fix page position on navigation (#2330)

DuckDuckGo.xcodeproj/xcshareddata/xcschemes/DuckDuckGo.xcscheme

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
    LastUpgradeVersion = "1500"
-   version = "1.3">
+   version = "1.7">
    <BuildAction
       parallelizeBuildables = "YES"
       buildImplicitDependencies = "YES">

DuckDuckGo/BarsAnimator.swift

@@ -84,10 +84,6 @@ class BarsAnimator {
         let ratio = calculateTransitionRatio(for: scrollView.contentOffset.y)
         delegate?.setBarsVisibility(1.0 - ratio, animated: false)
         transitionProgress = ratio
-
-        var offset = scrollView.contentOffset
-        offset.y = transitionStartPosY
-        scrollView.contentOffset = offset
     }
 
     private func transitioningAndScrolling(in scrollView: UIScrollView) {
@@ -103,10 +99,6 @@ class BarsAnimator {
 
         delegate?.setBarsVisibility(1.0 - ratio, animated: false)
         transitionProgress = ratio
-
-        var offset = scrollView.contentOffset
-        offset.y = transitionStartPosY
-        scrollView.contentOffset = offset
     }
 
     private func hiddenAndScrolling(in scrollView: UIScrollView) {
@@ -139,7 +131,12 @@ class BarsAnimator {
         let cumulativeDistance = (barsHeight * transitionProgress) + distance
         let normalizedDistance = max(cumulativeDistance, 0)
 
-        return min(normalizedDistance / barsHeight, 1.0)
+        // We used to fix the scroll position in place as the transition happened
+        //  but now the bars disappear too. This adjusts for that.
+        let transitionSpeed = 0.5
+
+        let ratio = min(normalizedDistance / barsHeight * transitionSpeed, 1.0)
+        return ratio
     }
 
     func didFinishScrolling(in scrollView: UIScrollView, velocity: CGFloat) {

DuckDuckGo/BrowserChromeManager.swift

@@ -38,7 +38,6 @@ protocol BrowserChromeDelegate: AnyObject {
 class BrowserChromeManager: NSObject, UIScrollViewDelegate {
 
     struct Constants {
-        static let dragThreshold: CGFloat = 30
         static let zoomThreshold: CGFloat = 0.1
 
         static let contentSizeKVOKey = "contentSize"

DuckDuckGo/BrowsingMenu/BrowsingMenuAnimator.swift

@@ -61,7 +61,7 @@ final class BrowsingMenuAnimator: NSObject, UIViewControllerAnimatedTransitionin
             transitionContext.containerView.addSubview(fromSnapshot)
         }
 
-        toViewController.bindConstraints(to: fromViewController.currentTab?.webView)
+        toViewController.bindConstraints(to: fromViewController.viewCoordinator.contentContainer)
         toViewController.view.layoutIfNeeded()
 
         let snapshot = toViewController.menuView.snapshotView(afterScreenUpdates: true)

DuckDuckGo/BrowsingMenu/BrowsingMenuViewController.swift

@@ -157,7 +157,7 @@ final class BrowsingMenuViewController: UIViewController {
 
         recalculatePreferredWidthConstraint()
         recalculateHeightConstraints()
-        webView.map(recalculateMenuConstraints(with:))
+        guideView.map(recalculateMenuConstraints(with:))
 
         if tableView.bounds.height < tableView.contentSize.height + tableView.contentInset.top + tableView.contentInset.bottom {
             tableView.isScrollEnabled = true
@@ -166,12 +166,12 @@ final class BrowsingMenuViewController: UIViewController {
         }
     }
 
-    private weak var webView: UIView?
-    private var webViewFrameObserver: NSKeyValueObservation?
-    func bindConstraints(to webView: UIView?) {
-        self.webView = webView
-        self.webViewFrameObserver = webView?.observe(\.frame, options: [.initial]) { [weak self] webView, _ in
-            self?.recalculateMenuConstraints(with: webView)
+    private weak var guideView: UIView?
+    private var guideViewFrameObserver: NSKeyValueObservation?
+    func bindConstraints(to guideView: UIView?) {
+        self.guideView = guideView
+        self.guideViewFrameObserver = guideView?.observe(\.frame, options: [.initial]) { [weak self] guideView, _ in
+            self?.recalculateMenuConstraints(with: guideView)
         }
     }
 
