freej2me-web

Here it is.. the browser version of my fork of freej2me!

This uses CheerpJ (pretty cool) to run Java in a web browser :) Running in the browser means you can now safely load any JAR file, since malicious JAR files won't be able to cause any damage thanks to the web platform sandbox.

Let's play!

https://zb3.github.io/freej2me-web/

Keyboard controls

Key	Functions As
Esc	Enter/exit freej2me options
F1 or Q	Left soft key
F2 or W	Right soft key
0 to 9	Keypad Numbers
Numpad keys	Numbers with keys 123 and 789 swaped
E	*
R	#
↑	Up
↓	Down
←	Left
→	Right
⏎ Enter	Action key (OK button)

Phone types and key mappings

Keys like left/right soft, arrows and the action key have different vendor-specific mappings. By default, freej2me uses the most common Nokia mapping, but this can be changed in settings by changing the Phone type. Note that in the Standard phone, arrow keys are mapped to 2, 4, 6, 8 and the enter key is mapped to 5.

When using the numpad keys, the 123 and 789 rows are swapped so as to resemble the key layout on a mobile phone.

Game doesn't work?

If a game doesn't work, first try changing the settings. Press the Esc key, change some settings and then restart the game. Try changing these:

• display size
• compatibility flags
• sound (turn off)

If it still doesn't work you can get more information by looking at the console. Note however that not every game will work with this emulator. You can report a bug though.

What's inside

• My fork of FreeJ2ME

• Graphics APIs implemented in JS using 2d canvas rendering context (faster than CheerpJ AWT)

• 3D support

  • Implemented using WebGL 2
  • M3G from KEmulator rewritten to use OpenGL ES 2, then optimized
  • Mascot Capsule v3 support from JL-Mod, optimized

• MIDI playback (libmidi)

  • modified and debloated fluidsynth compiled to WebAssembly
  • WebAudio API + AudioWorkletNode

• Media playback (libmedia)

  • ffmpeg compiled to WebAssembly (to decode formats like amr)
  • rudimentary - the file is fully converted before anything can be played
  • uses a <video> tag to play.. "usually" audio :)

Building

On the host, you need to have docker installed, currently the image assumes a linux host.

After cloning, build the builder image:

docker build --build-arg UID=$(id -u) -t freej2me-web-builder builder_image

Build the jar like this:

docker run --rm -it -uzb3 -w /app -v`pwd`:/app freej2me-web-builder ant

In case you want to rebuild libmidi / libmedia wasm files, build them like this:

docker run --rm -it -uzb3 -w /app -v`pwd`:/app freej2me-web-builder web/libmedia/transcode/wasm/build.sh --release
docker run --rm -it -uzb3 -w /app -v`pwd`:/app freej2me-web-builder web/libmidi/wasm/build.sh --release

Serving locally

Thanks to CheerpJ requirements regarding requests with the Range header, this is.. not that obvious. In practice, if you just want to serve locally, this one-liner seems to work:

npx serve -u web

CheerpJ?

freej2me-web currently works in the browser thanks to CheerpJ. However, since CheerpJ is proprietary, it introduces some limitations.. notably freej2me-web will not work without an internet connection, and it can be a little slow..

However, freej2me-web intentionally doesn't use its more advanced features like AWT GUI support or wasm JNI modules. In theory it should be possible to port it to a simpler (but most likely slower) VM if CheerpJ stops being available... but it's not planned for now.