UIBezierPath-Query
An extension to add several cool features to UIBezierPath and NSBezierPath.
Entirely based on UIBezierPath+Superpowers by Maximilian Kraus in order to make it available to CocoaPods.
All orignal work by its original author
Requirements
Tested in XCode 11.2.1 and Swift 5.1.
Xcode 11.2+
Swift 5.1+
Installation
UIBezierPath-Query is available through CocoaPods. To install it, simply add the following line to your Podfile:
pod 'UIBezierPath-Query'Example
To run the example project, clone the repo, and run pod install from the Example directory first.
Features
This library adds several major features to UIBezierPath.
Calculating path length
var mx_length: CGFloat
Returns the length of the path.
Calculating bezier points
mx_point(atFractionOfLength: CGFloat) -> CGPoint
Returns for a given fraction the point on the path fraction * pathLength in to the path.
Calculating perpendicular points and distances
mx_perpendicularPoint(for: CGPoint) -> CGPoint
Returns the closest point on the path to a given CGPoint, effectively letting fall a perpendicular on the path from point and returning the point of intersection.
Calculating path slope and tangent angles
mx_tangentAngle(atFractionOfLength: CGFloat) -> CGFloat
For a given fraction, returns the tangent angle of the path at the point fraction * length in to the path.
How it works
The backbone of it all is a function on CGPath called apply(info:, function:). This basically lets you iterate
all elements a given UIBezierPath is constructed of.
Short aside:
UIBezierPath and its Cocoa counterpart NSBezierPath are descriptions of bezier curves.
These curves are basically a clever way of feeding line drawing instructions to computers.
Bezier paths are composed of different types of path elements. Each element is either a straight line, quadratic curve or cubic
curve. At the end of the day, these curves boil down to mathematical functions which allows us to calculate things like
line lengths, tangent angles, etc.
If you are interested in more, there is a really well written and easy to understand article on Wikipedia.
What this library does is pull out all elements a path is constructed of and throw some geometric math at them. Since the extraction and initial computations are quite expensive, the results are cached internally if possible.
By default however, caching is disabled because - by design - the library lives in an extension and not a subclass of UIBezierPath and with that come some limitations regarding method overriding, internal vars, etc.
In order to enable the full superpower, you'll have to call UIBezierPath.mx_prepare(). This performs some runtime magic
under the hood which breaks the chains of extension and gives you full access to all features on any UIBezierPath object.
Contributing
Feel free to build upon this project and / or submit a PR anytime.
Authors
- Maximilian Kraus
License
This project is licensed under the MIT License - see the LICENSE.md file for details