Ok, perfect, now it's clear. giovanni
2012/12/11 Radim Blazek <[email protected]> > On Tue, Dec 11, 2012 at 2:23 PM, G. Allegri <[email protected]> wrote: > >> > >> Yes, you are right. Any class inheriting from QgsRasterInterface may > >> be plugged into the QgsRasterPipe but all interfaces will be in a > >> single line, no forks. > > > > > > Ok, Radim, I'm sorry if I insist on this, it's just to understand it > > correctly. > > To add a QgsRasterInterface in a QgsRasterPipe I would use > > QgsRasterPipe.insert(idx,QgsRasterInterface), but what is the > > QgsRasterInterface.setInput(QgsRasterInterface ) for? > > QgsRasterInterface.setInput(QgsRasterInterface ) is used to set input, > but you dont have to call it if you are using QgsRasterPipe because > it is called by QgsRasterPipe.insert(idx,QgsRasterInterface). > > > If I set a QgsRasterInterface, which will have its own input, as the > input > > for another QgsRasterInterface, I'm creating a chain of > > QgsRasterInterfaces... > > Yes, QgsRasterPipe just helps you to manage such chain. It will > automatically connect the interfaces. QgsRasterPipe represents a chain > of interfaces. > > Radim > > > Help me to understand it... > > > > giovanni > > > >> > >> > >> BTW, you should always test if QgsRasterPipe::insert() was successful, > >> because if connection of interfaces fails, the interface is not > >> inserted. Only compatible interfaces may be connected. For example, it > >> is not possible to connect QgsSingleBandGrayRenderer to an interface > >> of ARGB32 type, because it needs numerical data as input. > >> QgsRasterResampleFilter only works with ARGB32 as input etc. > >> > >> Radim > >> > >> > >> > [1] > >> > > >> > > https://github.com/qgis/Quantum-GIS/blob/master/src/core/raster/qgsrasterinterface.h#L108 > >> > > >> >> > >> >> > >> >> Radim > >> >> > >> >> > >> >> > giovanni > >> >> > > >> >> > > >> >> > 2012/12/11 Radim Blazek <[email protected]> > >> >> >> > >> >> >> On Tue, Dec 11, 2012 at 10:52 AM, G. Allegri <[email protected]> > >> >> >> wrote: > >> >> >> > Until now I've mostly created vector layers on QGIS, delegating > >> >> >> > raster > >> >> >> > creation to custom GDAL utilities. > >> >> >> > Recently I looked into QgsGdalProvider and I saw that it exposes > >> >> >> > the > >> >> >> > QgsRasterDataProvider::Create capability. > >> >> >> > I wonder if it's possible to create a brand new raster (geotiff > or > >> >> >> > what > >> >> >> > else) using this provider and, in case, what is the right > workflow > >> >> >> > to > >> >> >> > do > >> >> >> > that. I haven't found examples of doing it... > >> >> >> > >> >> >> Yes it is possible. You can use a provider directly > >> >> >> > >> >> >> QgsRasterDataProvider * provider = ( QgsRasterDataProvider* > >> >> >> )QgsProviderRegistry::instance()->provider( "gdal", dataSource ); > >> >> >> provider->write( data, band, width, height, xOffset, yOffset ) > >> >> >> > >> >> >> if you your algorithm implemented as QgsRasterInterface you can > use > >> >> >> higher level QgsRasterFileWriter which will do the work splitting > >> >> >> raster into parts > >> >> >> > >> >> >> QgsRasterPipe* pipe = new QgsRasterPipe(); > >> >> >> pipe->set( inputProvider->clone() ); > >> >> >> pipe->insert( 1, yourInterface ); > >> >> >> QgsRasterFileWriter fileWriter( fileName ); > >> >> >> fileWriter.writeRaster( pipe, width, height, extent, crs ); > >> >> >> > >> >> >> Radim > >> >> >> > >> >> >> > >> >> >> > giovanni > >> >> >> > > >> >> >> > _______________________________________________ > >> >> >> > Qgis-developer mailing list > >> >> >> > [email protected] > >> >> >> > http://lists.osgeo.org/mailman/listinfo/qgis-developer > >> >> >> > > >> >> > > >> >> > > >> > > >> > > > > > >
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