<AWT Dev> HiDPI and FontRenderContext

Hendrik Schreiber hs at tagtraum.com
Thu Nov 6 19:12:08 UTC 2014

On Nov 6, 2014, at 19:01, Alan Snyder <alan at cbfiddle.com> wrote:

> I’m curious about the behavior of FontRenderContext.getTransform() in HiDPI mode. The documentation says it maps points to pixels, but it doesn’t say what kind of pixels. I would have assumed virtual pixels (AWT pixels) for consistency with the rest of the API, but in fact I get a 2x mapping on a simulated Retina display. Is this a good thing or a bug?
> Some API to reveal the HiDPI scaling factor is needed, but I would think it should be a new API to avoid confusing old programs that don’t know about HiDPI mode.
> The larger issue - is there a plan to document HiDPI mode? I have not found any mention of it in the docs other than a cryptic message that Retina displays now work properly. All I have learned comes from mailing lists, blogs, and reading source code. Some programs need to be updated to work well in HiDPI mode, and documentation is needed on how to do that.

This is true. Improvement of the situation would be much appreciated.
Also, bringing OS X, Windows and others onto the same page would be a good idea. Last time I checked, HiDPI behavior of Swing was very different between OS X and Windows (e.g. https://bugs.openjdk.java.net/browse/JDK-8029087).


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