feat: new protocol for chained functions, and added support for explicit Y ranges. X coming as well

Sources/SwiftUICharts/Base/Axis/AxisLabels.swift

@@ -0,0 +1,40 @@
+import SwiftUI
+
+public struct AxisLabels<Content: View>: View {
+    var axisLabelsData = AxisLabelsData()
+    let content: () -> Content
+    // font
+    // foregroundColor
+
+    public init(@ViewBuilder content: @escaping () -> Content) {
+        self.content = content
+    }
+
+    public var body: some View {
+        HStack {
+            VStack {
+                ForEach(Array(axisLabelsData.axisYLabels.reversed().enumerated()), id: \.element) { index, axisYData in
+                    Text(axisYData)
+                    if index != axisLabelsData.axisYLabels.count - 1 {
+                        Spacer()
+                    }
+                }
+            }
+            .padding([.trailing], 8.0)
+            .padding([.bottom], axisLabelsData.axisXLabels.count > 0 ? 28.0 : 0)
+            .frame(maxHeight: .infinity)
+            VStack {
+                self.content()
+                HStack {
+                    ForEach(Array(axisLabelsData.axisXLabels.enumerated()), id: \.element) { index, axisXData in
+                        Text(axisXData)
+                        if index != axisLabelsData.axisXLabels.count - 1 {
+                            Spacer()
+                        }
+                    }
+                }
+            }
+            .padding([.top, .bottom], 10.0)
+        }
+    }
+}

Sources/SwiftUICharts/Base/Axis/Extension/AxisLabels+Extension.swift

@@ -0,0 +1,13 @@
+import SwiftUI
+
+extension AxisLabels {
+    public func setAxisYLabels(_ labels: [String]) -> AxisLabels {
+        self.axisLabelsData.axisYLabels = labels
+        return self
+    }
+
+    public func setAxisXLabels(_ labels: [String]) -> AxisLabels {
+        self.axisLabelsData.axisXLabels = labels
+        return self
+    }
+}

Sources/SwiftUICharts/Base/Axis/Model/AxisLablesData.swift

@@ -0,0 +1,10 @@
+import SwiftUI
+
+public final class AxisLabelsData: ObservableObject {
+    @Published public var axisYLabels: [String] = []
+    @Published public var axisXLabels: [String] = []
+
+    public init() {
+        // no-op
+    }
+}

Sources/SwiftUICharts/Base/Chart/ChartBase.swift

@@ -1,6 +1,6 @@
 import SwiftUI
 
 /// Protocol for any type of chart, to get access to underlying data
-public protocol ChartBase {
+public protocol ChartBase: View {
     var chartData: ChartData { get }
 }

Sources/SwiftUICharts/Base/Chart/ChartData.swift

@@ -2,37 +2,78 @@ import SwiftUI
 
 /// An observable wrapper for an array of data for use in any chart
 public class ChartData: ObservableObject {
-    @Published public var data: [(String, Double)] = []
+    @Published public var data: [(Double, Double)] = []
+    public var rangeY: ClosedRange<Double>?
+    public var rangeX: ClosedRange<Double>?
 
     var points: [Double] {
-        data.map { $0.1 }
+        data.filter { rangeX?.contains($0.0) ?? true }.map { $0.1 }
     }
 
-    var values: [String] {
-        data.map { $0.0 }
+    var values: [Double] {
+        data.filter { rangeX?.contains($0.0) ?? true }.map { $0.0 }
     }
 
     var normalisedPoints: [Double] {
         let absolutePoints = points.map { abs($0) }
-        return points.map { $0 / (absolutePoints.max() ?? 1.0) }
+        var maxPoint = absolutePoints.max()
+        if let rangeY = rangeY {
+            maxPoint = Double(rangeY.overreach)
+            return points.map { ($0 - rangeY.lowerBound) / (maxPoint ?? 1.0) }
+        }
+
+        return points.map { $0 / (maxPoint ?? 1.0) }
     }
 
-    var normalisedRange: Double {
-        (normalisedPoints.max() ?? 0.0) - (normalisedPoints.min() ?? 0.0)
+    var normalisedValues: [Double] {
+        let absoluteValues = values.map { abs($0) }
+        var maxValue = absoluteValues.max()
+        if let rangeX = rangeX {
+            maxValue = Double(rangeX.overreach)
+            return values.map { ($0 - rangeX.lowerBound) / (maxValue ?? 1.0) }
+        }
+
+        return values.map { $0 / (maxValue ?? 1.0) }
+    }
+
+    var normalisedData: [(Double, Double)] {
+        Array(zip(normalisedValues, normalisedPoints))
+    }
+
+    var normalisedYRange: Double {
+        if let _ = rangeY {
+            return 1
+        }
+
+        return (normalisedPoints.max() ?? 0.0) - (normalisedPoints.min() ?? 0.0)
+    }
+
+    var normalisedXRange: Double {
+        if let _ = rangeX {
+            return 1
+        }
+
+        return (normalisedValues.max() ?? 0.0) - (normalisedValues.min() ?? 0.0)
     }
 
     var isInNegativeDomain: Bool {
-        (points.min() ?? 0.0) < 0
+        if let rangeY = rangeY {
+            return rangeY.lowerBound < 0
+        }
+
+        return (points.min() ?? 0.0) < 0
     }
 
     /// Initialize with data array
     /// - Parameter data: Array of `Double`
-    public init(_ data: [Double]) {
-        self.data = data.map { ("", $0) }
+    public init(_ data: [Double], rangeY: ClosedRange<FloatLiteralType>? = nil) {
+        self.data = data.enumerated().map{ (index, value) in (Double(index), value) }
+        self.rangeY = rangeY
     }
 
-    public init(_ data: [(String, Double)]) {
+    public init(_ data: [(Double, Double)], rangeY: ClosedRange<FloatLiteralType>? = nil) {
         self.data = data
+        self.rangeY = rangeY
     }
 
     public init() {

Sources/SwiftUICharts/Base/Extensions/ChartBase+Extension.swift

@@ -1,21 +1,23 @@
 import SwiftUI
 
-extension View where Self: ChartBase {
-	
-	/// Set data for a chart
-	/// - Parameter data: array of `Double`
-	/// - Returns: modified `View` with data attached
-    public func data(_ data: [Double]) -> some View {
-        chartData.data = data.map { ("", $0) }
+extension ChartBase {
+    public func data(_ data: [Double]) -> some ChartBase {
+        chartData.data = data.enumerated().map{ (index, value) in (Double(index), value) }
         return self
-            .environmentObject(chartData)
-            .environmentObject(ChartValue())
     }
 
-    public func data(_ data: [(String, Double)]) -> some View {
+    public func data(_ data: [(Double, Double)]) -> some ChartBase {
         chartData.data = data
         return self
-            .environmentObject(chartData)
-            .environmentObject(ChartValue())
+    }
+
+    public func rangeY(_ range: ClosedRange<FloatLiteralType>) -> some ChartBase{
+        chartData.rangeY = range
+        return self
+    }
+
+    public func rangeX(_ range: ClosedRange<FloatLiteralType>) -> some ChartBase{
+        chartData.rangeX = range
+        return self
     }
 }

