QML设置圆角窗体

先看一个失败的案例,那黑色的就是主窗体，我已经找遍全网但依然是这样子。

下面贴上失败的代码

c++代码

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQuickWindow>
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) {