add delegate update

Sources/Down/AST/Styling/Stylers/AsyncImageLoad.swift

@@ -16,20 +16,29 @@ import AppKit
 
 #endif
 
+public protocol AsyncImageLoadDelegate
+{
+    func textAttachmentDidLoadImage(textAttachment: AsyncImageLoad, displaySizeChanged: Bool)
+}
+
 final public class AsyncImageLoad: NSTextAttachment
 {
     public var imageURL: URL?
-
+    
     public var displaySize: CGSize?
 
     public var maximumDisplayWidth: CGFloat?
-
+
+    public var delegate: AsyncImageLoadDelegate?
+
+    weak var textContainer: NSTextContainer?
+
     private var originalImageSize: CGSize?
 
-    public init(imageURL: URL? = nil)
+    public init(imageURL: URL? = nil, delegate: AsyncImageLoadDelegate? = nil)
     {
         self.imageURL = imageURL
-
+        self.delegate = delegate
         super.init(data: nil, ofType: nil)
     }
 
@@ -98,16 +107,33 @@ final public class AsyncImageLoad: NSTextAttachment
                 self.originalImageSize = imageSize
             }
             #endif
+
+            DispatchQueue.main.async {
+                if displaySizeChanged
+                {
+                    self.textContainer?.layoutManager?.setNeedsLayout(forAttachment: self)
+                }
+                else
+                {
+                    self.textContainer?.layoutManager?.setNeedsDisplay(forAttachment: self)
+                }
+
+                // notify the optional delegate
+                self.delegate?.textAttachmentDidLoadImage(textAttachment: self, displaySizeChanged: displaySizeChanged)
+            }
+
         }.resume()
     }
-
+    
     #if os(macOS)
     public override func image(forBounds imageBounds: CGRect, textContainer: NSTextContainer?, characterIndex charIndex: Int) -> NSImage?
     {
         if let image = image { return image }
 
         guard let contents = contents, let image = NSImage(data: contents) else
         {
+            self.textContainer = textContainer
+
             startAsyncImageDownload()
 
             return nil
@@ -122,6 +148,8 @@ final public class AsyncImageLoad: NSTextAttachment
 
         guard let contents = contents, let image = UIImage(data: contents) else
         {
+            self.textContainer = textContainer
+
             startAsyncImageDownload()
 
             return nil
@@ -149,3 +177,69 @@ final public class AsyncImageLoad: NSTextAttachment
         return CGRect.zero
     }
 }
+
+public extension NSLayoutManager
+{
+    /// Determine the character ranges for an attachment
+    private func rangesForAttachment(attachment: NSTextAttachment) -> [NSRange]?
+    {
+        guard let attributedString = self.textStorage else
+        {
+            return nil
+        }
+
+        // find character range for this attachment
+        let range = NSRange(location: 0, length: attributedString.length)
+
+        var refreshRanges = [NSRange]()
+
+        attributedString.enumerateAttribute(NSAttributedString.Key.attachment, in: range, options: []) { (value, effectiveRange, nil) in
+
+            guard let foundAttachment = value as? NSTextAttachment, foundAttachment == attachment else
+            {
+                return
+            }
+
+            // add this range to the refresh ranges
+            refreshRanges.append(effectiveRange)
+        }
+
+        if refreshRanges.count == 0
+        {
+            return nil
+        }
+
+        return refreshRanges
+    }
+
+    /// Trigger a relayout for an attachment
+    func setNeedsLayout(forAttachment attachment: NSTextAttachment)
+    {
+        guard let ranges = rangesForAttachment(attachment: attachment) else
+        {
+            return
+        }
+
+        // invalidate the display for the corresponding ranges
+        for range in ranges.reversed() {
+            self.invalidateLayout(forCharacterRange: range, actualCharacterRange: nil)
+
+            // also need to trigger re-display or already visible images might not get updated
+            self.invalidateDisplay(forCharacterRange: range)
+        }
+    }
+
+    /// Trigger a re-display for an attachment
+    func setNeedsDisplay(forAttachment attachment: NSTextAttachment)
+    {
+        guard let ranges = rangesForAttachment(attachment: attachment) else
+        {
+            return
+        }
+
+        // invalidate the display for the corresponding ranges
+        for range in ranges.reversed() {
+            self.invalidateDisplay(forCharacterRange: range)
+        }
+    }
+}

Sources/Down/AST/Styling/Stylers/DownStyler.swift

@@ -40,10 +40,12 @@ open class DownStyler: Styler {
         .font: fonts.listItemPrefix,
         .foregroundColor: colors.listItemPrefix]
     }
+
+    private var delegate: AsyncImageLoadDelegate?
 
     // MARK: - Life cycle
 
-    public init(configuration: DownStylerConfiguration = DownStylerConfiguration()) {
+    public init(configuration: DownStylerConfiguration = DownStylerConfiguration(), delegate: AsyncImageLoadDelegate? = nil) {
         fonts = configuration.fonts
         colors = configuration.colors
         paragraphStyles = configuration.paragraphStyles
@@ -52,6 +54,7 @@ open class DownStyler: Styler {
         codeBlockOptions = configuration.codeBlockOptions
         itemParagraphStyler = ListItemParagraphStyler(options: configuration.listItemOptions,
                                                       prefixFont: fonts.listItemPrefix)
+        self.delegate = delegate
     }
 
     // MARK: - Styling
@@ -221,7 +224,7 @@ open class DownStyler: Styler {
     }
 
     private func styleGenericImg(in str: NSMutableAttributedString, url: URL) {
-        let image1Attachment = AsyncImageLoad(imageURL: url)
+        let image1Attachment = AsyncImageLoad(imageURL: url, delegate: delegate)
         let image1String = NSAttributedString(attachment: image1Attachment)
 
         str.setAttributedString(image1String)