Macos backend needs a window delegate to capture events.

[geon]

I have some code halfway working in a branch, but I'm not sure how Capy works internally.

https://github.com/geon/capy/tree/window-delegate

[zenith391]

What's not working in your code? Also if you have any question for how Capy works, you can just ask me on capy's Matrix channel or on my Discord (although I'm more active on Discord)

[geon]

I was getting garbage data in the window size.

I think the getEventUserData isn't properly implemented. If I understand it correctly, it should return a separate object for each widget, while the macos backend only has one global object.

I think Capy uses native apis in both gtk and win32 apis for attaching custom data to widgets, but I'm not aware of something similar in macos. Perhaps we could just have a global hashmap, with the peer as key? Or would that leak?

[zenith391]

I think the getEventUserData isn't properly implemented. If I understand it correctly, it should return a separate object for each widget

Yea that's what getEventUserData should do.

I think Capy uses native apis in both gtk and win32 apis for attaching custom data to widgets, but I'm not aware of something similar in macos. Perhaps we could just have a global hashmap, with the peer as key? Or would that leak?

You can absolutely use a global hashmap for this usecase. Although, for the WebAssembly backend, when I faced the same problem, I ended up replacing the peer object by a manually allocated GuiWidget, which basically contains EventUserData's fields, alongside the actual peer object (which would be objc.Object).

So for the macOS backend, this would be equivalent to replacing, in Label and in Container, the field peer: objc.Object by peer: GuiWidget.
And creating the struct:

const GuiWidget = struct {
  object: objc.Object,
  // Either include EventUserData or just copy its fields. Although including
  // it might be better.
  data: EventUserData,
};

Then in Label.init and Container.init, you allocate an instance of GuiWidget and fill in the data.

[geon]

I don't really see how the GuiWidget struct helps.

in https://github.com/geon/capy/blob/1a22e734cb0fdd4504b388f11bf675a80dc40b29/src/backends/macos/CapyWindowDelegate.zig#L20 , I get access to the NSWindow, , but in the windowDidResize callback I can't use any kind of closure to access the GuiWidget outside the callback.

[geon]

In GuiWidget, shouldn't data be a pointer? The GuiWidget ends up getting passed around a lot, and without the pointer, it wouldn't get updated.

[geon]

I'm trying to implement the window delegate data as an Ivar. I haven't gotten it to work yet. Perhaps if you are good with the zig objc bindings you could have a look: geon@29213b3