Geometry Nodes: new geometry attribute API

Currently, there are two attribute API. The first, defined in `BKE_attribute.h` is
accessible from RNA and C code. The second is implemented with `GeometryComponent`
and is only accessible in C++ code. The second is widely used, but only being
accessible through the `GeometrySet` API makes it awkward to use, and even impossible
for types that don't correspond directly to a geometry component like `CurvesGeometry`.

This patch adds a new attribute API, designed to replace the `GeometryComponent`
attribute API now, and to eventually replace or be the basis of the other one.

The basic idea is that there is an `AttributeAccessor` class that allows code to
interact with a set of attributes owned by some geometry. The accessor itself has
no ownership. `AttributeAccessor` is a simple type that can be passed around by
value. That makes it easy to return it from functions and to store it in containers.

For const-correctness, there is also a `MutableAttributeAccessor` that allows
changing individual and can add or remove attributes.

Currently, `AttributeAccessor` is composed of two pointers. The first is a pointer
to the owner of the attribute data. The second is a pointer to a struct with
function pointers, that is similar to a virtual function table. The functions
know how to access attributes on the owner.

The actual attribute access for geometries is still implemented with the `AttributeProvider`
pattern, which makes it easy to support different sources of attributes on a
geometry and simplifies dealing with built-in attributes.

There are different ways to get an attribute accessor for a geometry:
* `GeometryComponent.attributes()`
* `CurvesGeometry.attributes()`
* `bke::mesh_attributes(const Mesh &)`
* `bke::pointcloud_attributes(const PointCloud &)`

All of these also have a `_for_write` variant that returns a `MutabelAttributeAccessor`.

Differential Revision: https://developer.blender.org/D15280

7 files changed, 213 insertions, 235 deletions

diff --git a/source/blender/geometry/intern/mesh_primitive_cuboid.cc b/source/blender/geometry/intern/mesh_primitive_cuboid.cc
index 07ac2419ad9..486d8adbf39 100644
--- a/source/blender/geometry/intern/mesh_primitive_cuboid.cc
+++ b/source/blender/geometry/intern/mesh_primitive_cuboid.cc
@@ -7,7 +7,6 @@
 #include "DNA_mesh_types.h"
 #include "DNA_meshdata_types.h"
 
-#include "BKE_attribute_access.hh"
 #include "BKE_geometry_set.hh"
 #include "BKE_mesh.h"
 
@@ -322,11 +321,10 @@ static void calculate_polys(const CuboidConfig &config,
 
 static void calculate_uvs(const CuboidConfig &config, Mesh *mesh, const bke::AttributeIDRef &uv_id)
 {
-  MeshComponent mesh_component;
-  mesh_component.replace(mesh, GeometryOwnershipType::Editable);
-  bke::OutputAttribute_Typed<float2> uv_attribute =
-      mesh_component.attribute_try_get_for_output_only<float2>(uv_id, ATTR_DOMAIN_CORNER);
-  MutableSpan<float2> uvs = uv_attribute.as_span();
+  bke::MutableAttributeAccessor attributes = bke::mesh_attributes_for_write(*mesh);
+  bke::SpanAttributeWriter<float2> uv_attribute =
+      attributes.lookup_or_add_for_write_only_span<float2>(uv_id, ATTR_DOMAIN_CORNER);
+  MutableSpan<float2> uvs = uv_attribute.span;
 
   int loop_index = 0;
 
@@ -394,7 +392,7 @@ static void calculate_uvs(const CuboidConfig &config, Mesh *mesh, const bke::Att
     }
   }
 
-  uv_attribute.save();
+  uv_attribute.finish();
 }
 
 Mesh *create_cuboid_mesh(const float3 &size,
diff --git a/source/blender/geometry/intern/mesh_to_curve_convert.cc b/source/blender/geometry/intern/mesh_to_curve_convert.cc
index 38f9da2a60c..681dfd15137 100644
--- a/source/blender/geometry/intern/mesh_to_curve_convert.cc
+++ b/source/blender/geometry/intern/mesh_to_curve_convert.cc
@@ -8,7 +8,7 @@
 #include "DNA_mesh_types.h"
 #include "DNA_meshdata_types.h"
 
-#include "BKE_attribute_access.hh"
+#include "BKE_attribute.hh"
 #include "BKE_attribute_math.hh"
 #include "BKE_curves.hh"
 #include "BKE_geometry_set.hh"
@@ -44,14 +44,13 @@ static Curves *create_curve_from_vert_indices(const MeshComponent &mesh_componen
   curves.cyclic_for_write().fill(false);
   curves.cyclic_for_write().slice(cyclic_curves).fill(true);
 
-  Set<bke::AttributeIDRef> source_attribute_ids = mesh_component.attribute_ids();
+  bke::MutableAttributeAccessor curves_attributes = curves.attributes_for_write();
+  const bke::AttributeAccessor mesh_attributes = *mesh_component.attributes();
 
-  CurveComponent curves_component;
-  curves_component.replace(curves_id, GeometryOwnershipType::Editable);
+  Set<bke::AttributeIDRef> source_attribute_ids = mesh_attributes.all_ids();
 
   for (const bke::AttributeIDRef &attribute_id : source_attribute_ids) {
-    if (mesh_component.attribute_is_builtin(attribute_id) &&
-        !curves_component.attribute_is_builtin(attribute_id)) {
+    if (mesh_attributes.is_builtin(attribute_id) && !curves_attributes.is_builtin(attribute_id)) {
       /* Don't copy attributes that are built-in on meshes but not on curves. */
       continue;
     }
@@ -60,8 +59,7 @@ static Curves *create_curve_from_vert_indices(const MeshComponent &mesh_componen
       continue;
     }
 
