Interface legacy C++ GUI Widget system with Python

[yuanming-hu]

Concisely describe the proposed feature
As mentioned in #478 we do have an old yet helpful C++ widget system that supports sliders, buttons, etc:

(How to run it: just use the latest commit, clone taichi_assets as taichi/assets, and execute ti test_gui)

Since literally nobody is using Taichi via C++ anymore, we should consider adding a Python binding via pybind11, potentially extending ti.GUI.

(Why don't we use Qt: Taichi used to depend on Qt, yet a lot of users had problems installing it, even PyQt... Also the types of widgets we need to support is rather minimal and Qt is an overkill.)

[archibate]

The old C++ widget system is good, but most people just using python now. I think pip users won't like the code never reached in libtaichi_core.so :)

Solution 1:
Add python bindings to these widget class. Further developments will be in C++.
Solution 2:
Move the widget system completely written python, just leaving font rendering & lower event system in C++, since GUI is not performance sensitive and python is easy to develop.
We can add more widgets, features in python without compile. Note that we are making a programming language. Language compiled libraries should be low-level enough, high-level things can be moved out of libtaichi_core.so.
Also because I see slider & button aren't dep on win32 hwnd.

How do you think? I personally tend to solution 2.

Btw, why not taichi-dev/taichi_assets?

[yuanming-hu]

My feeling is that we should first go 1 since it's not a lot of work (just export a few functions and callbacks). 2 sounds like more work but also more extensible. The question is as a compiler do we really need a super fancy widget system? My feeling tends to be no, but I'm open to any inputs.

Btw, why not taichi-dev/taichi_assets?

Currently the only file we need in that submodule is a font file (fonts/Go-Regular.ttf).

[archibate]

My feeling is that we should first go 1 since it's not a lot of work (just export a few functions and callbacks). 2 sounds like more work but also more extensible. The question is as a compiler do we really need a super fancy widget system? My feeling tends to be no, but I'm open to any inputs.

You're right. the GUI system isn't a center point of a compiler.

Currently the only file we need in that submodule is a font file (fonts/Go-Regular.ttf).

Yeah I made a symbolic link from /usr/share/fonts and it works :)

[github-actions]

Warning: The issue has been out-of-update for 50 days, marking stale.

[archibate]

People might be happy if they could use this in their TopOp build on taichi.py, working on this now :)

[yuanming-hu]

People might be happy if they could use this in their TopOp build on taichi.py, working on this now :)

That would be very helpful! But again, I suggest we go with your "Solution 1": simply add python bindings of existing C++ widget classes.