Move code

submodules/TelegramUI/Components/Calls/CallScreen/Sources/Animation/Bezier.swift

@@ -0,0 +1,53 @@
+import Foundation
+
+private func a(_ a1: CGFloat, _ a2: CGFloat) -> CGFloat
+{
+    return 1.0 - 3.0 * a2 + 3.0 * a1
+}
+
+private func b(_ a1: CGFloat, _ a2: CGFloat) -> CGFloat
+{
+    return 3.0 * a2 - 6.0 * a1
+}
+
+private func c(_ a1: CGFloat) -> CGFloat
+{
+    return 3.0 * a1
+}
+
+private func calcBezier(_ t: CGFloat, _ a1: CGFloat, _ a2: CGFloat) -> CGFloat
+{
+    return ((a(a1, a2)*t + b(a1, a2))*t + c(a1)) * t
+}
+
+private func calcSlope(_ t: CGFloat, _ a1: CGFloat, _ a2: CGFloat) -> CGFloat
+{
+    return 3.0 * a(a1, a2) * t * t + 2.0 * b(a1, a2) * t + c(a1)
+}
+
+private func getTForX(_ x: CGFloat, _ x1: CGFloat, _ x2: CGFloat) -> CGFloat {
+    var t = x
+    var i = 0
+    while i < 4 {
+        let currentSlope = calcSlope(t, x1, x2)
+        if currentSlope == 0.0 {
+            return t
+        } else {
+            let currentX = calcBezier(t, x1, x2) - x
+            t -= currentX / currentSlope
+        }
+        
+        i += 1
+    }
+    
+    return t
+}
+
+public func bezierPoint(_ x1: CGFloat, _ y1: CGFloat, _ x2: CGFloat, _ y2: CGFloat, _ x: CGFloat) -> CGFloat
+{
+    var value = calcBezier(getTForX(x, x1, x2), y1, y2)
+    if value >= 0.997 {
+        value = 1.0
+    }
+    return value
+}