[gdal-dev] Accessing OGRStyleTable

[Geo Aspects Development]

FWIW, here are the code fragments I added (to my copy of GDAL 1.4.0),  
though I have subsequently changed my strategy and don't use it any  
longer. This makes it possible to use the styles in a GUI, where you  
can list available styles and have the user select one.

The DataSource/Layer/Feature hierarchy would definitely be useful (to  
me!) But, long-term, wouldn't a more standards-based system (including  
GDAL and OGR) like SLD be a better idea?

regards
Tim



*******************************************************************************************************



In ogrfeaturestyle.cpp:

/*  
= 
= 
======================================================================  
*/
/*  
OGRStyleMgr 
                                                               */
/*  
= 
= 
======================================================================  
*/

...

/ 
****************************************************************************/
/*      const char  
**OGRStyleMgr::GetStyleCount()                           */
/ 
*                                                                          */
/ 
****************************************************************************/
int OGRStyleMgr::GetStyleCount()
{
     if (m_poDataSetStyleTable)
     {
         return  m_poDataSetStyleTable->Count();
     }
     return NULL;
}

/ 
****************************************************************************/
/*      const char  
**OGRStyleMgr::GetStyleNames()                           */
/ 
*                                                                          */
/ 
****************************************************************************/
char **OGRStyleMgr::GetStyleNames()
{
     if (m_poDataSetStyleTable)
     {
         return  m_poDataSetStyleTable->GetStyleNames();
     }
     return NULL;
}

...

/*  
= 
= 
======================================================================  
*/
/*                 
OGRStyleTable                                             */
/*     Object Used to manage and store a  
styletable                         */
/*  
= 
= 
======================================================================  
*/

...

/ 
****************************************************************************/
/*             int  
OGRStyleTable::Count()                                   */
/ 
*                                                                          */
/*   return the number of styles in the table otherwise return  
-1           */
/ 
****************************************************************************/
int OGRStyleTable::Count()
{
     return (m_papszStyleTable == NULL) ? -1 :  
CSLCount(m_papszStyleTable);
}

/ 
****************************************************************************/
/*             int  
OGRStyleTable::GetStyleNames()                           */
/ 
*                                                                          */
/*   return a index of the style in the table otherwise return  
-1           */
/ 
****************************************************************************/
char **OGRStyleTable::GetStyleNames()
{
     static char **pszNameList = NULL;
     const char *pszName = NULL;
     const char *pszStyleStringBegin = NULL;
     char *pszTmp;

     if (pszNameList)
         CSLDestroy(pszNameList);

     pszNameList = NULL;
     for (int i=0; i<Count(); i++)
     {
         pszStyleStringBegin = strstr(m_papszStyleTable[i],":");

         if (pszStyleStringBegin)
         {
             pszName = CPLStrdup(m_papszStyleTable[i]);
             pszTmp = strstr(pszName,":");
             if (pszTmp)
             {
                 pszTmp[0] = '\0';
                 pszNameList = CSLAddString(pszNameList, pszName);
             }
         }
     }

     return pszNameList;
}

...


In ogr_featurestyle.h:

class CPL_DLL OGRStyleMgr
{
...

     int GetStyleCount();
     char **GetStyleNames();

...
};

class CPL_DLL OGRStyleTable
{
...
     int   Count();
     char **GetStyleNames();
...
};


*******************************************************************************************************




On Sep 13, 2008, at 12:14 AM, Mateusz Łoskot wrote:

> Daniel Morissette pisze:
>> Mateusz Łoskot wrote:
>>>
>>> Now I've got what's the problem.
>>> Yes, looks like this part of API is missing or for some reasons  
>>> not planned. Perhaps Daniel or Frank will explain.
>>>
>> Style tables were part of the initial design, but were never  
>> implemented for any driver as far as I know. That's why the API may  
>> still be incomplete.
>
> Daniel,
>
> Thanks for clarifying it. OGR styling stuff is still a new beast to  
> me.
>
>> OTOH, if you have implemented drivers that support style tables  
>> then you're invited to contribute tickets, patches, or perhaps a  
>> RFC describing what you consider is missing to the API to make it  
>> really useful.
>
> Yes, I think it's reasonable approach.
>
> Best regards,
> -- 
> Mateusz Loskot, http://mateusz.loskot.net
> Charter Member of OSGeo, http://osgeo.org
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