[OpenJDK 2D-Dev] Pixel-perfect drawing on JPanel

[Michał Błaszak]

Hi All,

I hope this is a known problem but just in case it's not.

Trying to make an app drawing something on JPanel I noticed some annoying inaccuracies.

The attached piece of code is supposed to draw a series of lines one below the other (swapping colors are to demonstrate what's happening).
The result is presented in the following picture:
[cid:image003.jpg at 01D4985D.2FD2C670]

That means that some pixels are unreachable.

I tested it on several jdk releases. Results are:
OpenJDK Runtime Environment (build 1.8.0_40-b25): Works correctly
OpenJDK Runtime Environment (build 9+181): Wrong behavior
OpenJDK Runtime Environment 18.3 (build 10.0.2+13): Wrong behavior
OpenJDK Runtime Environment 18.9 (build 11.0.1+13): Wrong behavior

The same inaccuracies are observable when using drawRect() or fillRect().

I wanted to report is a bug but I do not know how to do it.
Thank you for looking at it.

Best regards

Michał Błaszak
Section Manager, Research & Development

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