Refactor custom GCode handling and mixed filament management

- Updated `custom_tool_changes` function to use filament IDs instead of extruder IDs, ensuring better compatibility with mixed filament configurations.
- Enhanced `MixedFilament` structure to include a `stable_id` for persistent identity across mixed filament entries, improving remapping during updates.
- Introduced new methods for stable ID allocation and normalization in `MixedFilamentManager`.
- Updated serialization and loading functions to maintain stable IDs, ensuring consistent behavior when mixed filament entries are modified.
- Added tests to verify the correct handling of tool changes and stable ID remapping in mixed filament scenarios.

tests/libslic3r/CMakeLists.txt

@@ -7,8 +7,10 @@ add_executable(${_TEST_NAME}_tests
 	test_clipper_offset.cpp
 	test_clipper_utils.cpp
 	test_config.cpp
+	test_custom_gcode.cpp
 	test_elephant_foot_compensation.cpp
 	test_geometry.cpp
+	test_mixed_filament.cpp
 	test_placeholder_parser.cpp
 	test_polygon.cpp
 	test_mutable_polygon.cpp

tests/libslic3r/test_custom_gcode.cpp

@@ -0,0 +1,28 @@
+#include <catch2/catch.hpp>
+
+#include "libslic3r/CustomGCode.hpp"
+
+using namespace Slic3r;
+
+TEST_CASE("Custom layer tool changes keep mixed virtual filament ids", "[CustomGCode]")
+{
+    CustomGCode::Info info;
+    info.gcodes.emplace_back(CustomGCode::Item{1.25, CustomGCode::ToolChange, 5, "", ""});
+
+    const auto tool_changes = CustomGCode::custom_tool_changes(info, 6);
+
+    REQUIRE(tool_changes.size() == 1);
+    CHECK(tool_changes.front().first == Approx(1.25));
+    CHECK(tool_changes.front().second == 5u);
+}
+
+TEST_CASE("Custom layer tool changes still clamp stale filament ids", "[CustomGCode]")
+{
+    CustomGCode::Info info;
+    info.gcodes.emplace_back(CustomGCode::Item{2.0, CustomGCode::ToolChange, 7, "", ""});
+
+    const auto tool_changes = CustomGCode::custom_tool_changes(info, 6);
+
+    REQUIRE(tool_changes.size() == 1);
+    CHECK(tool_changes.front().second == 1u);
+}

