Issue 99 documentation (#159)

* Starting on filling in documentation.

* First pass on most/all files

* more descriptions filled in

* Some documentation but TBH the author would be better suited to explain how this works!

* more basic stuff filled in

* Add a description and bunch of discussion text for most of the view `body` declarations

* more explanations

Co-authored-by: Dan Wood <danwood@users.noreply.github.com>

Sources/SwiftUICharts/Base/CardView/CardView.swift

@@ -1,5 +1,6 @@
 import SwiftUI
 
+/// View containing data and some kind of chart content
 public struct CardView<Content: View>: View, ChartBase {
     public var chartData = ChartData()
     let content: () -> Content
@@ -8,11 +9,18 @@ public struct CardView<Content: View>: View, ChartBase {
 
     @EnvironmentObject var style: ChartStyle
 
+	/// Initialize with view options and a nested `ViewBuilder`
+	/// - Parameters:
+	///   - showShadow: should card have a rounded-rectangle shadow around it
+	///   - content: <#content description#>
     public init(showShadow: Bool = true, @ViewBuilder content: @escaping () -> Content) {
         self.showShadow = showShadow
         self.content = content
     }
 
+	/// The content and behavior of the `CardView`.
+	///
+	///
     public var body: some View {
         ZStack{
             if showShadow {

Sources/SwiftUICharts/Base/Chart/ChartBase.swift

@@ -1,5 +1,6 @@
 import SwiftUI
 
+/// Protocol for any type of chart, to get access to underlying data
 public protocol ChartBase {
     var chartData: ChartData { get }
 }

Sources/SwiftUICharts/Base/Chart/ChartData.swift

@@ -1,8 +1,11 @@
 import SwiftUI
 
+/// An observable wrapper for an array of data for use in any chart
 public class ChartData: ObservableObject {
     @Published public var data: [Double] = []
 
+	/// Initialize with data array
+	/// - Parameter data: Array of `Double`
     public init(_ data: [Double]) {
         self.data = data
     }

Sources/SwiftUICharts/Base/Chart/ChartValue.swift

@@ -1,5 +1,6 @@
 import SwiftUI
 
+/// Representation of a single data point in a chart that is being observed
 public class ChartValue: ObservableObject {
     @Published var currentValue: Double = 0
     @Published var interactionInProgress: Bool = false

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

@@ -1,6 +1,10 @@
 import Foundation
 
 extension Array where Element == ColorGradient {
+
+	/// <#Description#>
+	/// - Parameter index: offset in data table
+	/// - Returns: <#description#>
     func rotate(for index: Int) -> ColorGradient {
         if self.isEmpty {
             return ColorGradient.orangeBright

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

@@ -1,6 +1,12 @@
 import SwiftUI
 
 extension CGPoint {
+
+	/// Calculate X and Y delta for each data point, based on data min/max and enclosing frame.
+	/// - Parameters:
+	///   - frame: Rectangle of enclosing frame
+	///   - data: array of `Double`
+	/// - Returns: X and Y delta as a `CGPoint`
     static func getStep(frame: CGRect, data: [Double]) -> CGPoint {
         let padding: CGFloat = 30.0
 

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

@@ -2,7 +2,9 @@ import Foundation
 import SwiftUI
 
 extension CGRect {
-    // Return the coordinate for a rectangle center
+
+	/// Midpoint of rectangle
+	/// - Returns: the coordinate for a rectangle center
     public var mid: CGPoint {
         return CGPoint(x: self.midX, y: self.midY)
     }

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

@@ -1,6 +1,10 @@
 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
         return self

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

@@ -1,6 +1,8 @@
 import SwiftUI
 
 extension Color {
+	/// Create a `Color` from a hexadecimal representation
+	/// - Parameter hexString: 3, 6, or 8-character string, with optional (ignored) punctuation such as "#"
     init(hexString: String) {
         let hex = hexString.trimmingCharacters(in: CharacterSet.alphanumerics.inverted)
         var int = UInt64()