On Wed, 5 Feb 2020 11:07:39 GMT, Ambarish Rapte <[email protected]> wrote:
> Issue: > Dragging a tab and dropping it back to it's original position causes an > incorrect reordering of tabs. Incorrect order of tabs can be observed using > arrow key traversal through tabs. > > Cause: > Below mechanism of identifying if tab header is dragged and dropped at same > position is not reliable. > When a tab is selected for dragging, the tab's layout X is stored as > `dragHeaderStartX`. > When the tab is dropped, the tab's destination layout X is saved as > `dragHeaderDestX`. > These two values are used to decide if the reordering of tabs is needed. > This is an unreliable mechanism in two cases, > > 1. When the `TabPane.TabClosingPolicy` is set to > `TabPane.TabClosingPolicy.SELECTED_TAB`, the close button icon gets added > only to the selected tab. > Each time when the tab selection is changed, the header region needs a > re-layout. When a non selected tab is chosen for dragging `dragHeaderStartX` > and `dragHeaderDestX` will always differ. > > 2. Calculation of `dragHeaderDestX` involves floating point operation. So the > computed `dragHeaderDestX` may sometimes vary by fraction than > `dragHeaderStartX`. > > Fix: > Use the index of tab header for identifying the tabs which are reordered. > Save the index when reordering begins. `dragTabHeaderStartIndex` > Save the index when tab is dropped. `dragTabHeaderIndex` > If the index are same then reordering of tabs is NOT needed. > If the index are NOT same then the tabs from `dragTabHeaderStartIndex` to > `dragTabHeaderIndex` are reordered. > > Verification: > This fix is specific to TabPane reordering. No other tests/behavior should be > affected. > Added a new system test. Looks good. ------------- Marked as reviewed by kcr (Lead). PR: https://git.openjdk.java.net/jfx/pull/106
