Show diffs without word wrapping

TESTING.md

@@ -200,7 +200,8 @@ xcrun simctl launch booted de.rfc1437.gotcha
 - [ ] Open a commit and verify Changed Files paths and statuses.
 - [ ] Open a changed file and verify the diff title, old/new line numbers,
       monospaced text, addition/removal/hunk colors, vertical scrolling, and
-      horizontal scrolling for long lines.
+      source-style horizontal scrolling for long lines without word wrapping,
+      clipped or jumping text, or content hidden beneath the navigation bar.
 - [ ] Long-press diff text and verify normal selection and copying.
 
 ## Repository files

ios/Sources/DetailScreens.swift

@@ -738,6 +738,60 @@ final class RepositoryHistoryViewController: RefreshingTableViewController {
     }
 }
 
+private final class CodeScrollView: UIScrollView {
+    private let textView = UITextView(frame: .zero)
+
+    override init(frame: CGRect) {
+        super.init(frame: frame)
+        translatesAutoresizingMaskIntoConstraints = false
+        alwaysBounceVertical = true
+        alwaysBounceHorizontal = true
+        isDirectionalLockEnabled = true
+        showsHorizontalScrollIndicator = true
+        contentInsetAdjustmentBehavior = .never
+        textView.textContainer.lineBreakMode = .byClipping
+        textView.textContainer.widthTracksTextView = false
+        textView.isEditable = false
+        textView.isScrollEnabled = false
+        textView.isSelectable = true
+        addSubview(textView)
+    }
+
+    @available(*, unavailable)
+    required init?(coder: NSCoder) { fatalError("init(coder:) is not supported") }
+
+    func display(_ text: NSAttributedString) {
+        let text = NSMutableAttributedString(attributedString: text)
+        let paragraph = NSMutableParagraphStyle()
+        paragraph.lineBreakMode = .byClipping
+        text.addAttribute(.paragraphStyle, value: paragraph, range: NSRange(location: 0, length: text.length))
+        textView.textStorage.setAttributedString(text)
+        setNeedsLayout()
+    }
+
+    override func layoutSubviews() {
+        super.layoutSubviews()
+        textView.textContainer.size = CGSize(
+            width: CGFloat.greatestFiniteMagnitude,
+            height: CGFloat.greatestFiniteMagnitude
+        )
+        textView.layoutManager.ensureLayout(for: textView.textContainer)
+        let textSize = textView.layoutManager.usedRect(for: textView.textContainer).size
+        let size = CGSize(
+            width: max(
+                bounds.width,
+                ceil(textSize.width + textView.textContainerInset.left + textView.textContainerInset.right)
+            ),
+            height: max(
+                bounds.height,
+                ceil(textSize.height + textView.textContainerInset.top + textView.textContainerInset.bottom)
+            )
+        )
+        textView.frame = CGRect(origin: .zero, size: size)
+        contentSize = size
+    }
+}
+
 @MainActor
 final class RepositoryFileViewController: UIViewController, QLPreviewControllerDataSource {
     private let context: AppContext
@@ -753,8 +807,6 @@ final class RepositoryFileViewController: UIViewController, QLPreviewControllerD
     private var historyController: RepositoryHistoryViewController?
     private var displayedController: UIViewController?
     private var displayedView: UIView?
-    private weak var sourceScrollView: UIScrollView?
-    private weak var sourceTextView: UITextView?
 
     init(context: AppContext, owner: String, repository: String, path: String, name: String) {
         self.context = context
@@ -791,11 +843,6 @@ final class RepositoryFileViewController: UIViewController, QLPreviewControllerD
         }
     }
 
