Fix manual tool change handling when loading G-code files (#15379)

Opened or drag-dropped G-code files ignored `; MANUAL_TOOL_CHANGE` comments, so the preview showed every move on the first filament. Only `apply_config(const PrintConfig&)` read `manual_filament_change`, and loading a file goes through `apply_config(const DynamicPrintConfig&)`. Read the option there too, initialize the flag to false, and add a regression test.

src/libslic3r/GCode/GCodeProcessor.cpp

@@ -3598,6 +3598,10 @@ void GCodeProcessor::apply_config(const DynamicPrintConfig& config)
     if (has_scarf_joint_seam != nullptr)
         m_detect_layer_based_on_tag = m_detect_layer_based_on_tag || has_scarf_joint_seam->value;
 
+    const ConfigOptionBool* manual_filament_change = config.option<ConfigOptionBool>("manual_filament_change");
+    if (manual_filament_change != nullptr)
+        m_manual_filament_change = manual_filament_change->value;
+
     const ConfigOptionEnumGeneric *bed_type = config.option<ConfigOptionEnumGeneric>("curr_bed_type");
     if (bed_type != nullptr)
         m_result.bed_type = (BedType)bed_type->value;

src/libslic3r/GCode/GCodeProcessor.hpp

@@ -1228,7 +1228,7 @@ inline constexpr float DEFAULT_FILAMENT_DENSITY = 1.245f;
         // m_result.nozzle_group_result, which is handed over only after the stream for the
         // pre-heat injector's second pass and gates the richer change-time model.
         std::shared_ptr<MultiNozzleUtils::NozzleGroupResultBase> m_nozzle_group_result;
-        bool m_manual_filament_change;
+        bool m_manual_filament_change{ false };
 
         //BBS: x, y offset for gcode generated
         double          m_x_offset{ 0 };

tests/fff_print/test_gcodeprocessor.cpp

@@ -178,6 +178,61 @@ bool is_block_move(const GCodeProcessorResult::MoveVertex &move)
 
 } // namespace
 
+TEST_CASE("Loaded manual tool change comments switch subsequent moves when enabled", "[GCodeProcessor][Regression]")
+{
+    const bool manual_filament_change = GENERATE(false, true);
+    CAPTURE(manual_filament_change);
+    const DynamicPrintConfig config = Test::multifilament_config(2, {
+        { "gcode_flavor",           "marlin" },
+        { "filament_type",          "PLA;PETG" },
+        { "manual_filament_change", manual_filament_change },
+    });
+    const bool was_bbl_printer = GCodeProcessor::s_IsBBLPrinter;
+    const ScopeGuard restore_bbl_printer([was_bbl_printer] { GCodeProcessor::s_IsBBLPrinter = was_bbl_printer; });
+    GCodeProcessor::s_IsBBLPrinter = false;
+
+    ScopedTemporaryFile temp(".gcode");
+    {
+        std::ofstream out(temp.string());
+        REQUIRE(out.is_open());
+        out << "; generated by OrcaSlicer\n"
+            << "G90\nM83\nT0\n"
+            << "G1 X10 Y10 Z0.2 F3000\n"
+            << "G1 X20 E1\n"
+            << "; MANUAL_TOOL_CHANGE T1\n"
+            << "G1 X30\nG1 X40 E1\nG1 X50\nG1 X60 E1\n";
+        // Let process_file load the embedded DynamicPrintConfig, as the standalone viewer does.
+        out << "; CONFIG_BLOCK_START\n";
+        for (const std::string &key : config.keys())
+            out << "; " << key << " = " << config.opt_serialize(key) << '\n';
+        out << "; CONFIG_BLOCK_END\n";
+        REQUIRE(out.good());
+    }
+
+    GCodeProcessor processor;
+    processor.process_file(temp.string());
+    const auto &result = processor.get_result();
+    REQUIRE(result.filaments_count == 2);
+
+    constexpr unsigned int tool_change_line = 7;
+    size_t before = 0;
+    size_t after = 0;
+    for (const auto &move : result.moves) {
+        if (!is_block_move(move))
+            continue;
+        CAPTURE(move.gcode_id, move.type);
+        if (move.gcode_id < tool_change_line) {
+            ++before;
+            CHECK(move.extruder_id == 0);
+        } else if (move.gcode_id > tool_change_line) {
+            ++after;
+            CHECK(move.extruder_id == (manual_filament_change ? 1 : 0));
+        }
+    }
+    REQUIRE(before > 0);
+    REQUIRE(after > 0);
+}
+
 TEST_CASE("Actual speed moves are inserted on their block's segment just before its move", "[GCodeProcessor]")
 {
     // 60 squares take several planner passes, which remap the blocks kept between passes.