On Sun, 21 Dec 2025 10:30:50 GMT, Cormac Redmond <[email protected]> wrote:
>> modules/javafx.controls/src/main/java/javafx/scene/control/skin/ToolBarSkin.java
>> line 706:
>>
>>> 704: // Use a small epsilon (1e-9 / 0.000000001) to tolerate
>>> floating-point rounding error when comparing
>>> 705: // doubles. E.g. 117.60000000000001 should be regarded as
>>> equal to 117.6.
>>> 706: if (x - length > 1e-9) {
>>
>> We don't really use tolerances like this in the UI code; instead the problem
>> is almost always because some floating point operations were done, but the
>> result wasn't (re)snapped.
>>
>> In the code above I see that `x` is modified without re-snapping. I think a
>> `snapPositionX/Y` should be applied on `x`, something like this:
>>
>> if (node.isManaged()) {
>> if (getSkinnable().getOrientation() == Orientation.VERTICAL)
>> {
>> x += snapPositionY(snapSizeY(node.prefHeight(-1)) +
>> getSpacing());
>> } else {
>> x += snapPositionX(snapSizeX(node.prefWidth(-1)) +
>> getSpacing());
>> }
>> }
>
> Thanks @hjohn.
>
> The problem here is caused by the repeated operations on x itself (+=), not
> the added getSpacing(), so the bug _still_ happens with the above (although,
> I'm sure getSpacing() could be a causing factor also if the value was
> something particular; in my case I haven't noticed it so so far).
>
> Anyway, this minor change fixes it and I think is in the spirit of your
> suggestion:
>
>
> if (node.isManaged()) {
> if (getSkinnable().getOrientation() == Orientation.VERTICAL) {
> x = snapPositionY(x + snapSizeY(node.prefHeight(-1)) + getSpacing());
> } else {
> x = snapPositionX(x + snapSizeX(node.prefWidth(-1)) + getSpacing());
> }
> }
>
>
> Pushed now...
Ah yes, you are right, I skipped over the `+=` operation; indeed it also needs
snapping. It is simply the reality that even when values are already snapped,
adding two snapped values together can still introduce a rounding error that
must be resnapped.
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PR Review Comment: https://git.openjdk.org/jfx/pull/2016#discussion_r2637817273
