使用pycharm和pyqgis3.30在地图中显示点迹的牵引线

要在PyQGIS中显示点迹的牵引线，可以按照以下步骤进行操作：

1. 导入必要的模块：

   from qgis.core import QgsVectorLayer, QgsPointXY, QgsGeometry, QgsFeature, QgsProject
   from PyQt5.QtGui import QColor

2. 创建一个QgsVectorLayer来存储牵引线：

   line_layer = QgsVectorLayer('LineString?crs=EPSG:4326', 'Traces', 'memory')
   pr = line_layer.dataProvider()
   pr.addAttributes([QgsField('TraceID', QVariant.Int)])
   line_layer.updateFields()

3. 在地图上添加点迹：

   point_layer = QgsVectorLayer('Point?crs=EPSG:4326', 'Points', 'memory')
   pr = point_layer.dataProvider()
   pr.addAttributes([QgsField('PointID', QVariant.Int)])
   point_layer.updateFields()
   points = [(1, QgsPointXY(0,0)), (2, QgsPointXY(2,2)), (3, QgsPointXY(4,4))]
   for point in points:
       feat = QgsFeature()
       feat.setGeometry(QgsGeometry.fromPointXY(point[1]))
       feat.setAttributes([point[0]])
       pr.addFeature(feat)
   QgsProject.instance().addMapLayer(point_layer)

4. 计算并添加牵引线：

   feats = list(point_layer.getFeatures())
   for i in range(len(feats)-1):
       start_point = feats[i].geometry().asPoint()
       end_point = feats[i+1].geometry().asPoint()
       line_geom = QgsGeometry.fromPolyline([start_point, end_point])
       feat = QgsFeature()
       feat.setGeometry(line_geom)
       feat.setAttributes([i+1])
       pr.addFeature(feat)
   QgsProject.instance().addMapLayer(line_layer)

5. 设置牵引线的样式：

   line_renderer = line_layer.renderer()
   symbol = line_renderer.symbol()
   symbol.setColor(QColor(255,0,0))
   symbol.setWidth(2)
   line_layer.triggerRepaint()

这样，你就可以在地图中看到由点迹组成的牵引线了。