Importing a C++ types declared using the QML_ELEMENT return module is not installed

Mesrine

Hello everyone.

I have created an application using CMake.

The main executable is composed of 2 files "server_main.cpp" and "window_server.qml"

server_main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#ifdef USE_QtQrGen
#include "Qrimageprovider.hpp"
#endif
 
  
int main(int argc, char *argv[])
{
        QGuiApplication app(argc, argv);

        QQmlApplicationEngine engine;
#ifdef USE_QtQrGen
    engine.addImageProvider(QLatin1String("qrcodeblack"), new QRImageProvider("black",1));   
#endif
        const QUrl url(u"qrc:plugins/window_server.qml"_qs);
        QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                        &app, [url](QObject *obj, const QUrl &objUrl) {
                        if (!obj && url == objUrl)
                        QCoreApplication::exit(-1);
                        }, Qt::QueuedConnection);
        engine.load(url);

        return app.exec();
}

window_server.qml

import QtQuick.Controls
import plugins.interface
  
ApplicationWindow {
  x:700
  y:700
  width: 500 
  height: 800 
  visible: true
  StackView {
      id: stack
      initialItem: root
      anchors.fill: parent
  }   
  Main_view_server
  {   
      id:root
      anchors.fill: parent
      stack:stack
 }   
}

Here I import a c++ module called 'plugins.interface'. That is defined in a different c++ project that export a library.

The 'CMakeLists.txt' important parts of the main application are :

qt_add_executable(server_main server_main.cpp )
qt_add_qml_module(server_main
    URI plugins
    VERSION 1.0 
    QML_FILES window_server.qml)

target_link_libraries(server_main PRIVATE booking_interface)

where I add a module and link to other c++ and QML library "booking_interface" that defines the previous 'plugins.interface'' module.

The 'CMakeLists.txt' of the 'booking_interface' target important parts are:

qt6_add_qml_module(booking_interface
          URI plugins.interface
          VERSION 1.0
          SOURCES
          src/Hour_model.cpp src/Day_model.cpp  include/Day_model.hpp
          include/Hour_model.hpp
          QML_FILES
          qml/Enter_Pin_server.qml
          qml/Main_view_server.qml
          qml/window_server.qml
          OUTPUT_DIRECTORY
          plugins/interface
          )

When I compile this using gcc_64 there is no problem the application run smoothly.
When compiling with wasm_32 like

/path/to/qt-wasm/qtbase/bin/qt-cmake . -DCMAKE_C_COMPILER:FILEPATH=emcc -DCMAKE_CXX_COMPILER:FILEPATH=em++  -DCMAKE_BUILD_TYPE=Release ../
cmake --build .

The compilation do not give any errors or warnings and produce the files :

server_main.wasm
server_main.html
qtloader.js
server_main.js
server_main.worker.js

the problem is that when loading the .html file like

emrun server_main.html

The developer console of Firefox throws the error

QQmlApplicationEngine failed to load component
qrc:plugins/window_server.qml:2:1: module "plugins.interface" is not installed

So it seems QQmlApplicationEngine do not know about the plugins.interface module that was compiled in the 'booking_interface' target and linked to the 'server_main.wasm'.

I will appreciate any help to figure out what is wrong.

Also my understanding is that 'qt6_add_qml_module(booking_interface...' creates an static lib 'libbooking_interface.a' that has inside the 'plugins.interface' module. Where this 'plugins.interface' module has inside the c++ definitions of the class 'Hour_model' ... and the c++ definitions of custom qml types defined in 'qml/Enter_Pin_server.qml'... So if I link any application with this 'libbooking_interface.a' static library and import 'plugins.interface' I will have access to the c++ and QML custom types and I do not need any more the .qml files or the headers .h that I use to create 'libbooking_interface.a'.

If this a correct understanding?

SWMCODER

I think I might have a similar problem. Any update on your original issue?