@@ -205,9 +205,9 @@ final class BrowsingMenuViewController: UIViewController {
         }
     }
 
-    private func recalculateMenuConstraints(with webView: UIView) {
-        guard let frame = webView.superview?.convert(webView.frame, to: webView.window),
-              let windowBounds = webView.window?.bounds
+    private func recalculateMenuConstraints(with guideView: UIView) {
+        guard let frame = guideView.superview?.convert(guideView.frame, to: guideView.window),
+              let windowBounds = guideView.window?.bounds
         else { return }
 
         let isIPad = AppWidthObserver.shared.isLargeWidth

DuckDuckGo/MainView.swift

@@ -54,6 +54,7 @@ class MainViewFactory {
 extension MainViewFactory {
 
     private func createViews() {
+        createWebViewContainer()
         createLogoBackground()
         createContentContainer()
         createSuggestionTrayContainer()
@@ -64,13 +65,19 @@ extension MainViewFactory {
         createProgressView()
         createToolbar()
     }
+
+    final class WebViewContainerView: UIView { }
+    private func createWebViewContainer() {
+        coordinator.webViewContainer = WebViewContainerView()
+        superview.addSubview(coordinator.webViewContainer)
+    }
 
     private func createProgressView() {
         coordinator.progress = ProgressView()
         superview.addSubview(coordinator.progress)
     }
 
-    class NavigationBarContainer: UIView { }
+    final class NavigationBarContainer: UIView { }
     private func createNavigationBarContainer() {
         coordinator.omniBar = OmniBar.loadFromXib()
         coordinator.omniBar.translatesAutoresizingMaskIntoConstraints = false
@@ -79,31 +86,31 @@ extension MainViewFactory {
         superview.addSubview(coordinator.navigationBarContainer)
     }
 
-    class NotificationBarContainer: UIView { }
+    final class NotificationBarContainer: UIView { }
     private func createNotificationBarContainer() {
         coordinator.notificationBarContainer = NotificationBarContainer()
         superview.addSubview(coordinator.notificationBarContainer)
     }
 
-    class ContentContainer: UIView { }
+    final class ContentContainer: UIView { }
     private func createContentContainer() {
         coordinator.contentContainer = ContentContainer()
         superview.addSubview(coordinator.contentContainer)
     }
 
-    class StatusBackgroundView: UIView { }
+    final class StatusBackgroundView: UIView { }
     private func createStatusBackground() {
         coordinator.statusBackground = StatusBackgroundView()
         superview.addSubview(coordinator.statusBackground)
     }
 
-    class TabBarContainer: UIView { }
+    final class TabBarContainer: UIView { }
     private func createTabBarContainer() {
         coordinator.tabBarContainer = TabBarContainer()
         superview.addSubview(coordinator.tabBarContainer)
     }
 
-    class SuggestionTrayContainer: UIView { }
+    final class SuggestionTrayContainer: UIView { }
     private func createSuggestionTrayContainer() {
         coordinator.suggestionTrayContainer = SuggestionTrayContainer()
         coordinator.suggestionTrayContainer.isHidden = true
@@ -136,7 +143,7 @@ extension MainViewFactory {
         ], animated: true)
     }
 
-    class LogoBackgroundView: UIView { }
+    final class LogoBackgroundView: UIView { }
     private func createLogoBackground() {
         coordinator.logoContainer = LogoBackgroundView()
         coordinator.logo = UIImageView(image: UIImage(named: "Logo"))
@@ -156,6 +163,7 @@ extension MainViewFactory {
 extension MainViewFactory {
 
     private func constrainViews() {
+        constrainWebViewContainer()
         constrainLogoBackground()
         constrainContentContainer()
         constrainSuggestionTrayContainer()
@@ -166,6 +174,16 @@ extension MainViewFactory {
         constrainProgress()
         constrainToolbar()
     }
+
+    private func constrainWebViewContainer() {
+        let webViewContainer = coordinator.webViewContainer!
+        NSLayoutConstraint.activate([
+            webViewContainer.constrainView(superview, by: .width),
+            webViewContainer.constrainView(superview, by: .height),
+            webViewContainer.constrainView(superview, by: .centerX),
+            webViewContainer.constrainView(superview, by: .centerY),
+        ])
+    }
 
     private func constrainProgress() {
         let progress = coordinator.progress!
@@ -333,6 +351,7 @@ class MainViewCoordinator {
     var toolbarFireButton: UIBarButtonItem!
     var toolbarForwardButton: UIBarButtonItem!
     var toolbarTabSwitcherButton: UIBarButtonItem!
+    var webViewContainer: UIView!
 
