Qt for WebAssembly

Hi @SGaist , One thing that made me skeptical about the info on the introduction page, was the affirmative that webassembly doesn't support threads, which is not an absolute true, in fact is relatively simple to enable thread support with the correct emscripten version. But everything so far is telling me that is not possible, or at least it will be very hard to compile wasm as shared.

I found out that the QtWebEngine module is indeed not available and instead QtWebView is available. After replacing WebEngineView with WebView, the compiling error is gone and the program compiles. But yes QtWebview is unsupported as it is integrated with QtWebengineView

@RogueWarrior no experience with webassembly, but by creating and running a Qt app on the embedded device, you could leverage access via any VNC client using the VNC platform plugin i.e. ./yourQtApp -platform vnc

@Amin-Ya Would you please specify what exactly you are referring to when you are saying the C++ path? I seem to be having the same problem here.

@jsulm thank you for the answer. That might work indeed, but the thing is the same application works on Windows, iOS, Mac, Android, and Linux. I'd have to change the logic just to make it work with Wasm. I could easily run non-Qt application simply by proxifying the call to main, is there a way to get that to work with Qt5 apps?

@Ahmed-Yarub-Hani-Al-Nuaimi Oh ok I see, thanks for your time !

@kirill_f Problem solved. I just installed upstream version of emscrypten instead of fastcomp. emsdk install sdk-upstream-1.39.8-64bit emsdk activate sdk-upstream-1.39.8-64bit

I am not even sure how supported QtLottie is on the desktop, but not yet supported for Qt WebAssermbly. I do know that the Qt WebAssembly platform has a few issues like this regarding QLogging and Q_DECLARE_LOGGING_CATEGORY that do not happen on desktop, as we are built statically linked.

There is file access, both locally and for the system. Since WebAssembly lives in the browsers javascript sandbox, to access file content on the system, outside of the browser, we created QFileDialog::getOpenFileContent and QFileDialog::saveFileContent https://doc.qt.io/qt-5/qfiledialog.html#getOpenFileContent Also, there should be persistent files, but it's a bit broken at the moment in all the releases.

What version of Qt and what version of Emscripten are you using?

Hi @lorn-potter . Sorry for my super late reply. Your message was spot on. Not only that but it helped me understand some stuff about wasm that I wasn't very clear about. I did some changes and I got my app up and running with no issues. This is awesome. I'm loving Qt more and more everyday. Thank you very much and warm regards!

Thanks for the update. When can we expect this merged? Also why was QNetworkRequest::DefaultTransferTimeoutConstant used for default value? In the documentation https://doc.qt.io/qt-5/qnetworkrequest.html#setTransferTimeout if the function was never called the actual default value is stated to be 0 which is equal to no time limit. DefaultTransferTimeoutConstant is just used as default value if the function was called without any arguments.

@lorn-potter Thank you.I use OpenAL and it works for me.

QtCreator does not have full support for using emscripten, unless you use Qt 5.15. Even then it is still experimental and you need to enable the WebAssembly plugin from within QtCreator first. It's just easier to build using the commandline.