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QT笔记——信号转发器之QSignalMapper

网友: 文章列表 2024-03-22 02:39:37

QT笔记——信号转发器之QSignalMapper

QSignalMapper类可以看成是信号的翻译和转发器。
它可以把一个无参的信号翻译成带以下4种参数的信号再转发：int、QString、 QObject以及QWidget 。

应用场景一般是：有一些信号，发送的参数都是一样的情况下，常用的方法是给每一个信号都连接一个槽函数。但这样做，会让代码多一些不必要的复杂，这种情况下，你就可以使用QSignalMapper
QT笔记——信号转发器之QSignalMapper

下面是 3 个按钮连接 到 对应的 映射数据
setMapping 设置 发射对象 接受的数据

意思：m_signalMapper 作为一个中转站 点击按钮 给到 m_signalMapper，用map来翻译 这个 数据，然后m_signalMapper 发射mapped信号 将刚才翻译的数据发送给 this，这个this 就是我们最终的 接受者
目的：这时候我们就将3个按钮的点击信号 都交给 m_signalMapper 去处理，它发射一个信号mapped 就 节省了 3个按钮 都需要写connect 非必要操作，因为他们的 目的 都是 去 触发showName 这个槽函数，现在我们只需要一个 conenct 就可以解决

	m_signalMapper = new QSignalMapper(this);m_signalMapper->setMapping(ui.btn1, "Button 1 clicked");m_signalMapper->setMapping(ui.btn2, "Button 2 clicked");m_signalMapper->setMapping(ui.btn3, "Button 3 clicked");connect(ui.btn1, SIGNAL(clicked()), m_signalMapper, SLOT(map()));connect(ui.btn2, SIGNAL(clicked()), m_signalMapper, SLOT(map()));connect(ui.btn3, SIGNAL(clicked()), m_signalMapper, SLOT(map()));connect(m_signalMapper, SIGNAL(mapped(const QString&)), this, SLOT(showName(const QString&)));connect(m_signalMapper, SIGNAL(mapped(QString)), this, SLOT(showStrName(QString)));

结果：

QT笔记——信号转发器之QSignalMapper
来看一下如果参数为 QObejct是怎么回事

这里有一个StudentInfo 类型 是继承于QObject的，然后分别设置了它的参数，此时我们就知道，点击按钮，然后将 这个学生的信息 交给我们的 m_signalMapper，然后它 在转发给我们的 showStudentInfo 函数，这里函数展示了我们学生的信息情况，也同样不需要写 3个 connect 来操作

	m_s1.SetName("lion");m_s1.SetAge(20);StudentInfo* s2 = new StudentInfo("cxq", 18);StudentInfo* s3 = new StudentInfo("lion_cxq", 22);m_signalMapper->setMapping(ui.btn1, &m_s1);m_signalMapper->setMapping(ui.btn2, s2);m_signalMapper->setMapping(ui.btn3, s3);connect(ui.btn1, &QPushButton::clicked, m_signalMapper, QOverload<>::of(&QSignalMapper::map));connect(ui.btn2, &QPushButton::clicked, m_signalMapper, QOverload<>::of(&QSignalMapper::map));connect(ui.btn3, &QPushButton::clicked, m_signalMapper, QOverload<>::of(&QSignalMapper::map));connect(m_signalMapper, QOverload<QObject*>::of(&QSignalMapper::mapped), this, &QSignalMapperTest::showStudentInfo);

关键的一点是：
我们可以在槽函数中 将QObject 转化为我们 自定义的指针

void QSignalMapperTest::showStudentInfo(QObject* object)
{StudentInfo* s = qobject_cast<StudentInfo*>(object);if (s){qDebug() << s->GetAge() << s->GetName();}
}

还有一个就是我们遇到同名的 槽函数时，我们必须要同时两边重载，使用一个即可，否则会报错

	//第一个connect(m_signalMapper, QOverload<const QString&>::of(&QSignalMapper::mapped), this, QOverload<const QString&>::of(&QSignalMapperTest::showName));//第二个connect(m_signalMapper, static_cast<void (QSignalMapper::*)(const QString&)>(&QSignalMapper::mapped), this, static_cast<void (QSignalMapperTest::*)(const QString&)>
(&QSignalMapperTest::showName));

结果：
QT笔记——信号转发器之QSignalMapper
完整代码：
ui图
QT笔记——信号转发器之QSignalMapper

.h

#pragma once#include <QtWidgets/QWidget>
#include "ui_QSignalMapperTest.h"
#include <QSignalMapper>
#include <QDebug>
#include <QVariant>#define QT5typedef struct Student
{QString name;int age;
}Student;
Q_DECLARE_METATYPE(Student)class StudentInfo :public QObject
{Q_OBJECT
public:StudentInfo(QObject* parent = nullptr);StudentInfo(QString name, int age, QObject* parent = nullptr);void SetName(const QString&);QString GetName() const;void SetAge(const int&);int GetAge() const;private:QString m_name;int m_age;
};class QSignalMapperTest : public QWidget
{Q_OBJECTpublic:QSignalMapperTest(QWidget *parent = Q_NULLPTR);public Q_SLOTS:void showName(const QString&);void showName(QString, int);void showStrName(QString);void showStudentInfo(QObject* object);private:Ui::QSignalMapperTestClass ui;StudentInfo m_s1;QSignalMapper* m_signalMapper;
};

