Optionally Use System Cursor (#21)

### Description

Adds the ability to use the system cursor if available and enabled using a `useSystemCursor` variable on either `TextView` or `TextSelectionManager`.

### Related Issues

*  closes #5

### Checklist

<!--- Add things that are not yet implemented above -->

- [x] I read and understood the [contributing guide](https://github.com/CodeEditApp/CodeEdit/blob/main/CONTRIBUTING.md) as well as the [code of conduct](https://github.com/CodeEditApp/CodeEdit/blob/main/CODE_OF_CONDUCT.md)
- [x] The issues this PR addresses are related to each other
- [x] My changes generate no new warnings
- [x] My code builds and runs on my machine
- [x] My changes are all related to the related issue above
- [x] I documented my code

### Screenshots

Example usage in CodeEditSourceEditor:

https://github.com/CodeEditApp/CodeEditTextView/assets/35942988/5b5adeee-dd80-4f92-92d0-121be18ab6ae

Author: thecoolwinter

Sources/CodeEditTextView/Extensions/GC+ApproximateEqual.swift

@@ -0,0 +1,29 @@
+//
+//  GC+ApproximateEqual.swift
+//  CodeEditTextView
+//
+//  Created by Khan Winter on 2/16/24.
+//
+
+import Foundation
+
+extension CGFloat {
+    func approxEqual(_ other: CGFloat, tolerance: CGFloat = 0.5) -> Bool {
+        abs(self - other) <= tolerance
+    }
+}
+
+extension CGPoint {
+    func approxEqual(_ other: CGPoint, tolerance: CGFloat = 0.5) -> Bool {
+        return self.x.approxEqual(other.x, tolerance: tolerance)
+        && self.y.approxEqual(other.y, tolerance: tolerance)
+    }
+}
+
+extension CGRect {
+    func approxEqual(_ other: CGRect, tolerance: CGFloat = 0.5) -> Bool {
+        return self.origin.approxEqual(other.origin, tolerance: tolerance)
+        && self.width.approxEqual(other.width, tolerance: tolerance)
+        && self.height.approxEqual(other.height, tolerance: tolerance)
+    }
+}

Sources/CodeEditTextView/TextSelectionManager/TextSelectionManager.swift

@@ -23,7 +23,7 @@ public class TextSelectionManager: NSObject {
 
     public class TextSelection: Hashable, Equatable {
         public var range: NSRange
-        weak var view: CursorView?
+        weak var view: NSView?
         var boundingRect: CGRect = .zero
         var suggestedXPos: CGFloat?
         /// The position this selection should 'rotate' around when modifying selections.
@@ -71,12 +71,17 @@ public class TextSelectionManager: NSObject {
 
     public var insertionPointColor: NSColor = NSColor.labelColor {
         didSet {
-            textSelections.forEach { $0.view?.color = insertionPointColor }
+            textSelections.compactMap({ $0.view as? CursorView }).forEach { $0.color = insertionPointColor }
         }
     }
     public var highlightSelectedLine: Bool = true
     public var selectedLineBackgroundColor: NSColor = NSColor.selectedTextBackgroundColor.withSystemEffect(.disabled)
     public var selectionBackgroundColor: NSColor = NSColor.selectedTextBackgroundColor
+    public var useSystemCursor: Bool = false {
+        didSet {
+            updateSelectionViews()
+        }
+    }
 
     internal(set) public var textSelections: [TextSelection] = []
     weak var layoutManager: TextLayoutManager?
@@ -89,7 +94,8 @@ public class TextSelectionManager: NSObject {
         layoutManager: TextLayoutManager,
         textStorage: NSTextStorage,
         textView: TextView?,
-        delegate: TextSelectionManagerDelegate?
+        delegate: TextSelectionManagerDelegate?,
+        useSystemCursor: Bool = false
     ) {
         self.layoutManager = layoutManager
         self.textStorage = textStorage
@@ -168,21 +174,47 @@ public class TextSelectionManager: NSObject {
         for textSelection in textSelections {
             if textSelection.range.isEmpty {
                 let cursorOrigin = (layoutManager?.rectForOffset(textSelection.range.location) ?? .zero).origin
-                if textSelection.view == nil
-                    || textSelection.boundingRect.origin != cursorOrigin
-                    || textSelection.boundingRect.height != layoutManager?.estimateLineHeight() ?? 0 {
-                    textSelection.view?.removeFromSuperview()
-                    textSelection.view = nil
 