-    const GVArray mesh_attribute = mesh_component.attribute_try_get_for_read(attribute_id,
-                                                                             ATTR_DOMAIN_POINT);
+    const GVArray mesh_attribute = mesh_attributes.lookup(attribute_id, ATTR_DOMAIN_POINT);
     /* Some attributes might not exist if they were builtin attribute on domains that don't
      * have any elements, i.e. a face attribute on the output of the line primitive node. */
     if (!mesh_attribute) {
@@ -71,10 +69,10 @@ static Curves *create_curve_from_vert_indices(const MeshComponent &mesh_componen
     /* Copy attribute based on the map for this curve. */
     attribute_math::convert_to_static_type(mesh_attribute.type(), [&](auto dummy) {
       using T = decltype(dummy);
-      bke::OutputAttribute_Typed<T> attribute =
-          curves_component.attribute_try_get_for_output_only<T>(attribute_id, ATTR_DOMAIN_POINT);
-      copy_with_map<T>(mesh_attribute.typed<T>(), vert_indices, attribute.as_span());
-      attribute.save();
+      bke::SpanAttributeWriter<T> attribute =
+          curves_attributes.lookup_or_add_for_write_only_span<T>(attribute_id, ATTR_DOMAIN_POINT);
+      copy_with_map<T>(mesh_attribute.typed<T>(), vert_indices, attribute.span);
+      attribute.finish();
     });
   }
 
diff --git a/source/blender/geometry/intern/point_merge_by_distance.cc b/source/blender/geometry/intern/point_merge_by_distance.cc
index 6639ff650d3..40bc02cbd34 100644
--- a/source/blender/geometry/intern/point_merge_by_distance.cc
+++ b/source/blender/geometry/intern/point_merge_by_distance.cc
@@ -104,24 +104,24 @@ PointCloud *point_merge_by_distance(const PointCloudComponent &src_points,
     point_merge_counts[dst_index]++;
   }
 
-  Set<bke::AttributeIDRef> attributes = src_points.attribute_ids();
+  const bke::AttributeAccessor src_attributes = *src_points.attributes();
+  bke::MutableAttributeAccessor dst_attributes = *dst_points.attributes_for_write();
+  Set<bke::AttributeIDRef> attributes = src_attributes.all_ids();
 
   /* Transfer the ID attribute if it exists, using the ID of the first merged point. */
   if (attributes.contains("id")) {
-    VArray<int> src = src_points.attribute_get_for_read<int>("id", ATTR_DOMAIN_POINT, 0);
-    bke::OutputAttribute_Typed<int> dst = dst_points.attribute_try_get_for_output_only<int>(
+    VArraySpan<int> src = src_attributes.lookup_or_default<int>("id", ATTR_DOMAIN_POINT, 0);
+    bke::SpanAttributeWriter<int> dst = dst_attributes.lookup_or_add_for_write_only_span<int>(
         "id", ATTR_DOMAIN_POINT);
-    Span<int> src_ids = src.get_internal_span();
-    MutableSpan<int> dst_ids = dst.as_span();
 
     threading::parallel_for(IndexRange(dst_size), 1024, [&](IndexRange range) {
       for (const int i_dst : range) {
         const IndexRange points(map_offsets[i_dst], map_offsets[i_dst + 1] - map_offsets[i_dst]);
-        dst_ids[i_dst] = src_ids[points.first()];
+        dst.span[i_dst] = src[points.first()];
       }
     });
 
-    dst.save();
+    dst.finish();
     attributes.remove_contained("id");
   }
 
@@ -131,20 +131,19 @@ PointCloud *point_merge_by_distance(const PointCloudComponent &src_points,
       continue;
     }
 
-    bke::ReadAttributeLookup src_attribute = src_points.attribute_try_get_for_read(id);
+    bke::GAttributeReader src_attribute = src_attributes.lookup(id);
     attribute_math::convert_to_static_type(src_attribute.varray.type(), [&](auto dummy) {
       using T = decltype(dummy);
       if constexpr (!std::is_void_v<attribute_math::DefaultMixer<T>>) {
-        bke::OutputAttribute_Typed<T> dst_attribute =
-            dst_points.attribute_try_get_for_output_only<T>(id, ATTR_DOMAIN_POINT);
-        Span<T> src = src_attribute.varray.get_internal_span().typed<T>();
-        MutableSpan<T> dst = dst_attribute.as_span();
+        bke::SpanAttributeWriter<T> dst_attribute =
+            dst_attributes.lookup_or_add_for_write_only_span<T>(id, ATTR_DOMAIN_POINT);
+        VArraySpan<T> src = src_attribute.varray.typed<T>();
 
         threading::parallel_for(IndexRange(dst_size), 1024, [&](IndexRange range) {
           for (const int i_dst : range) {
             /* Create a separate mixer for every point to avoid allocating temporary buffers
              * in the mixer the size of the result point cloud and to improve memory locality. */
-            attribute_math::DefaultMixer<T> mixer{dst.slice(i_dst, 1)};
+            attribute_math::DefaultMixer<T> mixer{dst_attribute.span.slice(i_dst, 1)};
 
             const IndexRange points(map_offsets[i_dst],
                                     map_offsets[i_dst + 1] - map_offsets[i_dst]);
@@ -157,7 +156,7 @@ PointCloud *point_merge_by_distance(const PointCloudComponent &src_points,
           }
         });
 
-        dst_attribute.save();
+        dst_attribute.finish();
       }
     });
   }
diff --git a/source/blender/geometry/intern/realize_instances.cc b/source/blender/geometry/intern/realize_instances.cc
index 060a1aa7603..25bf00c5783 100644
--- a/source/blender/geometry/intern/realize_instances.cc
+++ b/source/blender/geometry/intern/realize_instances.cc
@@ -23,12 +23,13 @@
 namespace blender::geometry {
 
 using blender::bke::AttributeIDRef;
+using blender::bke::AttributeKind;
+using blender::bke::AttributeMetaData;
 using blender::bke::custom_data_type_to_cpp_type;
 using blender::bke::CustomDataAttributes;
+using blender::bke::GSpanAttributeWriter;
 using blender::bke::object_get_evaluated_geometry_set;
-using blender::bke::OutputAttribute;
-using blender::bke::OutputAttribute_Typed;
-using blender::bke::ReadAttributeLookup;
+using blender::bke::SpanAttributeWriter;
 
