Bugfixes/improve zoom (#82)

* create shortcut for initializing image carousel

* make zoom in more natural.

Author: michaelhenry

Sources/ImageCarouselViewController.swift

@@ -38,6 +38,30 @@ public class ImageCarouselViewController:UIPageViewController {
 
     private(set) lazy var navItem = UINavigationItem()
 
+    public static func create(
+        sourceView:UIImageView,
+        imageDataSource: ImageDataSource?,
+        options:[ImageViewerOption] = [],
+        initialIndex:Int = 0) -> ImageCarouselViewController {
+        
+        let pageOptions = [UIPageViewController.OptionsKey.interPageSpacing: 20]
+        
+        let imageCarousel = ImageCarouselViewController(
+            transitionStyle: .scroll,
+            navigationOrientation: .horizontal,
+            options: pageOptions)
+        
+        imageCarousel.modalPresentationStyle = .overFullScreen
+        imageCarousel.modalPresentationCapturesStatusBarAppearance = true
+        
+        imageCarousel.sourceView = sourceView
+        imageCarousel.imageDatasource = imageDataSource
+        imageCarousel.options = options
+        imageCarousel.initialIndex = initialIndex
+       
+        return imageCarousel
+    }
+    
     private func addNavBar() {
         // Add Navigation Bar
         let closeBarButton = UIBarButtonItem(

Sources/ImageViewerController.swift

@@ -36,6 +36,7 @@ class ImageViewerController:UIViewController, UIGestureRecognizerDelegate {
 
     private var lastLocation:CGPoint = .zero
     private var isAnimating:Bool = false
+    private var maxZoomScale:CGFloat = 1.0
 
     init(sourceView:UIImageView? = nil) {
         super.init(nibName: nil, bundle: nil)
@@ -205,31 +206,33 @@ class ImageViewerController:UIViewController, UIGestureRecognizerDelegate {
 
     func gestureRecognizerShouldBegin(
         _ gestureRecognizer: UIGestureRecognizer) -> Bool {
-        if let panGesture = gestureRecognizer as? UIPanGestureRecognizer {
-            let velocity = panGesture.velocity(in: scrollView)
-            return abs(velocity.y) > abs(velocity.x)
-        }
-        return false
+        guard scrollView.zoomScale == scrollView.minimumZoomScale,
+            let panGesture = gestureRecognizer as? UIPanGestureRecognizer else { return false }
+
+        let velocity = panGesture.velocity(in: scrollView)
+        return abs(velocity.y) > abs(velocity.x)
     }
 }
 
 // MARK: Adjusting the dimensions
 extension ImageViewerController {
 
     func updateMinMaxZoomScaleForSize(_ size: CGSize) {
-        let widthScale = size.width / imageView.bounds.width
-        let heightScale = size.height / imageView.bounds.height
+        let widthScale = (size.width + 1.0) / imageView.bounds.width
+        let heightScale = (size.height + 1.0) / imageView.bounds.height
         let minScale = min(widthScale, heightScale)
+        let maxScale = max(widthScale, heightScale)
 
         scrollView.minimumZoomScale = minScale
         scrollView.zoomScale = minScale
-        scrollView.maximumZoomScale = max(1, minScale) * 2
+        maxZoomScale = maxScale
+        scrollView.maximumZoomScale = maxZoomScale * 1.1
     }
 
 
     func zoomInOrOut(at point:CGPoint) {
         let newZoomScale = scrollView.zoomScale == scrollView.minimumZoomScale
-            ? scrollView.maximumZoomScale : scrollView.minimumZoomScale
+            ? maxZoomScale : scrollView.minimumZoomScale
         let size = scrollView.bounds.size
         let w = size.width / newZoomScale
         let h = size.height / newZoomScale

Sources/UIImageView_Extensions.swift

@@ -110,20 +110,12 @@ extension UIImageView {
     private func showImageViewer(_ sender:TapWithDataRecognizer) {
         guard let sourceView = sender.view as? UIImageView else { return }
 
-        let options = [UIPageViewController.OptionsKey.interPageSpacing: 20]
-        
-        let imageCarousel = ImageCarouselViewController(
-            transitionStyle: .scroll,
-            navigationOrientation: .horizontal,
-            options: options)
-        
-        imageCarousel.sourceView = sourceView
-        imageCarousel.imageDatasource = sender.imageDatasource
-        imageCarousel.initialIndex = sender.initialIndex
-        imageCarousel.imageDatasource = sender.imageDatasource
-        imageCarousel.options = sender.options
-        imageCarousel.modalPresentationStyle = .overFullScreen
-        imageCarousel.modalPresentationCapturesStatusBarAppearance = true
+        let imageCarousel = ImageCarouselViewController.create(
+            sourceView: sourceView,
+            imageDataSource: sender.imageDatasource,
+            options: sender.options,
+            initialIndex: sender.initialIndex)
+
         vc?.present(imageCarousel, animated: false, completion: nil)
     }
 }