     let constraints = Constraints()
 

DuckDuckGo/MainViewController.swift

@@ -137,6 +137,8 @@ class MainViewController: UIViewController {
 
     // Skip SERP flow (focusing on autocomplete logic) and prepare for new navigation when selecting search bar
     private var skipSERPFlow = true
+
+    private var keyboardHeight: CGFloat = 0.0
 
     required init?(coder: NSCoder) {
         fatalError("Use init?(code:")
@@ -430,6 +432,7 @@ class MainViewController: UIViewController {
     @objc func onAddressBarPositionChanged() {
         viewCoordinator.moveAddressBarToPosition(appSettings.currentAddressBarPosition)
         refreshViewsBasedOnAddressBarPosition(appSettings.currentAddressBarPosition)
+        refreshWebViewContentInsets()
     }
 
     func refreshViewsBasedOnAddressBarPosition(_ position: AddressBarPosition) {
@@ -475,7 +478,8 @@ class MainViewController: UIViewController {
         height = intersection.height
 
         findInPageBottomLayoutConstraint.constant = height
-        currentTab?.webView.scrollView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: height, right: 0)
+        keyboardHeight = height
+        refreshWebViewContentInsets()
 
         if let suggestionsTray = suggestionTrayController {
             let suggestionsFrameInView = suggestionsTray.view.convert(suggestionsTray.contentFrame, to: view)
@@ -640,7 +644,7 @@ class MainViewController: UIViewController {
             guard let tab = tabManager.current(createIfNeeded: true) else {
                 fatalError("Unable to create tab")
             }
-            addToView(tab: tab)
+            addToWebViewContainer(tab: tab)
             refreshControls()
         } else {
             attachHomeScreen()
@@ -700,7 +704,7 @@ class MainViewController: UIViewController {
         controller.chromeDelegate = self
         controller.delegate = self
 
-        addToView(controller: controller)
+        addToContentContainer(controller: controller)
 
         refreshControls()
         syncService.scheduler.requestSyncImmediately()
@@ -849,7 +853,7 @@ class MainViewController: UIViewController {
     private func addTab(url: URL?, inheritedAttribution: AdClickAttributionLogic.State?) {
         let tab = tabManager.add(url: url, inheritedAttribution: inheritedAttribution)
         dismissOmniBar()
-        addToView(tab: tab)
+        addToWebViewContainer(tab: tab)
     }
 
     func select(tabAt index: Int) {
@@ -863,7 +867,7 @@ class MainViewController: UIViewController {
         if tab.link == nil {
             attachHomeScreen()
         } else {
-            addToView(tab: tab)
+            addToWebViewContainer(tab: tab)
             refreshControls()
         }
         tabsBarController?.refresh(tabsModel: tabManager.model, scrollToSelected: true)
@@ -872,18 +876,29 @@ class MainViewController: UIViewController {
         }
     }
 
-    private func addToView(tab: TabViewController) {
+    private func addToWebViewContainer(tab: TabViewController) {
         removeHomeScreen()
         updateFindInPage()
         currentTab?.progressWorker.progressBar = nil
         currentTab?.chromeDelegate = nil
-        addToView(controller: tab)
+        currentTab?.webView.scrollView.contentInsetAdjustmentBehavior = .never
+
+        addChild(tab)
+        viewCoordinator.webViewContainer.subviews.forEach { $0.removeFromSuperview() }
+        viewCoordinator.webViewContainer.addSubview(tab.view)
+        tab.view.frame = self.viewCoordinator.webViewContainer.bounds
+        tab.didMove(toParent: self)
+
+        viewCoordinator.logoContainer.isHidden = true
+        viewCoordinator.contentContainer.isHidden = true
+
         tab.progressWorker.progressBar = viewCoordinator.progress
         chromeManager.attach(to: tab.webView.scrollView)
         tab.chromeDelegate = self
     }
 
