Polygons, Polylines, and Conversions

It turns out I forgot about two “minor” feature I should add before the two major features I mentioned in the previous post.

Feature 1: Polylines and Polygons

Polylines and Polygons currently have a set number of “segments”. To allow changing this, I will add a new LinearSegment class that allows splitting itself to increase the number of segments in a Polyline or Polygon.

Design in Froggum

The existing Segment class will be refactored into a base class Segment and a subclass PathSegment. All functionality related to arcs and curves will only be in PathSegment, and that is the class that will be used directly by Paths. The clicked method will continue to use Segment.
A new class LinearSegment will be created subclassing Segment that will be used by Polylines and Polygons.
- The options method will return an option to Split, which replaces the segment with two segments divided in the center of the original. This can be undone.

Checklist

Refactor Segment into PathSegment
Have Path now use PathSegment
Create base class Segment
Create class LinearSegment
Have Polygon use a closed loop of LinearSegments
Have Polyline use a sequence of LinearSegments
Ensure Polygons and Polylines can still be clicked
Add option to “Split Segment”
Make “Split Segment” undoable
Make moving points on LinearSegment undoable
Fix the bugs this will introduce
… Anything else I think of during development

Feature 2: Element Conversions

Most elements (not yet Lines and Polylines) have equivalent Path versions. It would be useful in many cases to allow converting elements to a more general format.

Design in Froggum

The following context menu options will be added:

Line:
- Convert to Polyline
Polyline:
- Close Loop
  
  This adds a LinearSegment between the end points of the line and creates a Polygon from the new closed loop.
Polygon:
- Convert to Path
Rectangle:
- Convert to Polygon
  
  This option only exists when not rounded.
- Convert to Path
  
  This option only exists when rounded.
Ellipse:
- Convert to Path
  
  Arc segments are difficult, so this will replace the element with one of the following:
  - A Path with a single Arc segment
  - A Path with two Arc segments, divided along the x axis
  - A Path with two Arc segments, divided along the x axis, with degenerate Line segments between them
  - Something else that results in an elliptical path
Circle:
- Convert to Ellipse

All of these options replace the element with an equivalent element of a more general type. Only the most specific more general element type is an option, so converting a Circle to a Path, for example, requires converting to an Ellipse first.

Converting an element keeps the transform, fill, and stroke of the original.

All of these actions can be undone.

Checklist

Add “Convert to Polyline” option to Lines
Add “Close Loop” option to Polylines
Add “Convert to Path” option to Polygons
Add “Convert to Polygon” option to unrounded Rectangles
Add “Convert to Path” option to rounded Rectangles
Add “Convert to Path” option to Ellipses
Decide what the “Convert to Path” option on Ellipses should do
Add “Convert to Ellipse” option to Circles
Make all conversions undoable
Fix the bugs this will introduce
… Anything else I think of during development