 /**
  * An ordered set of attribute ids. Attributes are ordered to avoid name lookups in many places.
@@ -287,26 +288,27 @@ static void copy_generic_attributes_to_result(
     const AttributeFallbacksArray &attribute_fallbacks,
     const OrderedAttributes &ordered_attributes,
     const FunctionRef<IndexRange(eAttrDomain)> &range_fn,
-    MutableSpan<GMutableSpan> dst_attributes)
+    MutableSpan<GSpanAttributeWriter> dst_attribute_writers)
 {
-  threading::parallel_for(dst_attributes.index_range(), 10, [&](const IndexRange attribute_range) {
-    for (const int attribute_index : attribute_range) {
-      const eAttrDomain domain = ordered_attributes.kinds[attribute_index].domain;
-      const IndexRange element_slice = range_fn(domain);
-
-      GMutableSpan dst_span = dst_attributes[attribute_index].slice(element_slice);
-      if (src_attributes[attribute_index].has_value()) {
-        threaded_copy(*src_attributes[attribute_index], dst_span);
-      }
-      else {
-        const CPPType &cpp_type = dst_span.type();
-        const void *fallback = attribute_fallbacks.array[attribute_index] == nullptr ?
-                                   cpp_type.default_value() :
-                                   attribute_fallbacks.array[attribute_index];
-        threaded_fill({cpp_type, fallback}, dst_span);
-      }
-    }
-  });
+  threading::parallel_for(
+      dst_attribute_writers.index_range(), 10, [&](const IndexRange attribute_range) {
+        for (const int attribute_index : attribute_range) {
+          const eAttrDomain domain = ordered_attributes.kinds[attribute_index].domain;
+          const IndexRange element_slice = range_fn(domain);
+
+          GMutableSpan dst_span = dst_attribute_writers[attribute_index].span.slice(element_slice);
+          if (src_attributes[attribute_index].has_value()) {
+            threaded_copy(*src_attributes[attribute_index], dst_span);
+          }
+          else {
+            const CPPType &cpp_type = dst_span.type();
+            const void *fallback = attribute_fallbacks.array[attribute_index] == nullptr ?
+                                       cpp_type.default_value() :
+                                       attribute_fallbacks.array[attribute_index];
+            threaded_fill({cpp_type, fallback}, dst_span);
+          }
+        }
+      });
 }
 
 static void create_result_ids(const RealizeInstancesOptions &options,
@@ -361,7 +363,7 @@ static Vector<std::pair<int, GSpan>> prepare_attribute_fallbacks(
     const OrderedAttributes &ordered_attributes)
 {
   Vector<std::pair<int, GSpan>> attributes_to_override;
-  const CustomDataAttributes &attributes = instances_component.attributes();
+  const CustomDataAttributes &attributes = instances_component.instance_attributes();
   attributes.foreach_attribute(
       [&](const AttributeIDRef &attribute_id, const AttributeMetaData &meta_data) {
         const int attribute_index = ordered_attributes.ids.index_of_try(attribute_id);
@@ -447,7 +449,7 @@ static void gather_realize_tasks_for_instances(GatherTasksInfo &gather_info,
 
   Span<int> stored_instance_ids;
   if (gather_info.create_id_attribute_on_any_component) {
-    std::optional<GSpan> ids = instances_component.attributes().get_for_read("id");
+    std::optional<GSpan> ids = instances_component.instance_attributes().get_for_read("id");
     if (ids.has_value()) {
       stored_instance_ids = ids->typed<int>();
     }
@@ -646,34 +648,34 @@ static AllPointCloudsInfo preprocess_pointclouds(const GeometrySet &geometry_set
     pointcloud_info.pointcloud = pointcloud;
 
     /* Access attributes. */
-    PointCloudComponent component;
-    component.replace(const_cast<PointCloud *>(pointcloud), GeometryOwnershipType::ReadOnly);
+    bke::AttributeAccessor attributes = bke::pointcloud_attributes(*pointcloud);
     pointcloud_info.attributes.reinitialize(info.attributes.size());
     for (const int attribute_index : info.attributes.index_range()) {
       const AttributeIDRef &attribute_id = info.attributes.ids[attribute_index];
       const eCustomDataType data_type = info.attributes.kinds[attribute_index].data_type;
       const eAttrDomain domain = info.attributes.kinds[attribute_index].domain;
-      if (component.attribute_exists(attribute_id)) {
-        GVArray attribute = component.attribute_get_for_read(attribute_id, domain, data_type);
+      if (attributes.contains(attribute_id)) {
+        GVArray attribute = attributes.lookup_or_default(attribute_id, domain, data_type);
         pointcloud_info.attributes[attribute_index].emplace(std::move(attribute));
       }
     }
     if (info.create_id_attribute) {
-      ReadAttributeLookup ids_lookup = component.attribute_try_get_for_read("id");
-      if (ids_lookup) {
-        pointcloud_info.stored_ids = ids_lookup.varray.get_internal_span().typed<int>();
+      bke::GAttributeReader ids_attribute = attributes.lookup("id");
+      if (ids_attribute) {
+        pointcloud_info.stored_ids = ids_attribute.varray.get_internal_span().typed<int>();
       }
     }
   }
   return info;
 }
 
-static void execute_realize_pointcloud_task(const RealizeInstancesOptions &options,
-                                            const RealizePointCloudTask &task,
-                                            const OrderedAttributes &ordered_attributes,
-                                            PointCloud &dst_pointcloud,
-                                            MutableSpan<GMutableSpan> dst_attribute_spans,
-                                            MutableSpan<int> all_dst_ids)
+static void execute_realize_pointcloud_task(
+    const RealizeInstancesOptions &options,
+    const RealizePointCloudTask &task,
+    const OrderedAttributes &ordered_attributes,
+    PointCloud &dst_pointcloud,
+    MutableSpan<GSpanAttributeWriter> dst_attribute_writers,
+    MutableSpan<int> all_dst_ids)
 {
   const PointCloudRealizeInfo &pointcloud_info = *task.pointcloud_info;
   const PointCloud &pointcloud = *pointcloud_info.pointcloud;
@@ -699,7 +701,7 @@ static void execute_realize_pointcloud_task(const RealizeInstancesOptions &optio
         UNUSED_VARS_NDEBUG(domain);
         return point_slice;
       },
-      dst_attribute_spans);
+      dst_attribute_writers);
 }
 
 static void execute_realize_pointcloud_tasks(const RealizeInstancesOptions &options,
@@ -721,42 +723,43 @@ static void execute_realize_pointcloud_tasks(const RealizeInstancesOptions &opti
   PointCloudComponent &dst_component =
       r_realized_geometry.get_component_for_write<PointCloudComponent>();
   dst_component.replace(dst_pointcloud);
+  bke::MutableAttributeAccessor dst_attributes = bke::pointcloud_attributes_for_write(
+      *dst_pointcloud);
 
   /* Prepare id attribute. */
-  OutputAttribute_Typed<int> point_ids;
-  MutableSpan<int> point_ids_span;
+  SpanAttributeWriter<int> point_ids;
   if (all_pointclouds_info.create_id_attribute) {
-    point_ids = dst_component.attribute_try_get_for_output_only<int>("id", ATTR_DOMAIN_POINT);
-    point_ids_span = point_ids.as_span();
+    point_ids = dst_attributes.lookup_or_add_for_write_only_span<int>("id", ATTR_DOMAIN_POINT);
   }
 
