feat: Re-parse G-code after post-processing scripts for live preview

[adele-with-a-b]

Post-Processing Script Preview

After slicing with post-processing scripts configured, the G-code is automatically re-parsed so the preview shows the post-processed toolpath. No need to export and drag the file back in.

Problem

Currently, when post-processing scripts (configured in Process Settings → Post-processing Scripts) modify the G-code after slicing, the slicer preview still shows the original unmodified toolpath. Users have to manually export the G-code and drag it back into the slicer to see the actual post-processed result.

This is especially painful for scripts like BrickLayers that modify layer Z-heights for interlocking — the whole point is to visually verify the interlocking pattern before printing.

Solution

In BackgroundSlicingProcess::finalize_gcode(), after run_post_process_scripts() completes, re-run GCodeProcessor::process_file() on the modified G-code and replace m_gcode_result with the new result. The existing on_process_completed → update_fff_scene() → reload_print() path then picks up the post-processed data and renders it in the preview.

The re-parsing only runs when post-processing scripts are configured and non-empty, so there is zero impact on normal slicing without scripts.

Implementation

// In BackgroundSlicingProcess::finalize_gcode()
const auto *post_process = m_fff_print->full_print_config().opt<ConfigOptionStrings>("post_process");
if (post_process && !post_process->values.empty() && m_gcode_result) {
    GCodeProcessor processor;
    processor.process_file(m_temp_output_path);
    *m_gcode_result = std::move(processor.extract_result());
}

10 lines added to one file.