Question

我正在尝试使用 QtQuick 与 C ++ 文件中的 qml 对象进行互动。但是现在不幸的是没有成功。知道我做错了吗？我试过两种方法怎么做，第一种结果是 findChild（）返回 nullptr ，在第二次尝试我得到 Qml comnponent还没有准备好错误。这样做的正确方法是什么？

主：

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

    QQmlApplicationEngine engine;
    engine.load(QUrl(QLatin1String("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;
    // 1-st attempt how to do it - Nothing Found
    QObject *object = engine.rootObjects()[0];
    QObject *mrect = object->findChild<QObject*>("mrect");
    if (mrect)
        qDebug("found");
    else
        qDebug("Nothing found");
    //2-nd attempt - QQmlComponent: Component is not ready
    QQmlComponent component(&engine, "Page1Form.ui.qml");
    QObject *object2 = component.create();
    qDebug() << "Property value:" << QQmlProperty::read(object, "mwidth").toInt();

    return app.exec();
}

main.qml

import QtQuick 2.7
import QtQuick.Controls 2.0
import QtQuick.Layouts 1.3

ApplicationWindow {
    visible: true
    width: 640
    height: 480

        Page1 {
        }

        Page {
        }
    }
}

Page1.qml：

import QtQuick 2.7

Page1Form {
...
}

Page1.Form.ui.qml

import QtQuick.Controls 2.0
import QtQuick.Layouts 1.3

Item {
    property alias mrect: mrect
    property alias mwidth: mrect.width

    Rectangle
    {
        id: mrect
        x: 10
        y: 20
        height: 10
        width: 10
    }
}

Answer 1

import { Component, ViewChild } from '@angular/core'; import { NavController, Slides, IonicPage } from 'ionic-angular'; @IonicPage() @Component({ selector: 'page-slide-custom-pagination', templateUrl: 'slide-custom-pagination.html' }) export class SlideCustomPaginationPage { @ViewChild('sliderOne') sliderOne: Slides; @ViewChild('sliderTwo') sliderTwo: Slides; @ViewChild('sliderThree') sliderThree: Slides; slides = [ { title: 'Dream\'s Adventure', imageUrl: 'assets/img/lists/wishlist-1.jpg', songs: 2, private: false }, { title: 'For the Weekend', imageUrl: 'assets/img/lists/wishlist-2.jpg', songs: 4, private: false }, { title: 'Family Time', imageUrl: 'assets/img/lists/wishlist-3.jpg', songs: 5, private: true }, { title: 'My Trip', imageUrl: 'assets/img/lists/wishlist-4.jpg', songs: 12, private: true } ]; constructor(public navCtrl: NavController) { } ngAfterViewInit() { this.sliderOne.paginationBulletRender = (index, className) => { return `<span class="custom-pagination ${className}>${index + 1}</\span>`; }; this.sliderTwo.paginationBulletRender = (index, className) => { return `<span class="custom-pagination-2 ${className}>${index + 1}</\span>`; }; this.sliderThree.paginationBulletRender = (index, className) => { return `<span class="custom-pagination-3 bullet-icon-${index + 1} ${className}></\span>`; }; } }将对象名称作为第一个参数。但不是ID。

http://doc.qt.io/qt-5/qobject.html#findChild

在您的代码中，您尝试使用标识findChild进行查询。所以它可能不起作用。

在QML中添加mrect，然后尝试使用对象名称访问objectName。

下面的内容（我没有尝试过。因此编译时错误的可能性）：

在QML中添加objectName

findChild

然后你的findChild如下所示

Rectangle
{
    id: mrect
    objectName: "mRectangle"
    x: 10
    y: 20
    height: 10
    width: 10
}

与C ++代码中的qml对象交互

1 个答案: