Query the metadata from input nodes.

source/blender/compositor/intern/COM_MetaData.cc

@@ -3,8 +3,11 @@
 
 #include "COM_MetaData.h"
 
+#include "BKE_idprop.h"
 #include "BKE_image.h"
 
+#include "IMB_metadata.h"
+
 #include "RE_pipeline.h"
 
 namespace blender::compositor {
@@ -14,6 +17,17 @@ void MetaData::add(const blender::StringRef key, const blender::StringRef value)
   entries_.add(key, value);
 }
 
+static void add_property(IDProperty *id_prop, void *user_data)
+{
+  MetaData *meta_data = static_cast<MetaData *>(user_data);
+  meta_data->add(id_prop->name, IDP_String(id_prop));
+}
+
+void MetaData::add(IDProperty *id_prop)
+{
+  IDP_foreach_property(id_prop, IDP_TYPE_FILTER_STRING, add_property, this);
+}
+
 void MetaData::add_cryptomatte_entry(const blender::StringRef layer_name,
                                      const blender::StringRefNull key,
                                      const blender::StringRef value)
@@ -50,6 +64,14 @@ void MetaData::add_to_render_result(RenderResult *render_result) const
   }
 }
 
+void MetaData::add_to_id_prop(IDProperty *id_properties) const
+{
+  BLI_assert(id_properties != nullptr);
+  for (Map<std::string, std::string>::Item entry : entries_.items()) {
+    IMB_metadata_set_field(id_properties, entry.key.c_str(), entry.value.c_str());
+  }
+}
+
 void MetaDataExtractCallbackData::add_meta_data(blender::StringRef key,
                                                 blender::StringRefNull value)
 {

source/blender/compositor/intern/COM_MetaData.h

@@ -43,6 +43,9 @@ class MetaData {
    */
   void replace_hash_neutral_cryptomatte_keys(const blender::StringRef layer_name);
   void add_to_render_result(RenderResult *render_result) const;
+  void add_to_id_prop(IDProperty *properties) const;
+  void add(IDProperty *properties);
+
 #ifdef WITH_CXX_GUARDEDALLOC
   MEM_CXX_CLASS_ALLOC_FUNCS("COM:MetaData")
 #endif

source/blender/compositor/intern/COM_NodeOperation.h

@@ -610,6 +610,25 @@ class NodeOperation {
    * The return parameter holds an instance or is an nullptr. */
   virtual std::unique_ptr<MetaData> get_meta_data()
   {
+    for (NodeOperationInput &input : inputs_) {
+      if (input.get_data_type() != DataType::Color) {
+        continue;
+      }
+      std::unique_ptr<MetaData> meta_data = input.get_reader()->get_meta_data();
+      if (meta_data.get()) {
+        return meta_data;
+      }
+    }
+    
+    for (NodeOperationInput &input : inputs_) {
+      if (input.get_data_type() == DataType::Color) {
+        continue;
+      }
+      std::unique_ptr<MetaData> meta_data = input.get_reader()->get_meta_data();
+      if (meta_data.get()) {
+        return meta_data;
+      }
+    }
     return std::unique_ptr<MetaData>();
   }
 

source/blender/compositor/operations/COM_ImageOperation.cc

@@ -215,4 +215,13 @@ void ImageDepthOperation::update_memory_buffer_partial(MemoryBuffer *output,
   }
 }
 
+std::unique_ptr<MetaData> ImageOperation::get_meta_data()
+{
+  MetaData meta_data;
+  if (buffer_->metadata != nullptr) {
+    meta_data.add(buffer_->metadata);
+  }
+  return std::make_unique<MetaData>(meta_data);
+}
+
 }  // namespace blender::compositor

source/blender/compositor/operations/COM_ImageOperation.h

@@ -78,6 +78,7 @@ class ImageOperation : public BaseImageOperation {
   void update_memory_buffer_partial(MemoryBuffer *output,
                                     const rcti &area,
                                     Span<MemoryBuffer *> inputs) override;
+  std::unique_ptr<MetaData> get_meta_data() override;
 };
 class ImageAlphaOperation : public BaseImageOperation {
  public:

source/blender/compositor/operations/COM_OutputFileOperation.cc

@@ -17,6 +17,7 @@
 #include "IMB_colormanagement.h"
 #include "IMB_imbuf.h"
 #include "IMB_imbuf_types.h"
+#include "IMB_metadata.h"
 
 #include "RE_pipeline.h"
 
@@ -255,6 +256,12 @@ void OutputSingleLayerOperation::deinit_execution()
     ibuf->mall |= IB_rectfloat;
     ibuf->dither = rd_->dither_intensity;
 
+    std::unique_ptr<MetaData> metadata = image_input_->get_meta_data();
+    if (metadata.get() != nullptr) {
+      IMB_metadata_ensure(&ibuf->metadata);
+      metadata->add_to_id_prop(ibuf->metadata);
+    }
+
     IMB_colormanagement_imbuf_for_write(ibuf, save_as_render_, false, &format_);
 
     suffix = BKE_scene_multiview_view_suffix_get(rd_, view_name_);

source/blender/compositor/operations/COM_ReadBufferOperation.cc

@@ -122,4 +122,9 @@ void ReadBufferOperation::update_memory_buffer()
   buffer_ = this->get_memory_proxy()->get_buffer();
 }
 
+std::unique_ptr<MetaData> ReadBufferOperation::get_meta_data()
+{
+  return get_memory_proxy()->get_write_buffer_operation()->get_meta_data();
+}
+
 }  // namespace blender::compositor

source/blender/compositor/operations/COM_ReadBufferOperation.h

@@ -57,6 +57,7 @@ class ReadBufferOperation : public NodeOperation {
   }
   void read_resolution_from_write_buffer();
   void update_memory_buffer();
+  std::unique_ptr<MetaData> get_meta_data() override;
 };
 
 }  // namespace blender::compositor