Merge pull request #161 from fermoya/feat/bounce-workaround

Feat/bounce workaround

Author: fermoya

Documentation/Usage.md

@@ -127,6 +127,17 @@ Pager(...)
 
 Be aware that this modifier will change the loading policy. See [Content Loading Policy](#content-loading-policy) for more information.
 
+### More modifiers
+| **Modifier** | **Description** |
+|---|---|
+| `allowsDragging` | whether or not dragging is allowed |
+| `disableDragging` | disables dragging |
+| `bounces` | whether or not `Pager` should bounce |
+| `delaysTouches` | whether or not touches shoulf be delayed. Useful if nested in `ScrollView` |
+| `pageOffset` | allows _manual_ scroll |
+| `expandPageToEdges` | modifies `itemAspectRatio` so that the use up all the space available |
+
+
 ## Paging Priority
 
 For complex pages where a `Gesture` might be used, or any other `View` that internally holds a `Gesture` like `Button` or `NavigationLink`, you might come across issues when trying to swipe on top of certain areas within the page. For these scenarios, use `pagingPriority` to select the option that best suits your purpose. For instance, a page containing a `NavigationLink` won't be scrollable over the link area unless `pagingPrioriry(.simultaneous)` is added:
@@ -197,7 +208,7 @@ Transform your `Pager` into an endless sroll by using `loopPages`:
 
 **Note**: You'll need a minimum number of elements to use this modifier based on the page size. If you need more items, use `loopPages(repeating:)` to let `Pager` know elements should be repeated in batches.
 
-## Page Tranistions
+## Page Transitions
 
 Use `pagingAnimation` to customize the _transition_ to the next page once the drag has ended. This is achieve by a block with a `DragResult`which contains:
 * Current page
@@ -225,6 +236,8 @@ Pager(...)
      })
 ```
 
+You can also use `onDraggingBegan`, `onDraggingChanged` and  `onDragginEnded` to keep track of the dragging.
+
 ## Add pages on demand
 
 You can use `onPageChanged` to add new items on demand whenever the user is getting to the last page:
@@ -247,6 +260,30 @@ var body: some View {
 }
 ```
 
+At the same time, items can be added at the start. Notice you'll need to update the page yourself (as you're inserting new elements) to keep `Pager` focused on the right element:
+
+```swift
+
+@State var count: Int = -1
+@State var page: Int = 3
+@State var data = Array(0..<5)
+
+Pager(page: self.$page,
+        data: self.data,
+        id: \.self) {
+    self.pageView($0)
+}
+.onPageChanged({ page in
+    guard page == 1 else { return }
+    let newData = (1...5).map { $0 * self.count }
+    withAnimation {
+        self.data1.insert(contentsOf: newData, at: 0)
+        self.page1 += 5
+        self.count -= 1
+    }
+})
+```
+
 ## Content Loading Policy
 
 `Pager` recycles views by default and won't have loaded all pages in memory at once. In some scenarios, this might be counterproductive, for example, if you're trying to manually scroll from the first page to the last. For these scenarios, use `.contentLoadingPolicy` and choose among the options available.

