Example loading spinners

[nicksenger]

This PR adds an example of how to implement animated loading spinner widgets. I went with the material design style because the animation easing curves etc are described in detail, but the colors can be changed through the theme, & the speed+sizing through the example widgets' APIs.

spinners.mov

TODO:

• I need to investigate whether requesting a redraw unconditionally like this is a viable approach, or if it would be better to determine an appropriate frame-rate and use RedrawRequest::At(), which may allow for some throttling/debouncing if necessary.

[13r0ck]

Iced aw has some spinners https://github.com/iced-rs/iced_aw/blob/main/src/native/spinner.rs

[hecrj]

You should be able to rely solely on iced if you enable the advanced feature, which will expose the advanced module.

See the custom_widget example:

iced/examples/custom_widget/src/main.rs

Lines 12 to 15 in c15f1b5

	use iced::advanced::layout::{self, Layout};
	use iced::advanced::renderer;
	use iced::advanced::widget::{self, Widget};
	use iced::{Color, Element, Length, Point, Rectangle, Size};

[nicksenger]

Oh cool, I also forgot to remove the flo_curves dependency now that it is instead using lyon for the easing curves. Updated in 56eacdb

[hecrj]

I need to investigate whether requesting a redraw unconditionally like this is a viable approach, or if it would be better to determine an appropriate frame-rate and use RedrawRequest::At(), which may allow for some throttling/debouncing if necessary.

Requesting NextFrame every time will render at the maximum framerate. Currently, this is quite inefficient since we don't support incremental rendering in iced_wgpu yet.

We should be able to efficiently incrementally re-render eventually, however!

[nicksenger]

Requesting NextFrame every time will render at the maximum framerate. Currently, this is quite inefficient since we don't support incremental rendering in iced_wgpu yet.

We should be able to efficiently incrementally re-render eventually, however!

I see, I've updated to use RedrawRequest::At and assume 60fps. Still probably not ideal, but at least it shouldn't go beyond that

[nicksenger]

Iced aw has some spinners https://github.com/iced-rs/iced_aw/blob/main/src/native/spinner.rs

Nice! I didn't realize that was there. If this PR is unnecessary then or more appropriate elsewhere I can close / move it.

[IohannRabeson]

There is an error here rotaion should be rotation

[nicksenger]

Oops, fixed it in 9d69af1

[hecrj]

Really cool example! Thanks 🥳