On Fri, 9 Feb 2024 14:29:18 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. > > Kevin Rushforth has updated the pull request incrementally with one > additional commit since the last revision: > > Address review feedback tests/system/src/test/java/test/robot/javafx/scene/TransparentLCDTest.java line 67: > 65: * > 66: * @test > 67: * @bug 8311492 for my education: what is the meaning of these tags? how are they used? tests/system/src/test/java/test/robot/javafx/scene/TransparentLCDTest.java line 81: > 79: // color, or in the middle of the text fill area, where we expect to > find > 80: // the unadjusted text color. > 81: private static final double TOLERANCE = 2.0 / 255.0; if the intent is to allow for 2 levels of difference, perhaps it should be (2.0 / 255) + 0.00001 or something tests/system/src/test/java/test/robot/javafx/scene/TransparentLCDTest.java line 190: > 188: @AfterEach > 189: public void doTeardown() { > 190: Platform.runLater(() -> { should this be Util.runAndWait() ? tests/system/src/test/java/test/robot/javafx/scene/TransparentLCDTest.java line 272: > 270: runTest(true); > 271: } > 272: extra newline? ------------- PR Review Comment: https://git.openjdk.org/jfx/pull/1361#discussion_r1484506628 PR Review Comment: https://git.openjdk.org/jfx/pull/1361#discussion_r1484509375 PR Review Comment: https://git.openjdk.org/jfx/pull/1361#discussion_r1484512177 PR Review Comment: https://git.openjdk.org/jfx/pull/1361#discussion_r1484513289
