Improve PDF reader and SaveAsPdf compatibility

.github/workflows/claude-code-review.yml

@@ -12,6 +12,7 @@ on:
 
 jobs:
   claude-review:
+    if: github.event.pull_request.head.repo.full_name == github.repository
     # Optional: Filter by PR author
     # if: |
     #   github.event.pull_request.user.login == 'external-contributor' ||

OfficeIMO.Pdf/Reading/Core/PdfReadDocument.cs

@@ -50,16 +50,15 @@ private List<PdfReadPage> CollectPages() {
         if (catalogId is int cat && _objects.TryGetValue(cat, out var catObj) && catObj.Value is PdfDictionary catalog) {
             var pagesNode = ResolveDict(catalog.Items.TryGetValue("Pages", out var v) ? v : null);
             if (pagesNode is not null) {
-                var kids = pagesNode.Get<PdfArray>("Kids");
+                var kids = ResolveArray(pagesNode.Items.TryGetValue("Kids", out var kidsObj) ? kidsObj : null);
                 int kidCount = kids?.Items.Count ?? 0;
                 var visited = new HashSet<int>();
-                var contentKeys = new HashSet<string>(StringComparer.Ordinal);
                 int? target = null;
                 var cnt = pagesNode.Get<PdfNumber>("Count");
                 if (cnt is not null) {
                     int cc = (int)cnt.Value; if (cc > 0) target = cc;
                 }
-                TraversePagesNodeDeepLimited(pagesNode, visited, contentKeys, result, target);
+                TraversePagesNodeDeepLimited(pagesNode, visited, result, target);
                 if (result.Count == 0 && kidCount > 0) {
                     // Build a reachable candidate set from Kids only
                     var reachable = CollectReachableLeafCandidates(pagesNode);
@@ -92,6 +91,13 @@ private List<PdfReadPage> CollectPages() {
         return null;
     }
 
+    private PdfArray? ResolveArray(PdfObject? obj) {
+        if (obj is null) return null;
+        if (obj is PdfArray a) return a;
+        if (obj is PdfReference r && _objects.TryGetValue(r.ObjectNumber, out var ind) && ind.Value is PdfArray aa) return aa;
+        return null;
+    }
+
     private void TraversePagesNode(PdfDictionary node, List<PdfReadPage> outList) {
         var type = node.Get<PdfName>("Type")?.Name;
         if (type == "Page" || (type is null && IsLikelyPage(node))) {
@@ -100,8 +106,9 @@ private void TraversePagesNode(PdfDictionary node, List<PdfReadPage> outList) {
             outList.Add(new PdfReadPage(objNum, node, _objects));
             return;
         }
-        if (type == "Pages" || (type is null && node.Get<PdfArray>("Kids") is not null)) {
-            var kids = node.Get<PdfArray>("Kids");
+        var kidsObj = node.Items.TryGetValue("Kids", out var kidsValue) ? kidsValue : null;
+        if (type == "Pages" || (type is null && ResolveArray(kidsObj) is not null)) {
+            var kids = ResolveArray(kidsObj);
             if (kids is null) return;
             foreach (var kid in kids.Items) {
                 var d = ResolveDict(kid);
@@ -111,45 +118,40 @@ private void TraversePagesNode(PdfDictionary node, List<PdfReadPage> outList) {
         }
     }
 
-    private static bool IsLikelyPage(PdfDictionary d) {
-        // Heuristic when /Type is missing: leaf node has Contents, and either its own Resources or MediaBox.
+    private bool IsLikelyPage(PdfDictionary d) {
+        // Heuristic when /Type is missing: leaf node has Contents, and page data can come from itself or inherited /Pages nodes.
         bool hasContents = d.Items.ContainsKey("Contents");
-        bool hasRes = d.Items.ContainsKey("Resources");
-        bool hasMedia = d.Items.ContainsKey("MediaBox") || d.Items.ContainsKey("CropBox");
-        bool hasKids = d.Items.ContainsKey("Kids");
+        bool hasRes = d.Items.ContainsKey("Resources") || HasInheritedValue(d, "Resources");
+        bool hasMedia = HasMedia(d) || HasInheritedValue(d, "MediaBox") || HasInheritedValue(d, "CropBox");
+        bool hasKids = ResolveArray(d.Items.TryGetValue("Kids", out var kidsObj) ? kidsObj : null) is not null;
         return !hasKids && hasContents && (hasRes || hasMedia);
     }
 