Sources/SwiftUICharts/Base/Extensions/Path+QuadCurve.swift

@@ -1,47 +1,31 @@
 import SwiftUI
 
 extension Path {
-
-	/// Returns a tiny segment of path based on percentage along the path
-	///
-	/// TODO: Explain why more than 1 gets 0 and why less than 0 gets 1
-	/// - Parameter percent: fraction along data set, between 0.0 and 1.0 (underflow and overflow are handled)
-	/// - Returns: tiny path right around the requested fraction
     func trimmedPath(for percent: CGFloat) -> Path {
         let boundsDistance: CGFloat = 0.001
         let completion: CGFloat = 1 - boundsDistance
         
         let pct = percent > 1 ? 0 : (percent < 0 ? 1 : percent)
 
-		// Start/end points centered around given percentage, but capped if right at the very end
+        // Start/end points centered around given percentage, but capped if right at the very end
         let start = pct > completion ? completion : pct - boundsDistance
         let end = pct > completion ? 1 : pct + boundsDistance
         return trimmedPath(from: start, to: end)
     }
 
-	/// Find the `CGPoint` for the given fraction along the path.
-	///
-	/// This works by requesting a very tiny trimmed section of the path, then getting the center of the bounds rectangle
-	/// - Parameter percent: fraction along data set, between 0.0 and 1.0 (underflow and overflow are handled)
-	/// - Returns: a `CGPoint` representing the location of that section of the path
     func point(for percent: CGFloat) -> CGPoint {
         let path = trimmedPath(for: percent)
         return CGPoint(x: path.boundingRect.midX, y: path.boundingRect.midY)
     }
 
-	/// <#Description#>
-	/// - Parameter maxX: <#maxX description#>
-	/// - Returns: <#description#>
     func point(to maxX: CGFloat) -> CGPoint {
         let total = length
         let sub = length(to: maxX)
         let percent = sub / total
         return point(for: percent)
     }
-    
-	/// <#Description#>
-	/// - Returns: <#description#>
-   var length: CGFloat {
+
+    var length: CGFloat {
         var ret: CGFloat = 0.0
         var start: CGPoint?
         var point = CGPoint.zero
@@ -73,9 +57,6 @@ extension Path {
         return ret
     }
 
-	/// <#Description#>
-	/// - Parameter maxX: <#maxX description#>
-	/// - Returns: <#description#>
     func length(to maxX: CGFloat) -> CGFloat {
         var ret: CGFloat = 0.0
         var start: CGPoint?
@@ -127,19 +108,13 @@ extension Path {
         return ret
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - points: <#points description#>
-	///   - step: <#step description#>
-	///   - globalOffset: <#globalOffset description#>
-	/// - Returns: <#description#>
     static func quadCurvedPathWithPoints(points: [Double], step: CGPoint, globalOffset: Double? = nil) -> Path {
         var path = Path()
         if points.count < 2 {
             return path
         }
         let offset = globalOffset ?? points.min()!
-//        guard let offset = points.min() else { return path }
+        //        guard let offset = points.min() else { return path }
         var point1 = CGPoint(x: 0, y: CGFloat(points[0]-offset)*step.y)
         path.move(to: point1)
         for pointIndex in 1..<points.count {
@@ -152,25 +127,83 @@ extension Path {
         return path
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - points: <#points description#>
-	///   - step: <#step description#>
-	///   - globalOffset: <#globalOffset description#>
-	/// - Returns: <#description#>
-    static func quadClosedCurvedPathWithPoints(points: [Double], step: CGPoint, globalOffset: Double? = nil) -> Path {
+    static func quadCurvedPathWithPoints(data: [(Double, Double)], in rect: CGRect) -> Path {
         var path = Path()
-        if points.count < 2 {
+        if data.count < 2 {
             return path
         }
-        let offset = globalOffset ?? points.min()!
 
-//        guard let offset = points.min() else { return path }
+        let convertedXValues = data.map { CGFloat($0.0) * rect.width }
+        let convertedYPoints = data.map { CGFloat($0.1) * rect.height }
+
+        var point1 = CGPoint(x: convertedXValues[0], y: convertedYPoints[0])
+        path.move(to: point1)
+        for pointIndex in 1..<data.count {
+            let point2 = CGPoint(x: CGFloat(convertedXValues[pointIndex]), y: CGFloat(convertedYPoints[pointIndex]))
+            let midPoint = CGPoint.midPointForPoints(firstPoint: point1, secondPoint: point2)
+            path.addQuadCurve(to: midPoint, control: CGPoint.controlPointForPoints(firstPoint: midPoint, secondPoint: point1))
+            path.addQuadCurve(to: point2, control: CGPoint.controlPointForPoints(firstPoint: midPoint, secondPoint: point2))
+            point1 = point2
+        }
+        return path
+    }
+
+    static func drawChartMarkers(data: [(Double, Double)], in rect: CGRect) -> Path {
+        var path = Path()
+        if data.count < 1 {
+            return path
+        }
+
+        let convertedXValues = data.map { CGFloat($0.0) * rect.width }
+        let convertedYPoints = data.map { CGFloat($0.1) * rect.height }
+
+        let markerSize = CGSize(width: 8, height: 8)
+        for pointIndex in 0..<data.count {
+            path.addRoundedRect(in: CGRect(origin: CGPoint(x: convertedXValues[pointIndex] - markerSize.width / 2,
+                                                           y: convertedYPoints[pointIndex] - markerSize.height / 2),
+                                           size: markerSize),
+                                cornerSize: CGSize(width: markerSize.width / 2,
+                                                   height: markerSize.height / 2))
+        }
+        return path
+    }
+
+    static func drawGridLines(numberOfHorizontalLines: Int, numberOfVerticalLines: Int, in rect: CGRect) -> Path {
+        var path = Path()
+
+        for index in 0..<numberOfHorizontalLines {
+            let normalisedSpacing = 1.0 / CGFloat(numberOfHorizontalLines - 1)
+            let startPoint = CGPoint(x: 0, y: normalisedSpacing * CGFloat(index) * rect.height)
+            let endPoint = CGPoint(x: rect.width, y: normalisedSpacing * CGFloat(index) * rect.height)
+            path.move(to: startPoint)
+            path.addLine(to: endPoint)
+        }
+
+        for index in 0..<numberOfVerticalLines {
+            let normalisedSpacing = 1.0 / CGFloat(numberOfVerticalLines - 1)
+            let startPoint = CGPoint(x: normalisedSpacing * CGFloat(index) * rect.width, y: 0)
+            let endPoint = CGPoint(x: normalisedSpacing * CGFloat(index) * rect.width, y: rect.height)
+            path.move(to: startPoint)
+            path.addLine(to: endPoint)
+        }
+
+        return path
+    }
+
+    static func quadClosedCurvedPathWithPoints(data: [(Double, Double)], in rect: CGRect) -> Path {
+        var path = Path()
+        if data.count < 2 {
+            return path
+        }
+
+        let convertedXValues = data.map { CGFloat($0.0) * rect.width }
+        let convertedYPoints = data.map { CGFloat($0.1) * rect.height }
+
         path.move(to: .zero)
-        var point1 = CGPoint(x: 0, y: CGFloat(points[0]-offset)*step.y)
+        var point1 = CGPoint(x: convertedXValues[0], y: convertedYPoints[0])
         path.addLine(to: point1)
-        for pointIndex in 1..<points.count {
-            let point2 = CGPoint(x: step.x * CGFloat(pointIndex), y: step.y*CGFloat(points[pointIndex]-offset))
+        for pointIndex in 1..<data.count {
+            let point2 = CGPoint(x: CGFloat(convertedXValues[pointIndex]), y: CGFloat(convertedYPoints[pointIndex]))
             let midPoint = CGPoint.midPointForPoints(firstPoint: point1, secondPoint: point2)
             path.addQuadCurve(to: midPoint, control: CGPoint.controlPointForPoints(firstPoint: midPoint, secondPoint: point1))
             path.addQuadCurve(to: point2, control: CGPoint.controlPointForPoints(firstPoint: midPoint, secondPoint: point2))
@@ -181,88 +214,64 @@ extension Path {
         return path
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - points: <#points description#>
-	///   - step: <#step description#>
-	/// - Returns: <#description#>
-    static func linePathWithPoints(points: [Double], step: CGPoint) -> Path {
+    static func linePathWithPoints(data: [(Double, Double)], in rect: CGRect) -> Path {
         var path = Path()
-        if points.count < 2 {
+        if data.count < 2 {
             return path
         }
-        guard let offset = points.min() else {
-            return path
-        }
-        let point1 = CGPoint(x: 0, y: CGFloat(points[0]-offset)*step.y)
+
+        let convertedXValues = data.map { CGFloat($0.0) * rect.width }
+        let convertedYPoints = data.map { CGFloat($0.1) * rect.height }
+
+        let point1 = CGPoint(x: convertedXValues[0], y: convertedYPoints[0])
         path.move(to: point1)
-        for pointIndex in 1..<points.count {
-            let point2 = CGPoint(x: step.x * CGFloat(pointIndex), y: step.y*CGFloat(points[pointIndex]-offset))
+        for pointIndex in 1..<data.count {
+            let point2 = CGPoint(x: CGFloat(convertedXValues[pointIndex]), y: CGFloat(convertedYPoints[pointIndex]))
             path.addLine(to: point2)
         }
         return path
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - points: <#points description#>
-	///   - step: <#step description#>
-	/// - Returns: <#description#>
-    static func closedLinePathWithPoints(points: [Double], step: CGPoint) -> Path {
+    static func closedLinePathWithPoints(data: [(Double, Double)], in rect: CGRect) -> Path {
         var path = Path()
-        if points.count < 2 {
+        if data.count < 2 {
             return path
         }
-        guard let offset = points.min() else {
-            return path
-        }
-        var point1 = CGPoint(x: 0, y: CGFloat(points[0]-offset)*step.y)
-        path.move(to: point1)
-        for pointIndex in 1..<points.count {
-            point1 = CGPoint(x: step.x * CGFloat(pointIndex), y: step.y*CGFloat(points[pointIndex]-offset))
-            path.addLine(to: point1)
+
+        let convertedXValues = data.map { CGFloat($0.0) * rect.width }
+        let convertedYPoints = data.map { CGFloat($0.1) * rect.height }
+        path.move(to: .zero)
+
+        let point1 = CGPoint(x: convertedXValues[0], y: convertedYPoints[0])
+        path.addLine(to: point1)
+
+        for pointIndex in 1..<data.count {
+            let point2 = CGPoint(x: CGFloat(convertedXValues[pointIndex]), y: CGFloat(convertedYPoints[pointIndex]))
+            path.addLine(to: point2)
         }
         path.addLine(to: CGPoint(x: point1.x, y: 0))
         path.closeSubpath()
+
         return path
     }
     
 }
 
 extension CGPoint {
-
-	/// <#Description#>
-	/// - Parameters:
-	///   - to: <#to description#>
-	///   - x: <#x description#>
-	/// - Returns: <#description#>
     func point(to: CGPoint, x: CGFloat) -> CGPoint {
         let a = (to.y - self.y) / (to.x - self.x)
         let y = self.y + (x - self.x) * a
         return CGPoint(x: x, y: y)
     }
 
-	/// <#Description#>
-	/// - Parameter to: <#to description#>
-	/// - Returns: <#description#>
     func line(to: CGPoint) -> CGFloat {
         dist(to: to)
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - to: <#to description#>
-	///   - x: <#x description#>
-	/// - Returns: <#description#>
     func line(to: CGPoint, x: CGFloat) -> CGFloat {
         dist(to: point(to: to, x: x))
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - to: <#to description#>
-	///   - control: <#control description#>
-	/// - Returns: <#description#>
     func quadCurve(to: CGPoint, control: CGPoint) -> CGFloat {
         var dist: CGFloat = 0
         let steps: CGFloat = 100
@@ -278,12 +287,6 @@ extension CGPoint {
         return dist
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - to: <#to description#>
-	///   - control: <#control description#>
-	///   - x: <#x description#>
-	/// - Returns: <#description#>
     func quadCurve(to: CGPoint, control: CGPoint, x: CGFloat) -> CGFloat {
         var dist: CGFloat = 0
         let steps: CGFloat = 100
@@ -309,12 +312,6 @@ extension CGPoint {
         return dist
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - to: <#to description#>
-	///   - t: <#t description#>
-	///   - control: <#control description#>
-	/// - Returns: <#description#>
     func point(to: CGPoint, t: CGFloat, control: CGPoint) -> CGPoint {
         let x = CGPoint.value(x: self.x, y: to.x, t: t, c: control.x)
         let y = CGPoint.value(x: self.y, y: to.y, t: t, c: control.y)
@@ -322,12 +319,6 @@ extension CGPoint {
         return CGPoint(x: x, y: y)
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - to: <#to description#>
-	///   - control1: <#control1 description#>
-	///   - control2: <#control2 description#>
-	/// - Returns: <#description#>
     func curve(to: CGPoint, control1: CGPoint, control2: CGPoint) -> CGFloat {
         var dist: CGFloat = 0
         let steps: CGFloat = 100
@@ -345,13 +336,6 @@ extension CGPoint {
         return dist
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - to: <#to description#>
-	///   - control1: <#control1 description#>
-	///   - control2: <#control2 description#>
-	///   - x: <#x description#>
-	/// - Returns: <#description#>
     func curve(to: CGPoint, control1: CGPoint, control2: CGPoint, x: CGFloat) -> CGFloat {
         var dist: CGFloat = 0
         let steps: CGFloat = 100
@@ -379,13 +363,6 @@ extension CGPoint {
         return dist
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - to: <#to description#>
-	///   - t: <#t description#>
-	///   - control1: <#control1 description#>
-	///   - control2: <#control2 description#>
-	/// - Returns: <#description#>
     func point(to: CGPoint, t: CGFloat, control1: CGPoint, control2: CGPoint) -> CGPoint {
         let x = CGPoint.value(x: self.x, y: to.x, t: t, control1: control1.x, control2: control2.x)
         let y = CGPoint.value(x: self.y, y: to.y, t: t, control1: control1.y, control2: control2.x)
@@ -393,13 +370,6 @@ extension CGPoint {
         return CGPoint(x: x, y: y)
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - x: <#x description#>
-	///   - y: <#y description#>
-	///   - t: <#t description#>
-	///   - c: <#c description#>
-	/// - Returns: <#description#>
     static func value(x: CGFloat, y: CGFloat, t: CGFloat, c: CGFloat) -> CGFloat {
         var value: CGFloat = 0.0
         // (1-t)^2 * p0 + 2 * (1-t) * t * c1 + t^2 * p1
@@ -409,14 +379,6 @@ extension CGPoint {
         return value
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - x: <#x description#>
-	///   - y: <#y description#>
-	///   - t: <#t description#>
-	///   - control1: <#control1 description#>
-	///   - control2: <#control2 description#>
-	/// - Returns: <#description#>
     static func value(x: CGFloat, y: CGFloat, t: CGFloat, control1: CGFloat, control2: CGFloat) -> CGFloat {
         var value: CGFloat = 0.0
         // (1-t)^3 * p0 + 3 * (1-t)^2 * t * c1 + 3 * (1-t) * t^2 * c2 + t^3 * p1
@@ -427,11 +389,6 @@ extension CGPoint {
         return value
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - point1: <#point1 description#>
-	///   - point2: <#point2 description#>
-	/// - Returns: <#description#>
     static func getMidPoint(point1: CGPoint, point2: CGPoint) -> CGPoint {
         return CGPoint(
             x: point1.x + (point2.x - point1.x) / 2,
@@ -439,29 +396,16 @@ extension CGPoint {
         )
     }
 
-	/// <#Description#>
-	/// - Parameter to: <#to description#>
-	/// - Returns: <#description#>
     func dist(to: CGPoint) -> CGFloat {
         return sqrt((pow(self.x - to.x, 2) + pow(self.y - to.y, 2)))
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - firstPoint: <#firstPoint description#>
-	///   - secondPoint: <#secondPoint description#>
-	/// - Returns: <#description#>
     static func midPointForPoints(firstPoint: CGPoint, secondPoint: CGPoint) -> CGPoint {
         return CGPoint(
             x: (firstPoint.x + secondPoint.x) / 2,
             y: (firstPoint.y + secondPoint.y) / 2)
     }
 
-	/// <#Description#>
-	/// - Parameters:
-	///   - firstPoint: <#firstPoint description#>
-	///   - secondPoint: <#secondPoint description#>
-	/// - Returns: <#description#>
     static func controlPointForPoints(firstPoint: CGPoint, secondPoint: CGPoint) -> CGPoint {
         var controlPoint = CGPoint.midPointForPoints(firstPoint: firstPoint, secondPoint: secondPoint)
         let diffY = abs(secondPoint.y - controlPoint.y)

Sources/SwiftUICharts/Base/Extensions/Range+Extension.swift

@@ -0,0 +1,7 @@
+import Foundation
+
+public extension ClosedRange where Bound: AdditiveArithmetic {
+    var overreach: Bound {
+        self.upperBound - self.lowerBound
+    }
+}

Sources/SwiftUICharts/Base/Extensions/Shape+Extension.swift

@@ -0,0 +1,17 @@
+import SwiftUI
+
+extension Shape {
+    func fill<Fill: ShapeStyle, Stroke: ShapeStyle>(_ fillStyle: Fill, strokeBorder strokeStyle: Stroke, lineWidth: Double = 1) -> some View {
+        self
+            .stroke(strokeStyle, lineWidth: lineWidth)
+            .background(self.fill(fillStyle))
+    }
+}
+
+extension InsettableShape {
+    func fill<Fill: ShapeStyle, Stroke: ShapeStyle>(_ fillStyle: Fill, strokeBorder strokeStyle: Stroke, lineWidth: Double = 1) -> some View {
+        self
+            .strokeBorder(strokeStyle, lineWidth: lineWidth)
+            .background(self.fill(fillStyle))
+    }
+}

Sources/SwiftUICharts/Base/Grid/ChartGrid.swift

@@ -1,53 +1,24 @@
 import SwiftUI
 
-public struct ChartGrid<Content: View>: View, ChartBase {
-    public var chartData = ChartData()
+public struct ChartGrid<Content: View>: View {
     let content: () -> Content
-    let numberOfHorizontalLines = 4
-
-    @EnvironmentObject var data: ChartData
-    @EnvironmentObject var style: ChartStyle
+    public var gridOptions = GridOptions()
 
     public init(@ViewBuilder content: @escaping () -> Content) {
         self.content = content
     }
 
     public var body: some View {
-        HStack {
-            ZStack {
-                VStack {
-                    ForEach(0..<numberOfHorizontalLines) { _ in 
-                        GridElement()
-                        Spacer()
-                    }
-                }
-                self.content()
+        ZStack {
+            ChartGridShape(numberOfHorizontalLines: gridOptions.numberOfHorizontalLines,
+                           numberOfVerticalLines: gridOptions.numberOfVerticalLines)
+            .stroke(gridOptions.color, style: gridOptions.strokeStyle)
+            if gridOptions.showBaseLine {
+                ChartGridBaseShape()
+                    .stroke(gridOptions.color, style: gridOptions.baseStrokeStyle)
+                    .rotationEffect(.degrees(180), anchor: .center)
             }
+            self.content()
         }
     }
 }
-
-struct GridElement: View {
-    var body: some View {
-        DashedLine()
-            .frame(maxHeight: 2, alignment: .center)
-    }
-}
-
-struct DashedLine: View {
-    func line(frame: CGRect) -> Path {
-        let baseLine: CGFloat = CGFloat(frame.height / 2)
-        var hLine = Path()
-        hLine.move(to: CGPoint(x:0, y: baseLine))
-        hLine.addLine(to: CGPoint(x: frame.width, y: baseLine))
-        return hLine
-    }
-
-    var body: some View {
-        GeometryReader { geometry in
-            line(frame: geometry.frame(in: .local))
-                .stroke(Color(white: 0.85), style: StrokeStyle(lineWidth: 1, lineCap: .round, dash: [5, 10]))
-        }
-    }
-}
-

Sources/SwiftUICharts/Base/Grid/ChartGridBaseShape.swift

@@ -0,0 +1,18 @@
+import SwiftUI
+
+struct ChartGridBaseShape: Shape {
+    func path(in rect: CGRect) -> Path {
+        var path = Path()
+        path.move(to: CGPoint(x: 0, y: 0))
+        path.addLine(to: CGPoint(x: rect.width, y: 0))
+        return path
+    }
+}
+
+struct ChartGridBaseShape_Previews: PreviewProvider {
+    static var previews: some View {
+        ChartGridBaseShape()
+            .stroke()
+            .rotationEffect(.degrees(180), anchor: .center)
+    }
+}

Sources/SwiftUICharts/Base/Grid/ChartGridShape.swift

@@ -0,0 +1,30 @@
+import SwiftUI
+
+struct ChartGridShape: Shape {
+    var numberOfHorizontalLines: Int
+    var numberOfVerticalLines: Int
+
+    func path(in rect: CGRect) -> Path {
+        let path = Path.drawGridLines(numberOfHorizontalLines: numberOfHorizontalLines,
+                                      numberOfVerticalLines: numberOfVerticalLines,
+                                      in: rect)
+        return path
+    }
+}
+
+struct ChartGridShape_Previews: PreviewProvider {
+    static var previews: some View {
+        Group {
+            ChartGridShape(numberOfHorizontalLines: 5, numberOfVerticalLines: 0)
+                .stroke()
+                .rotationEffect(.degrees(180), anchor: .center)
+                                    .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))
+
+            ChartGridShape(numberOfHorizontalLines: 4, numberOfVerticalLines: 4)
+                .stroke()
+                .rotationEffect(.degrees(180), anchor: .center)
+                                    .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))
+        }
+        .padding()
+    }
+}

Sources/SwiftUICharts/Base/Grid/Extension/Grid+Extension.swift

@@ -0,0 +1,31 @@
+import SwiftUI
+
+extension ChartGrid {
+    public func setNumberOfHorizontalLines(_ numberOfLines: Int) -> ChartGrid {
+        self.gridOptions.numberOfHorizontalLines = numberOfLines
+        return self
+    }
+
+    public func setNumberOfVerticalLines(_ numberOfLines: Int) -> ChartGrid {
+        self.gridOptions.numberOfVerticalLines = numberOfLines
+        return self
+    }
+
+    public func setStoreStyle(_ strokeStyle: StrokeStyle) -> ChartGrid {
+        self.gridOptions.strokeStyle = strokeStyle
+        return self
+    }
+
+    public func setColor(_ color: Color) -> ChartGrid {
+        self.gridOptions.color = color
+        return self
+    }
+
+    public func showBaseLine(_ show: Bool, with style: StrokeStyle? = nil) -> ChartGrid {
+        self.gridOptions.showBaseLine = show
+        if let style = style {
+            self.gridOptions.baseStrokeStyle = style
+        }
+        return self
+    }
+}

Sources/SwiftUICharts/Base/Grid/Model/GridOptions.swift

@@ -0,0 +1,14 @@
+import SwiftUI
+
+public final class GridOptions: ObservableObject {
+    @Published public var numberOfHorizontalLines: Int = 3
+    @Published public var numberOfVerticalLines: Int = 3
+    @Published public var strokeStyle: StrokeStyle = StrokeStyle(lineWidth: 1, lineCap: .round, dash: [5, 10])
+    @Published public var color: Color = Color(white: 0.85)
+    @Published public var showBaseLine: Bool = true
+    @Published public var baseStrokeStyle: StrokeStyle = StrokeStyle(lineWidth: 1.5, lineCap: .round, dash: [5, 0])
+
+    public init() {
+        // no-op
+    }
+}

Sources/SwiftUICharts/Base/Label/ChartLabel.swift

@@ -39,13 +39,13 @@ public struct ChartLabel: View {
     private var labelPadding: EdgeInsets {
         switch labelType {
         case .title:
-            return EdgeInsets(top: 16.0, leading: 8.0, bottom: 0.0, trailing: 8.0)
+            return EdgeInsets(top: 16.0, leading: 0, bottom: 0.0, trailing: 8.0)
         case .legend:
-            return EdgeInsets(top: 4.0, leading: 8.0, bottom: 0.0, trailing: 8.0)
+            return EdgeInsets(top: 4.0, leading: 0, bottom: 0.0, trailing: 8.0)
         case .subTitle:
-            return EdgeInsets(top: 8.0, leading: 8.0, bottom: 0.0, trailing: 8.0)
+            return EdgeInsets(top: 8.0, leading: 0, bottom: 0.0, trailing: 8.0)
         case .largeTitle:
-            return EdgeInsets(top: 24.0, leading: 8.0, bottom: 0.0, trailing: 8.0)
+            return EdgeInsets(top: 24.0, leading: 0, bottom: 0.0, trailing: 8.0)
         case .custom(_, let padding, _):
             return padding
         }
@@ -59,13 +59,13 @@ public struct ChartLabel: View {
     private var labelColor: Color {
         switch labelType {
         case .title:
-            return Color(UIColor.label)
+            return Color.primary
         case .legend:
-            return Color(UIColor.secondaryLabel)
+            return Color.secondary
         case .subTitle:
-            return Color(UIColor.label)
+            return Color.primary
         case .largeTitle:
-            return Color(UIColor.label)
+            return Color.primary
         case .custom(_, _, let color):
             return color
         }

Sources/SwiftUICharts/Base/Style/ChartStyle.swift

@@ -1,44 +1,24 @@
 import SwiftUI
 
-/// Descripton of colors/styles for any kind of chart
 public class ChartStyle: ObservableObject {
-
-	/// colors for background are of chart
 	public let backgroundColor: ColorGradient
-	/// colors for foreground fill of chart
     public let foregroundColor: [ColorGradient]
 
-	/// Initialize with a single background color and an array of `ColorGradient` for the foreground
-	/// - Parameters:
-	///   - backgroundColor: a `Color`
-	///   - foregroundColor: array of `ColorGradient`
     public init(backgroundColor: Color, foregroundColor: [ColorGradient]) {
         self.backgroundColor = ColorGradient.init(backgroundColor)
         self.foregroundColor = foregroundColor
     }
 
-	/// Initialize with a single background color and a single `ColorGradient` for the foreground
-	/// - Parameters:
-	///   - backgroundColor: a `Color`
-	///   - foregroundColor: a `ColorGradient`
     public init(backgroundColor: Color, foregroundColor: ColorGradient) {
         self.backgroundColor = ColorGradient.init(backgroundColor)
         self.foregroundColor = [foregroundColor]
     }
 
-	/// Initialize with a single background `ColorGradient` and a single `ColorGradient` for the foreground
-	/// - Parameters:
-	///   - backgroundColor: a `ColorGradient`
-	///   - foregroundColor: a `ColorGradient`
     public init(backgroundColor: ColorGradient, foregroundColor: ColorGradient) {
         self.backgroundColor = backgroundColor
         self.foregroundColor = [foregroundColor]
     }
 
-	/// Initialize with a  single background `ColorGradient` and an array of `ColorGradient` for the foreground
-	/// - Parameters:
-	///   - backgroundColor: a `ColorGradient`
-	///   - foregroundColor: array of `ColorGradient`
     public init(backgroundColor: ColorGradient, foregroundColor: [ColorGradient]) {
         self.backgroundColor = backgroundColor
         self.foregroundColor = foregroundColor

Sources/SwiftUICharts/Base/Style/ColorGradient.swift

@@ -1,39 +1,25 @@
 import SwiftUI
 
-/// An encapsulation of a simple gradient between one color and another
 public struct ColorGradient: Equatable {
 	public let startColor: Color
     public let endColor: Color
 
-	/// Initialize as a solid color
-	/// - Parameter color: a  single `Color` (no gradient effect visible)
     public init(_ color: Color) {
         self.startColor = color
         self.endColor = color
     }
 
-	/// Initialize a color gradient from two specified colors
-	/// - Parameters:
-	///   - startColor: starting color
-	///   - endColor: ending color
     public init(_ startColor: Color, _ endColor: Color) {
         self.startColor = startColor
         self.endColor = endColor
     }
 
-	/// Convert to a  `Gradient` object (more complicated than just two colors)
-	/// - Returns: a `Gradient` between the specified start and end colors
     public var gradient: Gradient {
         return Gradient(colors: [startColor, endColor])
     }
 }
 
 extension ColorGradient {
-    /// Convenience method to return a SwiftUI LinearGradient view from the ColorGradient
-    /// - Parameters:
-    ///   - startPoint: starting point
-    ///   - endPoint: ending point
-    /// - Returns: a Linear gradient
     public func linearGradient(from startPoint: UnitPoint, to endPoint: UnitPoint) -> LinearGradient {
         return LinearGradient(gradient: self.gradient, startPoint: startPoint, endPoint: endPoint)
     }

Sources/SwiftUICharts/Base/Style/Colors.swift

@@ -1,8 +1,6 @@
 import SwiftUI
 
-/// Some predefined colors, used for demos, defaults if color is missing, and data indicator point
 public enum ChartColors {
-    // Orange
     public static let orangeBright = Color(hexString: "#FF782C")
     public static let orangeDark = Color(hexString: "#EC2301")
 

Sources/SwiftUICharts/Charts/BarChart/BarChart.swift

@@ -1,17 +1,12 @@
 import SwiftUI
 
-/// A type of chart that displays vertical bars for each data point
-public struct BarChart: View, ChartBase {
+public struct BarChart: ChartBase {
     public var chartData = ChartData()
 
-    @EnvironmentObject var data: ChartData
     @EnvironmentObject var style: ChartStyle
 
-	/// The content and behavior of the `BarChart`.
-	///
-	///
     public var body: some View {
-        BarChartRow(chartData: data, style: style)
+        BarChartRow(chartData: chartData, style: style)
     }
 
     public init() {}

Sources/SwiftUICharts/Charts/BarChart/BarChartCell.swift

@@ -1,6 +1,5 @@
 import SwiftUI
 
-/// A single vertical bar in a `BarChart`
 public struct BarChartCell: View {
     var value: Double
     var index: Int = 0
@@ -19,9 +18,6 @@ public struct BarChartCell: View {
         self.touchLocation = touchLocation
     }
 
-	/// The content and behavior of the `BarChartCell`.
-	///
-	/// Animated when first displayed, using the `firstDisplay` variable, with an increasing delay through the data set.
     public var body: some View {
         BarChartCellShape(value: didCellAppear ? value : 0.0)
         .fill(gradientColor.linearGradient(from: .bottom, to: .top))        .onAppear {

Sources/SwiftUICharts/Charts/BarChart/BarChartCellShape.swift

@@ -3,6 +3,7 @@ import SwiftUI
 struct BarChartCellShape: Shape, Animatable {
     var value: Double
     var cornerRadius: CGFloat = 6.0
+    
     var animatableData: CGFloat {
         get { CGFloat(value) }
         set { value = Double(newValue) }
@@ -16,14 +17,14 @@ struct BarChartCellShape: Shape, Animatable {
         path.addArc(center: CGPoint(x: cornerRadius, y: adjustedOriginY +  cornerRadius),
                     radius: cornerRadius,
                     startAngle: Angle(radians: Double.pi),
-                    endAngle: Angle(radians: -Double.pi/2),
-                    clockwise: false)
-        path.addLine(to: CGPoint(x: rect.width - cornerRadius, y: adjustedOriginY))
+                    endAngle: Angle(radians: value < 0 ? Double.pi/2 : -Double.pi/2),
+                    clockwise: value < 0 ? true : false)
+        path.addLine(to: CGPoint(x: rect.width - cornerRadius, y: value < 0 ? adjustedOriginY + 2 * cornerRadius : adjustedOriginY))
         path.addArc(center: CGPoint(x: rect.width - cornerRadius, y: adjustedOriginY + cornerRadius),
                     radius: cornerRadius,
-                    startAngle: Angle(radians: -Double.pi/2),
+                    startAngle: Angle(radians: value < 0 ? Double.pi/2 : -Double.pi/2),
                     endAngle: Angle(radians: 0),
-                    clockwise: false)
+                    clockwise: value < 0 ? true : false)
         path.addLine(to: CGPoint(x: rect.width, y: rect.height))
         path.closeSubpath()
 
@@ -39,6 +40,10 @@ struct BarChartCellShape_Previews: PreviewProvider {
 
             BarChartCellShape(value: 0.3)
                 .fill(Color.blue)
+            
+            BarChartCellShape(value: -0.3)
+                .fill(Color.blue)
+                .offset(x: 0, y: -600)
         }
     }
 }

Sources/SwiftUICharts/Charts/BarChart/BarChartRow.swift

@@ -1,6 +1,5 @@
 import SwiftUI
 
-/// A single row of data, a view in a `BarChart`
 public struct BarChartRow: View {
     @EnvironmentObject var chartValue: ChartValue
     @ObservedObject var chartData: ChartData
@@ -15,11 +14,6 @@ public struct BarChartRow: View {
         return max != 0 ? max : 1
     }
 
-	/// The content and behavior of the `BarChartRow`.
-	///
-	/// Shows each `BarChartCell` in an `HStack`; may be scaled up if it's the one currently being touched.
-	/// Not using a drawing group for optimizing animation.
-	/// As touched (dragged) the `touchLocation` is updated and the current value is highlighted.
     public var body: some View {
         GeometryReader { geometry in
             HStack(alignment: .bottom,
@@ -52,11 +46,6 @@ public struct BarChartRow: View {
         }
     }
 
-	/// Size to scale the touch indicator
-	/// - Parameters:
-	///   - touchLocation: fraction of width where touch is happening
-	///   - index: index into data array
-	/// - Returns: a scale larger than 1.0 if in bounds; 1.0 (unscaled) if not in bounds
     func getScaleSize(touchLocation: CGFloat, index: Int) -> CGSize {
         if touchLocation > CGFloat(index)/CGFloat(chartData.data.count) &&
            touchLocation < CGFloat(index+1)/CGFloat(chartData.data.count) {
@@ -65,9 +54,6 @@ public struct BarChartRow: View {
         return CGSize(width: 1, height: 1)
     }
 
-	/// Get data value where touch happened
-	/// - Parameter width: width of chart
-	/// - Returns: value as `Double` if chart has data
     func getCurrentValue(width: CGFloat) -> Double? {
         guard self.chartData.data.count > 0 else { return nil}
             let index = max(0,min(self.chartData.data.count-1,Int(floor((self.touchLocation*width)/(width/CGFloat(self.chartData.data.count))))))

Sources/SwiftUICharts/Charts/LineChart/Extension/LineChart+Extension.swift

@@ -0,0 +1,23 @@
+import SwiftUI
+
+extension LineChart {
+    public func setLineWidth(width: CGFloat) -> LineChart {
+        self.chartProperties.lineWidth = width
+        return self
+    }
+
+    public func showBackground(_ show: Bool) -> LineChart {
+        self.chartProperties.showBackground = show
+        return self
+    }
+
+    public func showChartMarks(_ show: Bool) -> LineChart {
+        self.chartProperties.showChartMarks = show
+        return self
+    }
+
+    public func setLineStyle(to style: LineStyle) -> LineChart {
+        self.chartProperties.lineStyle = style
+        return self
+    }
+}

Sources/SwiftUICharts/Charts/LineChart/IndicatorPoint.swift

@@ -1,10 +1,6 @@
 import SwiftUI
 
-/// A dot representing a single data point as user moves finger over line in `LineChart`
 struct IndicatorPoint: View {
-	/// The content and behavior of the `IndicatorPoint`.
-	///
-	/// A filled circle with a thick white outline and a shadow
     public var body: some View {
         ZStack {
             Circle()

Sources/SwiftUICharts/Charts/LineChart/Line.swift

@@ -4,33 +4,38 @@ import SwiftUI
 public struct Line: View {
     @EnvironmentObject var chartValue: ChartValue
     @ObservedObject var chartData: ChartData
+    @ObservedObject var chartProperties: LineChartProperties
 
+    var curvedLines: Bool = true
     var style: ChartStyle
 
     @State private var showIndicator: Bool = false
     @State private var touchLocation: CGPoint = .zero
-    @State private var showBackground: Bool = true
     @State private var didCellAppear: Bool = false
 
-    var curvedLines: Bool = true
     var path: Path {
         Path.quadCurvedPathWithPoints(points: chartData.normalisedPoints,
                                       step: CGPoint(x: 1.0, y: 1.0))
     }
+
+    public init(chartData: ChartData,
+                style: ChartStyle,
+                chartProperties: LineChartProperties) {
+        self.chartData = chartData
+        self.style = style
+        self.chartProperties = chartProperties
+    }
     
-	/// The content and behavior of the `Line`.
-	/// Draw the background if showing the full line (?) and the `showBackground` option is set. Above that draw the line, and then the data indicator if the graph is currently being touched.
-	/// On appear, set the frame so that the data graph metrics can be calculated. On a drag (touch) gesture, highlight the closest touched data point.
-	/// TODO: explain rotation
     public var body: some View {
         GeometryReader { geometry in
             ZStack {
-                if self.didCellAppear && self.showBackground {
+                if self.didCellAppear && self.chartProperties.showBackground {
                     LineBackgroundShapeView(chartData: chartData,
                                             geometry: geometry,
                                             style: style)
                 }
                 LineShapeView(chartData: chartData,
+                              chartProperties: chartProperties,
                               geometry: geometry,
                               style: style,
                               trimTo: didCellAppear ? 1.0 : 0.0)
@@ -79,7 +84,7 @@ extension Line {
         let closest = self.path.point(to: normalisedTouchLocationX)
         var denormClosest = closest.denormalize(with: geometry)
         denormClosest.x = denormClosest.x / CGFloat(chartData.normalisedPoints.count - 1)
-        denormClosest.y = denormClosest.y / CGFloat(chartData.normalisedRange)
+        denormClosest.y = denormClosest.y / CGFloat(chartData.normalisedYRange)
         return denormClosest
     }
 
@@ -103,8 +108,12 @@ struct Line_Previews: PreviewProvider {
 
     static var previews: some View {
         Group {
-            Line(chartData:  ChartData([8, 23, 32, 7, 23, -4]), style: blackLineStyle)
-            Line(chartData:  ChartData([8, 23, 32, 7, 23, 43]), style: redLineStyle)
+            Line(chartData: ChartData([8, 23, 32, 7, 23, -4]),
+                 style: blackLineStyle,
+                 chartProperties: LineChartProperties())
+            Line(chartData:  ChartData([8, 23, 32, 7, 23, 43]),
+                 style: redLineStyle,
+                 chartProperties: LineChartProperties())
         }
     }
 }

Sources/SwiftUICharts/Charts/LineChart/LineBackgroundShape.swift

@@ -1,9 +1,9 @@
 import SwiftUI
 
 struct LineBackgroundShape: Shape {
-    var data: [Double]
+    var data: [(Double, Double)]
     func path(in rect: CGRect) -> Path {
-        let path = Path.quadClosedCurvedPathWithPoints(points: data, step: CGPoint(x: 1.0, y: 1.0))
+        let path = Path.quadClosedCurvedPathWithPoints(data: data, in: rect)
         return path
     }
 }
@@ -12,15 +12,13 @@ struct LineBackgroundShape_Previews: PreviewProvider {
     static var previews: some View {
         Group {
             GeometryReader { geometry in
-                LineBackgroundShape(data: [0, 0.5, 0.8, 0.6, 1])
-                    .transform(CGAffineTransform(scaleX: geometry.size.width / 4.0, y: geometry.size.height))
+                LineBackgroundShape(data: [(0, -0.5), (0.25, 0.8), (0.5,-0.6), (0.75,0.6), (1, 1)])
                     .fill(Color.red)
                     .rotationEffect(.degrees(180), anchor: .center)
                     .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))
             }
             GeometryReader { geometry in
-                LineBackgroundShape(data: [0, -0.5, 0.8, -0.6, 1])
-                    .transform(CGAffineTransform(scaleX: geometry.size.width / 4.0, y: geometry.size.height / 1.6))
+                LineBackgroundShape(data: [(0, 0), (0.25, 0.5), (0.5,0.8), (0.75, 0.6), (1, 1)])
                     .fill(Color.blue)
                     .rotationEffect(.degrees(180), anchor: .center)
                     .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))

Sources/SwiftUICharts/Charts/LineChart/LineBackgroundShapeView.swift

@@ -6,11 +6,9 @@ struct LineBackgroundShapeView: View {
     var style: ChartStyle
 
     var body: some View {
-        LineBackgroundShape(data: chartData.normalisedPoints)
-            .transform(CGAffineTransform(scaleX: geometry.size.width / CGFloat(chartData.normalisedPoints.count - 1),
-                                         y: geometry.size.height / CGFloat(chartData.normalisedRange)))
-            .fill(LinearGradient(gradient: Gradient(colors: [style.foregroundColor.first?.startColor ?? .white,
-                                                             style.backgroundColor.startColor]),
+        LineBackgroundShape(data: chartData.normalisedData)
+            .fill(LinearGradient(gradient: Gradient(colors: [style.backgroundColor.startColor,
+                                                             style.foregroundColor.first?.startColor ?? .white]),
                                  startPoint: .bottom,
                                  endPoint: .top))
             .rotationEffect(.degrees(180), anchor: .center)

Sources/SwiftUICharts/Charts/LineChart/LineChart.swift

@@ -1,17 +1,14 @@
 import SwiftUI
 
-/// A type of chart that displays a line connecting the data points
-public struct LineChart: View, ChartBase {
+public struct LineChart: ChartBase {
     public var chartData = ChartData()
-
-    @EnvironmentObject var data: ChartData
     @EnvironmentObject var style: ChartStyle
+    public var chartProperties = LineChartProperties()
 
-	/// The content and behavior of the `LineChart`.
-	///
-	///
     public var body: some View {
-        Line(chartData: data, style: style)
+       Line(chartData: chartData,
+            style: style,
+            chartProperties: chartProperties)
     }
     
     public init() {}

Sources/SwiftUICharts/Charts/LineChart/LineShape.swift

@@ -1,9 +1,16 @@
 import SwiftUI
 
 struct LineShape: Shape {
-    var data: [Double]
+    var data: [(Double, Double)]
+    var lineStyle: LineStyle = .curved
     func path(in rect: CGRect) -> Path {
-        let path = Path.quadCurvedPathWithPoints(points: data, step: CGPoint(x: 1.0, y: 1.0))
+        var path = Path()
+        switch lineStyle {
+        case .curved:
+            path = Path.quadCurvedPathWithPoints(data: data, in: rect)
+        case .straight:
+            path = Path.linePathWithPoints(data: data, in: rect)
+        }
         return path
     }
 }
@@ -11,20 +18,15 @@ struct LineShape: Shape {
 struct LineShape_Previews: PreviewProvider {
     static var previews: some View {
         Group {
-            GeometryReader { geometry in
-                LineShape(data: [0, 0.5, 0.8, 0.6, 1])
-                    .transform(CGAffineTransform(scaleX: geometry.size.width / 4.0, y: geometry.size.height))
-                    .stroke(Color.red)
-                    .rotationEffect(.degrees(180), anchor: .center)
-                    .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))
-            }
-            GeometryReader { geometry in
-                LineShape(data: [0, -0.5, 0.8, -0.6, 1])
-                    .transform(CGAffineTransform(scaleX: geometry.size.width / 4.0, y: geometry.size.height / 1.6))
-                    .stroke(Color.blue)
-                    .rotationEffect(.degrees(180), anchor: .center)
-                    .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))
-            }
+            LineShape(data: [(0, 0), (0.25, 0.5), (0.5,0.8), (0.75, 0.6), (1, 1)])
+                .stroke()
+                .rotationEffect(.degrees(180), anchor: .center)
+                                    .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))
+
+            LineShape(data: [(0, -0.5), (0.25, 0.8), (0.5,-0.6), (0.75,0.6), (1, 1)], lineStyle: .straight)
+                .stroke()
+                .rotationEffect(.degrees(180), anchor: .center)
+                                    .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))
         }
     }
 }

