为开发人员准备的文档,涵盖QGIS的多种功能实现和代码。

CHAPTER2

LoadingProjects

Sometimesyouneedtoloadanexistingprojectfromapluginor(moreoften)whendevelopingastand-alone

QGISPythonapplication(see:PythonApplications).

ToloadaprojectintothecurrentQGISaplicationyouneedaQgsProjectinstance()objectandcallits

read()methodpassingtoitaQFileInfoobjectthatcontainsthepathfromwheretheprojectwillbeloaded:

Incaseyouneedtomakesomemodi cationstotheproject(forexampleaddorremovesomelayers)andsave

yourchanges,youcancallthewrite()methodofyourprojectinstance.Thewrite()methodalsoacceptsan

optionalQFileInfothatallowsyoutospecifyapathwheretheprojectwillbesaved:

Bothread()andwrite()funtionsreturnabooleanvaluethatyoucanusetocheckiftheoperationwas

successful.