QT-创建具有复选框的树形控件

树形控件 QTreeWidget
控件节点 QTreeWidgetItem

实现过程：

在Qt设计器中，拖拽出一个QTreeWidget；
在主窗口中编写一个函数init初始化界面，连接树形控件的节点改变信号itemChange（QTreeWidgetItem*item,int column),实现这个信号即可。

具体实现：

1. 新建Qt Widget Application，项目名称为TreeWidget，基类选择QWidget，类名保持Widget不变，保持“创建界面”复选框选中状态。
2. 双击“widget.ui”文件，打开Qt设计器，拖拽出一个QTreeWidget。
3. 在头文件“widget.h”中添加代码

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QTreeWidgetItem>  //包含树形控件节点的头文件
namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT

public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();
public:
    void init();//初始化
    void updateParentItem(QTreeWidgetItem* Item);//可能是更新父节点
public slots://定义槽函数
    void treeItemChanged(QTreeWidgetItem* item,int column);

private:
    Ui::Widget *ui;
};

#endif // WIDGET_H

4.在源文件“widget.cpp”中的类Widget构造函数中添加代码：

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

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    init();//添加初始化函数
    //连接信号和槽
    connect(ui->treeWidget,SIGNAL(itemChanged(QTreeWidgetItem*,int)),
            **this,SLOT(treeItemChanged(QTreeWidgetItem*,int)));
}

Widget::~Widget()
{
    delete ui;
}
//初始化函数的实现
void Widget::init()     //初始化树形控件
{
    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->setFlags(Qt::ItemIsUserCheckable|Qt::ItemIsEnabled|Qt::ItemIsSelectable);
    subItem11->setText(0,"subItem11");
    subItem11->setCheckState(0,Qt::Unchecked);

    QTreeWidgetItem *subItem111=new QTreeWidgetItem(group1);
    subItem111->setFlags(Qt::ItemIsUserCheckable|Qt::ItemIsEnabled|Qt::ItemIsSelectable);
    subItem111->setText(0,"subItem111");
    subItem111->setCheckState(0,Qt::Unchecked);

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

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

    QTreeWidgetItem *subItem14 = new QTreeWidgetItem(group1);
    subItem14->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt:: ItemIsSelectable);
    subItem14->setText(0, "subItem14");
    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->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt:: ItemIsSelectable);
    subItem21->setText(0, "subItem21");
    subItem21->setCheckState(0, Qt::Unchecked);

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

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

//函数treeItemchanged()树形控件改变时的具体实现代码

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++)
            {
                //子节点也选中
                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);
        }
    }
}

//函数updateParentItem()的具体实现代码如下：

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