wx: delegate event handling to subwidget

[gselzer]

Found while working on pyapp-kit/ndv#114 that WxWgpuCanvas wasn't responding to events the way that I expected. With this change, we can react to events.

I didn't see any location within the tests folder that looked like a good location for automated testing code, but I manually tested this change using a modification of gui_wx.py, which prints many lines with the change and does not without the change. Tested on Windows 11, Python 3.11 and latest main:

"""
Run the triangle/cube example in the wx GUI backend.
"""

# run_example = false

import wx
from wgpu.gui.wx import WgpuCanvas

from triangle import setup_drawing_sync
# from cube import setup_drawing_sync


app = wx.App()
canvas = WgpuCanvas(title=f"Triangle example on {WgpuCanvas.__name__}")

draw_func = setup_drawing_sync(canvas)
canvas.request_draw(draw_func)

def on_mouse_move(event: wx.MouseEvent):
    print("Captured mouse event!")

canvas.Bind(wx.EVT_MOTION, on_mouse_move)

app.MainLoop()

Happy to add an automated test if there's somewhere that makes sense. Also, I'm also pretty naive about wx, so unsure about the correctness of the behavior (e.g. should calls to super().Bind()/super().Unbind() occur before calling them on the subwidget?

[almarklein]

Hi!

There's two ways that we intend that users use these canvas classes:

Use it as an abstract canvas, using the event-system (using canvas.add_event_handler()) that works the same for all the backends. You don't really care whether its wx or qt or glfw.

Or, using wx explicitly, probably because you're embedding it in a wx GUI. In this case you should probably use the WxWgpuWindow (or WxRenderWidget in rendercanvas).

If you want to use a toplevel wx canvas using wx events, I'd recommend either:

• import WxWgpuWindow and embed it in your own frame.
• import WxWgpuCanvas and maybe subclass it to expose the subwidget as a public property to which other code can Bind().

[almarklein]

Oh, and consider using rendercanvas which will replace wgpu.gui. Its (nearly) fully compatible, and improved in several ways.

[gselzer]

f you want to use a toplevel wx canvas using wx events, I'd recommend either:

* import `WxWgpuWindow` and embed it in your own frame.

* import `WxWgpuCanvas` and maybe subclass it to expose the subwidget as a public property to which other code can `Bind()`.

This is a good point, gotcha.

Do you still see value in this PR, or should we close it?

[almarklein]

Closing :)