GPv3: Copy and Paste operator for strokes and points, initial commit

@@ -855,2 +855,3 @@
                        const IndexMask &selection,
-                       MutableAttributeAccessor dst_attributes)
+                       MutableAttributeAccessor dst_attributes,
+                       std::optional<IndexRange> dst_range)

@@ -951,0 +955,4 @@
+/** \name Copy and Paste Operator
+ * \{ */
+
+static bool append_geometry_to_layer(Vector<bke::CurvesGeometry> &sources,

@@ -951,0 +958,4 @@
+static bool append_geometry_to_layer(Vector<bke::CurvesGeometry> &sources,
+                                     bke::CurvesGeometry &dest,
+                                     const eAttrDomain selection_domain)
+{

@@ -951,0 +962,4 @@
+  /* For safety, remove source geometries with zero points. */
+  sources.remove_if([](const bke::CurvesGeometry source) { return source.points_num() == 0; });
+  const int source_num = sources.size();
+  if (source_num == 0) {

@@ -951,0 +960,4 @@
+                                     const eAttrDomain selection_domain)
+{
+  /* For safety, remove source geometries with zero points. */
+  sources.remove_if([](const bke::CurvesGeometry source) { return source.points_num() == 0; });

@@ -951,0 +1125,4 @@
+  bke::CurvesGeometry &layer = drawing->strokes_for_write();
+
+  /* Append the geometry in the paste buffer to the active layer. */
+  const bool success = append_geometry_to_layer(

@@ -951,0 +1150,4 @@
+  int32_t num_copied = 0;
+
+  /* Copy all selected strokes/points on all editable layers. */
+  grease_pencil.foreach_editable_drawing(

@@ -2181,0 +2184,4 @@
+ * \{ */
+
+/* Global clipboard for Grease Pencil curves. */
+struct GreasePencilClipboard {

@@ -2181,0 +2189,4 @@
+  /* We store the material names of the copied curves, so we can match those when pasting the
+   * clipboard into another object. */
+  Vector<std::pair<std::string, int>> materials;
+  int materials_num;

@@ -2181,0 +2249,4 @@
+  clipboard_material_indices.span.varray().materialize(original_clipboard_materials);
+
+  /* Get a list of all materials in the scene. */
+  Map<std::string, Material *> scene_materials;

@@ -2181,0 +2323,4 @@
+  GreasePencilClipboard &grease_pencil_clipboard = get_grease_pencil_clipboard();
+
+  bool anything_copied = false;
+  int32_t num_copied = 0;

@@ -2181,0 +2339,4 @@
+    }
+
+    /* Get a copy of the selected geometry on this layer. */
+    const AnonymousAttributePropagationInfo propagation_info{};

@@ -330,6 +333,43 @@ void create_keyframe_edit_data_selected_frames_list(KeyframeEditData *ked,
   }
 }
 
+bool ensure_active_keyframe(const bContext *C, const wmOperator *op, GreasePencil &grease_pencil)

@@ -333,0 +340,4 @@
+  bke::greasepencil::Layer &active_layer = *grease_pencil.get_active_layer();
+
+  if (!active_layer.has_drawing_at(current_frame) && !blender::animrig::is_autokey_on(scene)) {
+    BKE_report(op->reports, RPT_ERROR, "No Grease Pencil frame to draw on");

@@ -160,0 +163,4 @@
+ * Autokey is on (taking Additive drawing setting into account).
+ * Returns false when no keyframe could be found or created.
+ */
+bool ensure_active_keyframe(const bContext *C, const wmOperator *op, GreasePencil &grease_pencil);

@@ -2181,0 +2188,4 @@
+  bke::CurvesGeometry curves;
+  /* We store the material names of the copied curves, so we can match those when pasting the
+   * clipboard into another object. */
+  Vector<std::pair<std::string, int>> materials;

@@ -2181,0 +2260,4 @@
+    /* Check if the material name exists in the scene. */
+    int target_index;
+    std::string material_name = grease_pencil_clipboard.materials[i].first;
+    if (!scene_materials.contains(material_name)) {

@@ -4615,0 +4615,4 @@
+        # Copy/paste
+        ("grease_pencil.copy", {"type": 'C', "value": 'PRESS', "ctrl": True}, None),
+        ("grease_pencil.paste", {"type": 'V', "value": 'PRESS', "ctrl": True}, None),
+        ("grease_pencil.paste", {"type": 'V', "value": 'PRESS', "shift": True, "ctrl": True}, 

@@ -2181,0 +2273,4 @@
+  }
+
+  /* Remap the material indices of the clipboard curves to the target object material indices. */
+  for (const int i : clipboard_material_indices.span.index_range()) {

@@ -2181,0 +2304,4 @@
+
+static int grease_pencil_copy_strokes_exec(bContext *C, wmOperator *op)
+{
+  using namespace blender::bke;

@@ -2181,0 +2283,4 @@
+  /* Remap the material indices of the pasted curves to the target object material indices. */
+  bke::MutableAttributeAccessor attributes =
+      target_drawing->strokes_for_write().attributes_for_write();
+  bke::SpanAttributeWriter<int> material_indices = attributes.lookup_or_add_for_write_span<int>(