Add imgui_bundle package

[pthom]

Description

Dear ImGui Bundle provides python bindings for Dear ImGui and lots of related libraries.

This PR adds support for the imgui_bundle package to Pyodide. It enables high-performance interactive GUIs (including 3D plotting, Markdown rendering, and immediate mode controls) directly in the browser using pure Python (no need for JavaScript, CSS, or WebAssembly glue code outside Pyodide’s core).

Demo

I prepared two demonstrations in order to showcase what is possible:

• An Interactive Playground where it is possible to run demos and edit their code (select examples in the top right corner, and click on "Run")
• A Minimal HTML page showcasing how to use it, with an extremely short source code

Discussion and related PR

This recipe requires a change inside pyodide/Makefile.envs (see technical note below: add -sMAX_WEBGL_VERSION=2).

A related PR was posted to the main pyodide repo, to add this flag.

The test for this new recipe will fail if this change is not applied.

Technical Notes:

1. Build configuration for Pyodide: -sMAX_WEBGL_VERSION=2

2. Link with SDL2 (fPIC):

meta.yaml/build will trigger the build of SDL2 and libtml5 with -fPIC

3. Running the tests

• the test need to be run via a browser (not via node). For example:

   pytest pyodide-recipes/packages/imgui-bundle --runtime chrome

[pthom]

Hello @ryanking13 ,

Following the merge of the WebGL2 PR, I rebased this PR.
It also now uses the latest release of imgui bundle (v1.92.0).

[github-actions]

Package Build Results

Total packages built: 35
Total build time: 0:09:53

Package Build Times (click to expand)

Package	Build Time
imgui-bundle	5m 48s
openssl	5m 12s
numpy	4m 42s
pydantic_core	3m 54s
sqlite3	2m 37s
liblzma	1m 5s
test	25s
regex	12s
ssl	12s
hashlib	10s
pydecimal	8s
pydoc_data	5s
lzma	5s
MarkupSafe	4s
atomicwrites	3s
pytz	3s
pydantic	2s
packaging	2s
Jinja2	2s
setuptools	1s
pyparsing	1s
pluggy	1s
six	1s
pytest-asyncio	1s
typing-extensions	1s
annotated-types	1s
micropip	1s
py	1s
exceptiongroup	1s
tblib	1s
attrs	1s
iniconfig	1s
pytest	1s
munch	0s
more-itertools	0s

Longest build: imgui-bundle (5m 48s)
Packages built in more than 10 minutes: 0

[pthom]

I had to do some modifications in order to correct the test. Sorry for force-pushing several times today.

• The test runs now correctly in Chrome.

• The test is expected to fail in Firefox Headless because Firefox Headless does not support WebGL unless a virtual display is set up.
  For info, Xvfb + GL drivers might be installed by adding this into the build.yml CI workflow

  - name: Start virtual display (for WebGL tests)
    run: |
      sudo apt-get update
      sudo apt-get install -y xvfb libgl1-mesa-dri
      Xvfb :99 -screen 0 1280x720x24 -ac &
      echo "DISPLAY=:99.0" >> $GITHUB_ENV
  

However, even with a virtual display headless there are remaining issues around requestAnimationFrame in Firefox, so the test is still expected to fail.

Of course when deployed, the package and the apps developed with it will work on Safari / Firefox / Chrome (this was tested on Windows, Linux, macOS and iOS).

[agriyakhetarpal]

Thanks for this work, @pthom! I am onboard with the testing criteria you proposed; I think it's a unique approach. Even if the tests work only for Chrome and not Firefox Headless, that is fine with me. I will wait for @ryanking13's comments/approval here.

[ryanking13]

The test runs now correctly in Chrome.

Yeah, I think it is okay to test it only in Chrome. We don't expect to test the full functionality of the packages in this repository anyways. If we have more packages that require WebGL, let's consider including it in our CI environment, for now it looks okay.

[ryanking13]

yields to JS

It won't. When JSPI is not enabled, time.sleep is busy wait.

You can use asyncio.sleep instead to ensure yielding to JS.

[pthom]

Thanks!

I replaced this with

    import asyncio, time
    deadline = time.time() + 6.0      # 6-second safety net (requestAnimationFrame may run slowly in headless mode)

    async def _wait_until_done():
        while not done and time.time() < deadline:
            await asyncio.sleep(0.05)

    asyncio.run(_wait_until_done())

[pthom]

@ryanking13 : I did all the changes you asked for.

[ryanking13]

Thanks @pthom!

[ryanking13]

It is worth noting that aysncio.run also works only if the JSPI is enabled.

So a safer way would be changing the test function to async, and simply using await asyncio.sleep(0.05). But we enable JSPI in our CI anyways, so probably it is okay.

[pthom]

Thank you!