QGIS二次开发中的路径规划实现

1、头文件

#include <qgsvectorlayerdirector.h>

#include <qgsgraphbuilder.h>

#include <qgsgraph.h>

#include <qgsgraphanalyzer.h>

#include <qgsvectorlayerdirector.h>

#include <qgsnetworkdistancestrategy.h>

2、需要用于路径规划的变量

QgsFeatureSource* mNetwork; //路网图层

QgsVectorLayerDirector *mDirector = nullptr;

std::unique_ptr< QgsGraphBuilder > mBuilder;

std::unique_ptr< QgsGraph > mGraph;

3、代码实现

mNetwork = roadLayer; //路网矢量图层 

mDirector = new QgsVectorLayerDirector(mNetwork, -1, "", "", "", QgsVectorLayerDirector::DirectionBoth);

QVector< QgsPointXY > points;

QVector< QgsPointXY > snappedPoints;

QgsPointXY startPt(123.0, 20.1);

QgsPointXY endPt(123.1, 20.2);

points << startPt << endPt;

mDirector->addStrategy(new QgsNetworkDistanceStrategy());

mBuilder = qgis::make_unique< QgsGraphBuilder >(mNetwork->sourceCrs(), true, 0.0);

mDirector->makeGraph(mBuilder.get(), points, snappedPoints);

QgsGraph *graph = mBuilder->graph();

int idxStart = graph->findVertex(snappedPoints[0]);

int idxEnd = graph->findVertex(snappedPoints[1]);

QVector< int > tree;

QVector< double > costs;

QgsGraphAnalyzer::dijkstra(graph, idxStart, 0, &tree, &costs);

if (tree.at(idxEnd) == -1)

{

throw QgsProcessingException(QObject::tr("There is no route from start point to end point."));

}

QgsPolyline route;

route.append(QgsPoint(graph->vertex(idxEnd).point()));

while (idxEnd != idxStart)

{

idxEnd = graph->edge(tree.at(idxEnd)).fromVertex();

route.append(QgsPoint(graph->vertex(idxEnd).point()));

}

QgsGeometry geom = QgsGeometry::fromPolyline(route); //生成规划后的最短路径线几何对象

得到这个几何对象后，就可以在地图上显示了。

4、存在的问题

路径规划的效率较低，通过QGIS桌面端也是这个效率，所以，应该没有优化的空间了，如果想得到效率高的路径规划功能，就需要自己写或者用开源的pgrounting。

后续准备试试pgrounting，敬请期待！