On Fri, 9 Feb 2024 12:56:15 GMT, Kevin Rushforth <k...@openjdk.org> wrote:
> JavaFX LCD text rendering (aka sub-pixel antialiasing) uses a pixel shader > and alpha blending. The alpha channel is used is ways that interfere with its > use for transparency. The existing logic checks that the current blend > equation is SRC_OVER and that the surface is opaque, and that we are > rendering using a Paint of type Color. It fails to check that the text color > is opaque. When it isn't, the resulting alpha value is not preserved, even in > the middle of the filled portion of the text, resulting in a visually > noticeable difference in color. > >  > > The solution is to add the missing check for alpha == 1 to the test that > checks whether we can use LCD text rendering. I note that Java2D falls back > to gray scale when the text color is transparent for a similar reason. > > I added a robot test that checks the color in the middle of the filled > portion of a rendered text character and also checks that we use LCD for > opaque colors and GRAY scale for transparent colors. This pull request has now been integrated. Changeset: a39732a3 Author: Kevin Rushforth <k...@openjdk.org> URL: https://git.openjdk.org/jfx/commit/a39732a3c66e7168f3a9be84743eb52d4fd0043c Stats: 276 lines in 3 files changed: 274 ins; 0 del; 2 mod 8311492: FontSmoothingType LCD produces wrong color when transparency is used Reviewed-by: jhendrikx, angorya, prr ------------- PR: https://git.openjdk.org/jfx/pull/1361
