From 3b23101710b802566ad4492832e6c8a4f943fa27 Mon Sep 17 00:00:00 2001
From: "Xinlei(Ryan) Pan" <xinleiryan.pan@verizonwireless.com>
Date: Mon, 27 Apr 2020 15:22:40 -0400
Subject: [PATCH] update tabs model

---
 .../HorizontalCombinationViews/Tabs.swift     | 53 ++++++-------------
 1 file changed, 15 insertions(+), 38 deletions(-)

diff --git a/MVMCoreUI/Atomic/Molecules/HorizontalCombinationViews/Tabs.swift b/MVMCoreUI/Atomic/Molecules/HorizontalCombinationViews/Tabs.swift
index 6caa6a03..dc8b9cae 100644
--- a/MVMCoreUI/Atomic/Molecules/HorizontalCombinationViews/Tabs.swift
+++ b/MVMCoreUI/Atomic/Molecules/HorizontalCombinationViews/Tabs.swift
@@ -31,6 +31,8 @@ import UIKit
     var bottomLineLeftConstraint: NSLayoutConstraint?
     var bottomLineWidthConstraint: NSLayoutConstraint?
     
+    private var widthLabel = Label()
+    
     //delegate
     weak public var delegate: TabsDelegate?
     
@@ -186,11 +188,14 @@ extension Tabs: UICollectionViewDelegateFlowLayout {
         return CGSize(width: getLabelWidth(labelModel).width, height: cellHeight)
     }
     
+    //pre calculate the width of the collection cell
+    //when user select tabs, it will reload related collectionview, if we use autosize, it would relayout the width, need to keep the cell width constant.
     func getLabelWidth(_ labelModel: LabelModel?) -> CGSize {
         guard let labelModel = labelModel else { return .zero}
-        let label = Label()
-        label.set(with: labelModel, nil, nil)
-        return label.intrinsicContentSize
+        widthLabel.set(with: labelModel, nil, nil)
+        let cgSize = widthLabel.intrinsicContentSize
+        widthLabel.reset()
+        return cgSize
     }
     
     public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
@@ -244,6 +249,10 @@ extension Tabs: UICollectionViewDelegateFlowLayout {
 
 extension Tabs: UIScrollViewDelegate {
     public func scrollViewDidScroll(_ scrollView: UIScrollView) {
+        /*bottomScrollview is subview of self, it's not belongs to collectionview.
+        When collectionview is scrolling, bottomScrollView will stay without moving
+        Adding collectionview's offset to bottomScrollView, will make the bottomScrollview looks like scrolling with the selected tab item.
+         */
         guard let offsetX = collectionView?.contentOffset.x else { return }
         bottomScrollView.setContentOffset(CGPoint(x: offsetX, y: bottomScrollView.contentOffset.y), animated: false)
     }
@@ -272,46 +281,14 @@ extension Tabs {
             animationBlock()
         }
     }
-    
-    public func progress(fromIndex: Int, toIndex: Int, progressPercentage percent: CGFloat) {
-        guard let _ = collectionView else { return }
-        MVMCoreDispatchUtility.performBlock(onMainThread: {
-            self.setBottomLine(fromIndex: IndexPath(row: fromIndex, section: 0), toIndex: IndexPath(row: toIndex, section: 0), percent: percent)
-        })
-    }
-    
-    func setBottomLine(fromIndex: IndexPath, toIndex: IndexPath, percent: CGFloat) {
-        guard let fromCell = collectionView?.cellForItem(at: fromIndex) as? TabItemCell, let toCell = collectionView?.cellForItem(at: toIndex) as? TabItemCell else {
-            return
-        }
-        let fromWidth = getLabelWidth(fromCell.labelModel).width
-        let toWidth = getLabelWidth(toCell.labelModel).width
-        let finalWidth = (toWidth - fromWidth) * percent + fromWidth
-        bottomLineWidthConstraint?.constant = finalWidth
-        let xDifference = toCell.frame.origin.x - fromCell.frame.origin.x
-        let finalX = xDifference * percent + fromCell.frame.origin.x
-        bottomLineLeftConstraint?.constant = finalX
-        bottomContentView.layoutIfNeeded()
-    }
 }
 
-
-
-@objcMembers public class TabItemCell: UICollectionViewCell {
+@objcMembers public class TabItemCell: CollectionViewCell {
     public let label = Label()
     public var labelModel: LabelModel?
     
-    override init(frame: CGRect) {
-        super.init(frame: frame)
-        setupView()
-    }
-    
-    required init?(coder: NSCoder) {
-        super.init(coder: coder)
-        setupView()
-    }
-    
-    func setupView() {
+    public override func setupView() {
+        super.setupView()
         contentView.addSubview(label)
         NSLayoutConstraint.constraintPinSubview(label, pinTop: false, pinBottom: false, pinLeft: true, pinRight: true)
         label.centerYAnchor.constraint(equalTo: contentView.centerYAnchor).isActive = true