On Sun, 20 Oct 2024 21:55:54 GMT, John Hendrikx <jhendr...@openjdk.org> wrote:
>> John Hendrikx has updated the pull request incrementally with one additional >> commit since the last revision: >> >> Add information about how ScrollPane acts on key presses. > > For users to get back to old behavior, some calculations need to be done as > `ScrollPane` doesn't offer any helpful programmatic methods to scroll the > pane (which is perhaps something that could be addressed in a separate issue, > I filed https://bugs.openjdk.org/browse/JDK-8342654). > > The most useful helper is one that scroll by a fraction, shown below: > > static void scrollByFraction(ScrollPane scrollPane, double x, double y) { > Node content = scrollPane.getContent(); > > if (content == null) { > return; > } > > Bounds viewportBounds = scrollPane.getViewportBounds(); > Bounds layoutBounds = content.getLayoutBounds(); > > if (x != 0) { > double visibleFraction = viewportBounds.getWidth() / > layoutBounds.getWidth(); > double range = scrollPane.getHmax() - scrollPane.getHmin(); > double scrollFactor = range * visibleFraction / (1 - > visibleFraction); > > scrollPane.setHvalue(scrollPane.getHvalue() + x * scrollFactor); > } > > if (y != 0) { > double visibleFraction = viewportBounds.getHeight() / > layoutBounds.getHeight(); > double range = scrollPane.getVmax() - scrollPane.getVmin(); > double scrollFactor = range * visibleFraction / (1 - > visibleFraction); > > scrollPane.setVvalue(scrollPane.getVvalue() + y * scrollFactor); > } > } > > Then to get something similar to the old behavior back is to install an event > handler: > > scrollPane.addEventHandler(KeyEvent.KEY_PRESSED, e -> { > double x = 0; > double y = 0; > > switch(e.getCode()) { > case KeyCode.LEFT -> x = -0.1; > case KeyCode.RIGHT -> x = 0.1; > case KeyCode.UP -> y = -0.1; > case KeyCode.DOWN -> y = 0.1; > case KeyCode.PAGE_UP -> y = -0.9; > case KeyCode.PAGE_DOWN -> y = 0.9; > case KeyCode.SPACE -> y = 0.9; > case KeyCode.HOME -> x = y = Double.NEGATIVE_INFINITY; > case KeyCode.END -> x = y = Double.POSITIVE_INFINITY; > default -> {} > } > > if (x != 0 || y != 0) { > scrollByFraction(scrollPane, x, y); > e.consume(); > } > }); > > Note that this doesn't exactly replicate the old behavior, but is probably a > much more useful implementation than what was provided as standard before. @hjohn In case you missed the notification, this is ready to integrate. ------------- PR Comment: https://git.openjdk.org/jfx/pull/1582#issuecomment-2448697737
