Qt for WebAssembly

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with Multimedia as he didn't manage to have his project built, on the pinned discussion almost all links are dead or out of date which doesn't help much.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.

@Mesrine Thank you again for your quick reply. I was so focused on the UI portion, that I didn't read the Networking section of the documentation properly. I need to investigate an alternative way to share data between the utility and the Remote UI. Thanks again for your help.

Likely a glitch Since it's working now, please mark the thread as solved :-)

Strange, I know for a fact that QNetworkAccessManager works on wasm, so you may want to use that instead.

Confirmed：Qt6.8.1, it's finally possible to input Chinese. Thanks for all.

AutoPlay and loops do not work in Qt 6.8.0/6.8.1. In 6.7.2, autoPlay is normal but there can only be one visible videooutput. Loops does not work either. In addition, your wasm must set the source externally, such as after clicking a button or "Component.onCompleted" . mediaPlayer.source = "xxx.mp3" Also, even if you only play audio, it seems that you need to set videoOutput, and since 6.7.3, there may be memory problems when using loader and mediaplayer. So it's better to avoid using mediaplayer.

Hi, I have the same problem. Have developen a qt widget webasm application on qt 6.8 where the main annoyance right now is this problem. If browser windows is lesser than the default widget size it will not adjust to the browser window unless browser window is resized just so little it adjusts just fine to the size. It is like it fails to read the browser size when layout the main window.

on 2 dec. 2024, I asked that question again and someone gave me an answer, see https://forum.qt.io/topic/159970/using-qsvggenerator-with-webassembly

@jsulm Thank you, I try that ASAP. It works fine either on Desktop and Wasm. Now I need to plug my data. void MainWindow::exporter() { QSvgGenerator SG; SG.setSize(QSize(200, 200)); SG.setViewBox(QRect(0, 0, 200, 200)); SG.setTitle(tr("SVG Generator Example Drawing")); SG.setDescription(tr("An SVG drawing created by the SVG Generator " "Example provided with Qt.")); QPainter painter; QBuffer buffer; SG.setOutputDevice(&buffer); painter.begin(&SG); painter.end(); QFileDialog::saveFileContent(buffer.data(), "myExport.svg"); }

By using tf = QFont("Bitstream Vera Sans", 8); tf.setLetterSpacing(QFont::AbsoluteSpacing, -1); I almost have the same rendering, except a small vertical offset that I can correct, My alignment formula is using an absolute value and I need to change it to relative.

@Birk-Skyum Thanks - this prompted me to try with the multithreaded Qt 6.8 version and (once I enable SharedArrayBuffer in Chrome) it solves the issue in Windows. Looks like I'll have to compile two versions for the forseeable future...)

I amost got it, now I only need to press TAB after I clicked on a new color to be able to use keyboard shortcuts to rotate my 3d model. It breaks the working flow, but is usable. I'm using code (on the cellpress event handler of my TableWidget) to try to give the focus to my GraphicsView, but on WASM it doesn't seem to do anything. To be able to have the selected row showing the row color instead of its negative, I needed to add a label widget and add it to the first cell of the row, I added noTextInteraction to its TextInteractionFlags otherwise it has the focus when I click on it and handle keystrokes. Is there anything I can do ? is it possible to send a TAB keystroke at the end of my code so that the user doesn't need to do it ? ui->tableCouleurs->releaseKeyboard(); ui->vue3d->setFocus(Qt::OtherFocusReason); [image: 1f07cc19-95d1-456b-b5e1-355b106ffc90.png]