如何将通过 C++ 中的另一个类添加到 ListView、QML 的数据显示出来? [英] How to display data added via another class in C ++ to ListView, QML?
问题描述
我需要呈现 QLinkedList 容器中的所有数据(这是由任务提供的).我创建了两个类，DataObject 用于 ListView 中的代表，Glav 用于具有 DataObject 对象的容器.我有一个按钮，可以在该按钮上向容器中添加数据(Glav 类中的 addItem 函数).数据已添加但未显示在 ListView 中.如何显示它们?我通过信号试了一下，还是不行.这是项目的完整代码.
I need to present all the data in the QLinkedList container (this was given by the task). I created two classes, DataObject for my delegates in ListView, Glav for container with DataObject objects. I have a button on which I add data to the container (the addItem function in the Glav class). The data is added but not displayed in the ListView. How to display them? I tried it through signals, it didn't work. Here is the complete code of the project.
main.cpp
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QStringListModel>
#include <QQmlContext>
#include <QLinkedList>
#include <QQuickView>
#include <container.h>
#include <dataobject.h>
#include "glav.h"
//#include <container.cpp>
int main(int argc, char *argv[])
{
#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
#endif
QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
qmlRegisterUncreatableType<tile::Glav>( "Tile", 1, 0, "DataItem", "interface" );
qmlRegisterType<tile::Glav>( "Tile", 1, 0, "Glav");
const QUrl url(QStringLiteral("qrc:/main.qml"));
QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
&app, [url](QObject *obj, const QUrl &objUrl) {
if (!obj && url == objUrl)
QCoreApplication::exit(-1);
}, Qt::QueuedConnection);
engine.load(url);
return app.exec();
}
main.qml
import QtQuick 2.12
import QtQuick.Controls 2.5
//import App 1.0
import Tile 1.0
ApplicationWindow {
width: 640
height: 480
visible: true
title: qsTr("Scroll")
// Container {
// id: container
// }
Glav {
id: glav
}
Row {
id: buttons
spacing: 20
padding: 10
anchors.horizontalCenter: parent.horizontalCenter
RoundButton {
padding: 20
text: "add item"
onClicked: {
glav.addItem()
listView.currentIndex = -1
}
}
Connections{
target: myModelObjectWhichWasSetAsContextProperty
onRowsInserted: console.log("rows were inserted")
}
ScrollView {
anchors.fill: parent
anchors.topMargin: buttons.implicitHeight + 10
ListView {
id: listView
width: parent.width
model: glav.list
//required model
delegate: Text {
property var d
d: model.modelData.id
text: model.modelData.name
}
removeDisplaced: Transition {
NumberAnimation { properties: "x,y"; duration: 100; easing.type: Easing.InOutQuad }
}
}
}
}
数据对象.h
#ifndef DATAOBJECT_H
#define DATAOBJECT_H
#include <QObject>
namespace tile {
class DataObject : public QObject
{
Q_OBJECT
Q_PROPERTY(QString name READ name WRITE setName NOTIFY changed)
Q_PROPERTY(QString color READ color WRITE setColor NOTIFY changed)
Q_PROPERTY(int id READ id WRITE setId NOTIFY changed)
public:
explicit DataObject(QString name = "Wana", QString color = "red", int id = 1, QObject *parent = nullptr);
QString name();
void setName(const QString &name);
QString color();
void setColor(const QString &color);
int id() const;
void setId(int id);
signals:
void changed();
private:
QString m_name;
QString m_color;
int m_id;
};
}
#endif // DATAOBJECT_H
数据对象.cpp
#include "dataobject.h"
#include <QDebug>
namespace tile {
DataObject::DataObject(QString name, QString color, int id, QObject* parent) :
QObject(parent)
, m_name (name)
, m_color (color)
, m_id (id)
{
//new DataObject();
qDebug() << m_name;
//emit changed();
}
QString DataObject::name()
{
return m_name;
}
void DataObject::setName(const QString &name)
{
m_name = name;
qDebug() << m_name;
emit changed();
}
QString DataObject::color()
{
return m_color;
}
void DataObject::setColor(const QString &color)
{
m_color = color;
emit changed();
}
int DataObject::id() const
{
return m_id;
}
void DataObject::setId(int id)
{
m_id = id;
emit changed();
}
}
glav.h
#ifndef GLAV_H
#define GLAV_H
#include <QObject>
#include <QLinkedList>
namespace tile {
class Glav : public QObject
{
Q_OBJECT
Q_PROPERTY( QLinkedList<QObject *> list READ list CONSTANT )
public:
explicit Glav(QObject *parent = nullptr);
//QLinkedList<QObject *> list();
//void setList(const QLinkedList<QObject *> &list);
Q_INVOKABLE QLinkedList<QObject *> pollist();
Q_INVOKABLE void addItem();
// Q_INVOKABLE QVariant pol();
signals:
void changed();
private:
QLinkedList<QObject *> m_list;
QLinkedList<QObject *> list();
};
}
#endif // GLAV_H
glav.cpp
#include "glav.h"
#include "dataobject.h"
#include <QDebug>
#include <QAbstractListModel>
namespace tile {
Glav::Glav(QObject *parent) : QObject(parent)
{
QLinkedList<QObject *> dataList = {
new DataObject("Item 1", "red"),
new DataObject("Item 2", "green"),
new DataObject("Item 3", "blue"),
new DataObject("Item 9", "yellow")
};
m_list << dataList;
QVariant::fromValue(m_list);
}
QLinkedList<QObject *> Glav::list()
{
return m_list;
}
//void Glav::setList(const QLinkedList<QObject *> &list)
//{
// m_list = list;
//}
//QVariant Glav::pol(){
// QVariant re = QVariant::fromValue(m_list);
// return re;
//}
QLinkedList<QObject *> Glav::pollist()
{
//qDebug() << QVariant::fromValue(m_list);
//QLinkedList<QObject *> f = m_list;
//QVariant::fromValue(m_list);
//qDebug() <<m_list;
return m_list;
}
void Glav::addItem()
{
qDebug() << m_list.count();
m_list << new DataObject();
qDebug() << m_list.count();
emit changed();
}
}
推荐答案
你的 Glav 类有一个 changed() 信号，但它什么也没做，因为你的 list 属性是常量(Q_PROPERTY(QLinkedList)
Your Glav class has a changed() signal but it doesn't do anything because your list property is constant (Q_PROPERTY( QLinkedList<QObject *> list READ list CONSTANT ))
你应该把它改成这样:
Q_PROPERTY(QLinkedList<QObject*> list READ list NOTIFY changed)
这样，您可以通过发出 changed() 信号让 ListView 知道列表刚刚被更改.
That way you can let the ListView know that the list has just been changed by emitting the changed() signal.
另外，最好按照信号对应的属性来命名:listChanged.
Also, it's better to name the signal in accordance with the property it corresponds to: listChanged.
有关 Q_PROPERTY 如何工作的更多信息，请参阅官方文档:https://doc.qt.io/qt-5/properties.html
More info on how Q_PROPERTY works in the official documentation: https://doc.qt.io/qt-5/properties.html
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