GraphViewport class final

Represents the viewport transformation for a node flow graph.

The viewport defines how the infinite graph coordinate space is mapped to the finite screen space. It consists of:

• Pan offset (x, y): Translation of the graph on screen
• Zoom level (zoom): Scale factor for the graph

Graph coordinates are independent of screen size and allow nodes to be positioned anywhere. The viewport transforms these coordinates to screen pixels for rendering.

All coordinate transformations use typed extension types (GraphPosition, ScreenPosition, GraphOffset, ScreenOffset) to prevent accidentally mixing coordinate spaces.

Example:

// Create a viewport centered at origin with 100% zoom
final viewport = GraphViewport(x: 0, y: 0, zoom: 1.0);

// Convert screen position to graph coordinates (type-safe!)
final screenPos = ScreenPosition.fromXY(100, 100);
final graphPos = viewport.toGraph(screenPos);

// Convert graph position to screen coordinates
final nodePos = GraphPosition.fromXY(50, 50);
final screenNodePos = viewport.toScreen(nodePos);

// Check if a rectangle is visible
final bounds = GraphRect.fromLTWH(0, 0, 100, 100);
final isVisible = viewport.isRectVisible(bounds, Size(800, 600));