[Bug swing/24871] New: Poor JTree painting performance

[roman at kennke dot org]

Hi Lillian,

I notice that the painting performance of JTree breaks down when the tree has a
certain size. The reason is that the JTree is painted as a whole, regardless of
the current clip setting. This should really be improved because JTree is
nearly not usable with bigger trees. This is especially important when used
inside a JScrollPane, because when scrolling, usually only a thin line of some
pixels must be repainted, the remainder is simply copied by the JViewport
painting mechanism.

However, I think in order to achieve this, you need to rework the JTree
painting a little. At the moment the painting is performed recursivly, this
seems wrong to me. This should really be implemented in a non-recursive way.
Then we could do something like this:

int startIndex = tree.getRowForLocation(clip.x, clip.y);
int endIndex = tree.getRowForLocation(clip.x + clip.width, clip.y
+clip.height);
int current = startIndex;
while (current <= endIndex)
  // Perform painting....

I think you are most familiar with this area, so I assign the bug to you.


-- 
           Summary: Poor JTree painting performance
           Product: classpath
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: swing
        AssignedTo: langel at redhat dot com
        ReportedBy: roman at kennke dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24871