ObjectModel:Qml 使用C++model

用QList 来实现model 官方为何叫做ObjectModel 打比方有一个QObject* obj ; Q_INVOKABLE QVariant _get() { QObject* obj = xxx; Variant::fromValue(obj ); } Qml调用它打印返回值:ObjectModel..

ObjectModel是把QObject对象当做model的每一项,优势是访问方便扩展强,劣势是要手动删除指针,避免内存泄漏,并且需要自己刷新model(每次数据变化视图不会改变,要在代码中重新赋值)

#ifndef OBJECTMODEL_H
#define OBJECTMODEL_H

#include 
#include
class ObjectModel : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QString data READ get WRITE set  NOTIFY dataChanged)


public:
    explicit ObjectModel(QObject *parent = 0);
    ~ObjectModel() {
    }
    void set(QString s)
    {
        data = s;
    }
    QString get()
    {
        return data;
    }


signals:
void  dataChanged(QString data);
public slots:
private:
    QString  data;
};

#endif // OBJECTMODEL_H

#ifndef QMLGLOBALDATA_H
#define QMLGLOBALDATA_H

#include
#include
#include
#include
#include "objectmodel.h"
using namespace  std;
class QmlGlobalData : public QObject
{
    Q_OBJECT
public:

    explicit QmlGlobalData(QObject *parent = 0);
    ~QmlGlobalData(); 
    //获取
    Q_INVOKABLE  QVariant _objmodel()
    {
        return QVariant::fromValue(objmodellist);
    }
//添加
    Q_INVOKABLE  QVariant _objmodel_add(QString var1)
    {
        ObjectModel*  j;
        (j = new ObjectModel())->set(var1); 
        objmodellist.append(j); 
        return QVariant::fromValue(objmodellist);
    }
//清空
    Q_INVOKABLE  void _objmodel_cls()
    {
        for (int x = 0; x < objmodellist.count(); x++)
        {
            /*qDebug() << "delete";*/
           delete   objmodellist.at(x);
        }
        objmodellist.clear();

    }
//得到大小
    Q_INVOKABLE  int _objmodel_size()
    {
        return objmodellist.count();

    }

//获取
    Q_INVOKABLE  QVariant _objmodel_get(int index)
    {
        QObject*  obj = objmodellist.at(index);
        return QVariant::fromValue(obj);
    }
//删除
    Q_INVOKABLE  QVariant _objmodel_delete(int index)
    {
        if (index < 0  || index >= objmodellist.count())
        {
            return  QVariant::fromValue(objmodellist);
        }
        QObject*  obj = objmodellist.at(index);
        if (obj!=NULL)
        {
            delete obj;
            objmodellist.removeAt(index);
        }
        return QVariant::fromValue(objmodellist);
    }


signals:

public slots:
private: 
    QList  objmodellist;
};

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QGuiApplication app(argc, argv); 

     QQmlApplicationEngine engine;
    // 首先注册一下类 为了触发语法高亮
    qmlRegisterType(
                "Global",
                1,
                0,
                "Global");
    QmlGlobalData*  tmp = new QmlGlobalData();
    engine.rootContext()->setContextProperty("Global", tmp);  
    engine.load(QUrl(QLatin1String("qrc:/main.qml")));

    return app.exec();
}

import QtQuick 2.7
import QtQuick.Controls 2.0
import QtQuick.Layouts 1.0
ApplicationWindow {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")

    property var xx: 0
    Flickable{
        width: parent.width
        height: parent.height
        contentHeight: col.height

        Column{

            id:col
            ListView{
                id:list
                width: parent.width
                height: contentHeight
                delegate: Text{
                    text:model.modelData.data
                    //Global._objmodel_get(index).data
                }
                Component.onCompleted: {

                }


            }


            Button{
                text:"添加"
                onClicked: {
                    append(xx)
                }
            }

            Button{
                text:"清空"
                onClicked: {
                    clear()
                }
            }

            Button{
                text:"遍历"
                onClicked: {
                    _Enumdata()
                }
            }

            Row{
                Button{
                    text:"删除第x行:"
                    onClicked: {
                        removeAt(_index.text)
                    }
                }

                TextField{id:_index}
            }
        }


    }

    function append(var1) {
        list.model= Global._objmodel_add(var1);
        xx++;
    }

    function clear() {
        list.model= Global._objmodel_cls();
    }

    function _Enumdata() {
        var _size =  Global._objmodel_size();
        for(var i=0;i<_size;i++)
        {
            console.log("get:"+i+","+Global._objmodel_get(i).data)
        }
    }

    function removeAt(index) {
        list.model=Global._objmodel_delete(index)
    }

}