Add Overridable Layout To LayoutManager

Author: thecoolwinter

Sources/CodeEditTextView/MarkedTextManager/MarkedTextManager.swift

@@ -7,15 +7,15 @@
 
 import AppKit
 
+/// Struct for passing attribute and range information easily down into line fragments, typesetters w/o
+/// requiring a reference to the marked text manager.
+public struct MarkedRanges {
+    let ranges: [NSRange]
+    let attributes: [NSAttributedString.Key: Any]
+}
+
 /// Manages marked ranges. Not a public API.
 class MarkedTextManager {
-    /// Struct for passing attribute and range information easily down into line fragments, typesetters w/o
-    /// requiring a reference to the marked text manager.
-    struct MarkedRanges {
-        let ranges: [NSRange]
-        let attributes: [NSAttributedString.Key: Any]
-    }
-
     /// All marked ranges being tracked.
     private(set) var markedRanges: [NSRange] = []
 

Sources/CodeEditTextView/TextLayoutManager/TextLayoutManager.swift

@@ -8,16 +8,6 @@
 import Foundation
 import AppKit
 
-public protocol TextLayoutManagerDelegate: AnyObject {
-    func layoutManagerHeightDidUpdate(newHeight: CGFloat)
-    func layoutManagerMaxWidthDidChange(newWidth: CGFloat)
-    func layoutManagerTypingAttributes() -> [NSAttributedString.Key: Any]
-    func textViewportSize() -> CGSize
-    func layoutManagerYAdjustment(_ yAdjustment: CGFloat)
-
-    var visibleRect: NSRect { get }
-}
-
 /// The text layout manager manages laying out lines in a code document.
 public class TextLayoutManager: NSObject {
     // MARK: - Public Properties
@@ -65,6 +55,8 @@ public class TextLayoutManager: NSObject {
         }
     }
 
+    public weak var renderDelegate: TextLayoutManagerRenderDelegate?
+
     // MARK: - Internal
 
     weak var textStorage: NSTextStorage?
@@ -207,7 +199,7 @@ public class TextLayoutManager: NSObject {
         #endif
     }
 
-    // MARK: - Layout
+    // MARK: - Layout Lines
 
     /// Lays out all visible lines
     func layoutLines(in rect: NSRect? = nil) { // swiftlint:disable:this function_body_length
@@ -300,6 +292,8 @@ public class TextLayoutManager: NSObject {
         needsLayout = false
     }
 
+    // MARK: - Layout Single Line
+
     /// Lays out a single text line.
     /// - Parameters:
     ///   - position: The line position from storage to use for layout.
@@ -320,13 +314,24 @@ public class TextLayoutManager: NSObject {
         )
 
         let line = position.data
-        line.prepareForDisplay(
-            displayData: lineDisplayData,
-            range: position.range,
-            stringRef: textStorage,
-            markedRanges: markedTextManager.markedRanges(in: position.range),
-            breakStrategy: lineBreakStrategy
-        )
+        if let renderDelegate {
+            renderDelegate.prepareForDisplay(
+                textLine: line,
+                displayData: lineDisplayData,
+                range: position.range,
+                stringRef: textStorage,
+                markedRanges: markedTextManager.markedRanges(in: position.range),
+                breakStrategy: lineBreakStrategy
+            )
+        } else {
+            line.prepareForDisplay(
+                displayData: lineDisplayData,
+                range: position.range,
+                stringRef: textStorage,
+                markedRanges: markedTextManager.markedRanges(in: position.range),
+                breakStrategy: lineBreakStrategy
+            )
+        }
 
         if position.range.isEmpty {
             return CGSize(width: 0, height: estimateLineHeight())
@@ -353,6 +358,8 @@ public class TextLayoutManager: NSObject {
         return CGSize(width: width, height: height)
     }
 
+    // MARK: - Layout Fragment
+
     /// Lays out a line fragment view for the given line fragment at the specified y value.
     /// - Parameters:
     ///   - lineFragment: The line fragment position to lay out a view for.
@@ -363,6 +370,7 @@ public class TextLayoutManager: NSObject {
     ) {
         let view = viewReuseQueue.getOrCreateView(forKey: lineFragment.data.id)
         view.setLineFragment(lineFragment.data)
+        view.renderDelegate = renderDelegate
         view.frame.origin = CGPoint(x: edgeInsets.left, y: yPos)
         layoutView?.addSubview(view)
         view.needsDisplay = true

Sources/CodeEditTextView/TextLayoutManager/TextLayoutManagerDelegate.swift

@@ -0,0 +1,18 @@
+//
+//  TextLayoutManagerDelegate.swift
+//  CodeEditTextView
+//
+//  Created by Khan Winter on 4/10/25.
+//
+
+import AppKit
+
+public protocol TextLayoutManagerDelegate: AnyObject {
+    func layoutManagerHeightDidUpdate(newHeight: CGFloat)
+    func layoutManagerMaxWidthDidChange(newWidth: CGFloat)
+    func layoutManagerTypingAttributes() -> [NSAttributedString.Key: Any]
+    func textViewportSize() -> CGSize
+    func layoutManagerYAdjustment(_ yAdjustment: CGFloat)
+
+    var visibleRect: NSRect { get }
+}

