On Thu, 23 Jul 2026 10:01:06 GMT, Marius Hanl <[email protected]> wrote:
>> I uncovered a problem that has been in the CSS engine for a long time, even >> before #1076 was applied. However, #1076 made this problem more obvious >> because of a side fix that was done there: >> >> - The `BitSet` `equals` implementation was updated to NOT take the length of >> the allocated array (to store the bits in) into account for equality. As >> this array is just allocated on demand depending on what bits were set and >> reset, it should not be taken into account for equality >> >> The above bug hid problems when nodes were **supposed to** share a CSS cache >> entry, but didn't because their `BitSet`s were considered different (even >> though semantically, they were the same). >> >> With the fix in #1076, a lot more cases were sharing CSS cache entries (as >> they should) but this now exposed a bug in how `CssStyleHelper` handled the >> absence of a cached property. Basically, absence could mean two things >> before this change: >> >> - The property was not computed at all: it either didn't exist at the time >> (due to `CssMetaData` changing!) or because the property was not settable >> (because it was bound) >> - The property was computed but no styles applied to it, so no need to cache >> anything... >> >> The CSS engine always assumed the latter, which means that if for whatever >> reason the cache entry was created by a Node that had outdated `CssMetaData` >> (a Control that is yet to be skinned, or one where a CSS property was >> unsettable), the engine would assume that such a missing property was >> unstyled and can safely be reset. As entries are shared, this doesn't hold >> true for all nodes that share the same entry (if another node that shares >> the same entry has different `CssMetaData` or did not have the same property >> bound, then it may have been styled, and should not be reset!). >> >> ## Tests that confirm the problem >> >> I added 4 new test cases, for four paths that could potentially result in >> the wrong things being in the cache: >> >> - A cache entry being created for a Node that has bound properties (and is >> later shared with a different node) >> - A cache entry being created for a Node that isn't skinned yet (and so it's >> CssMetaData may change); the CSS engine simply can never assume that >> CssMetaData is stable (skins can also be changed at any time) >> - Ensuring that an exception during `applyStyle` still results in a `SKIP` >> entry in the cache >> - Ensuring that we still put a value in the cache, even if the Node can't >> use it itself directly as its value is bound (this test overlaps a b... > > Tested on multiple applications yesterday and today, all good. Also no > performance issues or anything noticeable. Agree with @Maran23 , this is an improvement and looks good. I would like to know your take on these two comments: 1. is it possible to have a more formalized approach to testing the CSS subsystem. Like, exhaustively enumerate all possible transitions and develop a test for each? 2. could relaxing the constraint on `isSettable()` API backfire somehow? And, a question for @kevinrushforth : would the `isSettable()` javadoc change require a CSR? ------------- PR Comment: https://git.openjdk.org/jfx/pull/2218#issuecomment-5092970884