tests/libslic3r/test_mixed_filament.cpp

@@ -0,0 +1,125 @@
+#include <catch2/catch.hpp>
+
+#include "libslic3r/PresetBundle.hpp"
+
+#include <sstream>
+#include <vector>
+
+using namespace Slic3r;
+
+namespace {
+
+static std::vector<std::string> split_rows(const std::string &serialized)
+{
+    std::vector<std::string> rows;
+    std::stringstream ss(serialized);
+    std::string row;
+    while (std::getline(ss, row, ';')) {
+        if (!row.empty())
+            rows.push_back(row);
+    }
+    return rows;
+}
+
+static std::string join_rows(const std::vector<std::string> &rows)
+{
+    std::ostringstream ss;
+    for (size_t i = 0; i < rows.size(); ++i) {
+        if (i != 0)
+            ss << ';';
+        ss << rows[i];
+    }
+    return ss.str();
+}
+
+static unsigned int virtual_id_for_stable_id(const std::vector<MixedFilament> &mixed, size_t num_physical, uint64_t stable_id)
+{
+    unsigned int next_virtual_id = unsigned(num_physical + 1);
+    for (const MixedFilament &mf : mixed) {
+        if (!mf.enabled || mf.deleted)
+            continue;
+        if (mf.stable_id == stable_id)
+            return next_virtual_id;
+        ++next_virtual_id;
+    }
+    return 0;
+}
+
+} // namespace
+
+TEST_CASE("Mixed filament remap follows stable row ids when same-pair rows reorder", "[MixedFilament]")
+{
+    PresetBundle bundle;
+    bundle.filament_presets = {"Default Filament", "Default Filament"};
+    bundle.project_config.option<ConfigOptionStrings>("filament_colour")->values = {"#FF0000", "#0000FF"};
+    bundle.update_multi_material_filament_presets();
+
+    auto &mgr = bundle.mixed_filaments;
+    auto &mixed = mgr.mixed_filaments();
+    REQUIRE(mixed.size() == 1);
+
+    mixed[0].deleted = true;
+    mixed[0].enabled = false;
+
+    const auto colors = bundle.project_config.option<ConfigOptionStrings>("filament_colour")->values;
+    mgr.add_custom_filament(1, 2, 25, colors);
+    mgr.add_custom_filament(1, 2, 75, colors);
+
+    auto &old_mixed = mgr.mixed_filaments();
+    REQUIRE(old_mixed.size() == 3);
+    REQUIRE(old_mixed[1].enabled);
+    REQUIRE(old_mixed[2].enabled);
+    const uint64_t first_custom_id = old_mixed[1].stable_id;
+    const uint64_t second_custom_id = old_mixed[2].stable_id;
+
+    std::vector<std::string> rows = split_rows(mgr.serialize_custom_entries());
+    REQUIRE(rows.size() == 3);
+    std::swap(rows[1], rows[2]);
+
+    auto *definitions = bundle.project_config.option<ConfigOptionString>("mixed_filament_definitions");
+    REQUIRE(definitions != nullptr);
+    definitions->value = join_rows(rows);
+
+    bundle.filament_presets.push_back(bundle.filament_presets.back());
+    bundle.project_config.option<ConfigOptionStrings>("filament_colour")->values.push_back("#00FF00");
+    bundle.update_multi_material_filament_presets(size_t(-1), 2);
+
+    const std::vector<unsigned int> remap = bundle.consume_last_filament_id_remap();
+    REQUIRE(remap.size() >= 5);
+
+    const auto &rebuilt = bundle.mixed_filaments.mixed_filaments();
+    const unsigned int new_first_custom_virtual_id = virtual_id_for_stable_id(rebuilt, 3, first_custom_id);
+    const unsigned int new_second_custom_virtual_id = virtual_id_for_stable_id(rebuilt, 3, second_custom_id);
+
+    REQUIRE(new_first_custom_virtual_id != 0);
+    REQUIRE(new_second_custom_virtual_id != 0);
+    CHECK(remap[3] == new_first_custom_virtual_id);
+    CHECK(remap[4] == new_second_custom_virtual_id);
+}
+
+TEST_CASE("Mixed filament remap keeps later painted colors stable when an earlier mixed row is deleted", "[MixedFilament]")
+{
+    PresetBundle bundle;
+    bundle.filament_presets = {"Default Filament", "Default Filament", "Default Filament", "Default Filament"};
+    bundle.project_config.option<ConfigOptionStrings>("filament_colour")->values = {"#FF0000", "#00FF00", "#0000FF", "#FFFF00"};
+    bundle.update_multi_material_filament_presets();
+
+    auto &mixed = bundle.mixed_filaments.mixed_filaments();
+    REQUIRE(mixed.size() >= 10);
+
+    const uint64_t stable_id_6 = mixed[1].stable_id;
+    const uint64_t stable_id_7 = mixed[2].stable_id;
+    const uint64_t stable_id_8 = mixed[3].stable_id;
+
+    const std::vector<MixedFilament> old_mixed = mixed;
+    mixed[0].enabled = false;
+    mixed[0].deleted = true;
+
+    bundle.update_mixed_filament_id_remap(old_mixed, 4, 4);
+    const std::vector<unsigned int> remap = bundle.consume_last_filament_id_remap();
+
+    REQUIRE(remap.size() >= 15);
+    CHECK(remap[6] == virtual_id_for_stable_id(mixed, 4, stable_id_6));
+    CHECK(remap[7] == virtual_id_for_stable_id(mixed, 4, stable_id_7));
+    CHECK(remap[8] == virtual_id_for_stable_id(mixed, 4, stable_id_8));
+}