-                    let cursorView = CursorView(color: insertionPointColor)
+                var doesViewNeedReposition: Bool
+
+                // If using the system cursor, macOS will change the origin and height by about 0.5, so we do an
+                // approximate equals in that case to avoid extra updates.
+                if useSystemCursor, #available(macOS 14.0, *) {
+                    doesViewNeedReposition = !textSelection.boundingRect.origin.approxEqual(cursorOrigin)
+                    || !textSelection.boundingRect.height.approxEqual(layoutManager?.estimateLineHeight() ?? 0)
+                } else {
+                    doesViewNeedReposition = textSelection.boundingRect.origin != cursorOrigin
+                    || textSelection.boundingRect.height != layoutManager?.estimateLineHeight() ?? 0
+                }
+
+                if textSelection.view == nil || doesViewNeedReposition {
+                    let cursorView: NSView
+
+                    if let existingCursorView = textSelection.view {
+                        cursorView = existingCursorView
+                    } else {
+                        textSelection.view?.removeFromSuperview()
+                        textSelection.view = nil
+
+                        if useSystemCursor, #available(macOS 14.0, *) {
+                            let systemCursorView = NSTextInsertionIndicator(frame: .zero)
+                            cursorView = systemCursorView
+                            systemCursorView.displayMode = .automatic
+                        } else {
+                            let internalCursorView = CursorView(color: insertionPointColor)
+                            cursorView = internalCursorView
+                            cursorTimer.register(internalCursorView)
+                        }
+
+                        textView?.addSubview(cursorView)
+                    }
+
                     cursorView.frame.origin = cursorOrigin
                     cursorView.frame.size.height = layoutManager?.estimateLineHeight() ?? 0
-                    textView?.addSubview(cursorView)
+
                     textSelection.view = cursorView
                     textSelection.boundingRect = cursorView.frame
 
-                    cursorTimer.register(cursorView)
-
                     didUpdate = true
                 }
             } else if !textSelection.range.isEmpty && textSelection.view != nil {

Sources/CodeEditTextView/TextView/TextView+Setup.swift

@@ -26,4 +26,35 @@ extension TextView {
             delegate: self
         )
     }
+
+    func setUpScrollListeners(scrollView: NSScrollView) {
+        NotificationCenter.default.removeObserver(self, name: NSScrollView.willStartLiveScrollNotification, object: nil)
+        NotificationCenter.default.removeObserver(self, name: NSScrollView.didEndLiveScrollNotification, object: nil)
+
+        NotificationCenter.default.addObserver(
+            self,
+            selector: #selector(scrollViewWillStartScroll),
+            name: NSScrollView.willStartLiveScrollNotification,
+            object: scrollView
+        )
+
+        NotificationCenter.default.addObserver(
+            self,
+            selector: #selector(scrollViewDidEndScroll),
+            name: NSScrollView.didEndLiveScrollNotification,
+            object: scrollView
+        )
+    }
+
+    @objc func scrollViewWillStartScroll() {
+        if #available(macOS 14.0, *) {
+            inputContext?.textInputClientWillStartScrollingOrZooming()
+        }
+    }
+
+    @objc func scrollViewDidEndScroll() {
+        if #available(macOS 14.0, *) {
+            inputContext?.textInputClientDidEndScrollingOrZooming()
+        }
+    }
 }

Sources/CodeEditTextView/TextView/TextView.swift

@@ -178,6 +178,22 @@ public class TextView: NSView, NSTextContent {
         }
     }
 
+    /// Determines if the text view uses the macOS system cursor or a ``CursorView`` for cursors.
+    ///
+    /// - Important: Only available after macOS 14.
+    public var useSystemCursor: Bool {
+        get {
+            selectionManager?.useSystemCursor ?? false
+        }
+        set {
+            guard #available(macOS 14, *) else {
+                logger.warning("useSystemCursor only available after macOS 14.")
+                return
+            }
+            selectionManager?.useSystemCursor = newValue
+        }
+    }
+
     open var contentType: NSTextContentType?
 
     /// The text view's delegate.
@@ -225,6 +241,7 @@ public class TextView: NSView, NSTextContent {
     ///   - isEditable: Determines if the view is editable.
     ///   - isSelectable: Determines if the view is selectable.
     ///   - letterSpacing: Sets the letter spacing on the view.
+    ///   - useSystemCursor: Set to true to use the system cursor. Only available in macOS >= 14.
     ///   - delegate: The text view's delegate.
     public init(
         string: String,
@@ -235,6 +252,7 @@ public class TextView: NSView, NSTextContent {
         isEditable: Bool,
         isSelectable: Bool,
         letterSpacing: Double,
+        useSystemCursor: Bool = false,
         delegate: TextViewDelegate
     ) {
         self.textStorage = NSTextStorage(string: string)
@@ -264,6 +282,7 @@ public class TextView: NSView, NSTextContent {
         layoutManager = setUpLayoutManager(lineHeightMultiplier: lineHeightMultiplier, wrapLines: wrapLines)
         storageDelegate.addDelegate(layoutManager)
         selectionManager = setUpSelectionManager()
+        selectionManager.useSystemCursor = useSystemCursor
 
         _undoManager = CEUndoManager(textView: self)
 
@@ -370,6 +389,14 @@ public class TextView: NSView, NSTextContent {
         layoutManager.layoutLines()
     }
 
+    override public func viewWillMove(toSuperview newSuperview: NSView?) {
+        guard let scrollView = enclosingScrollView else {
+            return
+        }
+
+        setUpScrollListeners(scrollView: scrollView)
+    }
+
     override public func viewDidEndLiveResize() {
         super.viewDidEndLiveResize()
         updateFrameIfNeeded()