Qt for WebAssembly

@lorn-potter I'm using 6.4.2

@lorn-potter thank yoy

https://qmlonline.kde.org/ https://qt-webassembly.io/designviewer/ an example of the Slate desktop app ported to WebAssembly: https://www.qt.io/web-assembly-example-slate

@jsulm ok... i'll have a try.

You need to install ninja and use that to build. MSVC compiler and Emscripten don't mix well.

Thank you very much for taking the time to reply. Gary

Indeed it does. This is a bug, I will report it for you. https://bugreports.qt.io/browse/QTBUG-110941

When I removed all the code and left only a declaration of the QWebSocket type variable in the code, I got the following error. I am including <QtWebSockets/QWebSocket> and added websockets to my qmake. I added -lwebsocket.js to make arguments in the creator as well. The -lwebsocket.js seems to be the problem. I tried to build a minimal project w/ WebSocket outside Qt, using the emscripten API and I received a similar error when I did not include -lwebsocket.js into the build command. Apparently, when using Qt creator the compiler is not receiving the argument, regardless of where I'll put it. I tried adding it to the .pro file in several ways as well (using: QMAKE_LFLAGS, QMAKE_CXXFLAGS, LIBS, CONFIG) error: undefined symbol: _ZN10QWebSocketC1ERK7QStringN18QWebSocketProtocol7VersionEP7QObject (referenced by top-level compiled C/C++ code) warning: Link with -sLLD_REPORT_UNDEFINED to get more information on undefined symbols warning: To disable errors for undefined symbols use -sERROR_ON_UNDEFINED_SYMBOLS=0 warning: __ZN10QWebSocketC1ERK7QStringN18QWebSocketProtocol7VersionEP7QObject may need to be added to EXPORTED_FUNCTIONS if it arrives from a system library error: undefined symbol: _ZN10QWebSocketD1Ev (referenced by top-level compiled C/C++ code) warning: __ZN10QWebSocketD1Ev may need to be added to EXPORTED_FUNCTIONS if it arrives from a system library Error: Aborting compilation due to previous errors em++: error: ' /emsdk/node/14.18.2_64bit/bin/node /emsdk/upstream/emscripten/src/compiler.js /var/folders/qn/gzn_l03x2ds1cdh94cysrhfw0000gq/T/tmp4su37te2.json'

It seems i need to add to qt_add_qml_module the [OUTPUT_TARGETS out_targets_var] and export the additional targets in out_targets_var variable . If the backing target is a static library and that static library will be installed, OUTPUT_TARGETS should be given to provide a variable in which to store a list of additional targets that will also need to be installed. These additional targets are generated internally by qt_add_qml_module() and are referenced by the backing target's linking requirements as part of ensuring that resources are set up and loaded correctly.

ok. cool. thanks :)

Success! Works with Qt6.4.1 and Emscripten 3.1.14 (was trying later versions of both which was giving above error)

For Qt 6.3.0 you need Emscripten 3.0.0. Is that what you have installed? Those errors look like something that happens when a mis-match of Emscripten versions are used, where Qt uses one version and a developer uses a different one.

I noticed that ed25519 do not need blake2b. A temporal solution was to remove the object "libsodium_la-blake2b-ref.o" from libsodium.a by using ar dv libsodium.a libsodium_la-blake2b-ref.o I can not remove "qcryptographichash.cpp.o" from libQt6Core.a because I use that on other libraries.

@lorn-potter I figured out how to export custom functions, but there's still a problem with exporting the runtime ones. I am adding the -s EXPORTED_RUNTIME_METHODS=UTF8ToString argument and keep receiving "Uncaught RuntimeError: Aborted('UTF8ToString' was not exported. add it to EXPORTED_RUNTIME_METHODS (see the FAQ))" error.

Thanks Karmo! Guess I have to do similar thing.