[gdal-dev] Usage of styles in C API
Chaitanya kumar CH
chaitanya.ch at gmail.com
Sun Aug 3 04:52:27 PDT 2014
With Nik available for testing, I can update the style table definition.
On 3 Aug 2014 16:39, "Even Rouault" <even.rouault at mines-paris.org> wrote:
> Le dimanche 03 août 2014 12:55:44, Nik Sands a écrit :
> > Thanks Even,
> >
> > Yes, deleting the spaces seems to get it working correctly. Is this
> > expected? Are spaces an illegal part of a style string?
> >
> > The documentation includes spaces in the example .ofs file there, so I
> had
> > copied that format when creating my text file.
>
> I guess we should be tolerant with spaces. The grammar of the style string
> itself seems to indicate that no spaces are expected in the style_def
> itself.
> But the format of the .ofs file is not really well defined.
>
> Perhaps Chaitanya will take care of that. See previous email.
>
> >
> > Cheers,
> > Nik.
> >
> > On 3 Aug 2014, at 8:45 pm, Even Rouault <even.rouault at mines-paris.org>
> wrote:
> > > Le dimanche 03 août 2014 12:41:56, Nik Sands a écrit :
> > >> Sorry, my mistake... I had my logging in the wrong place. styleChars
> is
> > >>
> > >> actually of the form (including the leading space):
> > >> ' PEN(c:#A08080,w:2pt); LABEL(c:#000000,s:18pt,t:{title})'
> > >
> > > The issue must be the leading space before PEN, and potentially LABEL
> > > too.
> > >
> > >> On 3 Aug 2014, at 8:35 pm, Nik Sands <nixanz at nixanz.com> wrote:
> > >>> On one of the iterations through this code, styleChars is:
> > >>> 'vegetation_low: BRUSH(fc:#A0F0A0); LABEL(c:#004000,s:18pt,t:
> {title})'
> > >>>
> > >>> So perhaps the inclusion of the style name is the problem?
> > >>>
> > >>> This was read into a style table from a text file using
> > >>> 'OGR_STBL_LoadStyleTable()'. I had assumed that a similar format to
> > >>> .ofs was suitable. If this is not the case, how should I read a
> style
> > >>> table from a text file in such a way that I can distinguish the
> various
> > >>> styles by name?
> > >>>
> > >>> In guess my more general question is: What is the correct way to
> read
> > >>> styles from an arbitrary text file into a style table, and then use a
> > >>> style manager to get the various parts/tools?
> > >>>
> > >>> On 3 Aug 2014, at 8:26 pm, Even Rouault <
> even.rouault at mines-paris.org>
> > >
> > > wrote:
> > >>>> Le dimanche 03 août 2014 12:11:42, Nik Sands a écrit :
> > >>>>> I'm just starting out using the styles features of OGR (using the C
> > >>>>> API) but at struggling with a few elements of it.
> > >>>>>
> > >>>>> My code (copied below) fails to get any OGRStyleToolH. Ie, the
> "if (
> > >>>>> tool )" block never gets run, because 'tool' is always NULL at the
> > >>>>> point indicated by the comment. But the execution does reach that
> > >>>>> point in the code which indicates that the OGRStyleMrgH does in
> fact
> > >>>>> include at least one part (tool).
> > >>>>>
> > >>>>> I'd be grateful if somebody could point out what I'm doing wrong.
> > >>>>
> > >>>> Nothing strikes me as wrong. A potential explanation is that
> > >>>> styleChars doesn't contain a valid OGR Feature Style string.
> > >>>> GetPartCount() counts the number of ";" separating style parts, but
> it
> > >>>> doens't check that each style part actually begins by a recognized
> > >>>> tool name (PEN, BRUSH, SYMBOL, LABEL). OGR_SM_GetPart() does this
> > >>>> check however and if it cannot recognize it it returns a NULL tool.
> > >>>>
> > >>>>> Thanks,
> > >>>>> Nik.
> > >>>>>
> > >>>>>
> > >>>>> -------------------------------------------
> > >>>>>
> > >>>>> const char *styleChars = OGR_STBL_GetNextStyle(table) ) )
> > >>>>> NSString *styleName = [NSString
> > >>>>>
> > >>>>> stringWithUTF8String:OGR_STBL_GetLastStyleName(table)];
> OGRStyleMgrH
> > >>>>> styleMgr = OGR_SM_Create(NULL);
> > >>>>>
> > >>>>> OGR_SM_InitStyleString(styleMgr, styleChars);
> > >>>>>
> > >>>>>
> > >>>>> for ( int i = 0; i < OGR_SM_GetPartCount(styleMgr, NULL);
> i++ )
> > >>>>> {
> > >>>>>
> > >>>>> OGRStyleToolH tool = OGR_SM_GetPart(styleMgr, i,
> NULL);
> > >>>>>
> > >>>>> if ( tool ) // 'tool' always NULL here
> > >>>>> {
> > >>>>>
> > >>>>> switch ( OGR_ST_GetType(tool) )
> > >>>>> {
> > >>>>>
> > >>>>> case OGRSTCPen:
> > >>>>> self.pen = tool;
> > >>>>> break;
> > >>>>>
> > >>>>> case OGRSTCBrush:
> > >>>>> self.brush = tool;
> > >>>>> break;
> > >>>>>
> > >>>>> case OGRSTCSymbol:
> > >>>>> self.symbol = tool;
> > >>>>> break;
> > >>>>>
> > >>>>> case OGRSTCLabel:
> > >>>>> self.label = tool;
> > >>>>> break;
> > >>>>>
> > >>>>> default:
> > >>>>> NSLog(@"Unknown style tool
> type!");
> > >>>>> break;
> > >>>>>
> > >>>>> }
> > >>>>>
> > >>>>> }
> > >>>>>
> > >>>>> }
> > >>>>>
> > >>>>> -------------------------------------------
> > >>>>>
> > >>>>>
> > >>>>> _______________________________________________
> > >>>>> gdal-dev mailing list
> > >>>>> gdal-dev at lists.osgeo.org
> > >>>>> http://lists.osgeo.org/mailman/listinfo/gdal-dev
> > >>>
> > >>> _______________________________________________
> > >>> gdal-dev mailing list
> > >>> gdal-dev at lists.osgeo.org
> > >>> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>
> --
> Geospatial professional services
> http://even.rouault.free.fr/services.html
>
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