Fixes #631 Scroll & constraint issues in BrowserViewController

Client/Frontend/Browser/BrowserViewController.swift

@@ -665,11 +665,7 @@ class BrowserViewController: UIViewController {
             webViewContainerTopOffset = make.top.equalTo(readerModeBar?.snp.bottom ?? self.header.snp.bottom).constraint
 
             let findInPageHeight = (findInPageBar == nil) ? 0 : UIConstants.ToolbarHeight
-            if let toolbar = self.toolbar {
-                make.bottom.equalTo(toolbar.snp.top).offset(-findInPageHeight)
-            } else {
-                make.bottom.equalTo(self.view).offset(-findInPageHeight)
-            }
+            make.bottom.equalTo(self.footer.snp.top).offset(-findInPageHeight)
         }
 
         // Setup the bottom toolbar
@@ -681,6 +677,9 @@ class BrowserViewController: UIViewController {
         footer.snp.remakeConstraints { make in
             scrollController.footerBottomConstraint = make.bottom.equalTo(self.view.snp.bottom).constraint
             make.leading.trailing.equalTo(self.view)
+            if self.toolbar == nil {
+                make.height.equalTo(0.0)
+            }
         }
 
         urlBar.setNeedsUpdateConstraints()
@@ -691,22 +690,16 @@ class BrowserViewController: UIViewController {
             webViewContainerTopOffset = make.top.equalTo(readerModeBar?.snp.bottom ?? self.header.snp.bottom).constraint
 
             make.left.right.equalTo(self.view)
-            if self.homePanelIsInline {
-                make.bottom.equalTo(self.toolbar?.snp.top ?? self.view.snp.bottom)
-            } else {
-                make.bottom.equalTo(self.view.snp.bottom)
-            }
+            make.bottom.equalTo(self.footer.snp.top)
         }
 
         alertStackView.snp.remakeConstraints { make in
             make.centerX.equalTo(self.view)
             make.width.equalTo(self.view.snp.width)
             if let keyboardHeight = keyboardState?.intersectionHeightForView(self.view), keyboardHeight > 0 {
                 make.bottom.equalTo(self.view).offset(-keyboardHeight)
-            } else if let toolbar = self.toolbar {
-                make.bottom.equalTo(toolbar.snp.top)
             } else {
-                make.bottom.equalTo(self.view)
+                make.bottom.equalTo(self.footer.snp.top)
             }
         }
     }

Client/Frontend/Browser/Tab.swift

@@ -189,6 +189,7 @@ class Tab: NSObject {
             configuration!.preferences = WKPreferences()
             configuration!.preferences.javaScriptCanOpenWindowsAutomatically = false
             configuration!.allowsInlineMediaPlayback = true
+            // Enables Zoom in website by ignoring their javascript based viewport Scale limits.
             configuration!.ignoresViewportScaleLimits = true
             let webView = TabWebView(frame: .zero, configuration: configuration!)
             webView.delegate = self

Client/Frontend/Browser/TabScrollController.swift

@@ -22,11 +22,11 @@ class TabScrollingController: NSObject {
     weak var tab: Tab? {
         willSet {
             self.scrollView?.delegate = nil
-            self.scrollView?.removeGestureRecognizer(panGesture)
+            self.scrollView?.panGestureRecognizer.removeTarget(self, action: nil)
         }
 
         didSet {
-            self.scrollView?.addGestureRecognizer(panGesture)
+            self.scrollView?.panGestureRecognizer.addTarget(self, action: #selector(handlePan))
             scrollView?.delegate = self
         }
     }
@@ -52,7 +52,7 @@ class TabScrollingController: NSObject {
 
     fileprivate var headerTopOffset: CGFloat = 0 {
         didSet {
-            headerTopConstraint?.update(offset: headerTopOffset - tabsBarOffset)
+            headerTopConstraint?.update(offset: headerTopOffset)
             header?.superview?.setNeedsLayout()
         }
     }
@@ -70,13 +70,6 @@ class TabScrollingController: NSObject {
         }
     }
 
-    fileprivate lazy var panGesture: UIPanGestureRecognizer = {
-        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
-        panGesture.maximumNumberOfTouches = 1
-        panGesture.delegate = self
-        return panGesture
-    }()
-
     fileprivate var scrollView: UIScrollView? { return tab?.webView?.scrollView }
     fileprivate var contentOffset: CGPoint { return scrollView?.contentOffset ?? .zero }
     fileprivate var contentSize: CGSize { return scrollView?.contentSize ?? .zero }
@@ -251,20 +244,9 @@ private extension TabScrollingController {
     }
 
     func animateToolbarsWithOffsets(_ animated: Bool, duration: TimeInterval, headerOffset: CGFloat, footerOffset: CGFloat, alpha: CGFloat, completion: ((_ finished: Bool) -> Void)?) {
-        guard let scrollView = scrollView else { return }
-        let initialContentOffset = scrollView.contentOffset
-
-        // If this function is used to fully animate the toolbar from hidden to shown, keep the page from scrolling by adjusting contentOffset,
-        // Otherwise when the toolbar is hidden and a link navigated, showing the toolbar will scroll the page and
-        // produce a ~50px page jumping effect in response to tap navigations.
-        let isShownFromHidden = headerTopOffset == -topScrollHeight && headerOffset == 0
-
+        self.headerTopOffset = headerOffset
+        self.footerBottomOffset = footerOffset
         let animation: () -> Void = {
-            if isShownFromHidden {
-                scrollView.contentOffset = CGPoint(x: initialContentOffset.x, y: initialContentOffset.y + self.topScrollHeight)
-            }
-            self.headerTopOffset = headerOffset + self.tabsBarOffset
-            self.footerBottomOffset = footerOffset
             self.urlBar?.updateAlphaForSubviews(alpha)
             self.tabsBar?.view.alpha = alpha
             self.header?.superview?.layoutIfNeeded()