Metron

Geometry, simplified.

Metron is a comprehensive collection of geometric functions and types that extend the 2D geometric primitives provided by CoreGraphics. Completely written in Swift, Metron allows you to express complex geometric calculations in very intuitive statements:

Example 1.

Circle(in: viewFrame).contains(touchPoint)

↳ creates a Circle that fits (centered) inside viewFrame, and checks if the touchPoint is inside that circle.

Example 2.

(Angle(.pi) + Angle(270, unit: .degrees)).normalized // Angle of 0.5pi (90°)

↳ adds two Angles, one expressed in radians (default) and one in degrees. The sum is normalized to within 0 and 2𝛑 radians (or 0 and 360 degrees).

Example 3.

LineSegment(a: startPoint, b: currentPoint).intersection(with: viewFrame.lineSegment(for: minYEdge))

↳ creates a LineSegment between a (touch) start point and current point, and returns the intersection with the minYEdge of a view’s frame (if these line segments indeed intersect).

Example 4.

let rotatedPoints = viewFrame.points.map { $0.applying(rotationTransform, anchorPoint: rotationPoint) }
let path: CGPath = Polygon(points: rotatedPoints).path

↳ maps each corner point of a view’s frame (a CGRect) to a point to which a rotationTransform is applied, taking rotationPoint as the anchor point for the transform. With these points, a Polygon is initialized, representing the rotated rectangular frame of the view. From that polygon, we derive a CGPath that can then be drawn.

And there’s much more…

Extensions

For CGPoint

• Distance to other CGPoint
• Clipping to CGRect
• Relative position in CGRect
• Normalized position in CGRect
• Convert to CGVector
• Round to non-decimal components
• Addition, subtraction, multiplication…
• Convex hull for an array of CGPoints (returns a Polygon)

For CGVector

• Magnitude
• Angle
• Convenience initializer with magnitude and angle
• Convert to CGPoint
• Inverse
• Dominant edge
• Dominant corner
• Derive line through point
• Derive line segment from point
• CGAffineTransform extensions
• Addition, subtraction, multiplication…

For CGSize

• Area
• Swap width and height
• Clip to other CGSize
• Scaling using multiplication and division

For CGRect

• Many convenience initializers, including AspectFit / AspectFill for size
• Scaling
• Corner points
• Edges as line segments
• Area
• Center
• Perimeter
• CGPath

For CGRectEdge

• Axis (x or y)
• Adjacent corners
• Opposite edge

For CGAffineTransform

• Create translation transform using CGVector
• Apply transform with a specified anchor point

New Types

Line

• Slope
• Y-intercept
• X-intercept
• Horizontal? / vertical? / parallel(to: …)?
• Get a perpendicular line
• Determine intersection with other Line or LineSegment

LineSegment

• Length
• Derive a Line
• Rotate
• Determine intersection with other Line or LineSegment
• CGPath

Circle

• Radius
• Diameter
• Circumference
• Area
• Center
• Width / Height
• Bounding rect
• Contains point?
• CGPath
• Points along the perimeter (divide the circle into steps, rotating in a specific direction…)

Triangle

• Vertices (as CGPoint)
• Sides (as LineSegment)
• Angles (as Angle, see further on)
• Angle bisectors (as LineSegment)
• Altitudes (as LineSegment)
• Equilateral? / isosceles? / scalene? / right? / oblique? / acute? / obtuse?
• Centroid
• Circumcenter
• Incenter
• Orthocenter
• Area
• Bounding rect
• Contains point?
• CGPath

Square

• Edge length
• Area
• Perimeter
• Center
• CGPath
• CGRect

Polygon

• Init with points or with line segments
• Edge count
• Self-intersecting?
• Convex? / concave?
• Area
• Perimeter
• Center
• Bounding rect
• Contains point?
• CGPath

Corner

• Adjacent edges (CGRectEdges)
• Opposite corner

Angle

• Init with radians or degrees
• Convert unit
• Normalize
• Invert
• Compare
• Addition, subtraction, multiplication…
• Basic trigonometric functions also accept Angle
• Create rotation CGAffineTransform with Angle

Installation

CocoaPods

Metron is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod "Metron"

Carthage

Metron is also available through Carthage. To install it, simply add the following line to your Cartfile:

github "toineheuvelmans/Metron"

Swift Package Manager

Metron can also be used with the Swift Package Manager. Add Metron to the dependencies value of your Package.swift:

dependencies: [
    .Package(url: "https://github.com/toineheuvelmans/metron.git", majorVersion: 1)
]

Suggestions or feedback?

Feel free to create a pull request, open an issue or find me on Twitter.

License

Metron is available under the MIT license. See the LICENSE file for more info.