double ANALYSIS_EXPORT angle(QgsPoint *p1, QgsPoint *p2, QgsPoint *p3, QgsPoint *p4)
Calculates the angle between two segments (in 2 dimension, z-values are ignored)
virtual QgsExpressionContext createExpressionContext() const =0
This method needs to be reimplemented in all classes which implement this interface and return an exp...
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
Abstract interface for generating an expression context.