If a raster source image does not have a .wld file, then we should look at any wms_extent data

[eric.sokolowsky@…]

Raster images require georegistration information, which can be given with .wld
files in the same directory as the source images.  However, when using mapserver
as a WMS server, this georegistration information can be derived from the
"wms_extent" tag in the METADATA section of the LAYER object, and the size of
the image.  The patches below to mapdrawgdal.c, mapraster.c, mapresample.c will
add this support when GDAL is used to read raster images.  The logic is, if a
.wld file cannot be found, then try the "wms_extent" tag.  If this is not found
either, then continue as before.

Index: mapdrawgdal.c
===================================================================
RCS file: /data2/cvsroot/mapserver/mapdrawgdal.c,v
retrieving revision 1.13
diff -r1.13 mapdrawgdal.c
238,239c238,255
<           GDALReadWorldFile((char *)GDALGetDescription(hDS),
<                             "wld", adfGeoTransform);
---
>     {
>         if (!GDALReadWorldFile((char *)GDALGetDescription(hDS),
>                             "wld", adfGeoTransform))
>         {
>             rectObj rect;
>             if (msOWSGetLayerExtent(map, layer, &rect) == MS_SUCCESS)
>             {
>                adfGeoTransform[0] = rect.minx;
>                adfGeoTransform[1] = (rect.maxx - rect.minx) /
>                   (double) src_xsize;
>                adfGeoTransform[2] = 0;
>                adfGeoTransform[3] = rect.maxy;
>                adfGeoTransform[4] = 0;
>                adfGeoTransform[5] = (rect.miny - rect.maxy) /
>                   (double) src_ysize;
>             }
>         }
>     }

Index: mapraster.c
===================================================================
RCS file: /data2/cvsroot/mapserver/mapraster.c,v
retrieving revision 1.106
diff -r1.106 mapraster.c
1436,1437c1436,1453
<                 GDALReadWorldFile(msBuildPath(szPath, cwd, filename),
<                                   "wld", adfGeoTransform);
---
>           {
>               if (!GDALReadWorldFile(msBuildPath(szPath, cwd, filename),
>                                   "wld", adfGeoTransform))
>               {
>                   rectObj rect;
>                   if (msOWSGetLayerExtent(map, layer, &rect) == MS_SUCCESS)
>                   {
>                       adfGeoTransform[0] = rect.minx;
>                       adfGeoTransform[1] = (rect.maxx - rect.minx) /
>                           (double) GDALGetRasterXSize(hDS);
>                       adfGeoTransform[2] = 0;
>                       adfGeoTransform[3] = rect.maxy;
>                       adfGeoTransform[4] = 0;
>                       adfGeoTransform[5] = (rect.miny - rect.maxy) /
>                           (double) GDALGetRasterYSize(hDS);
>                   }
>               }
>           }

Index: mapresample.c
===================================================================
RCS file: /data2/cvsroot/mapserver/mapresample.c,v
retrieving revision 1.42
diff -r1.42 mapresample.c
850a851,853
>     nSrcXSize = GDALGetRasterXSize( hDS );
>     nSrcYSize = GDALGetRasterYSize( hDS );
>
861c864,879
<         GDALReadWorldFile(GDALGetDescription(hDS), "wld", adfSrcGeoTransform);---
>       if (!GDALReadWorldFile(GDALGetDescription(hDS), "wld",
>           adfSrcGeoTransform))
>       {
>           rectObj rect;
>           if (msOWSGetLayerExtent(map, layer, &rect) == MS_SUCCESS)
>           {
>               adfSrcGeoTransform[0] = rect.minx;
>               adfSrcGeoTransform[1] = (rect.maxx - rect.minx) /
>                   (double) nSrcXSize;
>               adfSrcGeoTransform[2] = 0;
>               adfSrcGeoTransform[3] = rect.maxy;
>               adfSrcGeoTransform[4] = 0;
>               adfSrcGeoTransform[5] = (rect.miny - rect.maxy) /
>                   (double) nSrcYSize;
>           }
>       }
863,864d880
<     nSrcXSize = GDALGetRasterXSize( hDS );
<     nSrcYSize = GDALGetRasterYSize( hDS );

[fwarmerdam]

I took your logic, and a few other bits and pieces and created
msGetGDALGeoTransform() in mapdrawgdal.c and now call that from the 3 places
identified.  I believe the same effect is accomplished, with greater 
consistency on a few other issues.  

I also added a special test for the OWS extents in msautotest/gdal/ows_extent.map
within the automatic test suite. 

Thanks!

[jmckenna@…]

added a note on this in the wms_server_howto