[Bug swing/26414] New: inefficient selection painting

[thebohemian at gmx dot net]

When a selection is *changed* the current defaulthighlighter marks the combined
area of the old and the new selection as damaged. This is bad as the amount of
drawing operation linearly scales with the amount of selected text.

There must be some clever algorithm that can calculate the deltas: the areas
that have to be painted and the area that has to be cleared.

Applying this should lower the amount of drawing operations.

The clues:

n - new
o - old
p - paint
c - clear

nnnnnnnn
    oooooooooo
pppp    cccccc

(that one happens alot! eg when selecting with the mouse)
nnnnnnnnnnnnnn
 ooooooooooooo
p

(same with this one)
nnnnnnnnnnnnnn
oooooooooooo
            pp

nnnnn
         ooooo
ppppp    ccccc

nnnnnnnnnnnnnn
  oooooooo
pp        pppp

    nnnnnnn
pppppppppppppp
cccc       ccc

   nnnnnnnnnnn
oooooo
ccc   pppppppp

I think I have it. :)


-- 
           Summary: inefficient selection painting
           Product: classpath
           Version: 0.21
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: swing
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: thebohemian at gmx dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26414