Add small perimeter length in user interface

[gennartan]

Closed last pull request at #4581 because I did not succeed to remove all the useless space I removed.
Here is a new pull request taking into account the comments made on previous pull request.

[lordofhyphens]

I'd like to see a short test for this feature that implements the following:

• Given: A cylinder with diameter 10mm, and a config that sets 1 perimeter, no infill, external speed = 100mm/s and small perimeter speed = 15mm/s
• When slicing a the model with small_perimeter_length = 6.5
• Then: the speed chosen for the second layer's perimeter is 6000mm/minute in gcode (F6000).
• When slicing a the model with small_perimeter_length = 10.1
• Then: the speed chosen for the second layer's perimeter is 900mm/minute in gcode (F900).

[lordofhyphens]

Go ahead and leave this a 6.5 and change the usage in xs/src/libslic3r/GCode.cpp to
scale_(this->config.get_abs_value("small_perimeter_length")) * 2 * PI

[lordofhyphens]

To add the test:

Create a new file in https://github.com/slic3r/Slic3r/tree/master/src/test/libslic3r called test_gcode.cpp

Put the following contents in there to start:

#include <catch.hpp>
#include "GCodeWriter.hpp"
#include "test_options.hpp"
#include "test_data.hpp"

using namespace Slic3r;
using namespace std::literals::string_literals;

SCENARIO( "Small perimeter gcode speeds" ) {
  GIVEN( "A cylinder with diameter 10mm, and a config that sets 1 perimeter, no infill, external speed = 100mm/s and small perimeter speed = 15mm/s") {
    config_ptr test_config = Slic3r::Config::new_from_defaults();
    test_config->set("small_perimeter_length", 10); 
    test_config->set("external_perimeter_speed", 100);
    test_config->set("perimeters", 1);
    test_config->set("fill_density", "0%");
    test_config->set("top_solid_layers", 0);
    test_config->set("top_bottom_layers", 0);
    test_config->set("gcode_comments", true);
    test_config->set("cooling", false);
    Model test_model;
    auto setup = init_print(TriangleMesh::make_cylinder(10, 10), test_model, test_config);
    WHEN( "slicing the model with small_perimeter_length = 6.5" ) {
      print->process();
      Slic3r::Test::gcode(gcode, print);
      auto exported {gcode.str()};
      THEN( "the speed chosen for the second layer's perimeter is 6000mm/minute in gcode (F6000)." ) {
        int speed = 0;
        auto reader {GCodeReader()};
        reader.apply_config(print->config);
        reader.parse(exported, [&speed] (GCodeReader& self, const GCodeReader::GCodeLine& line) 
          {
            // code to read speed from gcode goes here, see
            // https://github.com/slic3r/Slic3r/blob/master/xs/src/libslic3r/GCodeReader.hpp
            // for documentation of GCodeReader and GCodeLine
            // and test_printgcode.cpp for examples in how it's used.
          });
        REQUIRE(speed == 6000);
      }
    }
    WHEN( "slicing the model with small_perimeter_length = 15" ) {
    test_config->set("small_perimeter_length", 15); 
      THEN( "the speed used for the second layer's perimeter is 900mm/minute in gcode (F900)." ) {
        int speed = 0;
        auto reader {GCodeReader()};
        reader.apply_config(print->config);
        reader.parse(exported, [&speed] (GCodeReader& self, const GCodeReader::GCodeLine& line) 
          {
            // code to read speed from gcode goes here, see
            // https://github.com/slic3r/Slic3r/blob/master/xs/src/libslic3r/GCodeReader.hpp
            // for documentation of GCodeReader and GCodeLine
            // and test_printgcode.cpp for examples in how it's used.
          });
        REQUIRE(speed == 900);
      }
    }
  }
} 

[lordofhyphens]

Then add ${TESTDIR}/libslic3r/test_gcode.cpp at the end of the list at https://github.com/slic3r/Slic3r/blob/master/src/CMakeLists.txt#L284

[gennartan]

Hello @lordofhyphens , I do not figure out how to get the speed of the perimeter while doing the test you described above.
Is the speed in the F variable (feedrate) of the Gcode ? I suppuse it is not that because I get a constant value, that does not depends on the diameter of the cylinder :/

[lordofhyphens]

F in gcode is the speed.
E is extrusion, X/Y/Z are coordinates.

[lordofhyphens]

@gennartan generally, Slic3r puts any speed changes on its own line.