   /* Prepare generic output attributes. */
-  Vector<OutputAttribute> dst_attributes;
-  Vector<GMutableSpan> dst_attribute_spans;
+  Vector<GSpanAttributeWriter> dst_attribute_writers;
   for (const int attribute_index : ordered_attributes.index_range()) {
     const AttributeIDRef &attribute_id = ordered_attributes.ids[attribute_index];
     const eCustomDataType data_type = ordered_attributes.kinds[attribute_index].data_type;
-    OutputAttribute dst_attribute = dst_component.attribute_try_get_for_output_only(
-        attribute_id, ATTR_DOMAIN_POINT, data_type);
-    dst_attribute_spans.append(dst_attribute.as_span());
-    dst_attributes.append(std::move(dst_attribute));
+    dst_attribute_writers.append(dst_attributes.lookup_or_add_for_write_only_span(
+        attribute_id, ATTR_DOMAIN_POINT, data_type));
   }
 
   /* Actually execute all tasks. */
   threading::parallel_for(tasks.index_range(), 100, [&](const IndexRange task_range) {
     for (const int task_index : task_range) {
       const RealizePointCloudTask &task = tasks[task_index];
-      execute_realize_pointcloud_task(
-          options, task, ordered_attributes, *dst_pointcloud, dst_attribute_spans, point_ids_span);
+      execute_realize_pointcloud_task(options,
+                                      task,
+                                      ordered_attributes,
+                                      *dst_pointcloud,
+                                      dst_attribute_writers,
+                                      point_ids.span);
     }
   });
 
-  /* Save modified attributes. */
-  for (OutputAttribute &dst_attribute : dst_attributes) {
-    dst_attribute.save();
+  /* Tag modified attributes. */
+  for (GSpanAttributeWriter &dst_attribute : dst_attribute_writers) {
+    dst_attribute.finish();
   }
   if (point_ids) {
-    point_ids.save();
+    point_ids.finish();
   }
 }
 
@@ -837,22 +840,21 @@ static AllMeshesInfo preprocess_meshes(const GeometrySet &geometry_set,
     }
 
     /* Access attributes. */
-    MeshComponent component;
-    component.replace(const_cast<Mesh *>(mesh), GeometryOwnershipType::ReadOnly);
+    bke::AttributeAccessor attributes = bke::mesh_attributes(*mesh);
     mesh_info.attributes.reinitialize(info.attributes.size());
     for (const int attribute_index : info.attributes.index_range()) {
       const AttributeIDRef &attribute_id = info.attributes.ids[attribute_index];
       const eCustomDataType data_type = info.attributes.kinds[attribute_index].data_type;
       const eAttrDomain domain = info.attributes.kinds[attribute_index].domain;
-      if (component.attribute_exists(attribute_id)) {
-        GVArray attribute = component.attribute_get_for_read(attribute_id, domain, data_type);
+      if (attributes.contains(attribute_id)) {
+        GVArray attribute = attributes.lookup_or_default(attribute_id, domain, data_type);
         mesh_info.attributes[attribute_index].emplace(std::move(attribute));
       }
     }
     if (info.create_id_attribute) {
-      ReadAttributeLookup ids_lookup = component.attribute_try_get_for_read("id");
-      if (ids_lookup) {
-        mesh_info.stored_vertex_ids = ids_lookup.varray.get_internal_span().typed<int>();
+      bke::GAttributeReader ids_attribute = attributes.lookup("id");
+      if (ids_attribute) {
+        mesh_info.stored_vertex_ids = ids_attribute.varray.get_internal_span().typed<int>();
       }
     }
   }
@@ -863,7 +865,7 @@ static void execute_realize_mesh_task(const RealizeInstancesOptions &options,
                                       const RealizeMeshTask &task,
                                       const OrderedAttributes &ordered_attributes,
                                       Mesh &dst_mesh,
-                                      MutableSpan<GMutableSpan> dst_attribute_spans,
+                                      MutableSpan<GSpanAttributeWriter> dst_attribute_writers,
                                       MutableSpan<int> all_dst_vertex_ids)
 {
   const MeshRealizeInfo &mesh_info = *task.mesh_info;
@@ -949,7 +951,7 @@ static void execute_realize_mesh_task(const RealizeInstancesOptions &options,
             return IndexRange();
         }
       },
-      dst_attribute_spans);
+      dst_attribute_writers);
 }
 
 static void execute_realize_mesh_tasks(const RealizeInstancesOptions &options,
@@ -973,6 +975,7 @@ static void execute_realize_mesh_tasks(const RealizeInstancesOptions &options,
   Mesh *dst_mesh = BKE_mesh_new_nomain(tot_vertices, tot_edges, 0, tot_loops, tot_poly);
   MeshComponent &dst_component = r_realized_geometry.get_component_for_write<MeshComponent>();
   dst_component.replace(dst_mesh);
+  bke::MutableAttributeAccessor dst_attributes = bke::mesh_attributes_for_write(*dst_mesh);
 
   /* Copy settings from the first input geometry set with a mesh. */
   const RealizeMeshTask &first_task = tasks.first();
@@ -986,24 +989,19 @@ static void execute_realize_mesh_tasks(const RealizeInstancesOptions &options,
   }
 
   /* Prepare id attribute. */
-  OutputAttribute_Typed<int> vertex_ids;
-  MutableSpan<int> vertex_ids_span;
+  SpanAttributeWriter<int> vertex_ids;
   if (all_meshes_info.create_id_attribute) {
-    vertex_ids = dst_component.attribute_try_get_for_output_only<int>("id", ATTR_DOMAIN_POINT);
-    vertex_ids_span = vertex_ids.as_span();
+    vertex_ids = dst_attributes.lookup_or_add_for_write_only_span<int>("id", ATTR_DOMAIN_POINT);
   }
 
