This is a very localized fix for the issue described in
https://bugs.openjdk.org/browse/JDK-8364049 which resulted from comparing
snapped and non-snapped values. The issue seems to happen only with fractional
scale, that is, on Windows at 125%, 150%, 175% etc. scales.
While looking at the `ToolBarSkin` code, I noticed a general pattern related to
snapping, that might cause similar issues in the tool bar skin and elsewhere.
Here is an example in `ToolBarSkin::computePrefWidth()` in L411:
if (toolbar.getOrientation() == Orientation.HORIZONTAL) {
for (Node node : toolbar.getItems()) {
if (!node.isManaged()) continue;
prefWidth += snapSizeX(node.prefWidth(-1)) + getSpacing();
}
prefWidth -= getSpacing();
} else {
the general issue, in my opinion, is that doing `prefWidth +=
snapSizeX(node.prefWidth(-1)) + getSpacing();` results in the `prefWidth` value
differ from its snapped value. In other words, whenever computation involves
snapped values, the result must be snapped as well - and that includes the case
when all the parts of the computation are snapped.
Another, related, topic is how to properly snap the values in the computation.
I would say ideally it should be done like this:
snappedResult = snap(snap(value1) .OP. snap(value2) .OP. ... snap (valueN))
It might be possible to skip the snapping of intermediary values, and only snap
the result, but one must be careful not to accumulate errors.
Getting back to the ToolBarSkin, one can see the issue on LL392, 399, 411, 417,
425, 436, 530, and so on.
I decided not to fix the snapping for the purpose of making this PR narrow in
scope with the goal to backport it to jfx25, but I did want to describe the
issue.
-------------
Commit messages:
- snap length
Changes: https://git.openjdk.org/jfx/pull/1856/files
Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1856&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8364049
Stats: 6 lines in 1 file changed: 5 ins; 0 del; 1 mod
Patch: https://git.openjdk.org/jfx/pull/1856.diff
Fetch: git fetch https://git.openjdk.org/jfx.git pull/1856/head:pull/1856
PR: https://git.openjdk.org/jfx/pull/1856