Example/SwiftUIPagerExample.xcodeproj/project.pbxproj

@@ -20,7 +20,6 @@
 		6B4EC8A8240D1182001E7490 /* BizarreExampleView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6B4EC8A7240D1182001E7490 /* BizarreExampleView.swift */; };
 		6B6FAA3D24D553C8000D1539 /* PagingAnimation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6B6FAA3C24D553C8000D1539 /* PagingAnimation.swift */; };
 		6B9C4A8A24B45F66004C06C5 /* OnDeactivateModifier.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6B9C4A8924B45F66004C06C5 /* OnDeactivateModifier.swift */; };
-		6BB1AAD324C9C9D20032B5A3 /* PagerProxy.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6BB1AAD224C9C9D20032B5A3 /* PagerProxy.swift */; };
 		6BB1AAD524C9CA1C0032B5A3 /* PagerContent.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6BB1AAD424C9CA1C0032B5A3 /* PagerContent.swift */; };
 		6BB1AAD724C9D0820032B5A3 /* Pager+Buildable.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6BB1AAD624C9D0820032B5A3 /* Pager+Buildable.swift */; };
 		6BC5EDFC24866D9500E1E78C /* PagerContent+Buildable.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6BC5EDF424866D9500E1E78C /* PagerContent+Buildable.swift */; };
@@ -67,7 +66,6 @@
 		6B4EC8A7240D1182001E7490 /* BizarreExampleView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BizarreExampleView.swift; sourceTree = "<group>"; };
 		6B6FAA3C24D553C8000D1539 /* PagingAnimation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = PagingAnimation.swift; path = ../../Sources/SwiftUIPager/PageConfiguration/PagingAnimation.swift; sourceTree = "<group>"; };
 		6B9C4A8924B45F66004C06C5 /* OnDeactivateModifier.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OnDeactivateModifier.swift; sourceTree = "<group>"; };
-		6BB1AAD224C9C9D20032B5A3 /* PagerProxy.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PagerProxy.swift; sourceTree = "<group>"; };
 		6BB1AAD424C9CA1C0032B5A3 /* PagerContent.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = PagerContent.swift; path = ../../Sources/SwiftUIPager/PagerContent.swift; sourceTree = "<group>"; };
 		6BB1AAD624C9D0820032B5A3 /* Pager+Buildable.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = "Pager+Buildable.swift"; path = "../../Sources/SwiftUIPager/Pager+Buildable.swift"; sourceTree = "<group>"; };
 		6BC5EDF424866D9500E1E78C /* PagerContent+Buildable.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = "PagerContent+Buildable.swift"; path = "../../Sources/SwiftUIPager/PagerContent+Buildable.swift"; sourceTree = "<group>"; };
@@ -147,21 +145,11 @@
 			path = Examples;
 			sourceTree = "<group>";
 		};
-		6BB1AAD124C9C9370032B5A3 /* Proxy */ = {
-			isa = PBXGroup;
-			children = (
-				6BB1AAD224C9C9D20032B5A3 /* PagerProxy.swift */,
-			);
-			name = Proxy;
-			path = ../../Sources/SwiftUIPager/Proxy;
-			sourceTree = "<group>";
-		};
 		6BC5EDEB24866D6000E1E78C /* Pagination */ = {
 			isa = PBXGroup;
 			children = (
 				6BC5EDF524866D9500E1E78C /* Helpers */,
 				6BEA730E24ACF8BB007EA8DC /* PageConfiguration */,
-				6BB1AAD124C9C9370032B5A3 /* Proxy */,
 				6BC5EDFA24866D9500E1E78C /* Pager.swift */,
 				6BB1AAD624C9D0820032B5A3 /* Pager+Buildable.swift */,
 				6BB1AAD424C9CA1C0032B5A3 /* PagerContent.swift */,
@@ -274,7 +262,6 @@
 			buildActionMask = 2147483647;
 			files = (
 				6B4EC8A2240D072B001E7490 /* ColorsExampleView.swift in Sources */,
-				6BB1AAD324C9C9D20032B5A3 /* PagerProxy.swift in Sources */,
 				17D9E0F423D4CF6700C5AE93 /* AppDelegate.swift in Sources */,
 				6BEF677024C98B62008533FE /* PageWrapper.swift in Sources */,
 				6BD3828224C97DE3007B1CF6 /* CGPoint+Angle.swift in Sources */,

Example/SwiftUIPagerExample/Examples/NestedExampleView.swift

@@ -11,6 +11,7 @@ import SwiftUI
 struct NestedExampleView: View {
 
     @State var page: Int = 0
+    @State var pageOffset: Double = 0
     @State var nestedPages: [Int] = [0, 0, 0, 0]
 
     var data = Array(0..<4)
@@ -22,6 +23,7 @@ struct NestedExampleView: View {
               id: \.self) { page in
                 self.nestedPager(page)
         }
+        .pageOffset(pageOffset)
         .swipeInteractionArea(.allAvailable)
         .background(Color.gray.opacity(0.2))
     }
@@ -47,9 +49,26 @@ struct NestedExampleView: View {
                   id: \.self) { page in
                     self.pageView(page)
             }
+            .bounces(false)
 			.onDraggingBegan({
 				print("Dragging Began")
 			})
+            .onDraggingChanged { increment in
+                withAnimation {
+                    if binding.wrappedValue == self.nestedData.count - 1, increment > 0 {
+                        pageOffset = increment
+                    } else if binding.wrappedValue == 0, increment < 0 {
+                        pageOffset = increment
+                    }
+                }
+            }
+            .onDraggingEnded { increment in
+                guard pageOffset != 0 else { return }
+                withAnimation {
+                    pageOffset = 0
+                    page += Int(increment.rounded())
+                }
+            }
             .itemSpacing(10)
             .itemAspectRatio(0.8, alignment: .end)
             .padding(8)

README.md

@@ -10,7 +10,7 @@
 
 _SwiftUIPager_ provides  a `Pager` component built with SwiftUI native components. `Pager` is a view that renders a scrollable container to display a handful of pages. These pages are recycled on scroll, so you don't have to worry about memory issues. `Pager` will load just a handful of items, enough to beatifully scroll along.
 
