Qt for WebAssembly

OK I just thought it was deprecated because starting my Qt Widgets-based application gives me the following errors: FATAL [0] - Cannot create window: no screens available Uncaught RuntimeError: Aborted(native code called abort()) at abort (custoservicecenter.js:844:41) at __abort_js (custoservicecenter.js:6355:3) at custoservicecenter.wasm.abort (custoservicecenter.wasm:0x3f81359) at custoservicecenter.wasm.qAbort() (http://localhost:6931/custoservicecenter.wasm) at invoke_v (custoservicecenter.js:15156:29) at custoservicecenter.wasm.qt_message(QtMsgType, QMessageLogContext const&, char const*, void*) (http://localhost:6931/custoservicecenter.wasm) at invoke_viiii (custoservicecenter.js:15011:29) at custoservicecenter.wasm.QMessageLogger::fatal(char const*, ...) const (http://localhost:6931/custoservicecenter.wasm) at custoservicecenter.wasm.QWindowPrivate::init(QWindow*, QScreen*) (http://localhost:6931/custoservicecenter.wasm) at custoservicecenter.wasm.QWindow::QWindow(QWindowPrivate&, QWindow*) (http://localhost:6931/custoservicecenter.wasm)

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

If I remember well, this SharedArrayBuffer is needed when using wasm multithreading. If your app does not need multithreading, use Qt wasm single threading. If multithreading is needed, check https://forum.qt.io/post/765010

@mv-whw Thanks for answering Yes, that is the solution, putting inside my hosting public www folder all my resources: index.html main.wasm images/image0.png images/image1.png inside the wasm code: Image { source: "images/image0.png" } That worked well... and is very nice, this saves a lot of loading times..

@Jan-Bakker Hey, sorry for answering an answered qustion. Justo happy to read it, so, it is possible to load external images in Your web app so your wasm file is smaller?

@Caro You might start by Googling webassembly memory () could not allocate memory and read through the other reports and comments.

@SGaist said in Qt 6.8.2 for wasm on android, the keyboard always auto popup ?: Can you share the bug report ? https://bugreports.qt.io/browse/QTBUG-134917 https://bugreports.qt.io/browse/QTBUG-133781

I can't figure out how to build a lib for qzxing so I can link it with my application. I've tried cmake and qmake and nothing out of the box works. How did you compile qzxing? I am using qt 6.8.2 on windows 11.

There are two fantistic api in c++ #ifdef __EMSCRIPTEN__ #include <emscripten.h> // Required for calling JavaScript #endif #ifdef __EMSCRIPTEN__ // WebAssembly-specific code emscripten_run_script("console.log('Running in WebAssembly');"); #endif #ifdef __EMSCRIPTEN__ const char* url = emscripten_run_script_string("window.location.href"); qDebug() << "Current Page URL:" << url; #endif

For WebAssembly you cannot use theme icons directly but must use the Qt Ressource System

This might be QTBUG-133781, which release are you using ?

The solution to the problem is to add the header res.addHeader("Access-Control-Allow-Origin", "*"); to the HTTP server; hServer.route("/", QHttpServerRequest::Method::Get, []() { QString testAnswer = "TEST REPLY"; res.addHeader("Access-Control-Allow-Origin", "*"); // Added line QHttpServerResponse res(testAnswer, QHttpServerResponse::StatusCode::Ok); return res; }); After adding this line, the browser forwarded the reply to my application.

After some investigation, I don't believe the issue is related to the attribute method. The entire received reply is empty. There are no headers or body received by the application. The Wireshark capture shows that the entire message is properly sent out by my HTTP server and received by the browser, however, the application does not receive it. I checked if any error was reported by the reply and received an error QNetworkReply::ProtocolFailure (399). I believe the browser strips that information and does not propagate it further to the application. I tested this in Firefox and Chrome with the same results. As I mentioned in my original post, the communication works perfectly when compiled as a desktop application. The issue was only observed when compiled by WebAssembly. I will close this post and reopen a new one with a new question.

@lorn-potter Thank you, I think the OP needs help from someone who already built a Wasm project with Multimedia as he didn't manage to have his project built, on the pinned discussion almost all links are dead or out of date which doesn't help much.

I am having a similar issue too. In one of my views (mixed Qml and C++) I have a Node editor, where nodes can be added and connected. I used to handle the Keys.onPressed event and delete selected nodes and connection when Delete is pressed. This worked very well with Qt 6.6.1 in Webassembly (I use Linux). Now, when I switched to 6.8.1, Keys.onPressed event is never generated in Webassempbly (works well on desktop). My scene receives the active focus (I am logging onActiveFocusChanged) but not the keyboard events.