[OpenJDK 2D-Dev] RFR: 8220150: macos10.14 Mojave returns anti-aliased glyphs instead of aliased B&W glyphs

[Philip Race]

Yeah. Faster.

-phil.

On 4/4/20, 9:57 PM, Sergey Bylokhov wrote:
> Hi, Phil.
>
> Does the SolidTextRenderer have some benefits over AATextRenderer so 
> we have to use it by default on 10.13 on jdk15?
>
> On 4/4/20 8:16 pm, Philip Race wrote:
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8220150
>> Webrev : http://cr.openjdk.java.net/~prr/8220150/
>>
>> We are being returned grey glyphs when asking for B&W.
>> The same is true for LCD, although they are a little different and 
>> not the main problem.
>>
>> The main problem is that when our software loops designed for B&W are 
>> handed greyscale
>> glyphs, every byte encoded pixel that has a bit that is 1 is treated 
>> as 255.
>> Once we are in those loops it is too late and the result is horrid 
>> blocky text.
>>
>> This hasn't been affecting too many people since the OpenGL pipeline 
>> treats
>> the bytes as a mask so works for both B&W and greyscale.
>>
>> But if you are drawing to a BufferedImage  the problem is there.
>> It can popup in a UI if the UI uses a s/w image as the backbuffer - 
>> in fact
>> that is how this bug was reported.
>>
>> There isn't anything I can find that will make 10.14 generate B&W 
>> glyphs again -
>> the workaround to change a system default is not viable for us, and 
>> it is a lot
>> of work to use freetype in this case and that will almost certainly 
>> cause inconsistencies.
>>
>> There is no sure way to know that you are going to be handed AA 
>> instead of B&W.
>> So the essence of the fix is that on 10.14 and later we use the AA 
>> rendering loops
>> to draw B&W. They will properly blend even if somehow we were handled 
>> B&W glyphs.
>> This is the change in SurfaceData.java.
>>
>> The other changes are a small optimisation, so that if B&W glyphs are 
>> requested we
>> re-direct to greyscale. This prevents wastefully caching the AA 
>> glyphs twice - once
>> as AA and once as (supposedly) B&W.
>>
>> -phil.
>>
>>
>
>