[OpenJDK 2D-Dev] RFR: 8217731: Font rendering and glyph spacing changed from jdk-8 to jdk-11

[Philip Race]

On 6/5/19, 4:18 PM, Semyon Sadetsky wrote:
> On 6/5/19 2:11 PM, Phil Race wrote:
>
>> It *can* make a difference and in fact we have a regression test
>> that now passes with this fix which tests different rendering modes.
> Which test is it? Why  you didn't mark it with the bug id?

See https://bugs.openjdk.java.net/browse/JDK-8199529

I only located this bug and verified this "resolves" it after sending 
out the review
but it "resolves" it due to luck as much as anything definite, so I 
don't think it is
required to link this as "solving" that.

>> However that is not a direct test for this potential difference.
>> You cannot say that this change *must* make a difference, it
>> just does. Sometimes.
>
> That's what we need to avoid regression again when fonts are updated. 
> Font appearance directly affects user experience. Fortunately this 
> happens not so often but we definitely need a test that will indicate 
> such changes before the bug is reported externally like it recently 
> happened. I thin everyone agrees that we should not repeat this 
> omission once again.

You misunderstand. There was no regression. There was a change in behaviour
which is completely allowable, and can happen all the time and is 
sensitive to
so many things. So there was no omission. Nothing can be tested and asserted
to be right or wrong. And the algorithms used are outside of our control.
But there is still value in the change to see if more people are happy 
with the
alternative rendering.


-phil



>
> --Semyon
>
>>
>> -phil.
>>
>> On 6/5/19 1:40 PM, semyon.sadetsky at oracle.com wrote:
>>> Can you clarify does the change affects font metrics?
>>>
>>> I see that it is a sub-pixel difference for each single glyph but if 
>>> a long line of text can accumulate a notable difference the reg test 
>>> can be provided.
>>>
>>> --Semyon
>>>
>>> On 6/5/19 11:43 AM, Phil Race wrote:
>>>> bug: https://bugs.openjdk.java.net/browse/JDK-8217731
>>>> webrev: http://cr.openjdk.java.net/~prr/8217731/
>>>>
>>>> This is intended to "help" but cannot completely cure, with
>>>> some of the rendering differences in JDK11 vs JDK 8.
>>>> In a typical Swing app on Windows using LCD rendering
>>>> it manifests as subtle adjustments in the spacing between glyphs.
>>>> There isn't an easy regression test for this, and it is subjective
>>>> as to how bad it was before and how much this improves it,
>>>> even if you were to accept that 8 is "better" .. and not just 
>>>> different ..
>>>>
>>>> -phil.
>>>
>>