[QGIS-trac] Re: [Quantum GIS] #3222: Fast, easy and beautiful on the fly rule-based rendering of OSM maps

[Quantum GIS]

#3222: Fast, easy and beautiful on the fly rule-based rendering of OSM maps
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   Reporter:  mayeulk                           |              Owner:  wonder       
       Type:  patch                             |             Status:  new          
   Priority:  major: does not work as expected  |          Milestone:  Version 1.7.0
  Component:  Symbology                         |            Version:               
   Keywords:                                    |   Platform_version:               
   Platform:  All                               |           Must_fix:  No           
Status_info:  0                                 |  
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Comment(by mayeulk):

 I have reversed symbolForFeature() (see patch above). I also put comments
 next to 3 lines:

 {{{
 //    return mCurrentSymbol; // uncomment this out to disable
 UsingSymbolLevels

     if( !usingSymbolLevels() )    return mCurrentSymbol;// comment this
 out to disable UsingSymbolLevels

  r->setUsingSymbolLevels( usingSymbolLevels() ); // comment this out to
 disable UsingSymbolLevels
 }}}

 Disabling symbollevels will simply draw not map if symbollevel checkbox is
 checked.
 If those 3 lines are left unchanged, symbol levels work correctly (still,
 only the first matching rule provides the symbol). Rendering without
 symbol levels work as well.


 Anyway, should you  apply or not those 3 lines, the result is the same:
 rendering works nicely and is stable, but trying to turn on or off symbol
 levels generally crashes qgis:

 Checking or unchecking the "Enable symbol levels" checkbox, then clicking
 "OK" then "Apply" generally crashes qgis.

 A workaround is to disable rendering or disable the layer, open the "Layer
 Properties" Dialog, open the "Symbol Levels" dialog, switch (on or off)
 the "Enable symbol levels" box, press "OK", then press "OK", then re-
 enable rendering or re-enable the layer. In this case it seems to be
 stable. I have no idea how to change the code to avoid that crash without
 this workaround 8-(

 Mayeul

-- 
Ticket URL: <http://trac.osgeo.org/qgis/ticket/3222#comment:13>
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