Do not show ProjectDropDialog when drag and dropping a 3mf file produced by other softwares and the plater is not empty

src/libslic3r/Format/3mf.cpp

@@ -3110,6 +3110,36 @@ static void handle_legacy_project_loaded(unsigned int version_project_file, Dyna
     }
 }
 
+bool is_project_3mf(const std::string& filename)
+{
+    mz_zip_archive archive;
+    mz_zip_zero_struct(&archive);
+
+    if (!open_zip_reader(&archive, filename))
+        return false;
+
+    mz_uint num_entries = mz_zip_reader_get_num_files(&archive);
+
+    // loop the entries to search for config
+    mz_zip_archive_file_stat stat;
+    bool config_found = false;
+    for (mz_uint i = 0; i < num_entries; ++i) {
+        if (mz_zip_reader_file_stat(&archive, i, &stat)) {
+            std::string name(stat.m_filename);
+            std::replace(name.begin(), name.end(), '\\', '/');
+
+            if (boost::algorithm::iequals(name, PRINT_CONFIG_FILE)) {
+                config_found = true;
+                break;
+            }
+        }
+    }
+
+    close_zip_reader(&archive);
+
+    return config_found;
+}
+
 bool load_3mf(const char* path, DynamicPrintConfig& config, ConfigSubstitutionContext& config_substitutions, Model* model, bool check_version)
 {
     if (path == nullptr || model == nullptr)

src/libslic3r/Format/3mf.hpp

@@ -29,6 +29,9 @@ namespace Slic3r {
     class DynamicPrintConfig;
     struct ThumbnailData;
 
+    // Returns true if the 3mf file with the given filename is a PrusaSlicer project file (i.e. if it contains a config).
+    extern bool is_project_3mf(const std::string& filename);
+
     // Load the content of a 3mf file into the given model and preset bundle.
     extern bool load_3mf(const char* path, DynamicPrintConfig& config, ConfigSubstitutionContext& config_substitutions, Model* model, bool check_version);
 

src/slic3r/GUI/Plater.cpp

@@ -5386,6 +5386,10 @@ bool Plater::load_files(const wxArrayString& filenames)
         if (boost::algorithm::iends_with(filename, ".3mf") || boost::algorithm::iends_with(filename, ".amf")) {
             LoadType load_type = LoadType::Unknown;
             if (!model().objects.empty()) {
+                if ((boost::algorithm::iends_with(filename, ".3mf") && !is_project_3mf(it->string())) ||
+                    (boost::algorithm::iends_with(filename, ".amf") && !boost::algorithm::iends_with(filename, ".zip.amf")))
+                    load_type = LoadType::OpenProject;
+                else {
                     if (wxGetApp().app_config->get("show_drop_project_dialog") == "1") {
                         ProjectDropDialog dlg(filename);
                         if (dlg.ShowModal() == wxID_OK) {
@@ -5398,6 +5402,7 @@ bool Plater::load_files(const wxArrayString& filenames)
                         load_type = static_cast<LoadType>(std::clamp(std::stoi(wxGetApp().app_config->get("drop_project_action")),
                             static_cast<int>(LoadType::OpenProject), static_cast<int>(LoadType::LoadConfig)));
                 }
+            }
             else
                 load_type = LoadType::OpenProject;