsEditable);
                }
                else 
                {
                    attrItem->setFlags(attrItem->flags() & ~Qt::ItemIsEditable);
                }
            }
        }

        // 设置编辑策略
        m_delegate = new MyTreeWidgetDelegate(this);
        setItemDelegateForColumn(1, m_delegate);
        setEditTriggers(QAbstractItemView::DoubleClicked);

        // 连接信号槽
        QObject::connect(m_delegate, &MyTreeWidgetDelegate::valueChanged, [&](const QString& student, const QString& property, QVariant value)
            {
                if (property == "性别")
                {
                    qDebug() << "学生:" << student << "属性:" << property << "值:" << value.toString();
                }
                else
                {
                    qDebug() << "学生:" << student << "属性:" << property << "值:" << value.toDouble();
                }
            });
    }

protected:
    void mousePressEvent(QMouseEvent* event) override {
        QTreeWidgetItem* item = itemAt(event->pos());
        if (item && item->columnCount() > 1)
        {
            int column = columnAt(event->x());
            if (column == 1 && item->parent() && item->parent()->parent())
            {
                editItem(item, column);
                return;
            }
        }
        QTreeWidget::mousePressEvent(event);
    }
private:
    MyTreeWidgetDelegate* m_delegate;
};

int main(int argc, char* argv[]) {
    QApplication a(argc, argv);
    CustomTreeWidget w;
    w.setGeometry(QRect(40, 30, 241, 501));
    w.expandAll();
    w.show();
    return a.exec();
}