JKQTPlotter
an extensive Qt4/Qt5 Plotter framework (including a fast variant and a LaTeX equation renderer!), written fully in C/C++ and without external dependencies
Geometric Elements (Lines, Rectangles, ...)
Collaboration diagram for Geometric Elements (Lines, Rectangles, ...):
Screenshot Classes
JKQTPGeoSymbol
JKQTPGeoText
JKQTPGeoLine, JKQTPGeoInfiniteLine, JKQTPGeoPolyLines
JKQTPGeoRectangle
JKQTPGeoPolygon
JKQTPGeoEllipse
JKQTPGeoArc
JKQTPGeoPie
JKQTPGeoChord
JKQTPBoxplotVerticalElement, JKQTPBoxplotHorizontalElement
JKQTPViolinplotVerticalElement, JKQTPViolinplotHorizontalElement

Examples: