收紧脚注图的 alt 兜底判定

原判定 alt 非空即视为脚注图,导致带 alt 的正常插图(如凡人修仙传的
logo)被缩到一个字号大小。改为 alt 长度达到脚注正文量级(≥8 字符)
且原图为小图标(≤50pt)双条件同时成立才走脚注缩放,与 HTML 归一化
层只认 qqreader-footnote class 的口径对齐。

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Sources/RDReaderView/EPUBTextRendering/Typesetter/RDEPUBAttachmentNormalizer.swift

@@ -136,8 +136,11 @@ struct RDEPUBAttachmentNormalizer {
     private static func isFootnoteAttachment(_ attachment: DTTextAttachment) -> Bool {
 
         let lowercasedClasses = ((attachment.attributes["class"] as? String) ?? "").lowercased()
+        if lowercasedClasses.contains("qqreader-footnote") {
+            return true
+        }
         let altText = attachment.attributes["alt"] as? String
-        return lowercasedClasses.contains("qqreader-footnote") || hasFootnoteAltText(altText)
+        return hasFootnoteAltText(altText) && isFootnoteSizedImage(attachment.originalSize)
     }
 
     private static func isCoverAttachment(_ attachment: DTTextAttachment) -> Bool {
@@ -224,10 +227,31 @@ struct RDEPUBAttachmentNormalizer {
         }
         let label = fileAttachment.accessibilityLabel
         let lowercasedLabel = (label ?? "").lowercased()
-        return lowercasedLabel.contains("qqreader-footnote") || hasFootnoteAltText(label)
+        if lowercasedLabel.contains("qqreader-footnote") {
+            return true
+        }
+        let imageSize = fileAttachment.image?.size ?? fileAttachment.bounds.size
+        return hasFootnoteAltText(label) && isFootnoteSizedImage(imageSize)
     }
 
+    // Footnote images without the qqreader-footnote class are recognized by their
+    // alt text carrying the note body. Short alts ("logo", "图1") are ordinary
+    // accessibility descriptions, and note markers are small inline icons, so both
+    // conditions must hold before an image is shrunk to footnote size.
+    private static let minimumFootnoteAltTextLength = 8
+
+    private static let maximumFootnoteImageDimension: CGFloat = 50
+
     private static func hasFootnoteAltText(_ text: String?) -> Bool {
-        text?.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty == false
+        guard let trimmed = text?.trimmingCharacters(in: .whitespacesAndNewlines) else {
+            return false
+        }
+        return trimmed.count >= minimumFootnoteAltTextLength
+    }
+
+    private static func isFootnoteSizedImage(_ size: CGSize) -> Bool {
+        guard size.width > 0, size.height > 0 else { return false }
+        return size.width <= maximumFootnoteImageDimension
+            && size.height <= maximumFootnoteImageDimension
     }
 }