[Mapguide-trac] [mapguide-trac] #743: AGG Renderer does not properly handle transparency for non-PNG image formats

[MapGuide Open Source]

#743: AGG Renderer does not properly handle transparency for non-PNG image
formats
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   Reporter:  gingerbbm          |       Owner:       
       Type:  defect             |      Status:  new  
   Priority:  medium             |   Milestone:  2.4  
  Component:  Rendering Service  |     Version:  2.2.0
   Severity:  major              |    Keywords:       
External_id:                     |  
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Comment(by bscott):

 Hi jackie,
 This patch only works if the resulting palette_scaling_maxval is 255.
 If the palette_scaling_maxval is lower than 255 we have to scale down all
 the map palette colors so the resulting png palette will be remap
 correctly.
   palette[i].a = (c.alpha() * (palette_scaling_maxval) + (255) / 2 ) /
 (255);
   palette[i].r = (c.red() * (palette_scaling_maxval) + (255) / 2 ) /
 (255);
   palette[i].g = (c.green() * (palette_scaling_maxval) + (255) / 2 ) /
 (255);
   palette[i].b = (c.blue() * (palette_scaling_maxval) + (255) / 2 ) /
 (255);

 We end up with a palette_scaling_maxval < 255 when we have a lot of colors
 in the map. Having a aerial picture in the background produce that effect
 all the times.

 Bruno

-- 
Ticket URL: <http://trac.osgeo.org/mapguide/ticket/743#comment:16>
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