I am working in c++/QT 4.5 with the qgis 2.8.2 api.I had to change the geometry of features in a layer each second.Each second new data comes from the Ethernet connection, the application get the data and call a function with parameters.
It look like a real time tracker.It works only if i put lLayer->startEditing and lLayer->commitChanges but it was too slow.
Here is my code (just an extract. Complete code is too long for the post.)
QgsVectorLayer * lLayer = mMapLayer.value(TRACKS);lLayer->startEditing();QgsVectorDataProvider * lDataProvider;lDataProvider = lLayer->dataProvider();//calc new random X and YPosX =(qrand()%(Xmax-Xmin)+Xmin);PosY =(qrand()%(Ymin-Ymax)+Ymax);//create pointQgsGeometry *MyPoint;MyPoint=QgsGeometry::fromPoint(QgsPoint(PosX,PosY));QgsGeometryMap MyGeometryMap;//get the feature of the specify IdQgsFeatureIterator MyFeatIter;MyFeatIter = lDataProvider->getFeatures();QgsFeature MyFeature;QgsFeatureId MyFeatureId;while ( MyFeatIter.nextFeature(MyFeature)) { if (pTrackId == MyFeature.attribute("TrackId")) { MyFeatureId=MyFeature.id(); MyFeature.setGeometry(*MyPoint); MyFeature.setAttribute(Longitude,PosY); MyFeature.setAttribute(Latitude,PosX); }}MyGeometryMap.insert(MyFeatureId,*MyPoint);bool lResult;lResult=lDataProvider->changeGeometryValues(MyGeometryMap);lLayer->commitChanges();With the starEditing and commitChanges, it works, but very slow.Without the startEditing and commitChanges, the coordinate seems to be modified, but on the layer the feature don't move anyway.
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It look like a real time tracker.It works only if i put lLayer->startEditing and lLayer->commitChanges but it was too slow.
Here is my code (just an extract. Complete code is too long for the post.)
QgsVectorLayer * lLayer = mMapLayer.value(TRACKS);lLayer->startEditing();QgsVectorDataProvider * lDataProvider;lDataProvider = lLayer->dataProvider();//calc new random X and YPosX =(qrand()%(Xmax-Xmin)+Xmin);PosY =(qrand()%(Ymin-Ymax)+Ymax);//create pointQgsGeometry *MyPoint;MyPoint=QgsGeometry::fromPoint(QgsPoint(PosX,PosY));QgsGeometryMap MyGeometryMap;//get the feature of the specify IdQgsFeatureIterator MyFeatIter;MyFeatIter = lDataProvider->getFeatures();QgsFeature MyFeature;QgsFeatureId MyFeatureId;while ( MyFeatIter.nextFeature(MyFeature)) { if (pTrackId == MyFeature.attribute("TrackId")) { MyFeatureId=MyFeature.id(); MyFeature.setGeometry(*MyPoint); MyFeature.setAttribute(Longitude,PosY); MyFeature.setAttribute(Latitude,PosX); }}MyGeometryMap.insert(MyFeatureId,*MyPoint);bool lResult;lResult=lDataProvider->changeGeometryValues(MyGeometryMap);lLayer->commitChanges();With the starEditing and commitChanges, it works, but very slow.Without the startEditing and commitChanges, the coordinate seems to be modified, but on the layer the feature don't move anyway.
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