From b1eb844752e59270594c2b759f3b6ca85e6aa7ee Mon Sep 17 00:00:00 2001
From: fermoya <fmdr.ct@gmail.com>
Date: Tue, 5 Apr 2022 13:36:17 +0100
Subject: [PATCH] Add support for watchOS digitalCrown

---
 Sources/SwiftUIPager/Page.swift         |  5 ++++
 Sources/SwiftUIPager/PagerContent.swift | 32 +++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/Sources/SwiftUIPager/Page.swift b/Sources/SwiftUIPager/Page.swift
index 7ecc402..cda1b39 100644
--- a/Sources/SwiftUIPager/Page.swift
+++ b/Sources/SwiftUIPager/Page.swift
@@ -80,6 +80,9 @@ extension Page {
         /// Will move to the first page
         case moveToFirst
 
+        /// Will increment or decrement the `index` by the passed argument
+        case move(increment: Int)
+
         /// Will move to the last page
         case moveToLast
 
@@ -116,6 +119,8 @@ extension Page {
             index = 0
         case .moveToLast:
             index = totalPages - 1
+        case .move(let increment):
+            index += increment
         case .new(let newIndex):
             index = newIndex
         }
diff --git a/Sources/SwiftUIPager/PagerContent.swift b/Sources/SwiftUIPager/PagerContent.swift
index e51c661..6ebac76 100644
--- a/Sources/SwiftUIPager/PagerContent.swift
+++ b/Sources/SwiftUIPager/PagerContent.swift
@@ -150,6 +150,16 @@ extension Pager {
         @GestureState var isGestureFinished = true
         #endif
 
+        #if os(watchOS)
+
+        /// Digital Crown offset
+        @State var digitalCrownPageOffset: CGFloat = 0
+
+        /// Digital Crown offset
+        @State var lastDigitalCrownPageOffset: CGFloat = 0
+
+        #endif
+
         /// Initializes a new `Pager`.
         ///
         /// - Parameter size: Available size
@@ -235,6 +245,28 @@ extension Pager {
             }
             #endif
 
+            #if os(watchOS)
+            resultView = resultView
+                .focusable()
+                .digitalCrownRotation(
+                    $digitalCrownPageOffset,
+                    from: 0,
+                    through: CGFloat(numberOfPages - 1),
+                    by: 1,
+                    sensitivity: .low
+                )
+                .onChange(of: digitalCrownPageOffset) { newValue in
+                    print(newValue)
+                    let increment = min(1, max(-1, Int(newValue - lastDigitalCrownPageOffset)))
+                    guard abs(increment) > 0 else { return }
+                    lastDigitalCrownPageOffset = newValue
+                    withAnimation {
+                        pagerModel.update(.move(increment: increment))
+                    }
+                }
+                .eraseToAny()
+            #endif
+
             return resultView.contentShape(Rectangle())
         }
     }