Qml 列表视图在重置模型时保留视图

我有一个qml列表视图，其中包含来自c ++的模型。数据从另一个线程生成，并在 C++ 代码中更新为模型。之后，我使用BeginResetModel()在 qml 中更新列表视图。除了 qml 中的视图之外，一切都可以正常工作，但我希望列表视图保留当前视图而不更改视图。

女工程师：

列表视图元素.cpp

ListViewElement::ListViewElement(int id,QString attr):m_id(id),m_attr(attr)
{
}
int ListViewElement::getId()
{
return m_id;
}
QString ListViewElement::getAttr()
{
return m_attr;
}

列表视图模型.cpp

ListViewModel::ListViewModel(QObject *parent): QAbstractListModel(parent)
, m_items(new QList<ListViewElement*>()){
}

QHash<int,QByteArray> ListViewModel::roleNames() const
{
qDebug() << Q_FUNC_INFO;
QHash<int,QByteArray> roles;
roles[ListViewEnum::ID] = "id";
roles[ListViewEnum::ATTR] = "attr";
return roles;
}
QVariant ListViewModel::data(const QModelIndex &index, int role) const
{
if (!index.isValid() || index.row() > m_items->size()-1)
return QVariant();
ListViewElement *dobj = m_items->at(index.row());
if (!dobj)
return QVariant();
switch (role) {
case ListViewEnum::ID:
return QVariant::fromValue(dobj->getId());
case ListViewEnum::ATTR:
return QVariant::fromValue(dobj->getAttr());
default:
return QVariant();
}
}
int ListViewModel::rowCount(const QModelIndex &parent) const
{
Q_UNUSED(parent)
return m_items? m_items->size(): 0;
}
void ListViewModel::generateData()
{
ListViewElement *ele = new ListViewElement(1,"attribute");
m_items->append(ele);
beginResetModel();
endResetModel();
}

主.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include "listviewmodel.h"
#include <QQmlContext>
#include <QTimer>
int main(int argc, char *argv[])
{
ListViewModel model;
QTimer *timer = new QTimer();
QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
engine.rootContext()->setContextProperty("listViewModel",&model);
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
QObject::connect(timer,SIGNAL(timeout()),&model,SLOT(generateData()));
timer->start(1000);
return app.exec();
}

主.qml

import QtQuick 2.5
import QtQuick.Window 2.2
Window {
id: appMain
visible: true
width: 640
height: 480
title: qsTr("Hello World")
color: "#FFFF88"
ListView {
id: mainListView
width: parent.width
height: parent.height
spacing: 10
highlight: Rectangle {color: "green";radius: 5; focus: true}
highlightFollowsCurrentItem: true
focus: true
cacheBuffer: 100
model: listViewModel
delegate: Rectangle {
width: parent.width
height: 35
color: "transparent"
Text {
text: "t" + id + "t" + attr
}
MouseArea {
width: parent.width
height: parent.height
onClicked: {
console.log("click item" + index)
mainListView.currentIndex = index
}
}
}
}
Item {
id: scrollBar
width: 12; height: mainListView.height
anchors.left: mainListView.left
opacity: 0.7
property real position: mainListView.visibleArea.yPosition
property real pageSize: mainListView.visibleArea.heightRatio/2
property int orientation: Qt.Vertical
visible: true
Rectangle {
id: background
anchors.fill: parent
radius: scrollBar.orientation == Qt.Vertical ? (width/2 - 1) : (height/2 - 1)
color: "white"
opacity: 1.0
}
Rectangle {
x: scrollBar.orientation == Qt.Vertical ? 1 : (scrollBar.position *(scrollBar.width - 2) + 1)
y: scrollBar.orientation == Qt.Vertical ? (scrollBar.position *(scrollBar.height - 2) + 1) : 1
width: scrollBar.orientation == Qt.Vertical ? (parent.width - 2) : (scrollBar.pageSize * (scrollBar.width - 2))
height: scrollBar.orientation == Qt.Vertical ? (scrollBar.pageSize * (scrollBar.height - 2)) : (parent.height - 2)
radius: scrollBar.orientation == Qt.Vertical ? (width/2 - 1) : (height/2 - 1)
color: "black"
opacity: 0.2
}
}
}