   /* Prepare generic output attributes. */
-  Vector<OutputAttribute> dst_attributes;
-  Vector<GMutableSpan> dst_attribute_spans;
+  Vector<GSpanAttributeWriter> dst_attribute_writers;
   for (const int attribute_index : ordered_attributes.index_range()) {
     const AttributeIDRef &attribute_id = ordered_attributes.ids[attribute_index];
     const eAttrDomain domain = ordered_attributes.kinds[attribute_index].domain;
     const eCustomDataType data_type = ordered_attributes.kinds[attribute_index].data_type;
-    OutputAttribute dst_attribute = dst_component.attribute_try_get_for_output_only(
-        attribute_id, domain, data_type);
-    dst_attribute_spans.append(dst_attribute.as_span());
-    dst_attributes.append(std::move(dst_attribute));
+    dst_attribute_writers.append(
+        dst_attributes.lookup_or_add_for_write_only_span(attribute_id, domain, data_type));
   }
 
   /* Actually execute all tasks. */
@@ -1011,16 +1009,16 @@ static void execute_realize_mesh_tasks(const RealizeInstancesOptions &options,
     for (const int task_index : task_range) {
       const RealizeMeshTask &task = tasks[task_index];
       execute_realize_mesh_task(
-          options, task, ordered_attributes, *dst_mesh, dst_attribute_spans, vertex_ids_span);
+          options, task, ordered_attributes, *dst_mesh, dst_attribute_writers, vertex_ids.span);
     }
   });
 
-  /* Save modified attributes. */
-  for (OutputAttribute &dst_attribute : dst_attributes) {
-    dst_attribute.save();
+  /* Tag modified attributes. */
+  for (GSpanAttributeWriter &dst_attribute : dst_attribute_writers) {
+    dst_attribute.finish();
   }
   if (vertex_ids) {
-    vertex_ids.save();
+    vertex_ids.finish();
   }
 }
 
@@ -1088,49 +1086,43 @@ static AllCurvesInfo preprocess_curves(const GeometrySet &geometry_set,
     curve_info.curves = curves_id;
 
     /* Access attributes. */
-    CurveComponent component;
-    component.replace(const_cast<Curves *>(curves_id), GeometryOwnershipType::ReadOnly);
+    bke::AttributeAccessor attributes = curves.attributes();
     curve_info.attributes.reinitialize(info.attributes.size());
     for (const int attribute_index : info.attributes.index_range()) {
       const eAttrDomain domain = info.attributes.kinds[attribute_index].domain;
       const AttributeIDRef &attribute_id = info.attributes.ids[attribute_index];
       const eCustomDataType data_type = info.attributes.kinds[attribute_index].data_type;
-      if (component.attribute_exists(attribute_id)) {
-        GVArray attribute = component.attribute_get_for_read(attribute_id, domain, data_type);
+      if (attributes.contains(attribute_id)) {
+        GVArray attribute = attributes.lookup_or_default(attribute_id, domain, data_type);
         curve_info.attributes[attribute_index].emplace(std::move(attribute));
       }
     }
     if (info.create_id_attribute) {
-      ReadAttributeLookup ids_lookup = component.attribute_try_get_for_read("id");
-      if (ids_lookup) {
-        curve_info.stored_ids = ids_lookup.varray.get_internal_span().typed<int>();
+      bke::GAttributeReader id_attribute = attributes.lookup("id");
+      if (id_attribute) {
+        curve_info.stored_ids = id_attribute.varray.get_internal_span().typed<int>();
       }
     }
 
     /* Retrieve the radius attribute, if it exists. */
-    if (component.attribute_exists("radius")) {
-      curve_info.radius = component
-                              .attribute_get_for_read<float>("radius", ATTR_DOMAIN_POINT, 0.0f)
-                              .get_internal_span();
+    if (attributes.contains("radius")) {
+      curve_info.radius =
+          attributes.lookup<float>("radius", ATTR_DOMAIN_POINT).get_internal_span();
       info.create_radius_attribute = true;
     }
 
     /* Retrieve the resolution attribute, if it exists. */
     curve_info.resolution = curves.resolution();
-    if (component.attribute_exists("resolution")) {
+    if (attributes.contains("resolution")) {
       info.create_resolution_attribute = true;
     }
 
     /* Retrieve handle position attributes, if they exist. */
-    if (component.attribute_exists("handle_right")) {
-      curve_info.handle_left = component
-                                   .attribute_get_for_read<float3>(
-                                       "handle_left", ATTR_DOMAIN_POINT, float3(0))
-                                   .get_internal_span();
-      curve_info.handle_right = component
-                                    .attribute_get_for_read<float3>(
-                                        "handle_right", ATTR_DOMAIN_POINT, float3(0))
-                                    .get_internal_span();
+    if (attributes.contains("handle_right")) {
+      curve_info.handle_left =
+          attributes.lookup<float3>("handle_left", ATTR_DOMAIN_POINT).get_internal_span();
+      curve_info.handle_right =
+          attributes.lookup<float3>("handle_right", ATTR_DOMAIN_POINT).get_internal_span();
       info.create_handle_postion_attributes = true;
     }
   }
@@ -1142,7 +1134,7 @@ static void execute_realize_curve_task(const RealizeInstancesOptions &options,
                                        const RealizeCurveTask &task,
                                        const OrderedAttributes &ordered_attributes,
                                        bke::CurvesGeometry &dst_curves,
-                                       MutableSpan<GMutableSpan> dst_attribute_spans,
+                                       MutableSpan<GSpanAttributeWriter> dst_attribute_writers,
                                        MutableSpan<int> all_dst_ids,
                                        MutableSpan<float3> all_handle_left,
                                        MutableSpan<float3> all_handle_right,
@@ -1220,7 +1212,7 @@ static void execute_realize_curve_task(const RealizeInstancesOptions &options,
             return IndexRange();
         }
       },
-      dst_attribute_spans);
+      dst_attribute_writers);
 }
 
 static void execute_realize_curve_tasks(const RealizeInstancesOptions &options,
@@ -1244,57 +1236,45 @@ static void execute_realize_curve_tasks(const RealizeInstancesOptions &options,
   dst_curves.offsets_for_write().last() = points_num;
   CurveComponent &dst_component = r_realized_geometry.get_component_for_write<CurveComponent>();
   dst_component.replace(dst_curves_id);
+  bke::MutableAttributeAccessor dst_attributes = dst_curves.attributes_for_write();
 
   /* Prepare id attribute. */
-  OutputAttribute_Typed<int> point_ids;
-  MutableSpan<int> point_ids_span;
+  SpanAttributeWriter<int> point_ids;
   if (all_curves_info.create_id_attribute) {
-    point_ids = dst_component.attribute_try_get_for_output_only<int>("id", ATTR_DOMAIN_POINT);
-    point_ids_span = point_ids.as_span();
+    point_ids = dst_attributes.lookup_or_add_for_write_only_span<int>("id", ATTR_DOMAIN_POINT);
   }
 
