Gaphas Documentation

Gaphas is the diagramming widget library for Python.

Gaphas has been built with some extensibility in mind. It can be used for many drawing purposes, including vector drawing applications, diagram drawing tools and we even have a geographical map demo in our repository.

The basic idea is:

• Items (canvas items) can be added to a Canvas.

• A Canvas can be visualized by one or more Views.

• The canvas maintains the tree structure (parent-child relationships between items).

• A constraint solver is used to maintain item constraints and inter-item constraints.

• The item (and user) should not be bothered with things like bounding-box calculations.

• Very modular: e.g. handle support could be swapped in and swapped out.

• Rendering using Cairo. This implies the diagrams can be exported in a number of formats, including PNG and SVG.

Gaphas is released under the terms of the Apache Software License, version 2.0.

Gaphas has been build using setuptools and can be installed as Python Egg.

• Git repository: https://github.com/gaphor/gaphas

• Python Package index (PyPI): https://pypi.org/project/gaphas

Table of Contents

• Class diagram
  • Tools
• Interacting with diagrams
  • Separating the What from the How
• Ports
  • Port Types
  • Ports and Constraints (Covering Handles)
  • Connections
  • Examples
• State management
  • Observer
  • Reverser
  • What is Observed
• Undo - implementing basic undo behaviour with Gaphas
  • Undo functionality tests
• Quadtree implementation
  • Interface
  • Implementation
• Constraint Solver
  • Variables
  • Projections
• API reference
  • Canvas and Items
  • Miscellaneous

• Index

• Module Index

• Search Page