Added capability to auto resolve container scrollview for table viewport calculations

Author: rajdeep

Diff for: ExampleApp/ExampleApp/AdvancedFeatures/CommandsExampleViewController.swift

@@ -487,12 +487,15 @@ extension CommandsExampleViewController: TableViewDelegate {
         viewport.size.width -= (offsetX * 2)
         viewport.size.height -= (offsetY * 2)
 
-        Utility.drawRect(rect: CGRect(origin: CGPoint(x: offsetX, y: offsetY), size: viewport.size), color: .red, in: editor)
         return viewport
     }
 
     var containerScrollView: UIScrollView? {
-        editor.scrollView
+        nil
+    }
+
+    var resolvedViewportBorderDisplay: ViewportBorderDisplay {
+        .visible(color: .red, borderWidth: 1)
     }
 
     func tableView(_ tableView: TableView, didReceiveKey key: EditorKey, at range: NSRange, in cell: TableCell) { }

Diff for: Proton/Sources/Swift/Helpers/Utility.swift

@@ -25,18 +25,18 @@ import UIKit
 public class Utility {
     private init() { }
 
-    public static func drawRect(rect: CGRect, color: UIColor, in view: UIView, name: String = "rect_layer") {
+    public static func drawRect(rect: CGRect, color: UIColor, borderWidth: CGFloat = 1.0, in view: UIView, name: String = "rect_layer") {
         let path = UIBezierPath(rect: rect).cgPath
-        drawPath(path: path, color: color, in: view, name: name)
+        drawPath(path: path, color: color, borderWidth: borderWidth, in: view, name: name)
     }
 
-    public static func drawPath(path: CGPath, color: UIColor, in view: UIView, name: String = "path_layer") {
+    public static func drawPath(path: CGPath, color: UIColor, borderWidth: CGFloat = 1.0, in view: UIView, name: String = "path_layer") {
         let existingLayer = view.layer.sublayers?.first(where: { $0.name == name}) as? CAShapeLayer
         let shapeLayer = existingLayer ?? CAShapeLayer()
         shapeLayer.path = path
         shapeLayer.strokeColor = color.cgColor
         shapeLayer.fillColor = UIColor.clear.cgColor
-        shapeLayer.lineWidth = 1.0
+        shapeLayer.lineWidth = borderWidth
         shapeLayer.name = name
 
         if existingLayer == nil {

Diff for: Proton/Sources/Swift/Table/TableView.swift

@@ -38,12 +38,24 @@ public protocol TableCellLifeCycleObserver: AnyObject {
     func tableView(_ tableView: TableView, didRemoveCellFromViewport cell: TableCell)
 }
 
+
+public enum ViewportBorderDisplay {
+    case hidden
+    case visible(color: UIColor, borderWidth: CGFloat)
+}
+
 /// An object capable of handing `TableView` events
 public protocol TableViewDelegate: AnyObject {
     var containerScrollView: UIScrollView? { get }
 
     var viewport: CGRect? { get }
 
+    /// Governs whether resolved viewport is displayed
+    /// - Note: This may be used for debugging purposes.
+    /// - Important: It is responsibility of consumer of the API to ensure that this is not displayed in app if not intended to. i.e. display of viewport does not
+    /// check for DEBUG flags and would be displayed based on value provided.
+    var resolvedViewportBorderDisplay: ViewportBorderDisplay { get }
+
     /// Invoked when `EditorView` within the cell receives focus
     /// - Parameters:
     ///   - tableView: TableView containing cell
@@ -145,6 +157,10 @@ public protocol TableViewDelegate: AnyObject {
     func tableView(_ tableView: TableView, didRemoveCellFromViewport cell: TableCell)
 }
 
+public extension TableViewDelegate {
+    var resolvedViewportBorderDisplay: ViewportBorderDisplay { .hidden }
+}
+
 /// A view that provides a tabular structure where each cell is an `EditorView`.
 /// Since the cells contains an `EditorView` in itself, it is capable of hosting any attachment that `EditorView` can host
 /// including another `TableView` as an attachment.
@@ -165,6 +181,12 @@ public class TableView: UIView {
 
     private let repository = TableCellRepository()
 
+    private var _containerScrollView: UIScrollView? {
+        didSet {
+            _containerScrollView != nil ? setupScrollObserver() : removeScrollObserver()
+        }
+    }
+
     private lazy var columnRightBorderView: UIView = {
         makeSelectionBorderView()
     }()
@@ -345,6 +367,40 @@ public class TableView: UIView {
         }
     }
 
