Qt for WebAssembly

@lorn-potter Yes I want to do something like put a texture on the cube surface in WebAssembly. Could I ask what Qt components should I use?

Currently I tried QQuickFramebufferObject and QQuickItem (following the "Scene Graph - OpenGL Under QML" example), but haven't get a successful texture rendering in Chrome browser on Ubuntu 20.04 (Qt version 5.15.2). I also tried without WebAssembly using QOpenGLWidget, in this way the texture works normal.

Thanks Lorn,

I will give that a try.

Gary

Need more information, such as Qt version, any messages you may see in the browser console.

Try changing add_executable to qt_add_executable

@GirishSharma Any update Please?

Cool! If you see any issues, be sure to report them to https://bugreports.qt.io/

@Seishin Am stuck with the old Qt Creator 5... but thanks for the help :)
(Never got around that problem in the end, and gave up!)

@ericg_97477

I ended up trying an alternate way to use emrun...

$ emrun --no_browser --port 8080 ./default.html Web server root directory: /Users/ericg/depot_qt/default/build Now listening at http://0.0.0.0:8080/

I then went to http://0.0.0.0:8080/ in the browser. I was shown the expected page:

Directory listing for /

with all of the files in my build folder.

When I clicked on default.html, I saw the QT icon and it a message that it was downloading the program. Eventually, I saw the the hello world message appear.

I assume I would eventually be able to take control over the loading screen.

So, that worked.

Why didn't emrun — browser=firefox *.html?

I don't know, sorry. I only tried WASM a few times, years ago.

Kinda...

I documented my findings on https://github.com/jpgehrig/nextqt.

@SGaist said in How best to deploy a WebAssembly app:

nginx

Thank you!...Am a complete beginner. Just the help I needed! I'll try out nginx or something akin. :)

Hi
Yes.
Due to the sandbox nature,
I have not seen any WebAssem that could save the DB as local file , only in memory
which clearly won't fit your use case.

However, it does seem possible to save to a array and and load from it.
If your db is not big, it might be useful

https://sql.js.org/#/

I wonder if it would be possible to save and load the DB with javascript and then access it from
c++ as in-mem db. However, I never tried it.

Tested:

EMSDK 1.38.9: OpenSSL cannot be compiled, since the packed gcc is older than requested
EMSDK 1.39.16: Could compile but become frozen.
EMSDK 2.0.6: Compiled, but every time I add QQuickView *view = new QQuickView(), the console log says:

-- constructing QQuickView
qtloader.js:382 Blocking on the main thread is very dangerous, see https://emscripten.org/docs/porting/pthreads.html#blocking-
on-the-main-browser-thread

and the execution hangs.

It is possible that I oversee something, but every other modules are fine: multithreading is running, QGraphicsScene is there and works fine. I have only issue with this QML part.

@JKSH
true, my bad.
than thats not an option.

Hi,

I am currently using EMSDK 2.0.6 with Qt 5.15.2, but IIRC it was possible to compile Qt with ESMDK 2.0.14 as well.
The 2.x version of EMSDK greatly reduces the compilation time and feels to be more mature.