Whole Bunch of Fixes and Tests

Sources/CodeEditTextView/TextLayoutManager/TextAttachments/TextAttachmentManager.swift

@@ -24,7 +24,9 @@ public final class TextAttachmentManager {
         let insertIndex = findInsertionIndex(for: range.location)
         orderedAttachments.insert(box, at: insertIndex)
         layoutManager?.lineStorage.linesInRange(range).dropFirst().forEach {
-            layoutManager?.lineStorage.update(atOffset: $0.range.location, delta: 0, deltaHeight: -$0.height)
+            if $0.height != 0 {
+                layoutManager?.lineStorage.update(atOffset: $0.range.location, delta: 0, deltaHeight: -$0.height)
+            }
         }
         layoutManager?.invalidateLayoutForRange(range)
     }

Sources/CodeEditTextView/TextLayoutManager/TextLayoutManager+Iterator.swift

@@ -102,18 +102,23 @@ public extension TextLayoutManager {
         for originalPosition: TextLineStorage<TextLine>.TextLinePosition?
     ) -> (position: TextLineStorage<TextLine>.TextLinePosition, indexRange: ClosedRange<Int>)? {
         guard let originalPosition else { return nil }
+        return determineVisiblePosition(for: (originalPosition, originalPosition.index...originalPosition.index))
+    }
 
-        let attachments = attachments.get(overlapping: originalPosition.range)
+    func determineVisiblePosition(
+        for originalPosition: (position: TextLineStorage<TextLine>.TextLinePosition, indexRange: ClosedRange<Int>)
+    ) -> (position: TextLineStorage<TextLine>.TextLinePosition, indexRange: ClosedRange<Int>)? {
+        let attachments = attachments.get(overlapping: originalPosition.position.range)
         guard let firstAttachment = attachments.first, let lastAttachment = attachments.last else {
             // No change, either no attachments or attachment doesn't span multiple lines.
-            return (originalPosition, originalPosition.index...originalPosition.index)
+            return originalPosition
         }
 
-        var minIndex = originalPosition.index
-        var maxIndex = originalPosition.index
-        var newPosition = originalPosition
+        var minIndex = originalPosition.indexRange.lowerBound
+        var maxIndex = originalPosition.indexRange.upperBound
+        var newPosition = originalPosition.position
 
-        if firstAttachment.range.location < originalPosition.range.location,
+        if firstAttachment.range.location < originalPosition.position.range.location,
            let extendedLinePosition = lineStorage.getLine(atOffset: firstAttachment.range.location) {
             newPosition = TextLineStorage<TextLine>.TextLinePosition(
                 data: extendedLinePosition.data,
@@ -125,23 +130,24 @@ public extension TextLayoutManager {
             minIndex = min(minIndex, newPosition.index)
         }
 
-        if lastAttachment.range.max > originalPosition.range.max,
+        if lastAttachment.range.max > originalPosition.position.range.max,
            let extendedLinePosition = lineStorage.getLine(atOffset: lastAttachment.range.max) {
             newPosition = TextLineStorage<TextLine>.TextLinePosition(
                 data: newPosition.data,
                 range: NSRange(start: newPosition.range.location, end: extendedLinePosition.range.max),
                 yPos: newPosition.yPos,
                 height: newPosition.height,
-                index: newPosition.index
+                index: newPosition.index // We want to keep the minimum index.
             )
-            maxIndex = max(maxIndex, newPosition.index)
+            maxIndex = max(maxIndex, extendedLinePosition.index)
         }
 
-        if newPosition == originalPosition {
+        // Base case, we haven't updated anything
+        if minIndex...maxIndex == originalPosition.indexRange {
             return (newPosition, minIndex...maxIndex)
         } else {
             // Recurse, to make sure we combine all necessary lines.
-            return determineVisiblePosition(for: newPosition)
+            return determineVisiblePosition(for: (newPosition, minIndex...maxIndex))
         }
     }
 }

Tests/CodeEditTextViewTests/LayoutManager/TextLayoutManagerAttachmentsTests.swift

@@ -17,38 +17,95 @@ struct TextLayoutManagerAttachmentsTests {
     let layoutManager: TextLayoutManager
 
     init() throws {
-        textView = TextView(string: "A\nB\nC\nD")
+        textView = TextView(string: "12\n45\n78\n01\n")
         textView.frame = NSRect(x: 0, y: 0, width: 1000, height: 1000)
         textStorage = textView.textStorage
         layoutManager = try #require(textView.layoutManager)
     }
 
