On Wed, 6 Aug 2025 15:49:19 GMT, Phil Race <p...@openjdk.org> wrote: > > > Isn't this just a bug ? I get zero from the test whenever "-1" is the > > > direction - meaning scroll up - even if I use something like > > > https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/javax/swing/JList.html#getScrollableUnitIncrement(java.awt.Rectangle,int,int) > > > > > > If the `visibleRect` Rectangle points to the 1st row or row 0 and we are > > scrolling up i.e -1 direction there is no more space to scroll up so > > `getScrollableUnitIncrement` returns 0. If we modify the testcase to have > > `Rectangle cell = list.getCellBounds(data.length-1, data.length-1);` > > instead of `list.getCellBounds(0, 0);` to point to last cell, it returns > > positive number for -1 direction too > > As I wrote it returns zero for me no matter what. Eg if I use Rectangle cell > = list.getCellBounds(1, 2); > > so why is that ?
That is because of test does wrap layout via this line `list.setLayoutOrientation(JList.HORIZONTAL_WRAP);` whereby 1st and 2nd cell are in the same row 0 and then it wraps to next line where it displays 3rd and 4th cell so if we call `list.getCellBounds(1, 2)` it will still result in pointing to 1st row or row 0 but if we call getCellBounds(2, 3) it will have positive number and not 0 as then it will select the 2nd row because cell 3 is in 2nd row. If we remove `list.setLayoutOrientation(JList.HORIZONTAL_WRAP);` then it will layout each cell in separate line so we will get positive number for `list.getCellBounds(1, 2)` too as then it will select the 2nd row and not 1st row for which scrolling is not required. ------------- PR Comment: https://git.openjdk.org/jdk/pull/26500#issuecomment-3162394026
