如何解决QGIS QgsFeature未按特定比例显示
下面的代码是从多个点创建方位线。问题在于此行仅在我以较大比例放大时显示,通常此行不显示。函数algo-> getDFlist()返回方位点列表。谁能向我解释问题所在?
QgsVectorLayer* bearingLayer = new QgsVectorLayer("LineString","Bearing","memory"); QgsStringMap properties; properties.insert("color","red"); properties.insert("size","2"); QgsLineSymbol* symbol = QgsLineSymbol::createSimple(properties); QgsSingleSymbolRenderer* render = new QgsSingleSymbolRenderer(symbol); bearingLayer->setRenderer(render); QgsVectorDataProvider* bearing_provider = bearingLayer->dataProvider(); QgsFeature* bearing_feature = new QgsFeature; BearingAlgorithm* algo = new BearingAlgorithm; QList list = algo->getDFlist(105,21,30); QgsPolyline* lines = new QgsPolyline(list.count()); for (size_t i = 0; i append(QgsPoint(list[i].Longitude,list[i].Latitude)); } bearing_feature->setGeometry(QgsGeometry::fromPolyline(*lines)); bearing_provider->addFeature(*bearing_feature); bearingLayer->updateExtents(); bearingLayer->setScaleBasedVisibility(false);
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