Qt --- QTreeWidget 树形控件实例&遇到的问题

说明

• 环境
  Qt软件版本 : 5.9.9
  实例参考书籍 : Qt5开发及实例 陆文周
  系统 : Win10 专业版

• QTreeWidget 树形控件实例
  选中树形控件的父节点 或者 取消树形控件的父节点 子节点跟随父节点状态;
  子节点单独选中, 父节点在半选中状态;

代码

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();

    void init();
    void updateParentItem(QTreeWidgetItem* item);

public slots:
    void treeItemChanged(QTreeWidgetItem* item, int column);

private:
    Ui::Widget *ui;

};
#endif // WIDGET_H

widget.c

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

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);

    init();
    /* itemChanged() 当指定项中列的内容发生更改时，会发出此信号 */
    connect(ui->treeWidget, SIGNAL(itemChanged(QTreeWidgetItem* , int)), this , SLOT(treeItemChanged(QTreeWidgetItem* , int)) );
}

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

void Widget::init()
{
    ui->treeWidget->clear(); //* clear() 清除树内部的所有项选择

    ui->treeWidget->setHeaderHidden(true); //* 设置隐藏treeWidget表头显示

    //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::updateParentItem(QTreeWidgetItem* item) //* 判断并设置父节点的状态
{
    QTreeWidgetItem *parent = item ->parent(); //* parent() 返回项目的父级
    if(parent == NULL)
    {
        return;
    }
    /* 统计选中的子节点的个数 */
    int selectedCount = 0;
    int childCount = parent->childCount();  //* childCount() 返回子项目的数量

    for (int i = 0; i < childCount; i++)
    {
        QTreeWidgetItem *childItem =  parent->child(i);
        if(childItem->checkState(0) == Qt::Checked)
        {
            selectedCount++;
        }
    }
   /* 根据选中的子节点的个数 更新父节点的状态 */
    if(selectedCount <= 0)
    {
        parent->setCheckState(0, Qt::Unchecked);
    }
    else if(selectedCount > 0 && selectedCount < childCount)
    {
        //部分选中状态
        parent->setCheckState(0, Qt::PartiallyChecked);
    }
    else if(selectedCount == childCount)
    {
        //未选中状态
        parent->setCheckState(0, Qt::Checked);
    }
}

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(); // 获取子部件数目
        if(count > 0) //判断是否有子节点
        {
            for (int i = 0; i < count; i++)
            {
                //子节点也选中 有的话将下面子节点全部选中
                item ->child(i) ->setCheckState(0, Qt::Checked);
            }
        }
        else
        {
            //是子节点
            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);
        }
    }
}

源码下载

https://download.youkuaiyun.com/download/occasionally/87389132

遇到的问题

在使用Qt treeWidget 控件时发现总会出现表头显示1(如图片), 在ui中删除无效, 发现可以通过下列方式解决。

解决方式1

设计界面 选中UI组件treeWidget直接设置 HeaderHidden属性

解决方式2

2. 程序中使用 setHeaderHidden() 设置; 在界面构造函数中添加下面语句;

    ui->treeWidget->setHeaderHidden(true);

操作后的显示