Fix garbled G-code preview when a post-processing script is used (#15005)

* Rebuild the G-code line offsets after post-processing scripts run in place

* Clamp the G-code window reads to the mapped file size

* Add tests for rebuilding the G-code line offsets

* Include <mutex>, <ios> and boost/filesystem/operations.hpp where they are used

* Keep the preview's G-code lines and highlight in step with post-processing scripts

---------

Co-authored-by: SoftFever <103989404+SoftFever@users.noreply.github.com>
Co-authored-by: SoftFever <softfeverever@gmail.com>

src/libslic3r/Print.cpp

@@ -5340,6 +5340,31 @@ void Print::export_gcode_from_previous_file(const std::string& file, GCodeProces
     }
 }
 
+void Print::reload_gcode_moves(GCodeProcessorResult* result) const
+{
+    GCodeProcessor processor;
+    GCodeProcessor::s_IsBBLPrinter = is_BBL_printer();
+    const Vec3d origin = this->get_plate_origin();
+    processor.set_xy_offset(origin(0), origin(1));
+    // Estimate the per-move times with the same nozzle-grouping slot context as the export.
+    if (result->nozzle_group_result)
+        processor.initialize_from_context(result->nozzle_group_result);
+    try {
+        processor.process_file(result->filename);
+    } catch (const std::exception& ex) {
+        // The edited file is what gets printed, so failing to preview it must not fail the slice.
+        BOOST_LOG_TRIVIAL(error) << __FUNCTION__ << ": cannot re-read the G-code file " << result->filename << ": " << ex.what();
+        std::lock_guard<std::mutex> lock(result->result_mutex);
+        result->lines_ends.clear();
+        return;
+    }
+
+    GCodeProcessorResult& reloaded = processor.result();
+    std::lock_guard<std::mutex> lock(result->result_mutex);
+    result->moves      = std::move(reloaded.moves);
+    result->lines_ends = std::move(reloaded.lines_ends);
+}
+
 std::tuple<float, float> Print::object_skirt_offset(double margin_height) const
 {
     if (config().skirt_loops == 0 || config().skirt_type != stPerObject || m_objects.empty())

src/libslic3r/Print.hpp

@@ -1287,6 +1287,11 @@ public:
     void set_gcode_file_ready();
     void set_gcode_file_invalidated();
     void export_gcode_from_previous_file(const std::string& file, GCodeProcessorResult* result, ThumbnailsGeneratorCallback thumbnail_cb = nullptr);
+    // Re-reads the moves and line offsets of `result` from its G-code file after the file was rewritten in
+    // place (post-processing scripts or plugins), so the preview and its G-code window follow the file on
+    // disk. Everything else in `result` was computed while slicing and is kept. If the file cannot be
+    // re-read, the moves are kept and the line offsets are cleared, which hides the G-code window.
+    void reload_gcode_moves(GCodeProcessorResult* result) const;
     //BBS: add modify_count logic
     int get_modified_count() const {return m_modified_count;}
     //BBS: add status for whether support used

src/slic3r/GUI/BackgroundSlicingProcess.cpp

@@ -283,11 +283,12 @@ void BackgroundSlicingProcess::process_fff()
         m_temp_output_path = this->get_current_plate()->get_tmp_gcode_path();
         m_fff_print->export_gcode(m_temp_output_path, m_gcode_result,
                                   [this](const ThumbnailsParams& params) { return this->render_thumbnails(params); });
-        // Orca: BBL printers post-process the g-code in place here and never re-parse it into a fresh
-        // GCodeProcessorResult, so m_gcode_result->nozzle_group_result (consumed by the H2C print-dispatch
-        // nozzle mapping) survives post-processing. No preservation guard is needed on this path.
+        // Orca: BBL printers post-process the g-code in place here, in the file the G-code viewer maps, so
+        // the preview re-reads its moves and line offsets from the edited file. The rest of m_gcode_result,
+        // including nozzle_group_result (consumed by the H2C print-dispatch nozzle mapping), is kept.
         if (m_fff_print->is_BBL_printer()) {
-            run_post_process_scripts(m_temp_output_path, false, "File", m_temp_output_path, m_fff_print->full_print_config());
+            if (run_post_process_scripts(m_temp_output_path, false, "File", m_temp_output_path, m_fff_print->full_print_config()))
+                m_fff_print->reload_gcode_moves(m_gcode_result);
         }
 
         BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(": export gcode finished");

src/slic3r/GUI/GCodeViewer.cpp

@@ -895,10 +895,16 @@ void GCodeViewer::SequentialView::GCodeWindow::render(float top, float bottom, f
     auto update_lines = [this](uint64_t start_id, uint64_t end_id) {
         std::vector<Line> ret;
         ret.reserve(end_id - start_id + 1);
+        // Orca: m_lines_ends indexes into a memory mapping, so it must be clamped to the mapping. If the
+        // file was modified behind our back (an in-place post-processing script that shrank it), an
+        // unchecked read is an access violation, which the caller's try/catch cannot catch on Windows.
+        const size_t file_size = m_file.size();
         for (uint64_t id = start_id; id <= end_id; ++id) {
             // read line from file
-            const size_t start        = id == 1 ? 0 : m_lines_ends[id - 2];
-            const size_t original_len = m_lines_ends[id - 1] - start;
+            // Keep one entry per id: render() indexes m_lines by (id - start_id).
+            const size_t start = id == 1 ? 0 : std::min(m_lines_ends[id - 2], file_size);
+            const size_t end   = std::min(m_lines_ends[id - 1], file_size);
+            const size_t original_len = end > start ? end - start : 0;
             // A character is four bytes at most, so 55 of them always fit in 220.
             const size_t len          = std::min(original_len, (size_t) 55 * 4);
             std::string  gline(m_file.data() + start, len);

tests/fff_print/test_gcodeprocessor.cpp

@@ -9,6 +9,7 @@
 #include "libslic3r/Config.hpp"
 #include "libslic3r/GCode/GCodeProcessor.hpp"
 #include "libslic3r/Model.hpp"
+#include "libslic3r/Print.hpp"
 #include "libslic3r/Utils.hpp"
 
 #include "test_helpers.hpp"
@@ -221,3 +222,62 @@ TEST_CASE("Line ends of the exported G-code mark every newline in the file", "[G
     INFO("first difference at line " << difference.first - result.lines_ends.begin() + 1);
     CHECK(difference.first == result.lines_ends.end());
 }
+
+TEST_CASE("Reloaded moves name their lines in G-code a script rewrote in place", "[GCodeProcessor]")
+{
+    Print print;
+    Model model;
+    Test::init_print({ Test::cube(20) }, print, model);
+    GCodeProcessorResult result;
+    const std::string    gcode          = Test::gcode(print, &result);
+    const auto           exported_moves = result.moves;
+
+    // A script that prepends one comment and, writing in text mode on Windows, turns every LF into CRLF.
+    const std::string prepended = ";EDITED\r\n";
+    std::string       edited    = prepended;
+    for (const char c : gcode) {
+        if (c == '\n')
+            edited += '\r';
+        edited += c;
+    }
+    ScopedTemporaryFile temp(".gcode");
+    save_string_file(temp.path(), edited);
+    result.filename = temp.string();
+    print.reload_gcode_moves(&result);
+
+    std::vector<size_t> newline_ends;
+    for (size_t i = edited.find('\n'); i != std::string::npos; i = edited.find('\n', i + 1))
+        newline_ends.push_back(i + 1);
+    CHECK(result.lines_ends == newline_ends);
+
+    // Every move that came from a line now names the same line one further down.
+    REQUIRE(result.moves.size() == exported_moves.size());
+    const auto difference = std::mismatch(exported_moves.begin(), exported_moves.end(), result.moves.begin(),
+                                          [](const auto &exported, const auto &reloaded) {
+                                              return reloaded.gcode_id == (exported.gcode_id == 0 ? 0 : exported.gcode_id + 1);
+                                          });
+    INFO("first difference at move " << difference.first - exported_moves.begin());
+    CHECK(difference.first == exported_moves.end());
+}
+
+TEST_CASE("Rewritten G-code that cannot be re-read keeps the moves and hides the G-code window", "[GCodeProcessor]")
+{
+    Print print;
+    Model model;
+    Test::init_print({ Test::cube(20) }, print, model);
+    GCodeProcessorResult result;
+    const std::string    gcode          = Test::gcode(print, &result);
+    const auto           exported_moves = result.moves;
+
+    // A script that strips the trailing config block, which the G-code reader needs.
+    const size_t config_block = gcode.find("; CONFIG_BLOCK_START");
+    REQUIRE(config_block != std::string::npos);
+    ScopedTemporaryFile temp(".gcode");
+    save_string_file(temp.path(), gcode.substr(0, config_block));
+    result.filename = temp.string();
+    print.reload_gcode_moves(&result);
+
+    CHECK(result.lines_ends.empty());
+    REQUIRE(result.moves.size() == exported_moves.size());
+    CHECK(result.moves.back().gcode_id == exported_moves.back().gcode_id);
+}