-    private void TraversePagesNodeDeepLimited(PdfDictionary node, HashSet<int> visited, HashSet<string> contentKeys, List<PdfReadPage> outList, int? limit) {
+    private void TraversePagesNodeDeepLimited(PdfDictionary node, HashSet<int> visited, List<PdfReadPage> outList, int? limit) {
         var type = node.Get<PdfName>("Type")?.Name;
         if (type == "Page" || (type is null && IsLikelyPage(node))) {
             int objNum = FindObjectNumberFor(node);
             if (objNum > 0 && visited.Add(objNum)) {
-                if (HasMedia(node)) {
-                    var key = ContentsKey(node);
-                    if (key is null || contentKeys.Add(key)) {
-                        outList.Add(new PdfReadPage(objNum, node, _objects));
-                    }
+                if (type == "Page" || HasMedia(node) || HasInheritedValue(node, "MediaBox") || HasInheritedValue(node, "CropBox")) {
+                    outList.Add(new PdfReadPage(objNum, node, _objects));
                 }
             }
             return;
         }
-        var kids = node.Get<PdfArray>("Kids");
+        var kids = ResolveArray(node.Items.TryGetValue("Kids", out var kidsObj) ? kidsObj : null);
         if (kids is null) return;
         foreach (var kid in kids.Items) {
             if (limit.HasValue && outList.Count >= limit.Value) return;
             var d = ResolveDict(kid);
             if (d is null) { continue; }
             var t = d.Get<PdfName>("Type")?.Name;
-            if (t == "Pages" || (t is null && d.Get<PdfArray>("Kids") is not null)) TraversePagesNodeDeepLimited(d, visited, contentKeys, outList, limit);
-            else if ((t == "Page" || IsLikelyPage(d) || IsLeafPageByParent(d)) && HasMedia(d)) {
+            if (t == "Pages" || (t is null && ResolveArray(d.Items.TryGetValue("Kids", out var dKidsObj) ? dKidsObj : null) is not null)) TraversePagesNodeDeepLimited(d, visited, outList, limit);
+            else if ((t == "Page" || IsLikelyPage(d) || IsLeafPageByParent(d)) &&
+                     (t == "Page" || HasMedia(d) || HasInheritedValue(d, "MediaBox") || HasInheritedValue(d, "CropBox"))) {
                 int on = FindObjectNumberFor(d);
                 if (on > 0 && visited.Add(on)) {
-                    var key = ContentsKey(d);
-                    if (key is null || contentKeys.Add(key)) {
-                        outList.Add(new PdfReadPage(on, d, _objects));
-                        if (limit.HasValue && outList.Count >= limit.Value) return;
-                    }
+                    outList.Add(new PdfReadPage(on, d, _objects));
+                    if (limit.HasValue && outList.Count >= limit.Value) return;
                 }
             }
         }
@@ -162,13 +164,13 @@ private HashSet<int> CollectReachableLeafCandidates(PdfDictionary pagesRoot) {
         int guard = 0;
         while (stack.Count > 0 && guard++ < 10000) {
             var cur = stack.Pop();
-            var kids = cur.Get<PdfArray>("Kids");
+            var kids = ResolveArray(cur.Items.TryGetValue("Kids", out var kidsObj) ? kidsObj : null);
             if (kids is null) continue;
             foreach (var k in kids.Items) {
                 var d = ResolveDict(k);
                 if (d is null) continue;
                 var t = d.Get<PdfName>("Type")?.Name;
-                if (t == "Pages" || (t is null && d.Get<PdfArray>("Kids") is not null)) stack.Push(d);
+                if (t == "Pages" || (t is null && ResolveArray(d.Items.TryGetValue("Kids", out var dKidsObj) ? dKidsObj : null) is not null)) stack.Push(d);
                 else if (IsLikelyPage(d) || IsLeafPageByParent(d)) {
                     int on = FindObjectNumberFor(d);
                     if (on > 0) set.Add(on);
@@ -193,19 +195,30 @@ private bool IsLeafPageByParent(PdfDictionary d) {
         return false;
     }
 
-    private static bool HasMedia(PdfDictionary d) => d.Items.ContainsKey("MediaBox") || d.Items.ContainsKey("CropBox");
-    private static string? ContentsKey(PdfDictionary d) {
-        if (!d.Items.TryGetValue("Contents", out var c)) return null;
-        if (c is PdfReference r) return $"ref:{r.ObjectNumber}";
-        if (c is PdfArray arr) {
-            var sb = new System.Text.StringBuilder();
-            sb.Append("arr:");
-            foreach (var it in arr.Items) if (it is PdfReference rr) sb.Append(rr.ObjectNumber).Append(',');
-            return sb.ToString();
+    private bool HasInheritedValue(PdfDictionary start, string key) {
+        PdfDictionary? current = start;
+        int guard = 0;
+        while (current is not null && guard++ < 100) {
+            if (current.Items.ContainsKey(key)) {
+                return true;
+            }
+
+            if (!current.Items.TryGetValue("Parent", out var parentObj)) {
+                break;
+            }
+
+            var parent = ResolveDict(parentObj);
+            if (parent is null) {
+                break;
+            }
+
+            current = parent;
         }
-        return null;
+
+        return false;
     }
 
+    private static bool HasMedia(PdfDictionary d) => d.Items.ContainsKey("MediaBox") || d.Items.ContainsKey("CropBox");
     private int FindObjectNumberFor(PdfDictionary dict) {
         foreach (var kv in _objects) if (ReferenceEquals(kv.Value.Value, dict)) return kv.Key;
         // As a fallback when dictionary was re-parsed separately, match by identity via a simple scan of Page objects