oh-canvas-item: Make content use 100% height and align vertical centered

[florian-h05]

Related to https://community.openhab.org/t/vertical-alignment-of-standard-library-widgets-in-fixed-canvas-layout/168211.

[florian-h05]

Before:

After:

Note how the NULL value is properly aligned and the widget takes up the full frame.

[relativeci]

#4757 Bundle Size — 12.86MiB (~+0.01%).

b49fa93(current) vs 5f8928d main#4756(baseline)

Warning

Bundle contains 2 duplicate packages – View duplicate packages

Bundle metrics  no changes

	Current #4757	Baseline #4756
Initial JS	3.23MiB	3.23MiB
Initial CSS	0B	0B
Cache Invalidation	8.49%	8.49%
Chunks	592	592
Assets	669	669
Modules	2601	2601
Duplicate Modules	0	0
Duplicate Code	0%	0%
Packages	123	123
Duplicate Packages	1	1

Bundle size by type   1 change 1 regression

	Current #4757	Baseline #4756
JS	11.14MiB	11.14MiB
CSS	896.45KiB (+0.1%)	895.58KiB
Fonts	526.1KiB	526.1KiB
Media	295.6KiB	295.6KiB
IMG	45.73KiB	45.73KiB
Other	847B	847B

Bundle analysis report Branch florian-h05:canvas-alignment Project dashboard

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[florian-h05]

@JustinGeorgi @hmerk @stefan-hoehn WDYT? I think the change makes canvas bevave correctly, but I am neither actively using it nor want to break existing canvas.

[JustinGeorgi]

I have never used the canvas for anything significant, so I'm in the same situation. I think this looks like a good change but, I can't say if it will be problematic.

[hmerk]

Used canvas layout for the demo case only, so not really having much experience with it.

[peterkappes]

Here is my comment from the community post to continue discussion here:

First of all, thank you very much for the in-depth investigation of the problem and for proposing a way to fix it. Would this also “fix” the slider widget?

Perhaps the following questions can help point us in the right direction:

• What is the reason that, in a fixed grid, the item content is vertically centered?

• What is the goal of the “preserve classic style” option?

In my opinion, the widgets from the standard library are not really usable at all when working with a fixed canvas. They are not consistent with the row/column or fixed grid layout.

[jsjames]

@florian-h05 - just confirming this is no longer draft (as stated in the initial comment).

[florian-h05]

Let's undraft and merge this, we are far away from 5.2.0 so we have enough time to test this and revert in case it was a bad idea.