-Create vertical or horizontal pagers, align the cards, change the direction of the scroll, animate the pagintation... `Pager` lets you do anything you want.
+Create vertical or horizontal pagers, align the cards, change the direction of the scroll, animate the pagination... `Pager` lets you do anything you want.
 
 - [Requirements](#requirements)
 - [Installation](#installation)
@@ -28,12 +28,13 @@ Create vertical or horizontal pagers, align the cards, change the direction of t
         - [Alignment](Documentation/Usage.md#alignment)
         - [Partial pagination](Documentation/Usage.md#partial-pagination)
         - [Multiple pagination](Documentation/Usage.md#multiple-pagination)
+        - [More modifiers](Documentation/Usage.md#more-modifiers)
     - [Paging Priority](Documentation/Usage.md#paging-priority)
     - [Animations](Documentation/Usage.md#animations)
         - [Scale](Documentation/Usage.md#scale)
         - [Rotation](Documentation/Usage.md#rotation)
         - [Loop](Documentation/Usage.md#loop)
-    - [Page Tranistions](Documentation/Usage.md#page-transitions)
+    - [Page Transitions](Documentation/Usage.md#page-transitions)
     - [Add pages on demand](Documentation/Usage.md#add-pages-on-demand)
     - [Content Loading Policy](Documentation/Usage.md#content-loading-policy)
     - [Examples](Documentation/Usage.md#examples)

Sources/SwiftUIPager/Pager+Buildable.swift

@@ -9,7 +9,7 @@
 import SwiftUI
 
 @available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
-extension Pager: Buildable, PagerProxy {
+extension Pager: Buildable {
 
     /// Result of paginating
     public typealias DragResult = (page: Int, newPage: Int, translation: CGFloat, velocity: Double)
@@ -113,6 +113,32 @@ extension Pager: Buildable, PagerProxy {
         mutating(keyPath: \.swipeInteractionArea, value: value)
     }
 
+    /// Sets whether `Pager` should bounce or not
+    public func bounces(_ value: Bool) -> Self {
+        mutating(keyPath: \.bounces, value: value)
+    }
+
+    /// Adds a callback to react when dragging begins
+    ///
+    /// - Parameter callback: block to be called when  dragging begins
+    public func onDraggingBegan(_ callback: (() -> Void)?) -> Self {
+        mutating(keyPath: \.onDraggingBegan, value: callback)
+    }
+
+    /// Adds a callback to react when dragging changes
+    ///
+    /// - Parameter callback: block to be called when  dragging changes. `pageInrement` is passed as argument
+    public func onDraggingChanged(_ callback: ((Double) -> Void)?) -> Self {
+        mutating(keyPath: \.onDraggingChanged, value: callback)
+    }
+
+    /// Adds a callback to react when dragging ends
+    ///
+    /// - Parameter callback: block to be called when  dragging ends. `pageInrement` is passed as argument
+    public func onDraggingEnded(_ callback: ((Double) -> Void)?) -> Self {
+        mutating(keyPath: \.onDraggingEnded, value: callback)
+    }
+
     #endif
 
     /// Changes the a the  alignment of the pages relative to their container
@@ -216,13 +242,6 @@ extension Pager: Buildable, PagerProxy {
     public func onPageChanged(_ callback: ((Int) -> Void)?) -> Self {
         mutating(keyPath: \.onPageChanged, value: callback)
     }
-	
-	/// Adds a callback to react when dragging begins. Useful for dismissing a keyboard like a scrollview
-	///
-	/// - Parameter callback: block to be called when  dragging begins
-	public func onDraggingBegan(_ callback: (() -> Void)?) -> Self {
-		mutating(keyPath: \.onDraggingBegan, value: callback)
-	}
 
     /// Sets some padding on the non-scroll axis
     ///

Sources/SwiftUIPager/Pager.swift

@@ -64,6 +64,9 @@ public struct Pager<Element, ID, PageView>: View  where PageView: View, Element:
 
     /*** ViewModified properties ***/
 
+    /// Whether `Pager` should bounce or not
+    var bounces: Bool = true
+
     /// Max relative item size that `Pager` will scroll before determining whether to move to the next page
     var pageRatio: CGFloat = 1
 
@@ -139,6 +142,12 @@ public struct Pager<Element, ID, PageView>: View  where PageView: View, Element:
 	/// Callback for when dragging begins
 	var onDraggingBegan: (() -> Void)?
 
