From 7e30a316ecf25a677ea941069917e66d52c38737 Mon Sep 17 00:00:00 2001
From: Luke Zhao <me@lkzhao.com>
Date: Sat, 28 Dec 2019 10:06:08 -0800
Subject: [PATCH] fix zoom

---
 CollectionKit2/Sources/CollectionView.swift   | 22 +++++++++++++++++++
 .../Sources/Layout/FlowLayout.swift           |  2 +-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/CollectionKit2/Sources/CollectionView.swift b/CollectionKit2/Sources/CollectionView.swift
index d9ceacb9..65801037 100644
--- a/CollectionKit2/Sources/CollectionView.swift
+++ b/CollectionKit2/Sources/CollectionView.swift
@@ -72,6 +72,28 @@ open class CollectionView: UIScrollView {
       _loadCells(reloading: false)
     }
     contentView?.frame = CGRect(origin: .zero, size: contentSize)
+    ensureZoomViewIsCentered()
+  }
+
+    
+  public func ensureZoomViewIsCentered() {
+    guard let contentView = contentView else { return }
+    let boundsSize = bounds.inset(by: adjustedContentInset)
+    var frameToCenter = contentView.frame
+
+    if frameToCenter.size.width < boundsSize.width {
+      frameToCenter.origin.x = (boundsSize.width - frameToCenter.size.width) * 0.5
+    } else {
+      frameToCenter.origin.x = 0
+    }
+
+    if frameToCenter.size.height < boundsSize.height {
+      frameToCenter.origin.y = (boundsSize.height - frameToCenter.size.height) * 0.5
+    } else {
+      frameToCenter.origin.y = 0
+    }
+    
+    contentView.frame = frameToCenter
   }
 
   public func setNeedsReload() {
diff --git a/CollectionKit2/Sources/Layout/FlowLayout.swift b/CollectionKit2/Sources/Layout/FlowLayout.swift
index fd5cf278..79e4e2a1 100644
--- a/CollectionKit2/Sources/Layout/FlowLayout.swift
+++ b/CollectionKit2/Sources/Layout/FlowLayout.swift
@@ -8,7 +8,7 @@
 
 import UIKit
 
-public class FlowLayout: SortedLayoutProvider {
+open class FlowLayout: SortedLayoutProvider {
   public var lineSpacing: CGFloat
   public var interitemSpacing: CGFloat