[OpenJDK 2D-Dev] [PATCH] JDK-8146035: Windows - With LCD antialiasing, some glyphs are not rendered correctly

[Sergey Bylokhov]

Looks fine.

On 11.04.16 16:53, Alexey Ivanov wrote:
> Hello Dmitry,
>
> Thank you very much for your patch.
>
> The fix looks good to me.
>
> I will sponsor integrating the fix into the code base as soon as code
> review is complete.
>
> Thanks,
> Alexey
>
> On 07.04.2016 15:26, Dmitry Batrak wrote:
>> Hello,
>>
>> I'd like to propose a fix for JDK-8146035. I am not a committer,
>> so I hope someone can sponsor this fix.
>> I work at Jetbrains, which has signed a company-level contributor
>> agreement,
>> so, from a legal perspective, I believe, there are no obstacles.
>>
>> My investigation shows that the issue is caused by incorrect
>> determination
>> of bitmap size, prepared for glyph rendering, so only part of glyph
>> becomes visible due to cropping. This seems to happen because
>> compatible bitmap is not selected into memory device context (DC)
>> before calling GetTextMetrics. Documentation for CreateCompatibleDC call
>> (https://msdn.microsoft.com/en-us/library/windows/desktop/dd183489%28v=vs.85%29.aspx)
>>
>> says compatible bitmap needs to be selected into DC before any drawing
>> operation.
>> Even though GetTextMetrics is not a drawing operation, it turns out
>> to be affected by selected bitmap's type too (by default a monochrome
>> bitmap
>> is selected in a memory DC). This behaviour was also mentioned in the
>> following
>> MSDN blog post comment:
>> https://blogs.msdn.microsoft.com/oldnewthing/20060614-00/?p=30873#comment-392143
>>
>>
>> The proposed fix is to select a temporary 1x1 compatible bitmap
>> into memory DC before GetTextMetrics call.
>> Here's webrev link - http://adm-12504.intellij.net/
>> I didn't create a test case, as it would require a specific font file
>> (I couldn't reproduce the issue for fonts bundled with Windows).
>>
>> Best regards,
>> Dmitry Batrak
>


-- 
Best regards, Sergey.