ArcChart

Animated Dynamic Relational & Uniform ArcChart in SwiftUI

Work in Progress - Feature requests appreciated.

You can create your own custom chart implementation by subclassing

class BaseArcChart<T : BasicWedge> {
  ...
  init(_ wedges: [Int : T])
  ...

Provided examples are
RelationalArcChart<T : BasicWedge & RelationalWedgeConforming>: BaseArcChart<T>
UniformArcChart<T: BasicWedge>: BaseArcChart<T>

BasicWedge
To draw any Wedge, you must at minimum specify a WedgeFillStyle

protocol BasicWedge: Equatable {  
    var fill: WedgeFillStyle { get }  
    var start: Double { get set }  
    var end: Double { get set}
}

enum WedgeFillStyle: Equatable {
    ...
    case color(_ color: Color), gradient(_ gradient: Gradient)
}

RelationalWedge

protocol RelationalWedgeConforming {
    var value: Double { get }
}
struct RelationalWedge: BasicWedge, RelationalWedgeConforming {
    var fill: WedgeFillStyle
    var start: Double = 0.0
    var end: Double = 0.0
    var value: Double
}

ArcChartView<T : ArcChart> : View
The view that holds the chart and is responsible for drawing the chart based on the supplied parameters

init(_ chart: T, viewModel: ArcChartViewModel)

_ chart: T -

protocol ArcChart: ObservableObject {
    associatedtype T: BasicWedge
    func getWedges() -> [Int : T]
    func setWedges(_ wedges: [Int : T])
    func getWedgeIds() -> [Int]
}

Examples are UniformArcChart<UniformWedge> and RelationalArcChart<RelationalWedge>

struct ArcChartOptions {
    let desiredLineThickness: CGFloat
    let desiredLineSpacing: CGFloat
    let centerSpacing: CGFloat
    let overflowPolicy: ArcSegmentOverflowPolicy
    let fillPolicy: ArcSegmentFillPolicy
    let segmentLineCount: Int
}

desiredLineThickness: CGFloat - The desired lineThickness (depth) of each line in a segment.
This value of this property is not guaranteed to be used when drawing the chart, depending on Overflow Policy and Fill Policy
The chart will automatically resize desiredLineThickness and desiredLineSpacing based on policies to fit within its bounds.

desiredLineSpacing: CGFloat - The desired lineSpacing (depth) between each line in a segment.
This value of this property is not guaranteed to be used when drawing the chart, depending on Overflow Policy and Fill Policy
The chart will automatically resize desiredLineThickness and desiredLineSpacing based on policies to fit within its bounds.
The final value of desiredLineSpacing is also used as spacing between segments.

centerSpacing: CGFloat - The radius of the clear space in the center of the chart

overflowPolicy: ArcSegmentOverflowPolicy - Overflow Policy

/**
 If the chart can't fit within the available rect with the `desiredLineSpacing` and `desiredLineThickness`, one of these policies are applied.
 - `shrinkLineSpacing`: Shrink the `desiredLineSpacing` until the chart fits, or until it reaches the `minimumLineSpacing`.
    If that happens, `desiredLineThickness` is reduced until the chart fits, or `desiredLineSpacing`== `minimumLineSpacing` and `desiredLineThickness` == `minimumLineThickness`
 
 - `shrinkLineThickness`: Shrink the `desiredLineThickness` until the chart fits, or until it reaches the `minimumLineThickness`.
    If that happens, `desiredLineSpacing` is reduced until the chart fits, or `desiredLineSpacing`== `minimumLineSpacing` and `desiredLineThickness` == `minimumLineThickness`
 
 - `equalize` : Equalize so that the actual `lineThickness` and `lineSpacing` are equal. This setting has no minimum limit, but will eventually reach close to 0.
 */
enum ArcSegmentOverflowPolicy {
    case shrinkLineSpacing, shrinkLineThickness, equalize
}

fillPolicy: ArcSegmentFillPolicy : Should the size of the resulting ArcChart be smaller than the container, .fill will expand desiredLineThickness to fill the available space properly while .none will keep the size as is.

segmentLineCount: Int - The number of individual lines within each segment.
The RelationalArcChart example uses segmentLineCount: 1
The UniformArcChart example uses segmentLineCount: 10

This value can be anything, the UniformArcChart example provides a Stepper up to 100.
Keep in mind, excessive values may reduce performance.
Example:
segmentLineCount: 100 segments: 17 Shapes to draw: 100 * 17 => 1700

Even though it's all flattened using .drawingGroup(), it's not magic.

UniformArcChart Example

RelationalArcChart Example