   /* Prepare generic output attributes. */
-  Vector<OutputAttribute> dst_attributes;
-  Vector<GMutableSpan> dst_attribute_spans;
+  Vector<GSpanAttributeWriter> dst_attribute_writers;
   for (const int attribute_index : ordered_attributes.index_range()) {
     const AttributeIDRef &attribute_id = ordered_attributes.ids[attribute_index];
     const eAttrDomain domain = ordered_attributes.kinds[attribute_index].domain;
     const eCustomDataType data_type = ordered_attributes.kinds[attribute_index].data_type;
-    OutputAttribute dst_attribute = dst_component.attribute_try_get_for_output_only(
-        attribute_id, domain, data_type);
-    dst_attribute_spans.append(dst_attribute.as_span());
-    dst_attributes.append(std::move(dst_attribute));
+    dst_attribute_writers.append(
+        dst_attributes.lookup_or_add_for_write_only_span(attribute_id, domain, data_type));
   }
 
   /* Prepare handle position attributes if necessary. */
-  OutputAttribute_Typed<float3> handle_left;
-  OutputAttribute_Typed<float3> handle_right;
-  MutableSpan<float3> handle_left_span;
-  MutableSpan<float3> handle_right_span;
+  SpanAttributeWriter<float3> handle_left;
+  SpanAttributeWriter<float3> handle_right;
   if (all_curves_info.create_handle_postion_attributes) {
-    handle_left = dst_component.attribute_try_get_for_output_only<float3>("handle_left",
-                                                                          ATTR_DOMAIN_POINT);
-    handle_right = dst_component.attribute_try_get_for_output_only<float3>("handle_right",
+    handle_left = dst_attributes.lookup_or_add_for_write_only_span<float3>("handle_left",
                                                                            ATTR_DOMAIN_POINT);
-    handle_left_span = handle_left.as_span();
-    handle_right_span = handle_right.as_span();
+    handle_right = dst_attributes.lookup_or_add_for_write_only_span<float3>("handle_right",
+                                                                            ATTR_DOMAIN_POINT);
   }
 
   /* Prepare radius attribute if necessary. */
-  OutputAttribute_Typed<float> radius;
-  MutableSpan<float> radius_span;
+  SpanAttributeWriter<float> radius;
   if (all_curves_info.create_radius_attribute) {
-    radius = dst_component.attribute_try_get_for_output_only<float>("radius", ATTR_DOMAIN_POINT);
-    radius_span = radius.as_span();
+    radius = dst_attributes.lookup_or_add_for_write_only_span<float>("radius", ATTR_DOMAIN_POINT);
   }
 
   /* Prepare resolution attribute if necessary. */
-  OutputAttribute_Typed<int> resolution;
-  MutableSpan<int> resolution_span;
+  SpanAttributeWriter<int> resolution;
   if (all_curves_info.create_resolution_attribute) {
-    resolution = dst_component.attribute_try_get_for_output_only<int>("resolution",
-                                                                      ATTR_DOMAIN_CURVE);
-    resolution_span = resolution.as_span();
+    resolution = dst_attributes.lookup_or_add_for_write_only_span<int>("resolution",
+                                                                       ATTR_DOMAIN_CURVE);
   }
 
   /* Actually execute all tasks. */
@@ -1306,31 +1286,31 @@ static void execute_realize_curve_tasks(const RealizeInstancesOptions &options,
                                  task,
                                  ordered_attributes,
                                  dst_curves,
-                                 dst_attribute_spans,
-                                 point_ids_span,
-                                 handle_left_span,
-                                 handle_right_span,
-                                 radius_span,
-                                 resolution_span);
+                                 dst_attribute_writers,
+                                 point_ids.span,
+                                 handle_left.span,
+                                 handle_right.span,
+                                 radius.span,
+                                 resolution.span);
     }
   });
 
-  /* Save modified attributes. */
-  for (OutputAttribute &dst_attribute : dst_attributes) {
-    dst_attribute.save();
+  /* Tag modified attributes. */
+  for (GSpanAttributeWriter &dst_attribute : dst_attribute_writers) {
+    dst_attribute.finish();
   }
   if (point_ids) {
-    point_ids.save();
+    point_ids.finish();
   }
   if (radius) {
-    radius.save();
+    radius.finish();
   }
   if (resolution) {
-    resolution.save();
+    resolution.finish();
   }
   if (all_curves_info.create_handle_postion_attributes) {
-    handle_left.save();
-    handle_right.save();
+    handle_left.finish();
+    handle_right.finish();
   }
 }
 
@@ -1345,7 +1325,7 @@ static void remove_id_attribute_from_instances(GeometrySet &geometry_set)
   geometry_set.modify_geometry_sets([&](GeometrySet &sub_geometry) {
     if (sub_geometry.has<InstancesComponent>()) {
       InstancesComponent &component = sub_geometry.get_component_for_write<InstancesComponent>();
-      component.attributes().remove("id");
+      component.instance_attributes().remove("id");
     }
   });
 }
diff --git a/source/blender/geometry/intern/resample_curves.cc b/source/blender/geometry/intern/resample_curves.cc
index dd1da62408c..c9b8a032ce6 100644
--- a/source/blender/geometry/intern/resample_curves.cc
+++ b/source/blender/geometry/intern/resample_curves.cc
@@ -92,17 +92,18 @@ static void retrieve_attribute_spans(const Span<bke::AttributeIDRef> ids,
                                      CurveComponent &dst_component,
                                      Vector<GSpan> &src,
                                      Vector<GMutableSpan> &dst,
-                                     Vector<bke::OutputAttribute> &dst_attributes)
+                                     Vector<bke::GSpanAttributeWriter> &dst_attributes)
 {
   for (const int i : ids.index_range()) {
-    GVArray src_attribute = src_component.attribute_try_get_for_read(ids[i], ATTR_DOMAIN_POINT);
+    GVArray src_attribute = src_component.attributes()->lookup(ids[i], ATTR_DOMAIN_POINT);
     BLI_assert(src_attribute);
     src.append(src_attribute.get_internal_span());
 
     const eCustomDataType data_type = bke::cpp_type_to_custom_data_type(src_attribute.type());
-    bke::OutputAttribute dst_attribute = dst_component.attribute_try_get_for_output_only(
-        ids[i], ATTR_DOMAIN_POINT, data_type);
-    dst.append(dst_attribute.as_span());
+    bke::GSpanAttributeWriter dst_attribute =
+        dst_component.attributes_for_write()->lookup_or_add_for_write_only_span(
+            ids[i], ATTR_DOMAIN_POINT, data_type);
+    dst.append(dst_attribute.span);
     dst_attributes.append(std::move(dst_attribute));
   }
 }
@@ -111,7 +112,7 @@ struct AttributesForInterpolation : NonCopyable, NonMovable {
   Vector<GSpan> src;
   Vector<GMutableSpan> dst;
 
