RFR: 8211294: [windows] TextArea content is blurry with 125% scaling

[Kevin Rushforth]

On Sat, 5 Dec 2020 11:33:46 GMT, Frederic Thevenet <fthevenet at openjdk.org> wrote:

>> I hope to take a look at this, along with other pending reviews, early next week. There is still some time to get this into 16 if we can find a robust fix.
>
>> 
>> 
>> I hope to take a look at this, along with other pending reviews, early next week. There is still some time to get this into 16 if we can find a robust fix.
> 
> That's great news, thanks!

I spent a bit of time looking at this. I think the root cause of the problem is in ScrollPane itself. It is attempting to layout its children by doing a snap to pixel (meaning that the final scaled translation should be an integer value), but it is failing to do so. This is mostly not a problem when caching is disabled, since our text rendering does sub-pixel antialiasing that looks crisp even at non-integer boundaries. However, translating an already-rendered image by a non-integer boundary will cause the blurriness we are seeing. There is another issue with the Y translation which isn't 0 even when  not using a ScrollPane.

I'll continue looking at this in the coming week.

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PR: https://git.openjdk.java.net/jfx/pull/308