Qt 6.5 WebAssembly Dev Roadmap

Preliminary 6.5 R&D roadmap items, in no particular order:

(Note for external readers: this list includes way more than can be realistically delivered for 6.5. Some items, like wasm64, require improved browser support.)

• QML local file access
  Investigate if it’s possible to implement a Qt file system engine which gives access to local files.

• WebGPU
  Prototype WebGPU RHI backend.

• Testing
  Continue work on CI auto-testing
  Improve native test coverage (clipboard support, settings, app startup/shutdown)

• Wasm64 [done]
  Add 64-bit configure option.

• Multithreading [done]
  Add "mt" binary packages.
  Continue work on making sure the mt config is stable.
  Should it be the default mode?

• Supporting synchronous Qt APIs on top of async Web APIs
  Investigate if we can run Qt on a separate thread.
  Make use of asyncify where possible&required.
  Investigate if we can optimize asyncify usage.

• Multimedia [done]
  Implement video support

• qtloader.js
  Rework the current implementation to use modern js. Document public wasm instance API.

• Compositor, canvas-per-window mode [done]
  Make Qt create one canvas per window instead of one canvas per screen. Investigate options for window compositing.

• Dynamic loading
  Continue implementing support for more use cases.

• Build system options
  Make sure we have (documented) API for overriding all options Qt sets (INITIAL_MEMORY etc)

• Accessibility [done (and continuing)]
  Integrate patches currently on gerrit and align with other items (mobile virtual keyboard, canvas-per-window). Fill in missing gaps. Test with Qt Quick.

• Mobile
  Make sure the mobile virtual keyboard works, (also when accessibility is active). Create examples which shows mobile use cases - touch event handling, install on home screen.

• Resources (QTBUG-74568)
  Enable use of separate resource files to avoid piping resources through the wasm compiler(s).

• Server connectivity
  Verify that qtremoteobjects over qtwebsocokets works as expected on wasm.
  Database (postgres, mysql) over websockets

• Exceptions: Add configure option for enabling WebAssembly exceptions. [done]