Question

我编写了简单的脚本来检查python3上的QML功能（在我使用c ++之前）：

from PyQt5.QtCore import QUrl
from PyQt5.QtWidgets import QApplication
from PyQt5.QtQml import QQmlApplicationEngine
import sys
import logging


def run():
    logging.basicConfig(level = logging.DEBUG)
    logging.info("Create application object")
    app = QApplication(sys.argv)
    logging.info("Create qml engine/view")
    engine = QQmlApplicationEngine()
    logging.info("Loading qml file")
    engine.load(('./qml/CurrentValues.qml'))
    if not engine.rootObjects():
        logging.fatal("Engine root objects in empty")
        return -1

    engine.quit.connect(app.quit)
    logging.info("Run application")
    return app.exec_()

if __name__ == "__main__":
    sys.exit(run())

在“return app.exec_（）”行上，脚本冻结并且不显示窗口。脚本不会显示错误，也不会被Ctrl-C停止，只能被kill命令杀死。

我有ubuntu 17.10并安装了软件包：python3-pyqt5，python3-pyqt5.qtquick。我也尝试使用这个软件包的pip版本（PyQt5）并尝试使用PySide2。我使用了QCoreApplication，QGuiApplication，但它没有产生效果。它不适用于任何qml文件。

可能是什么问题？

CurrentValues.qml：

import QtQuick 2.0
import "."

ListView {
    orientation: ListView.Horizontal
    flickableDirection: Flickable.HorizontalFlick
    delegate: CurrentValueViewer {}
    model: ListModel {
        id: valuesModel
        ListElement {
            valueName: "Temp"
            curValue: "250°"
        }
        ListElement {
            valueName: "CO2"
            curValue: "125 PPM"
        }
        ListElement {
            valueName: "O2"
            curValue: "18 %"
        }
        ListElement {
            valueName: "N2"
            curValue: "15%"
        }
        ListElement {
            valueName: "RH"
            curValue: "80 %"
        }
    }
}

CurrentValueViewer.qml：

import QtQuick 2.0
import QtQuick.Controls 1.4

Rectangle {
    id: valueViewer
    width: 120
    height: 80
    color: "#d6d6d6"
    radius: 10

    Column {

        Text {
            id: name
            text: valueName
        }

        Text {
            id: value
            text: "<html><body>" + curValue +"<sup>°C</sup></body></html>"
            font.bold: true
            font.pointSize: 15
        }

        Text {
            id: moreInfo
            text: "And more..."
        }
    }
}

c ++上的工作版：

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include "currentmeasurement.h"
#include "currentmeasurementsmodel.h"

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

    QQmlApplicationEngine engine;
    engine.load(QUrl(QLatin1String("qrc:/CurrentValues.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;

    CurrentMeasurementsModel measurementList;
    measurementList.append(CurrentMeasurement("Temp", 25, "°C"));
    measurementList.append(CurrentMeasurement("CO2", 125, "PPM"));
    measurementList.append(CurrentMeasurement("O2", 18, "%"));
    measurementList.append(CurrentMeasurement("N2", 75, "%"));
    measurementList.append(CurrentMeasurement("RH", 85, "%"));
    QQmlContext *ctxt = engine.rootContext();
    ctxt->setContextProperty("measurementModel", &measurementList);

    return app.exec();
}

它使用基于QAbstractListModel的类

Answer 1

QQmlApplicationEngine只能显示QQuickWindow，因此无法显示ListView，因此可能的解决方案是以root身份使用ApplicationWindow。

import QtQuick 2.0
import QtQuick.Controls 1.4
import "."

ApplicationWindow {
    visible: true
    width: 640
    height: 480

    ListView {
        anchors.fill: parent
        orientation: ListView.Horizontal
        flickableDirection: Flickable.HorizontalFlick
        delegate: CurrentValueViewer {}
        model: ListModel {
            id: valuesModel
            ListElement {
                valueName: "Temp"
                curValue: "250°"
            }
            ListElement {
                valueName: "CO2"
                curValue: "125 PPM"
            }
            ListElement {
                valueName: "O2"
                curValue: "18 %"
            }
            ListElement {
                valueName: "N2"
                curValue: "15%"
            }
            ListElement {
                valueName: "RH"
                curValue: "80 %"
            }
        }
    }
}

QML应用程序在QApplication.exec（）上冻结，并且不显示窗口

1 个答案: