Implement pointer constraint.

[vanfanel]

Implements the previously missing pointer constraint functionality.
Most code came from Sway.

[joggee-fr]

Thanks for the PR @vanfanel. I am just taking a (very) quick look at it. Could you run clang-format to ensure modified files to be consistent with current format?

[vanfanel]

Thanks for the PR @vanfanel. I am just taking a (very) quick look at it. Could you run clang-format to ensure modified files to be consistent with current format?

Done. It was my first time using that tool, seems very useful indeed. The more you know!

[vanfanel]

@joggee-fr any news on merging this, please?
I had forgotten but I would need It working.

[joggee-fr]

@vanfanel, I am not confident enough in my knowloedge for this part to give it a go. I hope @emersion could give it a look. Especially for the so-called "big hack" part.
At least, you should rebase to current HEAD based on wlroots 0.17 now. Is the hack still necessary with this version of wlroots? And maybe squash the two commits also.

[vanfanel]

@joggee-fr I have done what you asked me: I rebased to latest Cage code, and squashed all commits into one.

And yes, the "big hack" part is needed with current wlroots 0.17, it comes directly from current Sway, you can see it here:

https://github.com/swaywm/sway/blob/88b2abf5f208422ffc503c2c1d2a0de95d9ec4c5/sway/input/cursor.c#L1372

[vanfanel]

@joggee-fr I have fixed those comment-related issues you pointed me to, and squashed all commits again.

[vanfanel]

@joggee-fr Is there anything else to get this merged, please?
It's a relatively simple PR, but very useful to me.

[joggee-fr]

@vanfanel,
@emersion will be a better reviewer than me to merge this PR or give you others comments. Hope he will have time to check it soon.

[Zorbatron]

This PR doesn't seem to work? I hope that I'm just doing something wrong.
After applying the patch and building, I tested it with Minecraft by adding the built cage binary as a wrapper command in Prism Launcher. I can see new confined_pointer and destroying constraint in the log as I alt-tab to and from cage, but my mouse pointer isn't actually being constrained since it moves off of the window when I look too far left or right.
I'm on Arch Linux with:

• Default kernal ver 6.12.4-arch1-1
• kwin ver 6.2.4-2
• wayland protocols ver 1.38-1

[KurtThiemann]

It definitely worked with Minecraft before, we used it last summer to run Minecraft at Gamescom.
This is the now slightly outdated version we used: https://github.com/KurtThiemann/cage

[Zorbatron]

Using that fork doesn't work either. Same results as with this. Is it supposed to "just work" or do I have to use a keybind or something?

[fxzzi]

also does not seem to be working for me either. Attempting with minecraft 1.8.9 it looks like the behaviour is the exact same as master. Cursor freely leaves the window in pause menus and looking around in game.

[KurtThiemann]

What exactly do you mean by "leave the window"? Are you running cage from within another desktop environment?
I'm not sure it is supposed to work if you use it as a virtual output.

[fxzzi]

What exactly do you mean by "leave the window"? Are you running cage from within another desktop environment? I'm not sure it is supposed to work if you use it as a virtual output.

I thought the entire point of pointer constraint would be to stop the cursor from leaving the cage window. I guess I didn't fully understand what it meant. Is this not what was implemented? I am running cage within another wayland desktop environment.

[KurtThiemann]

Cage is supposed to be used instead of a regular desktop environment. When run from inside another desktop environment, it will just create a virtual output, which to my understanding is mostly intended for testing purposes.
Cursor constraints are necessary, so games can let you look around using your mouse instead of moving a cursor across the screen, I don't think they are supposed to prevent you from leaving the virtual output window with your mouse.

Anyway, this is probably a bit off-topic for this pull request.