+    public override func didMoveToWindow() {
+        guard window != nil else {
+            removeScrollObserver()
+            return
+        }
+
+        // Only try to auto resolve container scrollview, if not already provided by the delegate
+        guard self.containerScrollView == nil else { return }
+
+        // If table has the Editor which is scrollable, use that as container for viewport
+        let containerEditorView = self.containerAttachment?.containerEditorView
+        if let scrollView = containerEditorView?.scrollView, scrollView.isScrollEnabled {
+            _containerScrollView = scrollView
+            return
+        }
+
+        // Else, find the next available scrollview up the hierarchy
+        var currentView: UIView? = containerEditorView
+        while let view = currentView, !(view is UIScrollView) {
+            currentView = view.superview
+        }
+
+        if let scrollView = currentView as? UIScrollView {
+            _containerScrollView = scrollView
+        }
+
+        // If there's still none, default to container editor scrollview
+        // This would typically be the case where the Editor starts off as non-scrollable but becomes scrollable
+        // as the content overflows in which case this should resolve correctly.
+        if _containerScrollView == nil {
+            _containerScrollView = containerEditorView?.scrollView
+        }
+    }
+
     /// Maintains the scroll lock on the cell passed in if the  original rect ends up moving as a result of cells getting rendered above this rect position
     /// - Parameters:
     ///   - cell: Cell to lock on
@@ -399,7 +455,7 @@ public class TableView: UIView {
     }
 
     private func setupScrollObserver() {
-        observation = delegate?.containerScrollView?.observe(\.bounds, options: [.new, .old]) { [weak self] container, change in
+        observation = containerScrollView?.observe(\.bounds, options: [.new, .old]) { [weak self] container, change in
             self?.viewportChanged()
         }
     }
@@ -450,7 +506,7 @@ public class TableView: UIView {
               // ensure editor is not hidden e.g. inside an Expand in collapsed state
               attachmentContentView.attachment?.containerEditorView?.isHidden == false,
               tableView.bounds != .zero,
-              let containerScrollView = delegate?.containerScrollView,
+              let containerScrollView = self.containerScrollView,
               let rootEditorView = containerAttachment?.containerEditorView?.rootEditor else {
             cellsInViewport = []
             return
@@ -472,8 +528,10 @@ public class TableView: UIView {
         // Convert the visible rectangle back to the nestedView's coordinate space
         let visibleRectOfNestedView = rootEditorView.convert(visibleRectOfNestedViewInScrollView, from: containerScrollView)
 
-        // Uncomment following line to show the resolved viewport
-//         Utility.drawRect(rect: visibleRectOfNestedView, color: .red, in: rootEditorView, name: "viewport")
+        if let viewportBorder = delegate?.resolvedViewportBorderDisplay,
+           case let ViewportBorderDisplay.visible(color, borderWidth) = viewportBorder {
+            Utility.drawRect(rect: visibleRectOfNestedView, color: color, borderWidth: borderWidth, in: rootEditorView, name: "viewport")
+        }
 
         let adjustedViewport = visibleRectOfNestedView.offsetBy(dx: tableView.bounds.minX, dy: tableView.bounds.minY)
 
@@ -834,7 +892,7 @@ extension TableView: UIScrollViewDelegate {
 
 extension TableView: TableContentViewDelegate {
     var containerScrollView: UIScrollView? {
-        delegate?.containerScrollView
+        delegate?.containerScrollView ?? _containerScrollView
     }
 
     var viewport: CGRect? {

Diff for: Proton/Tests/Table/TableViewTests.swift

@@ -52,6 +52,33 @@ class TableViewTests: XCTestCase {
         window.rootViewController = viewController
     }
 
+    func testResovlesContainerScrollView() throws {
+        delegate.containerScrollView = nil
+
+        let viewport = CGRect(x: 0, y: 100, width: 350, height: 200)
+        delegate.viewport = viewport
+
+        let attachment = AttachmentGenerator.makeTableViewAttachment(
+            id: 1,
+            numRows: 20,
+            numColumns: 5,
+            initialRowHeight: 100
+        )
+        let tableView = attachment.view
+
+        tableView.delegate = delegate
+
+        editor.replaceCharacters(in: .zero, with: "Some text in editor")
+        editor.insertAttachment(in: editor.textEndRange, attachment: attachment)
+        editor.replaceCharacters(in: editor.textEndRange, with: "Text after grid")
+
+        viewController.render()
+
+        XCTAssertNil(delegate.containerScrollView)
+        XCTAssertEqual(attachment.view.containerScrollView, editor.scrollView)
+
+    }
+
     func testReusesTextFromPreRenderedCells() throws {
         delegate.containerScrollView = editor.scrollView