Don't fill out of viewport text

[tarkah]

Super smol optimization. There's no need to submit this rendering operation when text is out of viewport. In halloy we leverage this optimization and it has a huge impact on primitive generation timings when dealing w/ lots of text in a scrollable.

[tsuza]

I've tested it with ~10k text widgets, containing Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua in one of my projects.
Scrolling with upstream iced is much, much, laggier. This PR makes it buttery smooth.

I've attached some screenshots of the debug info, before ( 0.13.1 stable branch ) & after ( this PR's branch ), while scrolling or idling.

There shouldn't have been too many changes in the dev branch ( 0.14.0 ) in comparison to the stable branch ( 0.13.1 ), so it shouldn't impact the fps too much. Though if it's the case, I can re-do the tests.

[tarkah]

Thanks for the detailed comparison. Render times are way down!

[tamewild]

IIRC, this might be fixed when Iced's glyphon has this: grovesNL/glyphon#108

Edit: This PR will still help though with primitive generation (particularly for a huge amount of small text widgets) I believe. The glyphon thing is more relevant for the editor and a single text widget with a huge amount of text

[hecrj]

I think it's better to cull primitives in column and row instead of text. This way, we cull any primitive and all widgets benefit.

Let me know if that works.

[tarkah]

LGTM!