Emphasize Brackets Surrounding Folds

Author: thecoolwinter

Sources/CodeEditSourceEditor/Controller/TextViewController+TextFormation.swift

@@ -11,23 +11,6 @@ import TextFormation
 import TextStory
 
 extension TextViewController {
-
-    internal enum BracketPairs {
-        static let allValues: [(String, String)] = [
-            ("{", "}"),
-            ("[", "]"),
-            ("(", ")"),
-            ("\"", "\""),
-            ("'", "'")
-        ]
-
-        static let emphasisValues: [(String, String)] = [
-            ("{", "}"),
-            ("[", "]"),
-            ("(", ")")
-        ]
-    }
-
     // MARK: - Filter Configuration
 
     /// Initializes any filters for text editing.

Sources/CodeEditSourceEditor/Enums/BracketPairs.swift

@@ -0,0 +1,29 @@
+//
+//  BracketPairs.swift
+//  CodeEditSourceEditor
+//
+//  Created by Khan Winter on 6/5/25.
+//
+
+enum BracketPairs {
+    static let allValues: [(String, String)] = [
+        ("{", "}"),
+        ("[", "]"),
+        ("(", ")"),
+        ("\"", "\""),
+        ("'", "'")
+    ]
+
+    static let emphasisValues: [(String, String)] = [
+        ("{", "}"),
+        ("[", "]"),
+        ("(", ")")
+    ]
+    
+    /// Checks if the given string is a matchable emphasis string.
+    /// - Parameter potentialMatch: The string to check for matches.
+    /// - Returns: True if a match was found with either start or end bracket pairs.
+    static func matches(_ potentialMatch: String) -> Bool {
+        allValues.contains(where: { $0.0 == potentialMatch || $0.1 == potentialMatch })
+    }
+}

Sources/CodeEditSourceEditor/Extensions/NSBezierPath+RoundedCorners.swift

@@ -22,6 +22,8 @@ extension NSBezierPath {
         public static let bottomLeft = Corners(rawValue: 1 << 1)
         public static let topRight = Corners(rawValue: 1 << 2)
         public static let bottomRight = Corners(rawValue: 1 << 3)
+
+        public static let all: Corners = Corners(rawValue: 0b1111)
     }
 
     // swiftlint:disable:next function_body_length

Sources/CodeEditSourceEditor/LineFolding/Model/LineFoldingModel.swift

@@ -19,6 +19,8 @@ import Combine
 /// - Loop through the list, creating nested folds as indents go up and down.
 ///
 class LineFoldingModel: NSObject, NSTextStorageDelegate, ObservableObject {
+    static let emphasisId = "lineFolding"
+
     /// An ordered tree of fold ranges in a document. Can be traversed using ``FoldRange/parent``
     /// and ``FoldRange/subFolds``.
     @Published var foldCache: LineFoldStorage = LineFoldStorage(documentLength: 0)
@@ -92,4 +94,35 @@ class LineFoldingModel: NSObject, NSTextStorageDelegate, ObservableObject {
         }
         return deepestFold
     }
+
+    func emphasizeBracketsForFold(_ fold: FoldRange) {
+        clearEmphasis()
+
+        // Find the text object, make sure there's available characters around the fold.
+        guard let text = controller?.textView.textStorage.string as? NSString,
+              fold.range.lowerBound > 0 && fold.range.upperBound < text.length - 1 else {
+            return
+        }
+
+        let firstRange = NSRange(location: fold.range.lowerBound - 1, length: 1)
+        let secondRange = NSRange(location: fold.range.upperBound, length: 1)
+
+        // Check if these are emphasizable bracket pairs.
+        guard BracketPairs.matches(text.substring(from: firstRange) ?? "")
+                && BracketPairs.matches(text.substring(from: secondRange) ?? "") else {
+            return
+        }
+
+        controller?.textView.emphasisManager?.addEmphases(
+            [
+                Emphasis(range: firstRange, style: .standard, flash: false, inactive: false, selectInDocument: false),
+                Emphasis(range: secondRange, style: .standard, flash: false, inactive: false, selectInDocument: false),
+            ],
+            for: Self.emphasisId
+        )
+    }
+
+    func clearEmphasis() {
+        controller?.textView.emphasisManager?.removeEmphases(for: Self.emphasisId)
+    }
 }

Sources/CodeEditSourceEditor/LineFolding/Placeholder/LineFoldPlaceholder.swift

@@ -10,22 +10,40 @@ import CodeEditTextView
 
 class LineFoldPlaceholder: TextAttachment {
     let fold: FoldRange
+    let charWidth: CGFloat
+    var isSelected: Bool = false
 
-    init(fold: FoldRange) {
+    init(fold: FoldRange, charWidth: CGFloat) {
         self.fold = fold
+        self.charWidth = charWidth
     }
 
