feat(layout): add Rect -> Size conversion methods

[joshka]

• add Size::new() constructor
• add Rect::as_size()
• impl From for Size
• document and add tests for Size

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ffd5fc7) 92.4% compared to head (6e2e4b1) 92.5%.

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #789   +/-   ##
=====================================
  Coverage   92.4%   92.5%           
=====================================
  Files         57      57           
  Lines      15038   15078   +40     
=====================================
+ Hits       13904   13948   +44     
+ Misses      1134    1130    -4     

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[Valentin271]

Looks good. Why do we need that? Maybe it's worth adding an example somewhere if its relevant to users.

[joshka]

In Oatmeal, I noticed some code where app was storing the most recent height and width of a rect and then later comparing those with each other (paraphrased a bit)

if area.width != state.width || area.height != state.height {
    state.width = area.width;
    state.height = area.height;
    do_some_update();
}

This simplifies that use case to:

if area.as_size() != state.size {
    state.size = area.as_size();
    do_some_update();
}

Maybe it's worth adding an example somewhere if its relevant to users.

I think this is more of a utility type method. Something that can be used optimistically when needed rather than something that needs a demo or examples.

I'm also going to add a Position { x, y } struct as a followup PR for similar reasons.

[Valentin271]

I think this is more of a utility type method. Something that can be used optimistically when needed rather than something that needs a demo or examples.

Seeing the usecase I agree. All good to me then.