Sources/SwiftUICharts/Charts/LineChart/LineShapeView.swift

@@ -2,6 +2,8 @@ import SwiftUI
 
 struct LineShapeView: View, Animatable {
     var chartData: ChartData
+    var chartProperties: LineChartProperties
+
     var geometry: GeometryProxy
     var style: ChartStyle
     var trimTo: Double = 0
@@ -12,15 +14,64 @@ struct LineShapeView: View, Animatable {
     }
 
     var body: some View {
-        LineShape(data: chartData.normalisedPoints)
-            .trim(from: 0, to: CGFloat(trimTo))
-            .transform(CGAffineTransform(scaleX: geometry.size.width / CGFloat(chartData.normalisedPoints.count - 1),
-                                         y: geometry.size.height / CGFloat(chartData.normalisedRange)))
-            .stroke(LinearGradient(gradient: style.foregroundColor.first?.gradient ?? ColorGradient.orangeBright.gradient,
-                                   startPoint: .leading,
-                                   endPoint: .trailing),
-                    style: StrokeStyle(lineWidth: 3, lineJoin: .round))
-            .rotationEffect(.degrees(180), anchor: .center)
-            .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))
+        ZStack {
+            LineShape(data: chartData.normalisedData, lineStyle: chartProperties.lineStyle)
+                .trim(from: 0, to: CGFloat(trimTo))
+                .stroke(LinearGradient(gradient: style.foregroundColor.first?.gradient ?? ColorGradient.orangeBright.gradient,
+                                       startPoint: .leading,
+                                       endPoint: .trailing),
+                        style: StrokeStyle(lineWidth: chartProperties.lineWidth, lineJoin: .round))
+                .rotationEffect(.degrees(180), anchor: .center)
+                .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))
+                .clipped()
+            if chartProperties.showChartMarks {
+                MarkerShape(data: chartData.normalisedData)
+                    .trim(from: 0, to: CGFloat(trimTo))
+                    .fill(.white,
+                          strokeBorder: LinearGradient(gradient: style.foregroundColor.first?.gradient ?? ColorGradient.orangeBright.gradient,
+                                                               startPoint: .leading,
+                                                               endPoint: .trailing),
+                          lineWidth: chartProperties.lineWidth)
+                    .rotationEffect(.degrees(180), anchor: .center)
+                    .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))
+            }
+        }
     }
 }
+
+struct LineShapeView_Previews: PreviewProvider {
+    static let chartData = ChartData([6, 8, 6], rangeY: 6...10)
+    static let chartDataOutOfRange = ChartData([-1, 8, 6, 12, 3], rangeY: -5...15)
+
+    static let chartDataOutOfRange2 = ChartData([6,6,8,5], rangeY: 5...10)
+
+    static let chartStyle = ChartStyle(backgroundColor: Color.white,
+                                       foregroundColor: [ColorGradient(Color.orange, Color.red)])
+    static var previews: some View {
+        Group {
+            GeometryReader { geometry in
+                LineShapeView(chartData: chartData,
+                              chartProperties: LineChartProperties(),
+                              geometry: geometry,
+                              style: chartStyle,
+                              trimTo: 1.0)
+            }
+            GeometryReader { geometry in
+                LineShapeView(chartData: chartDataOutOfRange,
+                              chartProperties: LineChartProperties(),
+                              geometry: geometry,
+                              style: chartStyle,
+                              trimTo: 1.0)
+            }
+            GeometryReader { geometry in
+                LineShapeView(chartData: chartDataOutOfRange2,
+                              chartProperties: LineChartProperties(),
+                              geometry: geometry,
+                              style: chartStyle,
+                              trimTo: 1.0)
+            }
+        }
+    }
+}
+
+

Sources/SwiftUICharts/Charts/LineChart/MarkerShape.swift

@@ -0,0 +1,25 @@
+import SwiftUI
+
+struct MarkerShape: Shape {
+    var data: [(Double, Double)]
+    func path(in rect: CGRect) -> Path {
+        let path = Path.drawChartMarkers(data: data, in: rect)
+        return path
+    }
+}
+
+struct MarkerShape_Previews: PreviewProvider {
+    static var previews: some View {
+        Group {
+            MarkerShape(data: [(0, 0), (0.25, 0.5), (0.5,0.8), (0.75, 0.6), (1, 1)])
+                .stroke()
+                .rotationEffect(.degrees(180), anchor: .center)
+                                    .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))
+
+            MarkerShape(data: [(0, -0.5), (0.25, 0.8), (0.5,-0.6), (0.75,0.6), (1, 1)])
+                .stroke()
+                .rotationEffect(.degrees(180), anchor: .center)
+                                    .rotation3DEffect(.degrees(180), axis: (x: 0, y: 1, z: 0))
+        }
+    }
+}

Sources/SwiftUICharts/Charts/LineChart/Model/LineChartProperties.swift

@@ -0,0 +1,12 @@
+import SwiftUI
+
+public class LineChartProperties: ObservableObject {
+    @Published var lineWidth: CGFloat = 2.0
+    @Published var showBackground: Bool = false
+    @Published var showChartMarks: Bool = true
+    @Published var lineStyle: LineStyle = .curved
+
+    public init() {
+        // no-op
+    }
+}

Sources/SwiftUICharts/Charts/LineChart/Model/LineStyle.swift

@@ -0,0 +1,6 @@
+import Foundation
+
+public enum LineStyle {
+    case curved
+    case straight
+}

Sources/SwiftUICharts/Charts/PieChart/PieChart.swift

@@ -1,17 +1,16 @@
 import SwiftUI
 
 /// A type of chart that displays a slice of "pie" for each data point
-public struct PieChart: View, ChartBase {
+public struct PieChart: ChartBase {
     public var chartData = ChartData()
 
-    @EnvironmentObject var data: ChartData
     @EnvironmentObject var style: ChartStyle
 
 	/// The content and behavior of the `PieChart`.
 	///
 	///
     public var body: some View {
-        PieChartRow(chartData: data, style: style)
+        PieChartRow(chartData: chartData, style: style)
     }
 
     public init() {}

Sources/SwiftUICharts/Charts/RingsChart/RingsChart.swift

@@ -1,22 +1,14 @@
-//
-//  RingsChart.swift
-//  ChartViewV2Demo
-//
-//  Created by Dan Wood on 8/20/20.
-//
-
 import SwiftUI
 
-public struct RingsChart: View, ChartBase {
+public struct RingsChart: ChartBase {
 	public var chartData = ChartData()
 
-	@EnvironmentObject var data: ChartData
 	@EnvironmentObject var style: ChartStyle
 
 	// TODO - should put background opacity, ring width & spacing as chart style values
 	
 	public var body: some View {
-		RingsChartRow(width:10.0, spacing:5.0, chartData: data, style: style)
+		RingsChartRow(width:10.0, spacing:5.0, chartData: chartData, style: style)
 	}
 
     public init() {}