RFR: 6510914: JScrollBar.getMinimumSize() breaks the contract of JComponent.setMinimumSize() [v6]

[Alexey Ivanov]

On Mon, 6 Nov 2023 06:22:33 GMT, Prasanta Sadhukhan <psadhukhan at openjdk.org> wrote:

>> javadoc contract for JComponent.setMinimumSize(Dimension) states:
>> 
>> "Sets the minimum size of this component to a constant value. Subsequent calls to getMinimumSize will always return this value..."
>> 
>> However, JScrollBar overrides getMinimumSize() and breaks this contract - it always returns a minimum size derived from the preferred size even if you have previously called setMinimumSize()
>> 
>> Fix is made to check if mnimumSize is set and if so, honour it..
>
> Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Reinstate setEnabled

> > But I do have another suggestion that actually might have been the best thing to do all those years ago. Keep the over-ride as the default behaviour, and document it better. But if the app calls setMaximumSize or setMinimumSize() then honour it like you are supposed to. I suspect very few apps actually call these since they are complete no-ops today. If we do that, then yes, you'll still see differences if you do call those APIs and forgot about it because it didn't make a difference.
> 
> Do you mean this way https://openjdk.github.io/cr/?repo=jdk&pr=15325&range=01#sdiff-0-src/java.desktop/share/classes/javax/swing/JScrollBar.java what I had done in the initial iteration? I guess that change will still show the above problem during frame resize, where scrollbars are not rigid

This is how I understand Phil's comment.

> I guess that change will still show the above problem during frame resize, where scrollbars are not rigid

Yes, it will, this is why update to the javadoc of `getMinimumSize` and `getMaximumSize` is required—to document their default behaviour and the fallback to returning the set sizes as per `JComponent` specification of `setMinimumSize` and `setMaximumSize`.

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PR Comment: https://git.openjdk.org/jdk/pull/15325#issuecomment-1819012794