RFR: JDK-8314215 Trailing Spaces before Line Breaks Affect the Center Alignment of Text [v15]

[Karthik P K]

On Sat, 10 Feb 2024 17:24:17 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:

>> There are a number of tickets open related to text rendering:
>> 
>> https://bugs.openjdk.org/browse/JDK-8314215
>> 
>> https://bugs.openjdk.org/browse/JDK-8145496
>> 
>> https://bugs.openjdk.org/browse/JDK-8129014
>> 
>> They have in common that wrapped text is taking the trailing spaces on each wrapped line into account when calculating where to wrap.  This looks okay for text that is left aligned (as the spaces will be trailing the lines and generally aren't a problem, but looks weird with CENTER and RIGHT alignments.  Even with LEFT alignment there are artifacts of this behavior, where a line like `AAA  BBB  CCC` (note the **double** spaces) gets split up into `AAA  `, `BBB  ` and `CCC`, but if space reduces further, it will wrap **too** early because the space is taken into account (ie. `AAA` may still have fit just fine, but `AAA  ` doesn't, so the engine wraps it to `AA` + `A  ` or something).
>> 
>> The fix for this is two fold; first the individual lines of text should not include any trailing spaces into their widths; second, the code that is taking the trailing space into account when wrapping should ignore all trailing spaces (currently it is ignoring all but one trailing space).  With these two fixes, the layout in LEFT/CENTER/RIGHT alignments all look great, and there is no more early wrapping due to a space being taking into account while the actual text still would have fit (this is annoying in tight layouts, where a line can be wrapped early even though it looks like it would have fit).
>> 
>> If it were that simple, we'd be done, but there may be another issue here that needs solving: wrapped aligned TextArea's.
>> 
>> TextArea don't directly support text alignment (via a setTextAlignment method like Label) but you can change it via CSS.
>> 
>> For Left alignment + wrapping, TextArea will ignore any spaces typed before a line that was wrapped.  In other words, you can type spaces as much as you want, and they won't show up and the cursor won't move.  The spaces are all getting appended to the previous line.  When you cursor through these spaces, the cursor can be rendered out of the control's bounds.  To illustrate, if you have the text `AAA                 BBB CCC`, and the text gets wrapped to `AAA`, `BBB`, `CCC`, typing spaces before `BBB` will not show up.  If you cursor back, the cursor may be outside the control bounds because so many spaces are trailing `AAA`.
>> 
>> The above behavior has NOT changed, is pretty standard for wrapped text controls,...
>
> John Hendrikx has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Change test to use the more common Arial font and add assumptions

I ran the tests in my Mac system with macOS 14.3 and found 2 tests are failing with following error:


TextLayoutTest > caseTest(Case) > test.com.sun.javafx.text.TextLayoutTest.caseTest(Case)[10] FAILED
    org.opentest4j.AssertionFailedError: left aligned rich text (spans): line 0 for Parameters[text=The quick brown लोमड़ी jumps over the lazy कुत्ता, wrapWidth=160.0, lineWidths=[158.1914, 93.134766]] ==> expected: <RectBounds { minX:0.0, minY:-10.863281, maxX:158.1914, maxY:2.9355469} (w:158.1914, h:13.798828)> but was: <RectBounds { minX:0.0, minY:-10.863281, maxX:155.3047, maxY:2.9355469} (w:155.3047, h:13.798828)>
        at app//org.junit.jupiter.api.AssertionUtils.fail(AssertionUtils.java:55)
        at app//org.junit.jupiter.api.AssertionUtils.failNotEqual(AssertionUtils.java:62)
        at app//org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:182)
        at app//org.junit.jupiter.api.Assertions.assertEquals(Assertions.java:1152)
        at app//test.com.sun.javafx.text.TextLayoutTest.caseTest(TextLayoutTest.java:501)

TextLayoutTest > caseTest(Case) > test.com.sun.javafx.text.TextLayoutTest.caseTest(Case)[11] FAILED
    org.opentest4j.AssertionFailedError: left aligned rich text (spans): line 0 for Parameters[text=The quick brown लोमड़ी jumps           over the lazy कुत्ता, wrapWidth=160.0, lineWidths=[158.1914, 93.134766]] ==> expected: <RectBounds { minX:0.0, minY:-10.863281, maxX:158.1914, maxY:2.9355469} (w:158.1914, h:13.798828)> but was: <RectBounds { minX:0.0, minY:-10.863281, maxX:155.3047, maxY:2.9355469} (w:155.3047, h:13.798828)>
        at app//org.junit.jupiter.api.AssertionUtils.fail(AssertionUtils.java:55)
        at app//org.junit.jupiter.api.AssertionUtils.failNotEqual(AssertionUtils.java:62)
        at app//org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:182)
        at app//org.junit.jupiter.api.Assertions.assertEquals(Assertions.java:1152)
        at app//test.com.sun.javafx.text.TextLayoutTest.caseTest(TextLayoutTest.java:501)

TextLayoutTest > fixedComplexTestsToEnsureNoFurtherRegressions() SKIPPED

TextLayoutTest > complexTestsThatAreBrokenSince2013() SKIPPED


The failing tests are SOFT_WRAP_WITH_COMPLEX_TEXT and SOFT_WRAP_WITH_COMPLEX_TEXT_AND_EXTRA_SPACE.

Added a minor comment inline as well.

modules/javafx.graphics/src/main/java/com/sun/javafx/text/PrismTextLayout.java line 1228:

> 1226:      *
> 1227:      * Text effects have no effect on the alignment, and so with underlining on
> 1228:      * the right right aligned text would look like:

Minor: "right" is repeated

-------------

PR Review: https://git.openjdk.org/jfx/pull/1236#pullrequestreview-1874624074
PR Review Comment: https://git.openjdk.org/jfx/pull/1236#discussion_r1485798441