.cpp

#include "QSignalMapperTest.h"QSignalMapperTest::QSignalMapperTest(QWidget *parent): QWidget(parent)
{ui.setupUi(this);m_signalMapper = new QSignalMapper(this);#if 1#ifdef QT5m_s1.SetName("lion");m_s1.SetAge(20);StudentInfo* s2 = new StudentInfo("cxq", 18);StudentInfo* s3 = new StudentInfo("lion_cxq", 22);m_signalMapper->setMapping(ui.btn1, &m_s1);m_signalMapper->setMapping(ui.btn2, s2);m_signalMapper->setMapping(ui.btn3, s3);connect(ui.btn1, &QPushButton::clicked, m_signalMapper, QOverload<>::of(&QSignalMapper::map));connect(ui.btn2, &QPushButton::clicked, m_signalMapper, QOverload<>::of(&QSignalMapper::map));connect(ui.btn3, &QPushButton::clicked, m_signalMapper, QOverload<>::of(&QSignalMapper::map));connect(m_signalMapper, QOverload<QObject*>::of(&QSignalMapper::mapped), this, &QSignalMapperTest::showStudentInfo);#elseStudentInfo* s = new StudentInfo("cxq", 18);m_signalMapper->setMapping(ui.btn1, s);m_signalMapper->setMapping(ui.btn2, s);m_signalMapper->setMapping(ui.btn3, s);connect(ui.btn1, SIGNAL(clicked()), m_signalMapper, SLOT(map()));connect(ui.btn2, SIGNAL(clicked()), m_signalMapper, SLOT(map()));connect(ui.btn3, SIGNAL(clicked()), m_signalMapper, SLOT(map()));connect(m_signalMapper, SIGNAL(mapped(QObject*)), this, SLOT(showStudentInfo(QObject*)));#endif
#endif#if 0#ifdef QT5m_signalMapper->setMapping(ui.btn1, "Button 1 clicked");m_signalMapper->setMapping(ui.btn2, "Button 2 clicked");m_signalMapper->setMapping(ui.btn3, "Button 3 clicked");connect(ui.btn1, &QPushButton::clicked, m_signalMapper, QOverload<>::of(&QSignalMapper::map));connect(ui.btn2, &QPushButton::clicked, m_signalMapper, QOverload<>::of(&QSignalMapper::map));connect(ui.btn3, &QPushButton::clicked, m_signalMapper, static_cast<void(QSignalMapper::*)()>(&QSignalMapper::map));//使用这个报错  必须使用下面第一种或者第二种  因为 槽函数也是重载的//connect(m_signalMapper, QOverload<const QString&>::of(&QSignalMapper::mapped), this, &QSignalMapperTest::showName);//第一个//connect(m_signalMapper, QOverload<const QString&>::of(&QSignalMapper::mapped), this, QOverload<const QString&>::of(&QSignalMapperTest::showName));//第二个connect(m_signalMapper, static_cast<void (QSignalMapper::*)(const QString&)>(&QSignalMapper::mapped), this, static_cast<void (QSignalMapperTest::*)(const QString&)>(&QSignalMapperTest::showName));#elsem_signalMapper->setMapping(ui.btn1, "Button 1 clicked");m_signalMapper->setMapping(ui.btn2, "Button 2 clicked");m_signalMapper->setMapping(ui.btn3, "Button 3 clicked");connect(ui.btn1, SIGNAL(clicked()), m_signalMapper, SLOT(map()));connect(ui.btn2, SIGNAL(clicked()), m_signalMapper, SLOT(map()));connect(ui.btn3, SIGNAL(clicked()), m_signalMapper, SLOT(map()));//可以connect(m_signalMapper, SIGNAL(mapped(const QString&)), this, SLOT(showName(const QString&)));connect(m_signalMapper, SIGNAL(mapped(QString)), this, SLOT(showStrName(QString)));//不可以  多个参数不可以//connect(m_signalMapper, SIGNAL(mapped(QString,int)), this, SLOT(showName(QString,int)));#endif
#endif
}void QSignalMapperTest::showName(const QString& str)
{qDebug() << str;
}void QSignalMapperTest::showName(QString name, int age)
{qDebug() << QStringLiteral("姓名:");
}void QSignalMapperTest::showStrName(QString str)
{qDebug() << str;
}void QSignalMapperTest::showStudentInfo(QObject* object)
{StudentInfo* s = qobject_cast<StudentInfo*>(object);if (s){qDebug() << s->GetAge() << s->GetName();}
}StudentInfo::StudentInfo(QObject* parent)
{}StudentInfo::StudentInfo(QString name, int age, QObject* parent )
{m_name = name;m_age = age;
}void StudentInfo::SetName(const QString& name )
{m_name = name;
}QString StudentInfo::GetName() const
{return m_name;
}void StudentInfo::SetAge(const int& age)
{m_age = age;
}int StudentInfo::GetAge() const
{return m_age;
}

参考博客：
QSignalMapper介绍
QSignalMapper使用

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