[OpenJDK 2D-Dev] RFR: 8233097: Fontmetrics for large Fonts has zero width

[Phil Race]

PS .. a positive from this is that with this fix the regression test
runs about 10X faster than it did with say JDK 13 GA .. due to
skipping the redundant images

-phil.

On 10/30/19 11:05 AM, Phil Race wrote:
> Bug: https://bugs.openjdk.java.net/browse/JDK-8233097
> Webrev: http://cr.openjdk.java.net/~prr/8233097/
>
> This bug is a regression from a fix in JDK 13.0.1 / 11.0.5
>
> To work around a bug in old versions of freetype we capped the size
> of the glyph image but overlooked that we may use that code to get
> metrics even when the glyph image isn't needed.
>
> The fix is to still get the metrics the same way but in such a case
> skip getting the image.
>
> When the new "renderImage" variable is true the changes in the
> code should be a no-op, and this is used for metrics and images
> for typical sizes. So theoretically at least, safe there.
>
> For renderImage == false, as used from the advance/metrics functions
> it guards against rendering the image or accessing bitmap fields.
>
> The advance/metrics cases discard the image so it should also be safe 
> there.
>
> I'm running regression tests as well as Font2DTest and all passes so far.
>
> This will need to be backported to 11u, so does still need careful 
> review.
>
> -phil.
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