From 53227eef948bf6bfd7e69bf45abe273edd7e61d7 Mon Sep 17 00:00:00 2001
From: Patrick Battisti Forsthofer <1729patrick@gmail.com>
Date: Fri, 25 Mar 2022 08:47:14 -0300
Subject: [PATCH] feat: add linechart change animation (#117)

---
 .../Base/Animatable/AnimatableVector.swift    | 36 +++++++++++++++++++
 .../SwiftUICharts/Charts/LineChart/Line.swift |  1 +
 .../LineChart/LineBackgroundShape.swift       |  8 ++++-
 .../Charts/LineChart/LineShape.swift          |  8 ++++-
 4 files changed, 51 insertions(+), 2 deletions(-)
 create mode 100644 Sources/SwiftUICharts/Base/Animatable/AnimatableVector.swift

diff --git a/Sources/SwiftUICharts/Base/Animatable/AnimatableVector.swift b/Sources/SwiftUICharts/Base/Animatable/AnimatableVector.swift
new file mode 100644
index 00000000..e43ab719
--- /dev/null
+++ b/Sources/SwiftUICharts/Base/Animatable/AnimatableVector.swift
@@ -0,0 +1,36 @@
+import SwiftUI
+import enum Accelerate.vDSP
+
+struct AnimatableVector: VectorArithmetic {
+    static var zero = AnimatableVector(values: [0.0])
+
+    static func + (lhs: AnimatableVector, rhs: AnimatableVector) -> AnimatableVector {
+        let count = min(lhs.values.count, rhs.values.count)
+        return AnimatableVector(values: vDSP.add(lhs.values[0..<count], rhs.values[0..<count]))
+    }
+
+    static func += (lhs: inout AnimatableVector, rhs: AnimatableVector) {
+        let count = min(lhs.values.count, rhs.values.count)
+        vDSP.add(lhs.values[0..<count], rhs.values[0..<count], result: &lhs.values[0..<count])
+    }
+
+    static func - (lhs: AnimatableVector, rhs: AnimatableVector) -> AnimatableVector {
+        let count = min(lhs.values.count, rhs.values.count)
+        return AnimatableVector(values: vDSP.subtract(lhs.values[0..<count], rhs.values[0..<count]))
+    }
+
+    static func -= (lhs: inout AnimatableVector, rhs: AnimatableVector) {
+        let count = min(lhs.values.count, rhs.values.count)
+        vDSP.subtract(lhs.values[0..<count], rhs.values[0..<count], result: &lhs.values[0..<count])
+    }
+
+    var values: [Double]
+
+    mutating func scale(by rhs: Double) {
+        values = vDSP.multiply(rhs, values)
+    }
+
+    var magnitudeSquared: Double {
+        vDSP.sum(vDSP.multiply(values, values))
+    }
+}
diff --git a/Sources/SwiftUICharts/Charts/LineChart/Line.swift b/Sources/SwiftUICharts/Charts/LineChart/Line.swift
index 107367fa..6ca1e4d6 100644
--- a/Sources/SwiftUICharts/Charts/LineChart/Line.swift
+++ b/Sources/SwiftUICharts/Charts/LineChart/Line.swift
@@ -29,6 +29,7 @@ public struct Line: View {
                     LineBackgroundShapeView(chartData: chartData,
                                             geometry: geometry,
                                             style: style)
+                    .animation(.easeIn)
                 }
                 LineShapeView(chartData: chartData,
                               geometry: geometry,
diff --git a/Sources/SwiftUICharts/Charts/LineChart/LineBackgroundShape.swift b/Sources/SwiftUICharts/Charts/LineChart/LineBackgroundShape.swift
index 06b02811..3e2cf2f9 100644
--- a/Sources/SwiftUICharts/Charts/LineChart/LineBackgroundShape.swift
+++ b/Sources/SwiftUICharts/Charts/LineChart/LineBackgroundShape.swift
@@ -1,7 +1,13 @@
 import SwiftUI
 
-struct LineBackgroundShape: Shape {
+struct LineBackgroundShape: Shape, Animatable {
     var data: [Double]
+    
+    var animatableData: AnimatableVector {
+        get { AnimatableVector(values: data)  }
+        set { data = newValue.values }
+    }
+    
     func path(in rect: CGRect) -> Path {
         let path = Path.quadClosedCurvedPathWithPoints(points: data, step: CGPoint(x: 1.0, y: 1.0))
         return path
diff --git a/Sources/SwiftUICharts/Charts/LineChart/LineShape.swift b/Sources/SwiftUICharts/Charts/LineChart/LineShape.swift
index 64fff658..72c08ee8 100644
--- a/Sources/SwiftUICharts/Charts/LineChart/LineShape.swift
+++ b/Sources/SwiftUICharts/Charts/LineChart/LineShape.swift
@@ -1,7 +1,13 @@
 import SwiftUI
 
-struct LineShape: Shape {
+struct LineShape: Shape, Animatable {
     var data: [Double]
+    
+    var animatableData: AnimatableVector {
+        get { AnimatableVector(values: data)  }
+        set { data = newValue.values }
+    }
+    
     func path(in rect: CGRect) -> Path {
         let path = Path.quadCurvedPathWithPoints(points: data, step: CGPoint(x: 1.0, y: 1.0))
         return path