Use current selection to determine proposed filename when exporting to stl files

src/libslic3r/Model.cpp

@@ -556,19 +556,9 @@ std::string Model::propose_export_file_name_and_path() const
     for (const ModelObject *model_object : this->objects)
         for (ModelInstance *model_instance : model_object->instances)
             if (model_instance->is_printable()) {
-                input_file = model_object->input_file;
-                if (! model_object->name.empty()) {
-                    if (input_file.empty())
-                        // model_object->input_file was empty, just use model_object->name
-                        input_file = model_object->name;
-                    else {
-                        // Replace file name in input_file with model_object->name, but keep the path and file extension.
-						input_file = (boost::filesystem::path(model_object->name).parent_path().empty()) ?
-							(boost::filesystem::path(input_file).parent_path() / model_object->name).make_preferred().string() :
-							model_object->name;
-					}
-                }
-                if (! input_file.empty())
+                input_file = model_object->get_export_filename();
+
+                if (!input_file.empty())
                     goto end;
                 // Other instances will produce the same name, skip them.
                 break;
@@ -1433,6 +1423,26 @@ void ModelObject::print_info() const
     cout << "volume = "           << mesh.volume()                  << endl;
 }
 
+std::string ModelObject::get_export_filename() const
+{
+    std::string ret = input_file;
+
+    if (!name.empty())
+    {
+        if (ret.empty())
+            // input_file was empty, just use name
+            ret = name;
+        else
+        {
+            // Replace file name in input_file with name, but keep the path and file extension.
+            ret = (boost::filesystem::path(name).parent_path().empty()) ?
+                (boost::filesystem::path(ret).parent_path() / name).make_preferred().string() : name;
+        }
+    }
+
+    return ret;
+}
+
 void ModelVolume::set_material_id(t_model_material_id material_id)
 {
     m_material_id = material_id;

src/libslic3r/Model.hpp

@@ -275,6 +275,8 @@ public:
     // Print object statistics to console.
     void print_info() const;
 
+    std::string get_export_filename() const;
+
 protected:
     friend class Print;
     friend class SLAPrint;

src/slic3r/GUI/Plater.cpp

@@ -1840,8 +1840,18 @@ wxString Plater::priv::get_export_file(GUI::FileType file_type)
 
     // Update printbility state of each of the ModelInstances.
     this->update_print_volume_state();
-    // Find the file name of the first printable object.
-	fs::path output_file = this->model.propose_export_file_name_and_path();
+
+    const Selection& selection = get_selection();
+    int obj_idx = selection.get_object_idx();
+
+    fs::path output_file;
+    // first try to get the file name from the current selection
+    if ((0 <= obj_idx) && (obj_idx < (int)this->model.objects.size()))
+        output_file = this->model.objects[obj_idx]->get_export_filename();
+
+    if (output_file.empty())
+        // Find the file name of the first printable object.
+        output_file = this->model.propose_export_file_name_and_path();
 
     wxString dlg_title;
     switch (file_type) {