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一、QML访问C++方法
- Qt元对象系统中注册C++类，在QML中实例化、访问。
- C++中实例化并设置为QML上下文属性，在QML中直接使用。
比较：方法1可以使C++类在QML中作为一个数据类型，例如函数参数类型或属性类型，也可以使用其枚举类型、单例等，功能更强大。
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二、QML访问C++条件
- 派生自QObject类或QObject类的子类
- 使用Q_OBJECT宏
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三、QML访问C++举例
使用方法1
信号与槽
#ifndef GEMINI_H
#define GEMINI_H
#include <QObject>
#include <QDebug>
class Gemini : public QObject
{
Q_OBJECT
signals: //1、先定义“信号”
void begin();
public slots: //1、先定义“槽”
void doSomething() {
qDebug() << "Gemini::doSomething() called";
}
};
#endif
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QtQml>
#include <Gemini.h>
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
qmlRegisterType<Gemini>("Union.Lotto.Gemini", 1, 0, "Gemini"); //一.注册c++类
QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:///main.qml")));
return app.exec();
}
import QtQuick 2.2
import QtQuick.Window 2.1
import Union.Lotto.Gemini 1.0 //二.导入
Window {
visible: true
width: 360; height: 360
title: "Union Lotto Game"
color: "white"
MouseArea {
anchors.fill: parent
onClicked: {
gemini.begin() //2.调用类信号
}
}
Gemini {
id: gemini
onBegin: doSomething() //2.调用类槽
}
}
2、枚举类型
#ifndef GEMINI_H
#define GEMINI_H
#include <QObject>
#include <QDebug>
class Gemini : public QObject
{
Q_OBJECT
Q_ENUMS(BALL_COLOR) //1、先定义。枚举类型在QML中使用，就用到了Q_ENUMS()宏
public:
Gemini() : m_ballColor(BALL_COLOR_YELLOW) {
qDebug() << "Gemini::Gemini() called";
}
enum BALL_COLOR {
BALL_COLOR_YELLOW,
BALL_COLOR_RED,
BALL_COLOR_BLUE,
BALL_COLOR_ALL
};
signals:
void begin();
public slots:
void doSomething(BALL_COLOR ballColor) {
qDebug() << "Gemini::doSomething() called with" << ballColor;
if(ballColor != m_ballColor) {
m_ballColor = ballColor;
qDebug() << "ball color changed";
}
}
private:
BALL_COLOR m_ballColor;
};
#endif
import QtQuick 2.2
import QtQuick.Window 2.1
import Union.Lotto.Gemini 1.0
Window {
visible: true
width: 360; height: 360
title: "Union Lotto Game"
color: "white"
MouseArea {
anchors.fill: parent
onClicked: {
gemini.begin()
}
}
Gemini {
id: gemini
onBegin: doSomething(Gemini.BALL_COLOR_RED) //2.调用，在QML中使用枚举类型的方式是<CLASS_NAME>.<ENUM_VALUE>
}
}
3、成员函数
#ifndef GEMINI_H
#define GEMINI_H
#include <QObject>
#include <QDebug>
class Gemini : public QObject
{
Q_OBJECT
Q_ENUMS(BALL_COLOR)
public:
Gemini() : m_ballColor(BALL_COLOR_YELLOW) {
qDebug() << "Gemini::Gemini() called";
}
enum BALL_COLOR {
BALL_COLOR_YELLOW,
BALL_COLOR_RED,
BALL_COLOR_BLUE,
BALL_COLOR_ALL
};
Q_INVOKABLE void stop() { //1、定义。访问的前提是public或protected成员函数，且使用Q_INVOKABLE宏
qDebug() << "Gemini::stop() called";
}
signals:
void begin();
public slots:
void doSomething(BALL_COLOR ballColor) {
qDebug() << "Gemini::doSomething() called with" << ballColor;
if(ballColor != m_ballColor) {
m_ballColor = ballColor;
qDebug() << "ball color changed";
}
}
private:
BALL_COLOR m_ballColor;
};
#endif
import QtQuick 2.2
import QtQuick.Window 2.1
import Union.Lotto.Gemini 1.0
Window {
visible: true
width: 360; height: 360
title: "Union Lotto Game"
color: "white"
MouseArea {
anchors.fill: parent
onClicked: {
gemini.begin()
gemini.stop() //2、调用，在QML中访问C++的成员函数的形式是<id>.<method>
}
}
Gemini {
id: gemini
onBegin: doSomething(Gemini.BALL_COLOR_RED)
}
}
4、C++类的属性
#ifndef GEMINI_H
#define GEMINI_H
#include <QObject>
#include <QDebug>
class Gemini : public QObject
{
Q_OBJECT
Q_ENUMS(BALL_COLOR)
Q_PROPERTY(unsigned int ballNumber READ ballNumber WRITE setBallNumber NOTIFY ballNumberChanged) //1、定义，Q_PROPERTY()宏，用来在QObject派生类中声明属性。
public:
Gemini() : m_ballColor(BALL_COLOR_YELLOW), m_ballNumber(0) {
qDebug() << "Gemini::Gemini() called";
}
enum BALL_COLOR {
BALL_COLOR_YELLOW,
BALL_COLOR_RED,
BALL_COLOR_BLUE,
BALL_COLOR_ALL
};
unsigned int ballNumber() const {
return m_ballNumber;
}
void setBallNumber(const unsigned int &ballNumber) {
if(ballNumber != m_ballNumber) {
m_ballNumber = ballNumber;
emit ballNumberChanged();
}
}
Q_INVOKABLE void stop() {
qDebug() << "Gemini::stop() called";
}
signals:
void begin();
void ballNumberChanged();
public slots:
void doSomething(BALL_COLOR ballColor) {
qDebug() << "Gemini::doSomething() called with" << ballColor;
if(ballColor != m_ballColor) {
m_ballColor = ballColor;
qDebug() << "ball color changed";
}
}
private:
BALL_COLOR m_ballColor;
unsigned int m_ballNumber;
};
#endif
import QtQuick 2.2
import QtQuick.Window 2.1
import Union.Lotto.Gemini 1.0
Window {
visible: true
width: 360; height: 360
title: "Union Lotto Game"
color: "white"
MouseArea {
anchors.fill: parent
onClicked: {
gemini.begin()
gemini.stop()
gemini.ballNumber = 10 //2、调用，Gemini类中的ballNumber属性可以在QML中访问、修改，访问时调用了ballNumber()函数，
// 修改时调用了setBallNumber()函数，同时还发送了一个信号来自动更新这个属性值。
}
}
Gemini {
id: gemini
onBegin: doSomething(Gemini.BALL_COLOR_RED)
onBallNumberChanged: console.log("new ball number is", ballNumber) // 10
Component.onCompleted: console.log("default ball number is", ballNumber) // 0
}
}
备注：1、参考网址：https://zhuanlan.zhihu.com/p/633999343
2、本文只为个人学习笔记，其他第三方可以任意使用。
标签：编程,C++,Gemini,QML,import,include,gemini From： https://www.cnblogs.com/wxzhrj/p/17899601.html