Dactyloidae iOS initial commit

mobile/ios/Client/Frontend/Browser/TopTabsLayout.swift

@@ -0,0 +1,113 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+import Foundation
+
+class TopTabsLayoutDelegate: NSObject, UICollectionViewDelegateFlowLayout {
+    weak var tabSelectionDelegate: TabSelectionDelegate?
+    let HeaderFooterWidth = TopTabsUX.SeparatorWidth + TopTabsUX.FaderPading
+    
+    @objc func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
+        return TopTabsUX.SeparatorWidth
+    }
+    
+    @objc func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
+        return CGSize(width: TopTabsUX.TabWidth, height: collectionView.frame.height)
+    }
+    
+    @objc func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
+        return UIEdgeInsets.zero
+    }
+    
+    @objc func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
+        return TopTabsUX.SeparatorWidth
+    }
+    
+    @objc func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
+        tabSelectionDelegate?.didSelectTabAtIndex(indexPath.row)
+    }
+
+    @objc func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
+        return CGSize(width: HeaderFooterWidth, height: 0)
+    }
+
+    @objc func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
+        return CGSize(width: HeaderFooterWidth, height: 0)
+    }
+
+}
+
+class TopTabsViewLayout: UICollectionViewFlowLayout {
+    var decorationAttributeArr: [Int: UICollectionViewLayoutAttributes?] = [:]
+    let separatorYOffset = TopTabsUX.SeparatorYOffset
+    let separatorSize = TopTabsUX.SeparatorHeight
+    let SeparatorZIndex = -2 ///Prevent the header/footer from appearing above the Tabs
+    
+    override var collectionViewContentSize: CGSize {
+        let tabsWidth = ((CGFloat(collectionView!.numberOfItems(inSection: 0))) * (TopTabsUX.TabWidth + TopTabsUX.SeparatorWidth)) - TopTabsUX.SeparatorWidth
+        return CGSize(width: tabsWidth + (TopTabsUX.TopTabsBackgroundShadowWidth * 2), height: collectionView!.bounds.height)
+    }
+    
+    override func prepare() {
+        super.prepare()
+        self.minimumLineSpacing = TopTabsUX.SeparatorWidth
+        scrollDirection = UICollectionViewScrollDirection.horizontal
+        register(TopTabsSeparator.self, forDecorationViewOfKind: TopTabsSeparatorUX.Identifier)
+    }
+    
+    override func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
+        decorationAttributeArr = [:]
+        return true
+    }
+
+    // MARK: layoutAttributesForElementsInRect
+    override func layoutAttributesForDecorationView(ofKind elementKind: String, at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
+        guard indexPath.row < self.collectionView!.numberOfItems(inSection: 0) else {
+            let separatorAttr = UICollectionViewLayoutAttributes(forDecorationViewOfKind: TopTabsSeparatorUX.Identifier, with: indexPath)
+            separatorAttr.frame = CGRect.zero
+            separatorAttr.zIndex = SeparatorZIndex
+            return separatorAttr
+        }
+
+        if let attr = self.decorationAttributeArr[indexPath.item] {
+            return attr
+        } else {
+            // Compute the separator if it does not exist in the cache
+            let separatorAttr = UICollectionViewLayoutAttributes(forDecorationViewOfKind: TopTabsSeparatorUX.Identifier, with: indexPath)
+            let x = TopTabsUX.TopTabsBackgroundShadowWidth + ((CGFloat(indexPath.row) * (TopTabsUX.TabWidth + TopTabsUX.SeparatorWidth)) - TopTabsUX.SeparatorWidth)
+            separatorAttr.frame = CGRect(x: x, y: separatorYOffset, width: TopTabsUX.SeparatorWidth, height: separatorSize)
+            separatorAttr.zIndex = SeparatorZIndex
+            return separatorAttr
+        }
+    }
+
+    override func layoutAttributesForSupplementaryView(ofKind elementKind: String, at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
+        let attributes = super.layoutAttributesForSupplementaryView(ofKind: elementKind, at: indexPath)
+        attributes?.zIndex = SeparatorZIndex
+        return attributes
+    }
+
+    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
+        var attributes = super.layoutAttributesForElements(in: rect)!
+
+        // Create attributes for the Tab Separator.
+        for i in attributes {
+            guard i.representedElementKind != UICollectionElementKindSectionHeader && i.representedElementKind != UICollectionElementKindSectionFooter else {
+                i.zIndex = SeparatorZIndex
+                continue
+            }
+            let sep = UICollectionViewLayoutAttributes(forDecorationViewOfKind: TopTabsSeparatorUX.Identifier, with: i.indexPath)
+            sep.frame = CGRect(x: i.frame.origin.x - TopTabsUX.SeparatorWidth, y: separatorYOffset, width: TopTabsUX.SeparatorWidth, height: separatorSize)
+            sep.zIndex = SeparatorZIndex
+            i.zIndex = 10
+
+            // Only add the seperator if it will be shown.
+            if i.indexPath.row != 0 && i.indexPath.row < self.collectionView!.numberOfItems(inSection: 0) {
+                attributes.append(sep)
+                decorationAttributeArr[i.indexPath.item] = sep
+            }
+        }
+
+        return attributes
+    }
+}