-    private func addToView(controller: UIViewController) {
+    private func addToContentContainer(controller: UIViewController) {
+        viewCoordinator.contentContainer.isHidden = false
         addChild(controller)
         viewCoordinator.contentContainer.subviews.forEach { $0.removeFromSuperview() }
         viewCoordinator.contentContainer.addSubview(controller.view)
@@ -1314,28 +1329,53 @@ extension MainViewController: BrowserChromeDelegate {
         let updateBlock = {
             self.updateToolbarConstant(percent)
             self.updateNavBarConstant(percent)
-            
+
             self.view.layoutIfNeeded()
 
-            self.viewCoordinator.omniBar.alpha = percent
+            self.viewCoordinator.navigationBarContainer.alpha = percent
             self.viewCoordinator.tabBarContainer.alpha = percent
             self.viewCoordinator.toolbar.alpha = percent
         }
-
+           
         if animated {
-            UIView.animate(withDuration: ChromeAnimationConstants.duration, animations: updateBlock)
+            UIView.animate(withDuration: ChromeAnimationConstants.duration, animations: updateBlock) { _ in
+                self.refreshWebViewContentInsets()
+            }
         } else {
             updateBlock()
+            self.refreshWebViewContentInsets()
         }
     }
 
+    func refreshWebViewContentInsets() {
+        guard let webView = currentTab?.webView else { return }
+
+        let top = viewCoordinator.statusBackground.frame.height
+        let bottom: CGFloat
+        if isToolbarHidden {
+            bottom = 0
+        } else if appSettings.currentAddressBarPosition.isBottom {
+            bottom = viewCoordinator.toolbar.frame.height
+                + viewCoordinator.navigationBarContainer.frame.height
+                + view.safeAreaInsets.bottom + additionalSafeAreaInsets.bottom
+                + keyboardHeight
+        } else {
+            bottom = viewCoordinator.toolbar.frame.height
+                + view.safeAreaInsets.bottom + additionalSafeAreaInsets.bottom
+                + keyboardHeight
+        }
+
+        webView.scrollView.contentInset = .init(top: top, left: 0, bottom: bottom, right: 0)
+    }
+
     func setNavigationBarHidden(_ hidden: Bool) {
         if hidden { hideKeyboard() }
 
         updateNavBarConstant(hidden ? 0 : 1.0)
         viewCoordinator.omniBar.alpha = hidden ? 0 : 1
         viewCoordinator.tabBarContainer.alpha = hidden ? 0 : 1
         viewCoordinator.statusBackground.alpha = hidden ? 0 : 1
+
     }
 
     var canHideBars: Bool {
@@ -1693,7 +1733,7 @@ extension MainViewController: TabDelegate {
             guard self.tabManager.model.tabs.contains(newTab.tabModel) else { return }
 
             self.dismissOmniBar()
-            self.addToView(tab: newTab)
+            self.addToWebViewContainer(tab: newTab)
             self.refreshOmniBar()
         }
 
@@ -1797,6 +1837,7 @@ extension MainViewController: TabDelegate {
 
     func showBars() {
         chromeManager.reset()
+        refreshWebViewContentInsets()
     }
 
     func tabDidRequestFindInPage(tab: TabViewController) {

DuckDuckGo/TabViewController.swift

@@ -1147,7 +1147,12 @@ extension TabViewController: WKNavigationDelegate {
         DispatchQueue.main.async { [weak self] in
             guard let webView = self?.webView,
                   webView.bounds.height > 0 && webView.bounds.width > 0 else { completion(nil); return }
-            UIGraphicsBeginImageContextWithOptions(webView.bounds.size, false, UIScreen.main.scale)
+
+            let size = CGSize(width: webView.frame.size.width,
+                              height: webView.frame.size.height - webView.scrollView.contentInset.top - webView.scrollView.contentInset.bottom)
+
+            UIGraphicsBeginImageContextWithOptions(size, false, UIScreen.main.scale)
+            UIGraphicsGetCurrentContext()?.translateBy(x: 0, y: -webView.scrollView.contentInset.top)
             webView.drawHierarchy(in: webView.bounds, afterScreenUpdates: true)
             if let jsAlertController = self?.jsAlertController {
                 jsAlertController.view.drawHierarchy(in: jsAlertController.view.bounds,