`Region.layoutInArea()` calls `Region.boundedNodeSizeWithBias()`, which derives
the dependent value from a potentially unsnapped value, after which
`layoutInArea()` assigns a potentially different, snapped value to the child.
This is wrong, because the dependent value is effectively computed against a
value that might not be assigned to the child.
For a horizontally biased child, the current sequence is effectively:
double rawWidth = boundedSize(...);
double rawHeight = boundedSize(
child.minHeight(rawWidth),
... child.prefHeight(rawWidth) ...,
child.maxHeight(rawWidth));
child.resize(
snapSize(rawWidth),
snapSize(rawHeight));
The correct sequence would be:
double width = snapSize(boundedSize(...));
double height = snapSize(boundedSize(
child.minHeight(width),
... child.prefHeight(width) ...,
child.maxHeight(width)));
child.resize(width, height);
This snapping bug can only be observed when all of the following conditions are
met:
1. pixel snapping is enabled
2. the child is resizable and has a horizontal or vertical content bias
3. the bounded primary dimension is not already correctly snapped
4. the dependent size constraints change between the raw and snapped primary
dimensions
This came out of the "snapping rules" I've compiled for PR #2260, specifically
the rule [Use the same snapped dependent dimension for measurement and
layout](https://github.com/openjdk/jfx/pull/2260/changes#diff-3fe4ab83269e3ae0ec167ebe622893aff218168e7cab666e5a64c99e6dfbfd4fR464).
---------
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-------------
Commit messages:
- fix
- tests
Changes: https://git.openjdk.org/jfx/pull/2261/files
Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=2261&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8390440
Stats: 252 lines in 6 files changed: 203 ins; 10 del; 39 mod
Patch: https://git.openjdk.org/jfx/pull/2261.diff
Fetch: git fetch https://git.openjdk.org/jfx.git pull/2261/head:pull/2261
PR: https://git.openjdk.org/jfx/pull/2261
