handle iden derived images

go/heif/heif.go

@@ -300,6 +300,8 @@ const (
 
 	SuberrorInvalidRegionData = C.heif_suberror_Invalid_region_data
 
+	SuberrorMissingIrefReference = C.heif_suberror_missing_iref_reference
+
 	SuberrorWrongTileImagePixelDepth = C.heif_suberror_Wrong_tile_image_pixel_depth
 
 	SuberrorUnknownNCLXColorPrimaries = C.heif_suberror_Unknown_NCLX_color_primaries

libheif/error.cc

@@ -158,7 +158,8 @@ const char* Error::get_error_string(heif_suberror_code err)
       return "Unknown NCLX matrix coefficients";
     case heif_suberror_Invalid_region_data:
       return "Invalid region item data";
-
+    case heif_suberror_missing_iref_reference:
+      return "'iref' box does not include a referenced item";
 
       // --- Memory_allocation_error ---
 

libheif/file.cc

@@ -365,7 +365,7 @@ Error HeifFile::parse_heif_file(BitstreamRange& range)
   m_iref_box = std::dynamic_pointer_cast<Box_iref>(m_meta_box->get_child_box(fourcc("iref")));
   if (m_iref_box) {
     Error error = check_for_ref_cycle(get_primary_image_ID(), m_iref_box);
-    if (error) {
+    if (error != Error::Ok) {
       return error;
     }
   }
@@ -397,15 +397,15 @@ Error HeifFile::parse_heif_file(BitstreamRange& range)
 
 
 Error HeifFile::check_for_ref_cycle(heif_item_id ID,
-                                    std::shared_ptr<Box_iref>& iref_box) const
+                                    const std::shared_ptr<Box_iref>& iref_box) const
 {
   std::unordered_set<heif_item_id> parent_items;
   return check_for_ref_cycle_recursion(ID, iref_box, parent_items);
 }
 
 
 Error HeifFile::check_for_ref_cycle_recursion(heif_item_id ID,
-                                    std::shared_ptr<Box_iref>& iref_box,
+                                    const std::shared_ptr<Box_iref>& iref_box,
                                     std::unordered_set<heif_item_id>& parent_items) const {
   if (parent_items.find(ID) != parent_items.end()) {
     return Error(heif_error_Invalid_input,
@@ -417,7 +417,7 @@ Error HeifFile::check_for_ref_cycle_recursion(heif_item_id ID,
   std::vector<heif_item_id> image_references = iref_box->get_references(ID, fourcc("dimg"));
   for (heif_item_id reference_idx : image_references) {
     Error error = check_for_ref_cycle_recursion(reference_idx, iref_box, parent_items);
-    if (error) {
+    if (error != Error::Ok) {
       return error;
     }
   }
@@ -697,6 +697,43 @@ int HeifFile::jpeg_get_bits_per_pixel(heif_item_id imageID) const
   return -1;
 }
 
+Error HeifFile::get_source_image_id(const heif_item_id from_ID, heif_item_id *to_ID) const
+{
+  // At this point iref is required (see ISO/IEC 23008-12:2022 Section 6.6.2.1)
+  if (!m_iref_box) {
+    return Error(heif_error_Invalid_input,
+                 heif_suberror_No_iref_box);
+  }
+  Error error = check_for_ref_cycle(from_ID, m_iref_box);
+  if (error != Error::Ok) {
+    return error;
+  }
+  std::vector<uint32_t> references = m_iref_box->get_references(from_ID, fourcc_to_uint32("dimg"));
+  if (references.size() != 1) {
+    return Error(heif_error_Invalid_input,
+                 heif_suberror_missing_iref_reference);
+  }
+  heif_item_id id = references[0];
+
+  if (!image_exists(id)) {
+    return Error(heif_error_Usage_error,
+                 heif_suberror_Nonexisting_item_referenced);
+  }
+
+  auto infe_box = get_infe(id);
+  if (!infe_box) {
+    return Error(heif_error_Usage_error,
+                 heif_suberror_Nonexisting_item_referenced);
+  }
+
+  std::string item_type = infe_box->get_item_type();
+  if (item_type == "iden") {
+    return get_source_image_id(id, to_ID);
+  }
+  *to_ID = id;
+
+  return Error::Ok;
+}
 
 Error HeifFile::get_compressed_image_data(heif_item_id ID, std::vector<uint8_t>* data) const
 {
@@ -719,6 +756,16 @@ Error HeifFile::get_compressed_image_data(heif_item_id ID, std::vector<uint8_t>*
   std::string item_type = infe_box->get_item_type();
   std::string content_type = infe_box->get_content_type();
 
+  if (item_type == "iden") {
+    // we want to return the image data for the source image
+    heif_item_id to_ID = 0;
+    Error error = get_source_image_id(ID, &to_ID);
+    if (error.error_code != heif_error_Ok) {
+      return error;
+    }
+    ID = to_ID;
+  }
+
   // --- get coded image data pointers
 
   auto items = m_iloc_box->get_items();

libheif/file.h

@@ -221,15 +221,17 @@ class HeifFile
   Error parse_heif_file(BitstreamRange& bitstream);
 
   Error check_for_ref_cycle(heif_item_id ID,
-                            std::shared_ptr<Box_iref>& iref_box) const;
+                            const std::shared_ptr<Box_iref>& iref_box) const;
 
   Error check_for_ref_cycle_recursion(heif_item_id ID,
-                                      std::shared_ptr<Box_iref>& iref_box,
+                                      const std::shared_ptr<Box_iref>& iref_box,
                                       std::unordered_set<heif_item_id>& parent_items) const;
 
   std::shared_ptr<Box_infe> get_infe(heif_item_id ID) const;
 
   int jpeg_get_bits_per_pixel(heif_item_id imageID) const;
+
+  Error get_source_image_id(const heif_item_id to_ID, heif_item_id *from_ID) const;
 };
 
 #endif

libheif/heif.h

@@ -229,6 +229,8 @@ enum heif_suberror_code
   // Invalid specification of region item
   heif_suberror_Invalid_region_data = 136,
 
+  // An item was referenced, but the iref entry didn't include it
+  heif_suberror_missing_iref_reference = 137,
 
   // --- Memory_allocation_error ---
 

libheif/heif_emscripten.h

@@ -353,6 +353,7 @@ EMSCRIPTEN_BINDINGS(libheif) {
     .value("heif_suberror_Item_reference_cycle", heif_suberror_Item_reference_cycle)
     .value("heif_suberror_Invalid_pixi_box", heif_suberror_Invalid_pixi_box)
     .value("heif_suberror_Invalid_region_data", heif_suberror_Invalid_region_data)
+    .value("heif_suberror_missing_iref_reference", heif_suberror_missing_iref_reference)
     .value("heif_suberror_Unsupported_codec", heif_suberror_Unsupported_codec)
     .value("heif_suberror_Unsupported_image_type", heif_suberror_Unsupported_image_type)
     .value("heif_suberror_Unsupported_data_version", heif_suberror_Unsupported_data_version)