extended_path

This library encapsulates the PathExtended object which serves as a extension to the parent Path class of Flutter. Internally a sampled representation of the Path is stored and updated, allowing to manipulate the Path object in powerful ways.

:construction: This library is still at early-stage development and might be subject to breaking API changes!!! :construction:

Supported PathEffects

Here is increasingly growing list with all available parameters and their visual effects. The animation serves for illustration purposes only. For creating such animations I would like to refer to drawing_animation, another package of mine.

Effect	Example
`ContinousLine` (default)
`DiscretePathEffect`
`DashPathEffect`
`PathDashPathEffect`

Getting Started

    Path p = Path()..addRect(Rect.fromCircle(center: Offset.zero, radius: 2.0));
    PathExtended pp = PathExtended(p)
      ..applyPathEffect(DashPathEffect([10,2], dashOffset: -1))
      ..addPath(circle(0,30.0),Offset.zero);

Design

The API design for the PathEffect classes is inspired by PathEffect for native Android but with some differences:

A PathEffect is applied to each Path object and not to the Paint object
Additionally a PathModifier is introduced. Contrary to the PathEffect the overall contour of the Path is changed. Internally a PathModifier manipulates the sampled representation directly while a PathEffect only changes the way how the sampling points are connected. This allows to combine a PathModifier with a PathEffect: For instance, a straight line can be transformed into a dashed sinus-curve. Soon a PathExtendedBuilder will be exposed which allows to set up a PathExtended object without rebuilding the internal structure every time.
Any feedback on the overall API design is really appreciated!

Current limitations

Internal sampling rate for the path data is currently hardcoded. This might noticeable when sampling a big amount of path data (bad performance) and also for very small paths (edgy lines).

TODO

PathEffect: How to determine optimal _delta value for sampling. Also consider defining _delta over amount of resulting sampling points (required for path morping). Your Path is discrete now: What happens when the Path is scaled, consider resampling dynamically.
PathDashPathEffect: Rotate Path elements according to normal of current Offset (see PathDashPathEffect.Style)
PathDashPathEffect: Implement advance field of PathDashPathEffect by setting inital offset to -dashOffset
DashPathEffect: Double dash pattern when odd (for now blocked by assert)

Milestones

[x] PathEffect: DashPathEffect
[x] PathEffect: DiscretePathEffect
[x] PathEffect: PathDashPathEffect
[ ] PathModifier: sin-wave
[ ] PathModifier: zick-zack
[ ] PathModifier: smoothing/simplify
[ ] (static) Lerp between two Paths/ Morphing
[ ] PathExtendedBuilder for better performance

biocarl / extended_path

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