RFR: 8316518 javafx.print.Paper getWidth / getHeight rounds values, causing errors.

[Florian Kirmaier]

On Tue, 19 Sep 2023 11:56:39 GMT, Florian Kirmaier <fkirmaier at openjdk.org> wrote:

> The Method javafx.print.getWidth and getHeight returns a double of points.
> But the values are always rounded to full integers. This causes especially problems,
> with mm based Papers.
> 
> I asked in the mailing list, with the conclusion (me and John Hendrix) that is best to just fix this behavior by removing the rounding.

Many of the Papers in the Paper Class are measured in MM, and the Paper Class simply returns wrong values.
A rounding like `.00001` should cause less problems than `.465` (A4).
A4 Paper simply returns wrong values.
If the developer uses these values, then the computations are wrong.
By using the correct values, we get visible more correct results.

In the mailing list, I also suggested 2 other solutions:
**Solution2:**
We could add new methods getExactWidth() / getExactHeight() , which returns the exact value without a rounding problem anywhere noticeable.

**Solution3:**
We could provide an API to access the width/height based on a given Unit.
like: getWidth(Unit.MM).
We already have implemented this, in our application code, so it wouldn’t be much effort.
But it would require moving com.sun.javafx.print.Units back to javafx.print.Paper.Units. (basically reverting JDK-8093699)


I could also implement one of these solutions, if that's preferred.
But i still don't see, how this rounding doesn't cause many unknown problems.

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PR Comment: https://git.openjdk.org/jfx/pull/1244#issuecomment-1729039960