Change timing to remove hanging indent cache

CHANGELOG.md

@@ -7,9 +7,8 @@ Change Log
 
 ### Improvements
 
-- Optimize the performance of the invisible character drawing.
+- Optimize the performance of the invisible character drawing, the hanging indent calculation, and the line number view drawing.
 - Make space to draw the invisible symbol for ZERO WIDTH SPACE (U+200B) when the “other invisible characters” option is enabled.
-- [trivial] Optimize the performance of the hanging indent calculation and the line number view drawing.
 
 
 ### Fixes

CotEditor/Sources/EditorTextView.swift

@@ -1211,8 +1211,6 @@ final class EditorTextView: NSTextView, Themable, CurrentLineHighlighting, Multi
         
         assert(Thread.isMainThread)
         
-        (self.textContainer as? TextContainer)?.indentAttributes = self.typingAttributes
-        
         guard let textStorage = self.textStorage else { return assertionFailure() }
         guard textStorage.length > 0 else { return }
         

CotEditor/Sources/TextContainer.swift

@@ -31,19 +31,40 @@ final class TextContainer: NSTextContainer {
     
     var isHangingIndentEnabled = false  { didSet { self.invalidateLayout() } }
     var hangingIndentWidth = 0  { didSet { self.invalidateLayout() } }
-    var indentAttributes: [NSAttributedString.Key: Any] = [:] { didSet { self.indentWidthCache = [:] } }
     
     
     // MARK: Private Properties
     
     private var lastLineStartIndex = 0
     private var indentWidthCache: [String: CGFloat] = [:]
+    private var indentAttributes: [NSAttributedString.Key: Any] = [:]
+    private var typingAttributesObserver: NSKeyValueObservation?
     
     
     
     // MARK: -
     // MARK: Text Container Methods
     
+    deinit {
+        self.typingAttributesObserver?.invalidate()
+    }
+    
+    
+    override weak var textView: NSTextView? {
+        
+        willSet {
+            self.typingAttributesObserver?.invalidate()
+        }
+        
+        didSet {
+            self.typingAttributesObserver = textView?.observe(\.typingAttributes, options: [.initial, .new]) { [weak self] (_, change) in
+                self?.indentAttributes = change.newValue ?? [:]
+                self?.indentWidthCache.removeAll()
+            }
+        }
+    }
+    
+    
     override var isSimpleRectangularTextContainer: Bool {
         
         return !self.isHangingIndentEnabled