From 0291829c9aa60b2794d27dd136f504493639e39a Mon Sep 17 00:00:00 2001
From: Gustav Sundin <sundin666@gmail.com>
Date: Fri, 20 Oct 2017 17:06:51 +0200
Subject: [PATCH] Readded code to handle rapid swicks

At the moment we only support this when horizontal swipes is the only swipe direction allowed.
---
 KSSwipeStack/Classes/SwipeHelper.swift | 24 ++++++++++++++++++++++++
 KSSwipeStack/Classes/SwipeView.swift   | 17 ++++++++++++++++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/KSSwipeStack/Classes/SwipeHelper.swift b/KSSwipeStack/Classes/SwipeHelper.swift
index 56fe91f..ada7ced 100644
--- a/KSSwipeStack/Classes/SwipeHelper.swift
+++ b/KSSwipeStack/Classes/SwipeHelper.swift
@@ -159,6 +159,30 @@ class SwipeHelper {
         return Double(abs(cardCenter.y - self.screenSize.height / 2))
     }
     
+    /// Calculate a proper destination for a dismissal of a view based on its position
+    /// Places the view far to the left if the view is to the left the the center of the screen and vice versa.
+    /// - Parameter card: View which endpoint to calculate
+    /// - Returns: Proper destination for the view
+    func calculateEndpoint(_ card: UIView) -> CGPoint {
+        let deltaX = card.center.x - screenSize.width / 2
+        let deltaY = card.center.y - screenSize.height / 2
+        
+        let k = deltaY / deltaX
+        let toX = deltaX < 0 ? -screenSize.height / 2 : screenSize.width + screenSize.height / 2
+        return CGPoint(x: toX, y: toX * k)
+    }
+    
+    /// Calculate a proper destination for a dismissal of a view based on current velocity
+    /// Places the view far to the left if the view is currently moving to the left and vice versa.
+    /// The angle from the center to the proposed destination of the view is based on the angle of the velocity vector
+    /// - Parameter card: View which endpoint to calculate
+    /// - Returns: Proper destination for the view
+    func calculateEndpoint(_ card: UIView, basedOn velocity: CGPoint) -> CGPoint {
+        let k = velocity.y / velocity.x
+        let toX = velocity.x < 0 ? -screenSize.height / 2 : screenSize.width + screenSize.height / 2
+        return CGPoint(x: toX, y: toX * k)
+    }
+    
     /// Converts a position with coordinates with the origin of the screen as origo to one using the center of the screen as origo.
     /// Can be used to convert a origin value to a center value refering to the same positioning of a full screen view.
     /// - Parameter center: Position using origin as origo
diff --git a/KSSwipeStack/Classes/SwipeView.swift b/KSSwipeStack/Classes/SwipeView.swift
index 13de824..c0a5e7b 100644
--- a/KSSwipeStack/Classes/SwipeView.swift
+++ b/KSSwipeStack/Classes/SwipeView.swift
@@ -318,7 +318,22 @@ public class SwipeView: UIView {
         
         isUserInteractionEnabled = !options.freezeWhenDismissing
         
-        let toPoint = swipeHelper.convertToCenter(origin: direction.getSwipeEndpoint())
+        var toPoint = swipeHelper.convertToCenter(origin: direction.getSwipeEndpoint())
+        
+        if options.allowHorizontalSwipes && !options.allowVerticalSwipes {
+            // Special case to better handle rapid flicks
+            if !(card.frame.origin.x == 0 && card.frame.origin.y == 0) {
+                if card.center.x > options.screenSize.width / 2 {
+                    toPoint = swipeHelper.calculateEndpoint(card)
+                } else if let gesture = gesture as? UIPanGestureRecognizer{
+                    let velocity = gesture.velocity(in: self)
+                    if !(velocity.x == 0 && velocity.y == 0) {
+                        toPoint = swipeHelper.calculateEndpoint(card, basedOn: velocity)
+                    }
+                }
+            }
+        }
+        
         swipeHelper.moveFastAndTransform(card, toPoint: toPoint, completion: {
             completion()
             self.showNextCard()