HyperlinkTextView

HyperlinkTextView.swift

//
//  BareTextView.swift
//  Cleepp
//
//  Created by Pierre Houston on 2024-03-27.
//  Copyright © 2024 Bananameter Labs. All rights reserved.
//
//  Based on snippits from https://stackoverflow.com/a/56854375/592739
//  and https://stackoverflow.com/a/14469815/592739
//  and https://gist.github.com/mminer/597c1b2c40adcf3c319f7feeade62ed4
//
//  I can't remember the state of this, whether it was working or not
//  before I implemented HyperlinkTextField instead. I think it was
//  working but once I saw that addHyperlinkCursorRects for the hand
//  cursor would work for a NSTextField subclass too, I saw no need to
//  use a NSTextView subclass for what I needed.
//

import AppKit

class HyperlinkTextView: NSTextView
{
  var maximumLines = 1
  var maximumWidth: CGFloat = 0.0
  
  init() {
    super.init(frame: NSRect.zero)
    configure()
  }
  
  //  It is not possible to set up a lone NSTextView in Interface Builder, however you can set it up
  //  as a CustomView if you are happy to have all your presentation properties initialised
  //  programatically. This initialises an NSTextView as it would be with the default init...
  required init(coder: NSCoder) {
    super.init(coder: coder)!
    
    let textStorage = NSTextStorage()
    let layoutManager = NSLayoutManager()
    textStorage.addLayoutManager(layoutManager)
    
    // By default, NSTextContainers do not track the bounds of the NSTextview
    let textContainer = NSTextContainer(containerSize: CGSize.zero)
    textContainer.widthTracksTextView = true
    textContainer.heightTracksTextView = true
    
    layoutManager.addTextContainer(textContainer)
    replaceTextContainer(textContainer)
    
    configure()
  }
  
  private func configure() {
    isEditable = false
    isSelectable = false
    backgroundColor = NSColor.clear
  }
  
  override var intrinsicContentSize: NSSize {
    if let textContainer = textContainer, let layoutManager = layoutManager {
      textContainer.maximumNumberOfLines = maximumLines
      textContainer.size = CGSize(width: maximumWidth, height: 0.0)
      layoutManager.ensureLayout(for: textContainer)
      let rect = layoutManager.usedRect(for: textContainer)
      return rect.size
    }
    return NSSize.zero
  }
  
  override func mouseDown(with event: NSEvent) {
    super.mouseDown(with: event)
    openClickedHyperlink(with: event)
  }
  
  override func resetCursorRects() {
    super.resetCursorRects()
    addHyperlinkCursorRects()
  }
  
  // Displays a hand cursor when a link is hovered over.
  private func addHyperlinkCursorRects() {
    guard let layoutManager = layoutManager, let textContainer = textContainer else {
      return
    }
    
    let attributedStringValue = attributedString()
    let range = NSRange(location: 0, length: attributedStringValue.length)
    
    attributedStringValue.enumerateAttribute(.link, in: range) { value, range, _ in
      guard value != nil else {
        return
      }
      
      let rect = layoutManager.boundingRect(forGlyphRange: range, in: textContainer)
      addCursorRect(rect, cursor: .pointingHand)
    }
  }
  
  // Opens links when clicked.
  private func openClickedHyperlink(with event: NSEvent) {
    let attributedStringValue = attributedString()
    let point = convert(event.locationInWindow, from: nil)
    let characterIndex = characterIndexForInsertion(at: point)
    
    guard characterIndex < attributedStringValue.length else {
      return
    }
    
    let attributes = attributedStringValue.attributes(at: characterIndex, effectiveRange: nil)
    
    var url = attributes[.link] as? URL
    // example code got this attribute as a string, maybe on certain versions of this OS? support this possibility
    if url == nil, let urlString = attributes[.link] as? String {
      url = URL(string: urlString)
    }
    guard let url = url else {
      return
    }
    
    NSWorkspace.shared.open(url)
  }
}