On Mon, 30 Mar 2026 17:12:14 GMT, Jeremy Wood <[email protected]> wrote:
>> Prasanta Sadhukhan has updated the pull request incrementally with one >> additional commit since the last revision: >> >> Expose API in ScrollBarUI > > I don't know the original ticket author's intent, but I can think of a few > use cases where this feature is helpful and extending BasicScrollBarUI is > actually a nonstarter. > > For ex: > A few years ago I wanted to create a tooltip-like control for sliders. The > finished result resembles: > > https://github.com/user-attachments/assets/76dc92f9-e5f3-4b8e-a32c-ff70e8407928 > > This was very hard/hacky, because the thumb rect was not publicly accessible. > (I ended up calling `slider.paint(g)` with a custom Graphics2D that recorded > paint instructions to tease out where the thumb was being painted.) > > In this case I wanted to preserve the existing L&F (either AquaSliderUI or > WindowsSliderUI), so creating a new subclass of a BasicSliderUI wouldn't work. > > The same basic idea could apply to scrollbars: I might want to show a tooltip > that points to the scrollbar thumb. Maybe as you scroll it shows some > identifying information about what section/chapter that portion relates to. > > Or I could create a subclass of JScrollBar that preserves the L&F's default > SliderUI, but the subclass decorates it. Similar to how IntelliJ shows > stripes in the scrollbar: > <img width="937" height="268" alt="image" > src="https://github.com/user-attachments/assets/b2e08b64-c4f7-40a8-b931-648b23f78f97"; > /> > > Again: I want to preserve the L&F's SliderUI for a native-looking experience, > so subclassing BasicSliderUI is problematic. > > (Admittedly: scrollbars are a little trickier than sliders because > AquaScrollBarUI does NOT extend BasicScrollBarUI. WindowsScrollBarUI does...) > > My point is: making these methods public may be useful in cases where > extending BasicScrollBarUI is problematic. @mickleness Would current PR help you in that scenario or do you expect more by making it public? ------------- PR Comment: https://git.openjdk.org/jdk/pull/30209#issuecomment-4159344885