-    override func viewDidLayoutSubviews() {
-        super.viewDidLayoutSubviews()
-        updateSourceLayout()
-    }
-
     deinit {
         loadingTask?.cancel()
         if let previewURL { try? FileManager.default.removeItem(at: previewURL) }
@@ -889,41 +936,16 @@ final class RepositoryFileViewController: UIViewController, QLPreviewControllerD
                 .font: UIFont.monospacedSystemFont(ofSize: 13, weight: .regular),
                 .foregroundColor: UIColor.label,
             ])
-        let text = NSMutableAttributedString(attributedString: highlighted)
+        let codeView = CodeScrollView()
-        let paragraph = NSMutableParagraphStyle()
+        codeView.display(highlighted)
-        paragraph.lineBreakMode = .byClipping
+        displayedView = codeView
-        text.addAttribute(.paragraphStyle, value: paragraph, range: NSRange(location: 0, length: text.length))
+        view.addSubview(codeView)
-
-        let scrollView = UIScrollView()
-        scrollView.translatesAutoresizingMaskIntoConstraints = false
-        scrollView.alwaysBounceHorizontal = true
-        scrollView.isDirectionalLockEnabled = true
-        scrollView.showsHorizontalScrollIndicator = true
-        scrollView.contentInsetAdjustmentBehavior = .never
-
-        let textView = UITextView(frame: .zero)
-        textView.textContainer.size = CGSize(
-            width: CGFloat.greatestFiniteMagnitude,
-            height: CGFloat.greatestFiniteMagnitude
-        )
-        textView.textContainer.lineBreakMode = .byClipping
-        textView.textContainer.widthTracksTextView = false
-        textView.textStorage.setAttributedString(text)
-        textView.isEditable = false
-        textView.isScrollEnabled = false
-        textView.isSelectable = true
-        sourceScrollView = scrollView
-        sourceTextView = textView
-        scrollView.addSubview(textView)
-        displayedView = scrollView
-        view.addSubview(scrollView)
         NSLayoutConstraint.activate([
-            scrollView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor),
+            codeView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor),
-            scrollView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor),
+            codeView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor),
-            scrollView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
+            codeView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
-            scrollView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
+            codeView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
         ])
-        updateSourceLayout()
     }
 
     private func removeDisplayedView() {
@@ -932,31 +954,6 @@ final class RepositoryFileViewController: UIViewController, QLPreviewControllerD
         displayedController?.removeFromParent()
         displayedController = nil
         displayedView = nil
-        sourceScrollView = nil
-        sourceTextView = nil
-    }
-
-    private func updateSourceLayout() {
-        guard let scrollView = sourceScrollView, let textView = sourceTextView else { return }
-        textView.textContainer.widthTracksTextView = false
-        textView.textContainer.size = CGSize(
-            width: CGFloat.greatestFiniteMagnitude,
-            height: CGFloat.greatestFiniteMagnitude
-        )
-        textView.layoutManager.ensureLayout(for: textView.textContainer)
-        let textSize = textView.layoutManager.usedRect(for: textView.textContainer).size
-        let contentSize = CGSize(
-            width: max(
-                scrollView.bounds.width,
-                ceil(textSize.width + textView.textContainerInset.left + textView.textContainerInset.right)
-            ),
-            height: max(
-                scrollView.bounds.height,
-                ceil(textSize.height + textView.textContainerInset.top + textView.textContainerInset.bottom)
-            )
-        )
-        textView.frame = CGRect(origin: .zero, size: contentSize)
-        scrollView.contentSize = contentSize
     }
 
     private func showQuickLook(_ data: Data, name: String) throws {
@@ -1002,7 +999,7 @@ enum DiffSource {
 final class DiffViewController: UIViewController {
     private let context: AppContext
     private let source: DiffSource
-    private let textView = UITextView()
+    private let codeView = CodeScrollView()
     private let spinner = UIActivityIndicatorView(style: .medium)
     private var loadingTask: Task<Void, Never>?
 
@@ -1018,22 +1015,14 @@ final class DiffViewController: UIViewController {
     override func viewDidLoad() {
         super.viewDidLoad()
         view.backgroundColor = .systemBackground
-        textView.translatesAutoresizingMaskIntoConstraints = false
+        codeView.refreshControl = UIRefreshControl()
-        textView.isEditable = false
+        codeView.refreshControl?.addTarget(self, action: #selector(reload), for: .valueChanged)
-        textView.isSelectable = true
+        view.addSubview(codeView)
-        textView.alwaysBounceVertical = true
-        textView.alwaysBounceHorizontal = true
-        textView.showsHorizontalScrollIndicator = true
-        textView.textContainer.widthTracksTextView = false
-        textView.textContainer.lineFragmentPadding = 8
-        textView.refreshControl = UIRefreshControl()
-        textView.refreshControl?.addTarget(self, action: #selector(reload), for: .valueChanged)
-        view.addSubview(textView)
         NSLayoutConstraint.activate([
-            textView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            codeView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor),
-            textView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+            codeView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor),
-            textView.topAnchor.constraint(equalTo: view.topAnchor),
+            codeView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
-            textView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
+            codeView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
         ])
         beginNavigationLoading(spinner)
         reload()
@@ -1063,12 +1052,12 @@ final class DiffViewController: UIViewController {
                     )
                 }
                 title = page.title
-                textView.attributedText = diffText(page)
+                codeView.display(diffText(page))
             } catch {
                 if !Task.isCancelled { show(error: error) }
             }
             endNavigationLoading(spinner)
-            textView.refreshControl?.endRefreshing()
+            codeView.refreshControl?.endRefreshing()
         }
     }