-    var width: CGFloat { 17 }
+    var width: CGFloat {
+        charWidth * 5
+    }
 
     func draw(in context: CGContext, rect: NSRect) {
         context.saveGState()
 
         let centerY = rect.midY - 1.5
 
+        if isSelected {
+            context.setFillColor(NSColor.controlAccentColor.cgColor)
+            context.addPath(
+                NSBezierPath(
+                    rect: rect.transform(x: 2.0, y: 3.0, width: -4.0, height: -6.0 ),
+                    roundedCorners: .all,
+                    cornerRadius: 2
+                ).cgPathFallback
+            )
+            context.fillPath()
+        }
+
         context.setFillColor(NSColor.secondaryLabelColor.cgColor)
-        context.addEllipse(in: CGRect(x: rect.minX + 2, y: centerY, width: 3, height: 3))
-        context.addEllipse(in: CGRect(x: rect.minX + 7, y: centerY, width: 3, height: 3))
-        context.addEllipse(in: CGRect(x: rect.minX + 12, y: centerY, width: 3, height: 3))
+        let size = charWidth / 2
+        context.addEllipse(in: CGRect(x: rect.minX + charWidth * 1.25, y: centerY, width: size, height: size))
+        context.addEllipse(in: CGRect(x: rect.minX + (charWidth * 2.25), y: centerY, width: size, height: size))
+        context.addEllipse(in: CGRect(x: rect.minX + (charWidth * 3.25), y: centerY, width: size, height: size))
         context.fillPath()
 
         context.restoreGState()

Sources/CodeEditSourceEditor/LineFolding/View/FoldingRibbonView+Draw.swift

@@ -130,7 +130,7 @@ extension FoldingRibbonView {
                 maxYPosition: maxYPosition,
                 in: context
             )
-        } else if hoveringFold?.isHoveringEqual(foldInfo.fold) == true {
+        } else if hoveringFold.fold?.isHoveringEqual(foldInfo.fold) == true {
             drawHoveredFold(
                 foldInfo: foldInfo,
                 foldCaps: foldCaps,
@@ -171,7 +171,8 @@ extension FoldingRibbonView {
         chevron.addLine(to: CGPoint(x: maxX, y: centerY))
         chevron.addLine(to: CGPoint(x: minX, y: maxY))
 
-        if let hoveringFoldMask, hoveringFoldMask.intersects(CGPath(rect: fillRect, transform: .none)) {
+        if let hoveringFoldMask = hoveringFold.foldMask,
+           hoveringFoldMask.intersects(CGPath(rect: fillRect, transform: .none)) {
             context.addPath(hoveringFoldMask)
             context.clip()
         }
@@ -205,8 +206,8 @@ extension FoldingRibbonView {
             yRadius: plainRect.width / 2
         )
 
-        context.setFillColor(hoverFillColor.copy(alpha: hoverAnimationProgress) ?? hoverFillColor)
-        context.setStrokeColor(hoverBorderColor.copy(alpha: hoverAnimationProgress) ?? hoverBorderColor)
+        context.setFillColor(hoverFillColor.copy(alpha: hoveringFold.progress) ?? hoverFillColor)
+        context.setStrokeColor(hoverBorderColor.copy(alpha: hoveringFold.progress) ?? hoverBorderColor)
         context.addPath(roundedRect.cgPathFallback)
         context.drawPath(using: .fillStroke)
 
@@ -220,7 +221,7 @@ extension FoldingRibbonView {
 
         let plainMaskRect = foldRect.transform(y: 1.0, height: -2.0)
         let roundedMaskRect = NSBezierPath(roundedRect: plainMaskRect, xRadius: Self.width / 2, yRadius: Self.width / 2)
-        hoveringFoldMask = roundedMaskRect.cgPathFallback
+        hoveringFold.foldMask = roundedMaskRect.cgPathFallback
 
         context.restoreGState()
     }
@@ -240,7 +241,7 @@ extension FoldingRibbonView {
             yPosition - chevronSize.height
         }
 
-        context.setStrokeColor(NSColor.secondaryLabelColor.withAlphaComponent(hoverAnimationProgress).cgColor)
+        context.setStrokeColor(NSColor.secondaryLabelColor.withAlphaComponent(hoveringFold.progress).cgColor)
         context.setLineCap(.round)
         context.setLineJoin(.round)
         context.setLineWidth(1.3)

Sources/CodeEditSourceEditor/LineFolding/View/FoldingRibbonView.swift

@@ -13,6 +13,18 @@ import CodeEditTextView
 ///
 /// This view draws its contents
 class FoldingRibbonView: NSView {
+    struct HoverAnimationDetails: Equatable {
+        var fold: FoldRange? = nil
+        var foldMask: CGPath?
+        var timer: Timer?
+        var progress: CGFloat = 0.0
+
+        static let empty = HoverAnimationDetails()
+
+        public static func == (_ lhs: HoverAnimationDetails, _ rhs: HoverAnimationDetails) -> Bool {
+            lhs.fold == rhs.fold && lhs.foldMask == rhs.foldMask && lhs.progress == rhs.progress
+        }
+    }
 
 #warning("Replace before release")
     private static let demoFoldProvider = IndentationLineFoldProvider()
@@ -21,13 +33,8 @@ class FoldingRibbonView: NSView {
 
     var model: LineFoldingModel?
 