+    @Test
+    func addAndGetAttachments() throws {
+        layoutManager.attachments.add(DemoTextAttachment(), for: NSRange(start: 2, end: 8))
+        #expect(layoutManager.attachments.get(overlapping: textView.documentRange).count == 1)
+        #expect(layoutManager.attachments.get(overlapping: NSRange(start: 0, end: 3)).count == 1)
+        #expect(layoutManager.attachments.get(startingIn: NSRange(start: 0, end: 3)).count == 1)
+    }
+
     // MARK: - Determine Visible Line Tests
 
     @Test
-    func determineVisibleLinesMovesForwards() {
-        layoutManager.attachments.attachments(overlapping: <#T##NSRange#>)
+    func determineVisibleLinesMovesForwards() throws {
+        // From middle of the first line, to middle of the third line
+        layoutManager.attachments.add(DemoTextAttachment(), for: NSRange(start: 2, end: 8))
+
+        // Start with the first line, should extend to the third line
+        let originalPosition = try #require(layoutManager.lineStorage.getLine(atIndex: 0)) // zero-indexed
+        let newPosition = try #require(layoutManager.determineVisiblePosition(for: originalPosition))
+
+        #expect(newPosition.indexRange == 0...2)
+        #expect(newPosition.position.range == NSRange(start: 0, end: 9)) // Lines one -> three
+    }
+
+    @Test
+    func determineVisibleLinesMovesBackwards() throws {
+        // From middle of the first line, to middle of the third line
+        layoutManager.attachments.add(DemoTextAttachment(), for: NSRange(start: 2, end: 8))
+
+        // Start with the third line, should extend back to the first line
+        let originalPosition = try #require(layoutManager.lineStorage.getLine(atIndex: 2)) // zero-indexed
+        let newPosition = try #require(layoutManager.determineVisiblePosition(for: originalPosition))
+
+        #expect(newPosition.indexRange == 0...2)
+        #expect(newPosition.position.range == NSRange(start: 0, end: 9)) // Lines one -> three
     }
 
     @Test
-    func determineVisibleLinesMovesBackwards() {
+    func determineVisibleLinesMergesMultipleAttachments() throws {
+        // Two attachments, meeting at the third line. `determineVisiblePosition` should merge all four lines.
+        layoutManager.attachments.add(DemoTextAttachment(), for: NSRange(start: 2, end: 7))
+        layoutManager.attachments.add(DemoTextAttachment(), for: NSRange(start: 7, end: 11))
+
+        let originalPosition = try #require(layoutManager.lineStorage.getLine(atIndex: 2)) // zero-indexed
+        let newPosition = try #require(layoutManager.determineVisiblePosition(for: originalPosition))
 
+        #expect(newPosition.indexRange == 0...3)
+        #expect(newPosition.position.range == NSRange(start: 0, end: 12)) // Lines one -> four
     }
 
     @Test
-    func determineVisibleLinesMergesMultipleAttachments() {
+    func determineVisibleLinesMergesOverlappingAttachments() throws {
+        // Two attachments, overlapping at the third line. `determineVisiblePosition` should merge all four lines.
+        layoutManager.attachments.add(DemoTextAttachment(), for: NSRange(start: 2, end: 7))
+        layoutManager.attachments.add(DemoTextAttachment(), for: NSRange(start: 5, end: 11))
 
+        let originalPosition = try #require(layoutManager.lineStorage.getLine(atIndex: 2)) // zero-indexed
+        let newPosition = try #require(layoutManager.determineVisiblePosition(for: originalPosition))
+
+        #expect(newPosition.indexRange == 0...3)
+        #expect(newPosition.position.range == NSRange(start: 0, end: 12)) // Lines one -> four
     }
 
     // MARK: - Iterator Tests
 
     @Test
     func iterateWithAttachments() {
+        layoutManager.attachments.add(DemoTextAttachment(), for: NSRange(start: 1, end: 2))
+
+        let lines = layoutManager.linesStartingAt(0, until: 1000)
 
+        // Line "5" is from the trailing newline. That shows up as an empty line in the view.
+        #expect(lines.map { $0.index } == [0, 1, 2, 3, 4])
     }
 
     @Test
     func iterateWithMultilineAttachments() {
+        // Two attachments, meeting at the third line.
+        layoutManager.attachments.add(DemoTextAttachment(), for: NSRange(start: 2, end: 7))
+        layoutManager.attachments.add(DemoTextAttachment(), for: NSRange(start: 7, end: 11))
+
+        let lines = layoutManager.linesStartingAt(0, until: 1000)
 
+        // Line "5" is from the trailing newline. That shows up as an empty line in the view.
+        #expect(lines.map { $0.index } == [0, 4])
     }
 }