[QGIS-trac] Re: [Quantum GIS] #1945: [Vista] Qgis crashes removing GRASS raster layer from map canvas

[Quantum GIS]

#1945: [Vista] Qgis crashes removing GRASS raster layer from map canvas
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        Reporter:  juanelz                                    |         Owner:  rugginoso    
            Type:  bug                                        |        Status:  closed       
        Priority:  critical: causes crash or data corruption  |     Milestone:  Version 1.5.0
       Component:  GRASS                                      |       Version:  HEAD         
      Resolution:  fixed                                      |      Keywords:  GRASS rasters
Platform_version:  Vista                                      |      Platform:  Windows      
        Must_fix:  Yes                                        |   Status_info:  0            
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Comment (by rblazek):

 Replying to [comment:26 lutra]:
 > Screenshot-1.png

 Nice, unfortunately i works for me both on ubuntu and xp.qgis.d.rast reads
 the raster row by row and for each cell prints to output BGRA (4 bytes) or
 ARGB (for big endian). QGIS reads everything and sets the QImage data with
 memcpy. It is a bit tricky, I used that way to get higher performance and
 well, also to enjoy it and get such a nice images. I could use idiotproof
 setPixel() but it would be too easy.

 Does it displays always with the same colors or they are random?

 You can tests qgis.d.rast directly from GRASS shell to see if the output
 is correct specifying window=xmin,ymin,xmax,ymax,ncols,nrows and pass it
 either to od, example:
 {{{
 /home/radim/apps/share/qgis/grass/modules/qgis.d.rast map=pok at demo
 window=-6.85857e+06,2.25129e+06,3.172e+06,7.79079e+06,10,10 | od -w40 -tx4
 }}}
 unfortunately support for bgra in imagemagic is too recent and I dont know
 how to change byte order from command line.

 Then you can replace the qgis.d.rast with a script like this
 {{{
 #!/usr/bin/perl
 for($i=0;$i<100000;$i=$i+1){
   printf "%c%c%c%c", 255, 0, 0, 255;
 }
 }}}
 to see if QGIS takes colors correctly.

 Size of integer and byte order could also be involved but I don't see how,
 I have checked that QImage is realy using uchar and the image size is
 correct.

-- 
Ticket URL: <https://trac.osgeo.org/qgis/ticket/1945#comment:27>
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