QT TreeWidget

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QTreeWidgetItem>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();
public:
    void init();
    void updateParentItem(QTreeWidgetItem* item);
public slots:
    void treeItemChanged(QTreeWidgetItem* item, int column);

private:
    Ui::Widget *ui;
};
#endif // WIDGET_H

widget.cpp

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    
    
    ui->setupUi(this);
    init();
    connect(ui->treeWidget, SIGNAL(itemChanged(QTreeWidgetItem*,int)),
            this, SLOT(treeItemChanged(QTreeWidgetItem*, int)));
}

Widget::~Widget()
{
    
    
    delete ui;
}

void Widget::init()
{
    
    
    ui->treeWidget->clear();
    // 第一个分组
    QTreeWidgetItem *group1 = new QTreeWidgetItem(ui->treeWidget);
    group1->setText(0, "group1");
    group1->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
    group1->setCheckState(0, Qt::Unchecked);

    QTreeWidgetItem *subItem11 = new QTreeWidgetItem(group1);
    subItem11->setText(0, "subItem11");
    subItem11->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
    subItem11->setCheckState(0, Qt::Unchecked);

    QTreeWidgetItem *subItem12 = new QTreeWidgetItem(group1);
    subItem12->setText(0, "subItem12");
    subItem12->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
    subItem12->setCheckState(0, Qt::Unchecked);

    QTreeWidgetItem *subItem13 = new QTreeWidgetItem(group1);
    subItem13->setText(0, "subItem13");
    subItem13->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
    subItem13->setCheckState(0, Qt::Unchecked);

    QTreeWidgetItem *subItem14 = new QTreeWidgetItem(group1);
    subItem14->setText(0, "subItem14");
    subItem14->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
    subItem14->setCheckState(0, Qt::Unchecked);

    //第二个分组
    QTreeWidgetItem *group2 = new QTreeWidgetItem(ui->treeWidget);
    group2->setText(0, "group2");
    group2->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
    group2->setCheckState(0, Qt::Unchecked);

    QTreeWidgetItem *subItem21 = new QTreeWidgetItem(group2);
    subItem21->setText(0, "subItem21");
    subItem21->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
    subItem21->setCheckState(0, Qt::Unchecked);

    QTreeWidgetItem *subItem22 = new QTreeWidgetItem(group2);
    subItem22->setText(0, "subItem22");
    subItem22->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
    subItem22->setCheckState(0, Qt::Unchecked);

    QTreeWidgetItem *subItem23 = new QTreeWidgetItem(group2);
    subItem23->setText(0, "subItem23");
    subItem23->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
    subItem23->setCheckState(0, Qt::Unchecked);
}

void Widget::treeItemChanged(QTreeWidgetItem* item, int column)
{
    
    
    QString itemText = item->text(0);
    //选中时
    if (Qt::Checked == item->checkState(0))
    {
    
    
        QTreeWidgetItem * parent = item->parent();
        int count = item->childCount();
        if (count > 0){
    
    
            for (int i=0; i<count; i++) {
    
    
                //子节点选中
                item->child(i)->setCheckState(0, Qt::Checked);
            }
        }else {
    
    
            //子节点
            updateParentItem(item);
        }
    } else if (Qt::Unchecked == item->checkState(0)) {
    
    
        int count = item->childCount();
        if (count > 0) {
    
    
            for (int i=0; i<count; i++) {
    
    
                item->child(i)->setCheckState(0, Qt::Unchecked);
            }
        } else {
    
    
            updateParentItem(item);
        }
    }
}

void Widget::updateParentItem(QTreeWidgetItem *item)
{
    
    
    QTreeWidgetItem *parent = item->parent();
    if (parent == NULL) {
    
    
        return;
    }

    // 选中的子节点个数
    int selectedCount = 0;
    int childCount = parent->childCount();
    for (int i=0; i<childCount; i++) {
    
    
        QTreeWidgetItem *childItem = parent->child(i);
        if (childItem->checkState(0) == Qt::Checked) {
    
    
            selectedCount++;
        }
    }

    if (selectedCount <= 0) {
    
    
        // 选中状态
        parent->setCheckState(0, Qt::Unchecked);
    } else if (selectedCount > 0 && selectedCount < childCount) {
    
    
        // 部分选中
        parent->setCheckState(0, Qt::PartiallyChecked);
    } else if (selectedCount == childCount) {
    
    
        // 未选中状态
        parent->setCheckState(0, Qt::Checked);
    }

}

#include "widget.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    
    
    QApplication a(argc, argv);
    Widget w;
    w.show();
    return a.exec();
}