Handle zero-sized buffers internally

[madsmtm]

The NonZeroU32 in our public API is ugly IMO. Is there a reason why we avoid resizing and rendering when the sizes are 0? Does it crash on some backends? Could we instead make it be a no-op?

See also discussion in #236 (comment).

[ids1024]

Using NonZeroU32 seems to match glutin: https://docs.rs/glutin/latest/glutin/surface/trait.GlSurface.html#tymethod.resize.

Meanwhile, https://docs.rs/wgpu/25.0.2/wgpu/type.SurfaceConfiguration.html uses u32, but documents width and height with "Must be the same size as the surface, and nonzero.".

(I seem to recall some discussion about changing winit to return the size as NonZeroU32, but I don't see anything, and I guess it's still u32 in git.)

So it seem to make some sense from a consistency standpoint.

On Wayland, https://wayland.app/protocols/wayland#wl_shm_pool:request:create_buffer doesn't really seem to properly document the error cases, but checking smithay and wlroots, they generate invalid_stride errors if 0 or a negative value is passed for width or height. It is possible to attach null instead of a wl_buffer to a surface, but this has the effect of hiding/unmapping a window.

So on Wayland anyway, there isn't really a concept of having a window containing a 0x0 buffer. To implement that without crashing the client with a protocol error, we'd have to special case it as either a null buffer (unmapping the window) or perhaps a 1x1 transparent buffer.

[madsmtm]

IIRC CGImageCreate will also fail if you provide 0 width/height. What I meant here was to special-case 0-sized buffers, and just no-op in Buffer::present (but still provide the empty pixels slice to users and everything).

The reason I think this makes a lot of sense is if you want to use softbuffer for subsurfaces, as those are a lot more likely to be zero-sized in some dimension.

I get that this might has weird interactions with surfaces that are tied to a window, not sure what we'd want to do there.

I seem to recall some discussion about changing winit to return the size as NonZeroU32

Maybe rust-windowing/winit#3433 (comment)?