qgis 二次开发绘制曲线 C++实现
时间: 2024-04-08 07:22:30 浏览: 11
QGIS 是一个开源的地理信息系统软件,它提供了丰富的 API 接口,便于二次开发。其中,绘制曲线可以使用 QgsCurveGeometry 类来实现。
具体实现步骤如下:
1. 创建 QgsCurveGeometry 对象,并设置其类型为曲线:
```
QgsCurveGeometry *curve = new QgsCurveGeometry(QgsGeometry::Curve);
```
2. 添加曲线节点:
```
curve->addCurvePoint(QgsPointXY(10, 10));
curve->addCurvePoint(QgsPointXY(20, 20));
curve->addCurvePoint(QgsPointXY(30, 10));
```
3. 创建 QgsFeature 对象,并设置其几何属性为曲线:
```
QgsFeature feature;
feature.setGeometry(QgsGeometry(curve));
```
4. 将 QgsFeature 对象添加到图层中:
```
QgsVectorLayer *layer = QgsVectorLayer("LineString", "line", "memory");
QgsVectorDataProvider *provider = layer->dataProvider();
provider->addFeatures(QList<QgsFeature>() << feature);
```
完整的 C++ 代码示例如下:
```
QgsCurveGeometry *curve = new QgsCurveGeometry(QgsGeometry::Curve);
curve->addCurvePoint(QgsPointXY(10, 10));
curve->addCurvePoint(QgsPointXY(20, 20));
curve->addCurvePoint(QgsPointXY(30, 10));
QgsFeature feature;
feature.setGeometry(QgsGeometry(curve));
QgsVectorLayer *layer = QgsVectorLayer("LineString", "line", "memory");
QgsVectorDataProvider *provider = layer->dataProvider();
provider->addFeatures(QList<QgsFeature>() << feature);
```