> Ensures proper propagation of layout flags when using `forceParentLayout =
> true`.
>
> This was the root cause of issue #1874
>
> ### Note
>
> Apparently it is still quite easy to mess up the layout flags. Basically, the
> layout flag tracked by Parent should always either be `CLEAN` for any scene
> graph branch, or `!CLEAN` + a layout pulse is scheduled on the corresponding
> `Scene`.
>
> However, with careful use of the public API `requestLayout` one can get these
> flags in a bad state still:
>
> Let's say I have a branch `A (root node under Scene) -> B -> C`, **and** a
> layout is in progress, **and** we're currently in the `layoutChildren` method
> of `C`. The flag `performingLayout` will be `true` for all nodes in the
> branch `A` -> `B` -> `C`. The `layout` method will set the layout flag to
> `CLEAN` as its first action, so when we're at `C::layoutChildren`, all flags
> have been reset to `CLEAN` already. See the `Parent::layout` method for how
> all this works.
>
> Now, to mess up the flags, all you need to do is call `requestLayout` on `B`
> or `C` from the `layoutChildren` of `C` (or indirectly by changing something
> and something is listening to this and schedules a layout on something
> somewhere in this branch); note that `requestLayout` is not documented to be
> illegal to call during layout, and some classes in FX will do so
> (ScrollPaneSkin, NumberAxis, etc..) risking the flags getting in a bad
> state... -- usually you get away with this, as there are many ways that
> layout is triggered, and eventually the flags will get overwritten and reset
> to a consistent state.
>
> The bad state occurs because this code path is followed (all code from
> `Parent`):
>
> public void requestLayout() {
> clearSizeCache();
> markDirtyLayout(false, forceParentLayout);
> }
>
> Calls to `markDirtyLayout(false, false)`:
>
> private void markDirtyLayout(boolean local, boolean forceParentLayout) {
> setLayoutFlag(LayoutFlags.NEEDS_LAYOUT);
> if (local || layoutRoot) {
> if (sceneRoot) {
> Toolkit.getToolkit().requestNextPulse();
> if (getSubScene() != null) {
> getSubScene().setDirtyLayout(this);
> }
> } else {
> markDirtyLayoutBranch();
> }
> } else {
> requestParentLayout(forceParentLayout);
> }
> }
>
> Before going into the `else` (as none of the nodes is a layout root, and
> `local` was set to `false`) it will do
> **setLayoutFlag(LayoutFlags.NEEDS_LAYOUT)** ...
John Hendrikx has updated the pull request incrementally with one additional
commit since the last revision:
Add test case
-------------
Changes:
- all: https://git.openjdk.org/jfx/pull/1879/files
- new: https://git.openjdk.org/jfx/pull/1879/files/59b5f287..4a6462fd
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jfx&pr=1879&range=01
- incr: https://webrevs.openjdk.org/?repo=jfx&pr=1879&range=00-01
Stats: 93 lines in 2 files changed: 93 ins; 0 del; 0 mod
Patch: https://git.openjdk.org/jfx/pull/1879.diff
Fetch: git fetch https://git.openjdk.org/jfx.git pull/1879/head:pull/1879
PR: https://git.openjdk.org/jfx/pull/1879