Sources/CodeEditTextView/TextLayoutManager/TextLayoutManagerLayoutDelegate.swift

@@ -0,0 +1,47 @@
+//
+//  TextLayoutManagerLayoutDelegate.swift
+//  CodeEditTextView
+//
+//  Created by Khan Winter on 4/10/25.
+//
+
+import AppKit
+
+/// Provide an instance of this class to the ``TextLayoutManager`` to override how the layout manager performs layout
+/// and display for text lines and fragments.
+///
+/// All methods on this protocol are optional, and default to the default behavior.
+public protocol TextLayoutManagerRenderDelegate: AnyObject {
+    func prepareForDisplay( // swiftlint:disable:this function_parameter_count
+        textLine: TextLine,
+        displayData: TextLine.DisplayData,
+        range: NSRange,
+        stringRef: NSTextStorage,
+        markedRanges: MarkedRanges?,
+        breakStrategy: LineBreakStrategy
+    )
+    func drawLineFragment(fragment: LineFragment, in context: CGContext)
+}
+
+extension TextLayoutManagerRenderDelegate {
+    func prepareForDisplay( // swiftlint:disable:this function_parameter_count
+        textLine: TextLine,
+        displayData: TextLine.DisplayData,
+        range: NSRange,
+        stringRef: NSTextStorage,
+        markedRanges: MarkedRanges?,
+        breakStrategy: LineBreakStrategy
+    ) {
+        textLine.prepareForDisplay(
+            displayData: displayData,
+            range: range,
+            stringRef: stringRef,
+            markedRanges: markedRanges,
+            breakStrategy: breakStrategy
+        )
+    }
+
+    func drawLineFragment(fragment: LineFragment, in context: CGContext) {
+        fragment.draw(in: context, yPos: 0.0)
+    }
+}

Sources/CodeEditTextView/TextLine/LineFragment.swift

@@ -12,18 +12,18 @@ import CodeEditTextViewObjC
 /// fragments, and any lines that need to be broken due to width constraints will contain more than one fragment.
 public final class LineFragment: Identifiable, Equatable {
     public let id = UUID()
-    private(set) public var ctLine: CTLine
-    public let width: CGFloat
-    public let height: CGFloat
-    public let descent: CGFloat
-    public let scaledHeight: CGFloat
+    public var ctLine: CTLine
+    public var width: CGFloat
+    public var height: CGFloat
+    public var descent: CGFloat
+    public var scaledHeight: CGFloat
 
     /// The difference between the real text height and the scaled height
     public var heightDifference: CGFloat {
         scaledHeight - height
     }
 
-    init(
+    public init(
         ctLine: CTLine,
         width: CGFloat,
         height: CGFloat,
@@ -81,7 +81,7 @@ public final class LineFragment: Identifiable, Equatable {
     /// Calculates the drawing rect for a given range.
     /// - Parameter range: The range to calculate the bounds for, relative to the line.
     /// - Returns: A rect that contains the text contents in the given range.
-    func rectFor(range: NSRange) -> CGRect {
+    public func rectFor(range: NSRange) -> CGRect {
         let minXPos = CTLineGetOffsetForStringIndex(ctLine, range.lowerBound, nil)
         let maxXPos = CTLineGetOffsetForStringIndex(ctLine, range.upperBound, nil)
         return CGRect(

Sources/CodeEditTextView/TextLine/LineFragmentView.swift

@@ -11,6 +11,8 @@ import AppKit
 final class LineFragmentView: NSView {
     private weak var lineFragment: LineFragment?
 
+    weak var renderDelegate: TextLayoutManagerRenderDelegate?
+
     override var isFlipped: Bool {
         true
     }
@@ -39,6 +41,11 @@ final class LineFragmentView: NSView {
         guard let lineFragment, let context = NSGraphicsContext.current?.cgContext else {
             return
         }
-        lineFragment.draw(in: context, yPos: 0.0)
+
+        if let renderDelegate {
+            renderDelegate.drawLineFragment(fragment: lineFragment, in: context)
+        } else {
+            lineFragment.draw(in: context, yPos: 0.0)
+        }
     }
 }

Sources/CodeEditTextView/TextLine/TextLine.swift

@@ -45,7 +45,7 @@ public final class TextLine: Identifiable, Equatable {
         displayData: DisplayData,
         range: NSRange,
         stringRef: NSTextStorage,
-        markedRanges: MarkedTextManager.MarkedRanges?,
+        markedRanges: MarkedRanges?,
         breakStrategy: LineBreakStrategy
     ) {
         let string = stringRef.attributedSubstring(from: range)
@@ -64,7 +64,7 @@ public final class TextLine: Identifiable, Equatable {
     }
 
