[英]How to register Qt C++ object to use it in QML
I try to register ColorsSource *pSource object to use it in QML but I get erreor in string: "QQmlContext *context = myObject->rootContext();"我尝试注册 ColorsSource *pSource object 以在 QML 中使用它,但在字符串中出现错误:“QQmlContext *context = myObject->rootContext();” undefined reference to
__imp__ZNK12QQuickWidget11rootContextEv
对
__imp__ZNK12QQuickWidget11rootContextEv
的未定义引用
main.cpp主文件
#include "ColorsSource.h"
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QtQuickWidgets/QQuickWidget>
#include <QQmlContext>
int main(int argc, char *argv[])
{
QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
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);
ColorsSource *pSource = new ColorsSource;
QQuickWidget *myObject = static_cast<QQuickWidget*>(engine.rootObjects().first());
QQmlContext *context = myObject->rootContext();
context->setContextProperty("ColorSource", pSource);
return app.exec();
}
You are missing the quickwidgets
Qt module.您缺少快速小
quickwidgets
模块。 Thats why it cannot find these Symbols.这就是它找不到这些符号的原因。 If you use qmake, add
QT += quickwidgets
to your pro file.如果您使用 qmake,请将
QT += quickwidgets
添加到您的 pro 文件中。
But that won't be your Problem.但这不是你的问题。 QQuickWidgets are widgets to display some QQuick code, to be used in a Widgets application.
QQuickWidgets 是用于显示一些 QQuick 代码的小部件,用于 Widgets 应用程序。 But as you use a QQmlApplicationEngine, you are working in Quick.
但是当您使用 QQmlApplicationEngine 时,您正在使用 Quick。 Your
rootObject()
won't be a QQuickWidget.您的
rootObject()
不会是 QQuickWidget。 So instead of looking for a QQuickWidget, access the engines rootContext - replace:因此,不要寻找 QQuickWidget,而是访问引擎 rootContext - 替换:
QQuickWidget *myObject = static_cast<QQuickWidget*>(engine.rootObjects().first());
QQmlContext *context = myObject->rootContext();
context->setContextProperty("ColorSource", pSource);
with和
QQmlContext *context = engine.rootContext();
context->setContextProperty("ColorSource", pSource);
This will make your code a lot less prone to errors.这将使您的代码更不容易出错。
Also, in an unrelated note, you should always check your pointers, to make sure your static_cast
went allright.此外,在不相关的注释中,您应该始终检查您的指针,以确保您的
static_cast
一切正常。 Otherwise you will get crashes if the engines rootObjects are empty or the first one is not a QQuickWidget.否则,如果引擎 rootObjects 为空或第一个不是 QQuickWidget,您将崩溃。
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