WPF 2D Graphics Patterns

Implement vector-based visual elements using WPF's 2D graphics system.

1. Graphics Hierarchy

UIElement
└── Shape (FrameworkElement)        ← Participates in layout, supports events
    ├── Ellipse
    ├── Rectangle
    ├── Line
    ├── Polyline
    ├── Polygon
    └── Path

Drawing                             ← Lightweight, no events
├── GeometryDrawing
├── ImageDrawing