RFR: JDK-8328750: [TestBug] Improve Stub Font Support

[Marius Hanl]

On Tue, 26 Mar 2024 20:40:11 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

> If I write a test that uses the StubToolkit, one that requires some kind of font metrics - would that work? Will I get some kind of semi-valid values for preferred width of a text (Text, Labeled, etc.), or I cannot really rely on the correctness of the StubTextLayout?

Yes, it should! Especially with the hopefully more clear rules here. I added more javadoc in my last commit and used the System font as fallback since this is more aligned with what JavaFX is doing. Local tests seems fine, but we will see here.

You could for example put a `Label` inside a container with the (max) width of 100px. With a normal font (size=12), 8 characters should be good (8x12=96), while 9 characters should make the `Label` truncated since we exceed the 100 pixels then. This is close to what JavaFX is doing, while you can still write a Headless tests about the basic rules of the truncated property.

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PR Comment: https://git.openjdk.org/jfx/pull/1422#issuecomment-2021445366