feat: display a block cursor in Vim Normal mode

Sources/Conjure/NotesTextView.swift

@@ -61,10 +61,14 @@ final class NotesTextView: NSTextView, @MainActor NSLayoutManagerDelegate {
     private var tasks: [(range: NSRange, attachment: ListAttachment)] = []
     private var checkboxes: [NSButton] = []
     private var horizontalSelection: (anchor: Int, head: Int)?
-    var vimState = NotesVimState()
+    var vimState = NotesVimState() {
+        didSet {
+            if oldValue.mode != vimState.mode { needsDisplay = true }
+        }
+    }
     var vimModeChanged: (() -> Void)?
     var vimEnabled = false {
-        didSet { resetVim() }
+        didSet { resetVim(); needsDisplay = true }
     }
 
     var markdownContents: NSAttributedString { Self.serialize(attributedString()) }
@@ -77,6 +81,29 @@ final class NotesTextView: NSTextView, @MainActor NSLayoutManagerDelegate {
         refreshTasks()
     }
 
+    private var normalCursorWidth: CGFloat {
+        let position = selectedRange().location
+        let cursorFont = position < (textStorage?.length ?? 0)
+            ? textStorage?.attribute(.font, at: position, effectiveRange: nil) as? NSFont : font
+        return max(2, ceil((cursorFont ?? NotesAppearance.font).maximumAdvancement.width))
+    }
+
+    override func drawInsertionPoint(in rect: NSRect, color: NSColor, turnedOn flag: Bool) {
+        guard vimEnabled, vimMode == .normal else {
+            super.drawInsertionPoint(in: rect, color: color, turnedOn: flag)
+            return
+        }
+        var block = rect
+        block.size.width = normalCursorWidth
+        super.drawInsertionPoint(in: block, color: color.withAlphaComponent(0.45), turnedOn: flag)
+    }
+
+    override func setNeedsDisplay(_ invalidRect: NSRect) {
+        var rect = invalidRect
+        if vimEnabled, vimMode == .normal { rect.size.width += normalCursorWidth }
+        super.setNeedsDisplay(rect)
+    }
+
     private static func serialize(_ contents: NSAttributedString, keepingMetadata: Bool = false) -> NSAttributedString {
         let result = NSMutableAttributedString(attributedString: contents)
         restoreListLayout(in: result)