Feedback request: Add new RenderingHints.KEY_FONT_HINTING

[Daniel Gredler]

Hi all,

We've had a bit of back-and-forth regarding whether font hinting is enabled
or disabled when drawing grayscale text with anti-aliasing and fractional
metrics enabled [1, 2]. Setting AA + FM disabled font hinting in JDK 8 -
10, then JDK 11 changed this so that AA + FM would *not* disable hinting,
and finally the behavior was reverted in JDK 14 (and backported to JDK 11).

Generalizing a bit, the current behavior (AA + FM disables hinting) is
optimal for "the desktop use case" (JavaFX, animations, smooth scaling,
etc). The JDK 11/12/13 behavior was optimal for "the backend use case"
(individual image creation, no animations).

I think it would be useful to have a new java.awt.RenderingHints key named
RenderingHints.KEY_FONT_HINTING, with the following possible values:
- RenderingHints.VALUE_FONT_HINTING_DEFAULT: current behavior, dictated by
AA + FM
- RenderingHints.VALUE_FONT_HINTING_ON: enable font hinting, regardless of
AA + FM
- RenderingHints.VALUE_FONT_HINTING_OFF: disable font hinting, regardless
of AA + FM

This new rendering hint would allow direct control over whether font
hinting is enabled or not, and would specifically enable the use of AA + FM
+ font hints in Java.

I'm happy to create a patch with this feature (I have a signed OCA on
file), but wanted to get feedback on the idea first. Let me know what you
think!

Take care,

Daniel

[1] https://bugs.openjdk.org/browse/JDK-8214481
[2] https://bugs.openjdk.org/browse/JDK-8242285
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.openjdk.org/pipermail/client-libs-dev/attachments/20240714/a43f5f52/attachment.htm>