-    // Disabling this lint rule because this initial value is required for @Invalidating
-    @Invalidating(.display)
-    var hoveringFold: FoldRange? = nil // swiftlint:disable:this redundant_optional_initialization
-    var hoveringFoldMask: CGPath?
-    var hoverAnimationTimer: Timer?
     @Invalidating(.display)
-    var hoverAnimationProgress: CGFloat = 0.0
+    var hoveringFold: HoverAnimationDetails = .empty
 
     @Invalidating(.display)
     var backgroundColor: NSColor = NSColor.controlBackgroundColor
@@ -129,7 +136,7 @@ class FoldingRibbonView: NSView {
             layoutManager.attachments.remove(atOffset: attachment.range.location)
             attachments.removeAll(where: { $0 === attachment.attachment })
         } else {
-            let placeholder = LineFoldPlaceholder(fold: fold)
+            let placeholder = LineFoldPlaceholder(fold: fold, charWidth: model?.controller?.fontCharWidth ?? 1.0)
             layoutManager.attachments.add(placeholder, for: NSRange(fold.range))
             attachments.append(placeholder)
         }
@@ -156,47 +163,58 @@ class FoldingRibbonView: NSView {
         guard let lineNumber = model?.controller?.textView.layoutManager.textLineForPosition(pointInView.y)?.index,
               let fold = model?.getCachedFoldAt(lineNumber: lineNumber),
               !fold.isCollapsed else {
-            hoverAnimationProgress = 0.0
-            hoveringFold = nil
-            hoveringFoldMask = nil
+            clearHoveredFold()
             return
         }
 
-        guard fold.range != hoveringFold?.range else {
+        guard fold.range != hoveringFold.fold?.range else {
             return
         }
-        hoverAnimationTimer?.invalidate()
+
+        setHoveredFold(fold: fold)
+    }
+
+    override func mouseExited(with event: NSEvent) {
+        super.mouseExited(with: event)
+        clearHoveredFold()
+    }
+    
+    /// Clears the current hovered fold. Does not animate.
+    func clearHoveredFold() {
+        hoveringFold = .empty
+        model?.clearEmphasis()
+    }
+    
+    /// Set the current hovered fold. This method determines when an animation is required and will facilitate it.
+    /// - Parameter fold: The fold to set as the current hovered fold.
+    func setHoveredFold(fold: FoldRange) {
+        defer {
+            model?.emphasizeBracketsForFold(fold)
+        }
+
+        hoveringFold.timer?.invalidate()
         // We only animate the first hovered fold. If the user moves the mouse vertically into other folds we just
         // show it immediately.
-        if hoveringFold == nil {
-            hoverAnimationProgress = 0.0
-            hoveringFold = fold
-            hoveringFoldMask = nil
-
+        if hoveringFold.fold == nil {
             let duration: TimeInterval = 0.2
             let startTime = CACurrentMediaTime()
-            hoverAnimationTimer = Timer.scheduledTimer(withTimeInterval: 1/60, repeats: true) { [weak self] timer in
-                guard let self = self else { return }
-                let now = CACurrentMediaTime()
-                let time = CGFloat((now - startTime) / duration)
-                self.hoverAnimationProgress = min(1.0, time)
-                if self.hoverAnimationProgress >= 1.0 {
-                    timer.invalidate()
+
+            hoveringFold = HoverAnimationDetails(
+                fold: fold,
+                timer: Timer.scheduledTimer(withTimeInterval: 1/60, repeats: true) { [weak self] timer in
+                    guard let self = self else { return }
+                    let now = CACurrentMediaTime()
+                    let time = CGFloat((now - startTime) / duration)
+                    self.hoveringFold.progress = min(1.0, time)
+                    if self.hoveringFold.progress >= 1.0 {
+                        timer.invalidate()
+                    }
                 }
-            }
+            )
             return
         }
 
         // Don't animate these
-        hoverAnimationProgress = 1.0
-        hoveringFold = fold
-        hoveringFoldMask = nil
-    }
-
-    override func mouseExited(with event: NSEvent) {
-        super.mouseExited(with: event)
-        hoverAnimationProgress = 0.0
-        hoveringFold = nil
-        hoveringFoldMask = nil
+        hoveringFold = HoverAnimationDetails(fold: fold, progress: 1.0)
     }
 }

Sources/CodeEditSourceEditor/RangeStore/RangeStore.swift

@@ -110,7 +110,10 @@ extension RangeStore {
             newLength = editedRange.length
         }
 
-        storageUpdated(replacedCharactersIn: storageRange, withCount: newLength)
+        storageUpdated(
+            replacedCharactersIn: storageRange.clamped(to: 0..<_guts.count(in: OffsetMetric())),
+            withCount: newLength
+        )
     }
 
     /// Handles keeping the internal storage in sync with the document.