+    /// Callback for when dragging changes
+    var onDraggingChanged: ((Double) -> Void)?
+
+    /// Callback for when dragging ends
+    var onDraggingEnded: ((Double) -> Void)?
+
     /*** State and Binding properties ***/
 
     /// Size of the view
@@ -200,7 +209,6 @@ public struct Pager<Element, ID, PageView>: View  where PageView: View, Element:
                 .itemSpacing(itemSpacing)
                 .itemAspectRatio(itemAspectRatio, alignment: itemAlignment)
                 .onPageChanged(onPageChanged)
-				.onDraggingBegan(onDraggingBegan)
                 .padding(sideInsets)
                 .pagingAnimation(pagingAnimation)
                 .partialPagination(pageRatio)
@@ -212,6 +220,10 @@ public struct Pager<Element, ID, PageView>: View  where PageView: View, Element:
             .pagingPriority(gesturePriority)
             .delaysTouches(delaysTouches)
             .sensitivity(sensitivity)
+            .onDraggingBegan(onDraggingBegan)
+            .onDraggingChanged(onDraggingChanged)
+            .onDraggingEnded(onDraggingEnded)
+            .bounces(bounces)
           #endif
 
         pagerContent = allowsMultiplePagination ? pagerContent.multiplePagination() : pagerContent

Sources/SwiftUIPager/PagerContent+Buildable.swift

@@ -9,7 +9,7 @@
 import SwiftUI
 
 @available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
-extension Pager.PagerContent: Buildable, PagerProxy {
+extension Pager.PagerContent: Buildable {
 
     /// Sets the animation to be applied when the user stops dragging
     ///
@@ -109,6 +109,32 @@ extension Pager.PagerContent: Buildable, PagerProxy {
         mutating(keyPath: \.swipeInteractionArea, value: value)
     }
 
+    /// Sets whether `Pager` should bounce or not
+    func bounces(_ value: Bool) -> Self {
+        mutating(keyPath: \.bounces, value: value)
+    }
+
+    /// Adds a callback to react when dragging begins. Useful for dismissing a keyboard like a scrollview
+    ///
+    /// - Parameter callback: block to be called when  dragging begins
+    func onDraggingBegan(_ callback: (() -> Void)?) -> Self {
+        mutating(keyPath: \.onDraggingBegan, value: callback)
+    }
+
+    /// Adds a callback to react when dragging changes
+    ///
+    /// - Parameter callback: block to be called when  dragging changes. `pageInrement` is passed as argument
+    func onDraggingChanged(_ callback: ((Double) -> Void)?) -> Self {
+        mutating(keyPath: \.onDraggingChanged, value: callback)
+    }
+
+    /// Adds a callback to react when dragging ends
+    ///
+    /// - Parameter callback: block to be called when  dragging ends. `pageInrement` is passed as argument
+    func onDraggingEnded(_ callback: ((Double) -> Void)?) -> Self {
+        mutating(keyPath: \.onDraggingEnded, value: callback)
+    }
+
     #endif
 
     /// Changes the a the  alignment of the pages relative to their container
@@ -205,13 +231,6 @@ extension Pager.PagerContent: Buildable, PagerProxy {
     func onPageChanged(_ callback: ((Int) -> Void)?) -> Self {
         mutating(keyPath: \.onPageChanged, value: callback)
     }
-
-	/// Adds a callback to react when dragging begins. Useful for dismissing a keyboard like a scrollview
-	///
-	/// - Parameter callback: block to be called when  dragging begins
-	func onDraggingBegan(_ callback: (() -> Void)?) -> Self {
-		mutating(keyPath: \.onDraggingBegan, value: callback)
-	}
 
     /// Sets some padding on the non-scroll axis
     ///

Sources/SwiftUIPager/PagerContent+Helper.swift

@@ -74,15 +74,16 @@ extension Pager.PagerContent {
     /// Minimum offset allowed. This allows a bounce offset
     var offsetLowerbound: CGFloat {
         guard currentPage == 0, !isInifinitePager else { return CGFloat(numberOfPages) * self.size.width }
-        return CGFloat(numberOfPagesDisplayed) / 2 * pageDistance - pageDistance / 4 + alignmentOffset
+        let bounceOffset = bounces ? -pageDistance / 4 : -pageDistance / 2
+        return CGFloat(numberOfPagesDisplayed) / 2 * pageDistance + bounceOffset + alignmentOffset
     }
 
     /// Maximum offset allowed. This allows a bounce offset
     var offsetUpperbound: CGFloat {
         guard currentPage == numberOfPages - 1, !isInifinitePager else { return -CGFloat(numberOfPages) * self.size.width }
         let a = -CGFloat(numberOfPagesDisplayed) / 2
-        let b = pageDistance / 4
-        return a * pageDistance + b + alignmentOffset
+        let bounceOffset = bounces ? pageDistance / 4 : pageDistance / 2
+        return a * pageDistance + bounceOffset + alignmentOffset
     }
 
     /// Addition of `draggingOffset` and `contentOffset`