How to solve QML ToolButton Icon blurred?

[Davidzouking]

I am new to QML, and I used a 48x48 pixal ico file as the ToolButton Icon. But the icon display is blurred. How to solve this?
QML:
header: ToolBar {
RowLayout {
ToolButton {
display: AbstractButton.IconOnly
text: qsTr("NewProject")
icon.source: "qrc:/images/icon/NewProject.ico"
icon.color: "transparent"
smooth: False
icon.width: 16
icon.height: 16
onClicked: stack.pop()
}
}
}
Main:
int main(int argc, char *argv[]) {
QGuiApplication app(argc, argv);
QGuiApplication::setAttribute(Qt::AA_EnableHighDpiScaling );
QGuiApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
QQmlComponent component(new QQmlApplicationEngine(), "qrc:/main.qml");
qDebug() << component.errors();
QWindow window = (QWindow)component.create();
window->setIcon(QIcon(":/images/icon/Logo.ico"));
window->showMaximized();
return app.exec();
}