[GRASS-dev] [GRASS GIS] #2503: wxdigit: wrong undo & redo

[GRASS GIS]

#2503: wxdigit: wrong undo & redo
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 Reporter:  mlennert     |       Owner:  grass-dev@…              
     Type:  defect       |      Status:  new                      
 Priority:  normal       |   Milestone:  7.0.0                    
Component:  wxGUI        |     Version:  svn-trunk                
 Keywords:  digitizer    |    Platform:  Unspecified              
      Cpu:  Unspecified  |  
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Comment(by mmetz):

 Replying to [comment:10 mlennert]:
 > Replying to [comment:9 mmetz]:
 > > Replying to [comment:8 mlennert]:
 > > > Replying to [comment:7 mmetz]:
 > > > > The list of updated lines as returned by the vector lib was
 incomplete. Fixed in r63349,50 (trunk, relbr70), please test.
 > > >
 > > > Still not quite:
 [http://tomahawk.ulb.ac.be/moritz/wxdigit_undo_redo4.ogv].
 > > >
 > > > If you need more explanation, I can write some, but right now I have
 to go.
 > >
 > > Got it. This bug (yet another one) should be fixed in r63364,5 (trunk
 only).
 >
 > Wow, great detective work there ! As of now I haven't been able to find
 any other bugs linked to undo/redo. This fix should be backported to
 grass7release and then I think we can close this bug for now.

 I do not fully understand 1) why the fix is needed, 2) why the fix is
 working. The GRASS vector library usually employs Copy On Write (COW) when
 a feature is modified. Sometimes a feature is modified in place,
 overwriting the previous version. The digitizer's undo/redo mechanism
 relies on COW, but the move tool seems to replace an older version of the
 feature, thus undo/redo should not work with the move tool (and maybe
 other tools, too).

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2503#comment:11>
GRASS GIS <http://grass.osgeo.org>