-  Vector<bke::OutputAttribute> dst_attributes;
+  Vector<bke::GSpanAttributeWriter> dst_attributes;
 
   Vector<GSpan> src_no_interpolation;
   Vector<GMutableSpan> dst_no_interpolation;
@@ -129,8 +130,8 @@ static void gather_point_attributes_to_interpolate(const CurveComponent &src_com
 
   VectorSet<bke::AttributeIDRef> ids;
   VectorSet<bke::AttributeIDRef> ids_no_interpolation;
-  src_component.attribute_foreach(
-      [&](const bke::AttributeIDRef &id, const AttributeMetaData meta_data) {
+  src_component.attributes()->for_all(
+      [&](const bke::AttributeIDRef &id, const bke::AttributeMetaData meta_data) {
         if (meta_data.domain != ATTR_DOMAIN_POINT) {
           return true;
         }
@@ -311,8 +312,8 @@ static Curves *resample_to_uniform(const CurveComponent &src_component,
   bke::curves::copy_point_data(
       src_curves, dst_curves, unselected_ranges, src_positions, dst_positions);
 
-  for (bke::OutputAttribute &attribute : attributes.dst_attributes) {
-    attribute.save();
+  for (bke::GSpanAttributeWriter &attribute : attributes.dst_attributes) {
+    attribute.finish();
   }
 
   return dst_curves_id;
@@ -433,8 +434,8 @@ Curves *resample_to_evaluated(const CurveComponent &src_component,
   bke::curves::copy_point_data(
       src_curves, dst_curves, unselected_ranges, src_positions, dst_positions);
 
-  for (bke::OutputAttribute &attribute : attributes.dst_attributes) {
-    attribute.save();
+  for (bke::GSpanAttributeWriter &attribute : attributes.dst_attributes) {
+    attribute.finish();
   }
 
   return dst_curves_id;
diff --git a/source/blender/geometry/intern/set_curve_type.cc b/source/blender/geometry/intern/set_curve_type.cc
index d7a5bc9b27d..08888a74973 100644
--- a/source/blender/geometry/intern/set_curve_type.cc
+++ b/source/blender/geometry/intern/set_curve_type.cc
@@ -290,32 +290,32 @@ struct GenericAttributes : NonCopyable, NonMovable {
   Vector<GSpan> src;
   Vector<GMutableSpan> dst;
 
-  Vector<bke::OutputAttribute> attributes;
+  Vector<bke::GSpanAttributeWriter> attributes;
 };
 
-static void retrieve_generic_point_attributes(const CurveComponent &src_component,
-                                              CurveComponent &dst_component,
+static void retrieve_generic_point_attributes(const bke::AttributeAccessor &src_attributes,
+                                              bke::MutableAttributeAccessor &dst_attributes,
                                               GenericAttributes &attributes)
 {
-  src_component.attribute_foreach(
-      [&](const bke::AttributeIDRef &id, const AttributeMetaData meta_data) {
+  src_attributes.for_all(
+      [&](const bke::AttributeIDRef &id, const bke::AttributeMetaData meta_data) {
         if (meta_data.domain != ATTR_DOMAIN_POINT) {
           /* Curve domain attributes are all copied directly to the result in one step. */
           return true;
         }
-        if (src_component.attribute_is_builtin(id)) {
+        if (src_attributes.is_builtin(id)) {
           if (!(id.is_named() && ELEM(id, "tilt", "radius"))) {
             return true;
           }
         }
 
-        GVArray src_attribute = src_component.attribute_try_get_for_read(id, ATTR_DOMAIN_POINT);
+        GVArray src_attribute = src_attributes.lookup(id, ATTR_DOMAIN_POINT);
         BLI_assert(src_attribute);
         attributes.src.append(src_attribute.get_internal_span());
 
-        bke::OutputAttribute dst_attribute = dst_component.attribute_try_get_for_output_only(
+        bke::GSpanAttributeWriter dst_attribute = dst_attributes.lookup_or_add_for_write_span(
             id, ATTR_DOMAIN_POINT, meta_data.data_type);
-        attributes.dst.append(dst_attribute.as_span());
+        attributes.dst.append(dst_attribute.span);
         attributes.attributes.append(std::move(dst_attribute));
 
         return true;
@@ -367,8 +367,11 @@ static Curves *convert_curves_to_bezier(const CurveComponent &src_component,
   bke::curves::accumulate_counts_to_offsets(dst_offsets);
   dst_curves.resize(dst_offsets.last(), dst_curves.curves_num());
 
+  const bke::AttributeAccessor src_attributes = *src_component.attributes();
+  bke::MutableAttributeAccessor dst_attributes = *dst_component.attributes_for_write();
+
   GenericAttributes attributes;
-  retrieve_generic_point_attributes(src_component, dst_component, attributes);
+  retrieve_generic_point_attributes(src_attributes, dst_attributes, attributes);
 
   MutableSpan<float3> dst_positions = dst_curves.positions_for_write();
   MutableSpan<float3> dst_handles_l = dst_curves.handle_positions_left_for_write();
@@ -494,8 +497,8 @@ static Curves *convert_curves_to_bezier(const CurveComponent &src_component,
         src_curves, dst_curves, unselected_ranges, attributes.src[i], attributes.dst[i]);
   }
 
-  for (bke::OutputAttribute &attribute : attributes.attributes) {
-    attribute.save();
+  for (bke::GSpanAttributeWriter &attribute : attributes.attributes) {
+    attribute.finish();
   }
 
   return dst_curves_id;
@@ -524,8 +527,11 @@ static Curves *convert_curves_to_nurbs(const CurveComponent &src_component,
   bke::curves::accumulate_counts_to_offsets(dst_offsets);
   dst_curves.resize(dst_offsets.last(), dst_curves.curves_num());
 