     /// Contains all required data to perform a typeset and layout operation on a text line.
-    struct DisplayData {
+    public struct DisplayData {
         let maxWidth: CGFloat
         let lineHeightMultiplier: CGFloat
         let estimatedLineHeight: CGFloat

Sources/CodeEditTextView/TextLine/Typesetter.swift

@@ -8,20 +8,20 @@
 import Foundation
 import CoreText
 
-final class Typesetter {
-    var typesetter: CTTypesetter?
-    var string: NSAttributedString!
-    var lineFragments = TextLineStorage<LineFragment>()
+final public class Typesetter {
+    public var typesetter: CTTypesetter?
+    public var string: NSAttributedString!
+    public var lineFragments = TextLineStorage<LineFragment>()
 
     // MARK: - Init & Prepare
 
-    init() { }
+    public init() { }
 
-    func typeset(
+    public func typeset(
         _ string: NSAttributedString,
         displayData: TextLine.DisplayData,
         breakStrategy: LineBreakStrategy,
-        markedRanges: MarkedTextManager.MarkedRanges?
+        markedRanges: MarkedRanges?
     ) {
         lineFragments.removeAll()
         if let markedRanges {

Tests/CodeEditTextViewTests/OverridingLayoutManagerRenderingTests.swift

@@ -0,0 +1,94 @@
+import Testing
+import AppKit
+@testable import CodeEditTextView
+
+class MockRenderDelegate: TextLayoutManagerRenderDelegate {
+    var prepareForDisplay: ((
+        _ textLine: TextLine,
+        _ displayData: TextLine.DisplayData,
+        _ range: NSRange,
+        _ stringRef: NSTextStorage,
+        _ markedRanges: MarkedRanges?,
+        _ breakStrategy: LineBreakStrategy
+    ) -> Void)?
+
+    func prepareForDisplay( // swiftlint:disable:this function_parameter_count
+        textLine: TextLine,
+        displayData: TextLine.DisplayData,
+        range: NSRange,
+        stringRef: NSTextStorage,
+        markedRanges: MarkedRanges?,
+        breakStrategy: LineBreakStrategy
+    ) {
+        prepareForDisplay?(
+            textLine,
+            displayData,
+            range,
+            stringRef,
+            markedRanges,
+            breakStrategy
+        ) ?? textLine.prepareForDisplay(
+            displayData: displayData,
+            range: range,
+            stringRef: stringRef,
+            markedRanges: markedRanges,
+            breakStrategy: breakStrategy
+        )
+    }
+}
+
+@Suite
+@MainActor
+struct OverridingLayoutManagerRenderingTests {
+    let mockDelegate: MockRenderDelegate
+    let textView: TextView
+    let textStorage: NSTextStorage
+    let layoutManager: TextLayoutManager
+
+    init() throws {
+        textView = TextView(string: "A\nB\nC\nD")
+        textView.frame = NSRect(x: 0, y: 0, width: 1000, height: 1000)
+        textStorage = textView.textStorage
+        layoutManager = try #require(textView.layoutManager)
+        mockDelegate = MockRenderDelegate()
+        layoutManager.renderDelegate = mockDelegate
+    }
+
+    @Test
+    func overriddenLineHeight() {
+        mockDelegate.prepareForDisplay = { textLine, displayData, range, stringRef, markedRanges, breakStrategy in
+            textLine.prepareForDisplay(
+                displayData: displayData,
+                range: range,
+                stringRef: stringRef,
+                markedRanges: markedRanges,
+                breakStrategy: breakStrategy
+            )
+            // Update all text fragments to be height = 2.0
+            textLine.lineFragments.forEach { fragmentPosition in
+                let idealHeight: CGFloat = 2.0
+                textLine.lineFragments.update(
+                    atIndex: fragmentPosition.index,
+                    delta: 0,
+                    deltaHeight: -(fragmentPosition.height - idealHeight)
+                )
+                fragmentPosition.data.height = 2.0
+                fragmentPosition.data.scaledHeight = 2.0
+            }
+        }
+
+        layoutManager.invalidateLayoutForRect(NSRect(x: 0, y: 0, width: 1000, height: 1000))
+        layoutManager.layoutLines(in: NSRect(x: 0, y: 0, width: 1000, height: 1000))
+
+        // 4 lines, each 2px tall
+        #expect(layoutManager.lineStorage.height == 8.0)
+
+        // Edit some text
+
+        textStorage.replaceCharacters(in: NSRange(location: 0, length: 0), with: "0\n1\r\n2\r")
+
+        #expect(layoutManager.lineCount == 7)
+        #expect(layoutManager.lineStorage.height == 14.0)
+        layoutManager.lineStorage.validateInternalState()
+    }
+}