Question

这是问题，我创建了一个C ++类，它加载一个本地文件，并为每个新行发送一个信号。我想要做的是在我的QML文件中我想将这些行打印到我已经完成的列表视图中但现在的问题是C ++函数甚至在应用程序启动之前加载，它会读取文件并填充listview然后显示页面。

这是我的代码。

的main.cpp

#include <QtCore/QCoreApplication>
#include <QtGui/QGuiApplication>
#include <QtQuick/QQuickView>
#include <QtQml>


#include "boot.h"

int main(int argc, char *argv[])
{
    QCoreApplication::setApplicationName("xyz");
    QCoreApplication::setAttribute(Qt::AA_X11InitThreads);

    qmlRegisterType<Boot>("xyx", 1, 0, "Boot");

    QGuiApplication app(argc, argv);

    QQuickView quickView;
    quickView.setSource(QUrl(QStringLiteral("qrc:/Boot.qml")));
    quickView.setResizeMode(QQuickView::SizeRootObjectToView);
    quickView.showMaximized();

    return app.exec();
}

Boot.qml

import QtQuick 2.0
import "."
import QtQuick.XmlListModel 2.0
import xyz 1.0

Item{

    Loader{
        id: bootPageLoader
        anchors.fill:parent
        sourceComponent: bootSystem
        focus:true
    }

    Component{
        id:bootSystem

        Rectangle{
            width: 640
            height: 480
            color:"black"
            focus:true

            Component.onCompleted: {
                booting.load();
            }

            Boot{
                id:booting

                onErrorMsgChanged: {
                     console.log("New Boot Log Message: " + errorMsg);
                     //This is where I am adding to the listview every time I receive a signal 
                     logModel.append({msg:errorMsg});
                     log.positionViewAtEnd();


                }
           }

           ListView {
               id:log
               anchors.left: parent.left
               anchors.leftMargin: 10
               anchors.topMargin: 10
               anchors.bottomMargin:10
               anchors.top: parent.top
               width:(parent.width*40)/100
               height:parent.height-20

               model: BootLogModel{
                   id:logModel
               }
               delegate: Text {
                   text: msg
                   color: "green"
                   font.pixelSize: 15
               }
           }

           Text{
               id: loading
               anchors{
                   horizontalCenter: parent.horizontalCenter
                   verticalCenter: parent.verticalCenter
               }

               text: "LOADING..."
               color: "white"
               font.pixelSize: Math.round(parent.height/20)
               font.bold: true
           }
       }
   }
}

BootLogModel.qml

import QtQuick 2.0
ListModel {

}

这是C ++代码段

在boot.h中

#ifndef BOOT_H
#define BOOT_H

#include <QObject>
#include <QString>
#include <string>

class Boot : public QObject{
    Q_OBJECT
    Q_PROPERTY(QString errorMsg READ errorMsg NOTIFY errorMsgChanged)

    public:
        explicit Boot(QObject *parent = 0);
        Q_INVOKABLE void load();

        QString errorMsg();
        void setErrorMsg(const QString &errorMsg);

    signals:
        void errorMsgChanged();
    private:
        QString m_errorMsg;
};
#endif // BOOT_H

在boot.cpp中

Boot::Boot(QObject *parent) : QObject(parent)
{
}
QString Boot::errorMsg()
{
    return m_errorMsg;
}

void Boot::setErrorMsg(const QString &errorMsg)
{
    m_errorMsg = errorMsg;

    emit errorMsgChanged();
}

void Boot::load()
{
    int i = 0;
   while(i < 10000)
   {
       setErrorMsg("test: " + QString::number(i));
       i++;
   }

}

我首先在GUI之前看到这个

然后这是显示并已填充的GUI

Answer 1

循环在GUI中始终是一个问题，寻找更友好的GUI替代方案总是更好，在本例中为QTimer：

<强> boot.h

int counter = 0;

<强> bool.cpp

void Boot::load()
{
    QTimer *timer = new QTimer(this);

    connect(timer, &QTimer::timeout, [timer, this](){
        setErrorMsg("test: "  + QString::number(counter));
        counter++;
        if(counter > 10000){
            timer->stop();
            timer->deleteLater();
        }
    });
    timer->start(0); //delay
}

即使使用Component.onCompleted，也会在页面加载之前调用C ++函数

1 个答案: