如何在QT信号中传递结构体或者复杂数据类型

如何在QT信号中传递结构体或者复杂数据类型

1. 传递复杂类型的方法

关于传递复杂数据类型QT内部提供了一组宏：

Q_DECLARE_ASSOCIATIVE_CONTAINER_METATYPE(Container)

Q_DECLARE_METATYPE(Type)

Q_DECLARE_OPAQUE_POINTER(PointerType)

Q_DECLARE_SEQUENTIAL_CONTAINER_METATYPE(Container)

Q_DECLARE_SMART_POINTER_METATYPE(SmartPointer)

2. Q_DECLARE_METATYPE(Type)使用说明

以信号和槽函数传递结构体为例：

假设我们现在有这样一种需求：点击界面一个Button, A类中的结构体数据需要通过信号和槽传递给B类。

//widget.h
#ifndef WIDGET_H
#define WIDGET_H

#include 
#include 
#include 

namespace Ui {
class Widget;
}

struct Student
{
    int  m_age;
    char m_Name[32];
};

struct Packet
{
    int     m_id;
    Student m_stInfo[3];
    bool    m_blRecord;
};

// 注册元对象
Q_DECLARE_METATYPE(Packet)

class CTest;
class Widget : public QWidget
{
    Q_OBJECT

public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();
private slots:
    void SlotButtonClick(bool);
signals:
    void SigParamUpdate(int param, const QVariant varValue);
private:
    Ui::Widget *ui;
    CTest     *m_pTest;
};

class CTest:public QObject
{
    Q_OBJECT
public:
    CTest():m_blRecord(false){}
    ~CTest(){}
public slots:
    void SlotParamUpdate(int param, const QVariant varValue);
private:
    bool    m_blRecord;
    QString m_strName;
};

#endif // WIDGET_H

//widget.cpp
#include "widget.h"
#include "ui_widget.h"
#include 

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget),
    m_pTest(new CTest)
{
    ui->setupUi(this);
    connect(this, SIGNAL(SigParamUpdate(int,QVariant)),
            m_pTest, SLOT(SlotParamUpdate(int,QVariant)));
    connect(ui->pushButton, SIGNAL(clicked(bool)), this, SLOT(SlotButtonClick(bool)));
}

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

void Widget::SlotButtonClick(bool)
{
    Packet iPackInfo;
    memset(&iPackInfo, 0, sizeof(iPackInfo));
    iPackInfo.m_id = 1;
    iPackInfo.m_stInfo[1].m_age = 22;
    char *name = "DDZ";
    int length = sizeof(iPackInfo.m_stInfo[0].m_Name)/sizeof(*iPackInfo.m_stInfo[0].m_Name);
    for(int i= 0; i < 3; i++)
    {
        memset(iPackInfo.m_stInfo[i].m_Name, 0, length);
        memcpy(iPackInfo.m_stInfo[i].m_Name, name, strlen(name));
    }
    iPackInfo.m_blRecord = true;
    QVariant varValue = QVariant::fromValue(iPackInfo);
    emit SigParamUpdate(1, varValue);
}

void CTest::SlotParamUpdate(int param, const QVariant varValue)
{
    qDebug()<<"param: "<<param;
    if (varValue.canConvert<Packet>())
    {
        Packet PacketInfo = varValue.value<Packet>();
        m_blRecord = PacketInfo.m_blRecord;
        m_strName = QString(PacketInfo.m_stInfo[param].m_Name);
    }
    qDebug()<<"m_strName: "<< m_strName;
    qDebug()<<"m_blRecord: "<< m_blRecord;
}

测试结果，点击界面Button后，在CTest类中可以接受到另外一个类发送的信息：

param: 1
m_strName: “DDZ”
m_blRecord: true

3. 主要步骤

• 注册元对象 Q_DECLARE_METATYPE(T)

• 注意QVariant的赋值 QVariant varValue = QVariant::fromValue(T);

• 注意槽函数中取值的方法

   if (varValue.canConvert())
   {
       T obj = varValue.value();
       ...
   }