Font rendering issue on macOS - cut off characters

[Philip Race]

On 5/24/20, 3:25 PM, Rob Nikander wrote:
>
>> On May 24, 2020, at 4:47 PM, Philip Race<philip.race at oracle.com>  wrote:
>>
>> Should I understand 10.15.4 is the only version of macOS you've tried ?
>> Not some earlier version of Catalina for example ?
> Yes, it’s all I’ve tried.
>
>> As to the cause ? I can only speculate. Rounding error in the bitmap size ?
>> Being over-written by the next glyph (d) - possibly due to some rounding issue again ?
>>
>> If you display just "ao" does it all render ?
>> That might point to being over-written.
> Yes, the “d” appears to be overwriting it. I put the following in a Label: "o od o od o od, o od o od o od”. The isolated “o”s are fine, but 4 of 6 of the “o”s next to the “d”s are shaved off.
>
> Does JavaFX have its own text rendering engine? It’s not deferring to CoreText on macOS?

core text generates all glyph image and all information about it.
But FX uses its own OpenGL code to render the provided glyphs.

>
> The text render seems to have other problems compared to native apps. There is a barely-visible color in anti-aliased pixels. It’s so faint I can barely see it, but it gives me an unpleasant feeling,

That's likely LCD sub-pixel text. Its normal to see it if you squint. 
Not new.
macOS has been moving away from it but people with non-retina displays 
have lamented its passing.

https://osxdaily.com/2018/09/26/fix-blurry-thin-fonts-text-macos-mojave/

FX still requests LCD tho'. Although it is not clear how long macOS will 
continue to provide it.

-phil.

>   like my eyes are having trouble focusing. The macOS has a utility program called Digital Color Meter, which lets you see zoomed pixels of the screen. Using that, I can see clearly see that while native black on white text is black with anti-aliased pixels appearing some shade of gray, as you’d expect; the JavaFX black-on-white text has non gray colors in the anti-aliased pixels.
>
> I thought high res screens still used anti-aliasing for text. (?) I wonder if this is a fainter problem on retina screens as well. I have no way of checking at the moment.
>
> Rob
>