+  const bke::AttributeAccessor src_attributes = *src_component.attributes();
+  bke::MutableAttributeAccessor dst_attributes = *dst_component.attributes_for_write();
+
   GenericAttributes attributes;
-  retrieve_generic_point_attributes(src_component, dst_component, attributes);
+  retrieve_generic_point_attributes(src_attributes, dst_attributes, attributes);
 
   MutableSpan<float3> dst_positions = dst_curves.positions_for_write();
 
@@ -659,8 +665,8 @@ static Curves *convert_curves_to_nurbs(const CurveComponent &src_component,
         src_curves, dst_curves, unselected_ranges, attributes.src[i], attributes.dst[i]);
   }
 
-  for (bke::OutputAttribute &attribute : attributes.attributes) {
-    attribute.save();
+  for (bke::GSpanAttributeWriter &attribute : attributes.attributes) {
+    attribute.finish();
   }
 
   return dst_curves_id;
diff --git a/source/blender/geometry/intern/subdivide_curves.cc b/source/blender/geometry/intern/subdivide_curves.cc
index 4fb21e53013..914174235cd 100644
--- a/source/blender/geometry/intern/subdivide_curves.cc
+++ b/source/blender/geometry/intern/subdivide_curves.cc
@@ -79,16 +79,17 @@ static void calculate_result_offsets(const bke::CurvesGeometry &src_curves,
 struct AttributeTransferData {
   /* Expect that if an attribute exists, it is stored as a contiguous array internally anyway. */
   GVArraySpan src;
-  bke::OutputAttribute dst;
+  bke::GSpanAttributeWriter dst;
 };
 
-static Vector<AttributeTransferData> retrieve_point_attributes(const CurveComponent &src_component,
-                                                               CurveComponent &dst_component,
-                                                               const Set<std::string> &skip = {})
+static Vector<AttributeTransferData> retrieve_point_attributes(
+    const bke::AttributeAccessor &src_attributes,
+    bke::MutableAttributeAccessor &dst_attributes,
+    const Set<std::string> &skip = {})
 {
   Vector<AttributeTransferData> attributes;
-  src_component.attribute_foreach(
-      [&](const bke::AttributeIDRef &id, const AttributeMetaData meta_data) {
+  src_attributes.for_all(
+      [&](const bke::AttributeIDRef &id, const bke::AttributeMetaData meta_data) {
         if (meta_data.domain != ATTR_DOMAIN_POINT) {
           /* Curve domain attributes are all copied directly to the result in one step. */
           return true;
@@ -97,9 +98,9 @@ static Vector<AttributeTransferData> retrieve_point_attributes(const CurveCompon
           return true;
         }
 
-        GVArray src = src_component.attribute_try_get_for_read(id, ATTR_DOMAIN_POINT);
+        GVArray src = src_attributes.lookup(id, ATTR_DOMAIN_POINT);
         BLI_assert(src);
-        bke::OutputAttribute dst = dst_component.attribute_try_get_for_output_only(
+        bke::GSpanAttributeWriter dst = dst_attributes.lookup_or_add_for_write_only_span(
             id, ATTR_DOMAIN_POINT, meta_data.data_type);
         BLI_assert(dst);
         attributes.append({std::move(src), std::move(dst)});
@@ -384,28 +385,27 @@ Curves *subdivide_curves(const CurveComponent &src_component,
 
   dst_curves.resize(dst_curves.offsets().last(), dst_curves.curves_num());
 
+  const bke::AttributeAccessor src_attributes = *src_component.attributes();
+  bke::MutableAttributeAccessor dst_attributes = *dst_component.attributes_for_write();
+
   auto subdivide_catmull_rom = [&](IndexMask selection) {
-    for (auto &attribute : retrieve_point_attributes(src_component, dst_component)) {
+    for (auto &attribute : retrieve_point_attributes(src_attributes, dst_attributes)) {
       subdivide_attribute_catmull_rom(src_curves,
                                       dst_curves,
                                       selection,
                                       point_offsets,
                                       cyclic,
                                       attribute.src,
-                                      attribute.dst.as_span());
-      attribute.dst.save();
+                                      attribute.dst.span);
+      attribute.dst.finish();
     }
   };
 
   auto subdivide_poly = [&](IndexMask selection) {
-    for (auto &attribute : retrieve_point_attributes(src_component, dst_component)) {
-      subdivide_attribute_linear(src_curves,
-                                 dst_curves,
-                                 selection,
-                                 point_offsets,
-                                 attribute.src,
-                                 attribute.dst.as_span());
-      attribute.dst.save();
+    for (auto &attribute : retrieve_point_attributes(src_attributes, dst_attributes)) {
+      subdivide_attribute_linear(
+          src_curves, dst_curves, selection, point_offsets, attribute.src, attribute.dst.span);
+      attribute.dst.finish();
     }
   };
 
@@ -443,20 +443,16 @@ Curves *subdivide_curves(const CurveComponent &src_component,
       }
     });
 
-    for (auto &attribute : retrieve_point_attributes(src_component,
-                                                     dst_component,
+    for (auto &attribute : retrieve_point_attributes(src_attributes,
+                                                     dst_attributes,
                                                      {"position",
                                                       "handle_type_left",
                                                       "handle_type_right",
                                                       "handle_right",
                                                       "handle_left"})) {
-      subdivide_attribute_linear(src_curves,
-                                 dst_curves,
-                                 selection,
-                                 point_offsets,
-                                 attribute.src,
-                                 attribute.dst.as_span());
-      attribute.dst.save();
+      subdivide_attribute_linear(
+          src_curves, dst_curves, selection, point_offsets, attribute.src, attribute.dst.span);
+      attribute.dst.finish();
     }
   };
 
@@ -473,10 +469,10 @@ Curves *subdivide_curves(const CurveComponent &src_component,
                                      subdivide_nurbs);
 
   if (!unselected_ranges.is_empty()) {
-    for (auto &attribute : retrieve_point_attributes(src_component, dst_component)) {
+    for (auto &attribute : retrieve_point_attributes(src_attributes, dst_attributes)) {
       bke::curves::copy_point_data(
-          src_curves, dst_curves, unselected_ranges, attribute.src, attribute.dst.as_span());
-      attribute.dst.save();
+          src_curves, dst_curves, unselected_ranges, attribute.src, attribute.dst.span);
+      attribute.dst.finish();
     }
   }