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                   freehand drawing tool
                    
                   Copyright 2012 L. Konneker
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1. About
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A freehand drawing tool.
Input: pointer device (e.g. mouse) events.
Output: graphic vector path (lines and splines) which a GUI toolkit renders.
Not a complete app, mostly the model component.
Includes a rudimentary GUI app for testing (draw with LMB, distort with key or Ctl-key)
Written in pure Python.
Emphasis on domain objects and class/responsibility/collaboration documentation.

Tags:
- freehand drawing.
- computational geometry.
- incremental (dynamic) line tracing.
- Python coroutines.
- pipe of filters.
- GUI toolkit Qt.

References:
- Derived from potrace by Peter Selinger.
- Object model somewhat similar to Shapely/GEOS

See much more technical discussion in the code.


2. Version 2.0
==============

SegmentString, Segment, ControlPoint classes.
Explicitly model the abstractions of a SegmentString.
This more cleanly separates freehandTool from what it produces.
Demonstrates editing a SegmentString by manipulation of its ControlPoints.
(Although editing is not graphical, just crude demo via keystrokes.)


3. Version 3.0
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- Relations between ControlPoints defines actions (behavior of user manipulations.)
- Cusps known by SegmentString 
- Actions defined as a Strategy/Policy
- An API that can be cleanly hooked to a GUI editor.


4. Serialize/Deserialize
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TODO
Calculate cuspness geometrically.
Cuspness is not currently serializable/deserializable, only exists just after SegmentString creation.