From 98cb9f0e18767b772c409ceff802107a89c9df70 Mon Sep 17 00:00:00 2001
From: Alessandro Ranellucci <aar@cpan.org>
Date: Sun, 30 Nov 2014 18:09:06 +0100
Subject: [PATCH] Refactoring: moved G-code export logic into new
 Slic3r::Print::GCode class. Removed Slic3r::GCode::Layer class. Fixes the
 order of post-processing filters so that cooling buffer is applied before any
 other filter whose logic is affected by speeds

---
 lib/Slic3r.pm             |   2 +-
 lib/Slic3r/GCode/Layer.pm | 251 -------------------
 lib/Slic3r/Print.pm       | 243 +------------------
 lib/Slic3r/Print/GCode.pm | 491 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 497 insertions(+), 490 deletions(-)
 delete mode 100644 lib/Slic3r/GCode/Layer.pm
 create mode 100644 lib/Slic3r/Print/GCode.pm

diff --git a/lib/Slic3r.pm b/lib/Slic3r.pm
index d9b159118..e2c2646ef 100644
--- a/lib/Slic3r.pm
+++ b/lib/Slic3r.pm
@@ -48,7 +48,6 @@ use Slic3r::Format::STL;
 use Slic3r::GCode;
 use Slic3r::GCode::ArcFitting;
 use Slic3r::GCode::CoolingBuffer;
-use Slic3r::GCode::Layer;
 use Slic3r::GCode::MotionPlanner;
 use Slic3r::GCode::PlaceholderParser;
 use Slic3r::GCode::PressureRegulator;
@@ -65,6 +64,7 @@ use Slic3r::Point;
 use Slic3r::Polygon;
 use Slic3r::Polyline;
 use Slic3r::Print;
+use Slic3r::Print::GCode;
 use Slic3r::Print::Object;
 use Slic3r::Print::Simple;
 use Slic3r::Print::SupportMaterial;
diff --git a/lib/Slic3r/GCode/Layer.pm b/lib/Slic3r/GCode/Layer.pm
deleted file mode 100644
index b13eab6a0..000000000
--- a/lib/Slic3r/GCode/Layer.pm
+++ /dev/null
@@ -1,251 +0,0 @@
-package Slic3r::GCode::Layer;
-use Moo;
-
-use List::Util qw(first);
-use Slic3r::Geometry qw(X Y unscale);
-
-has 'print'                         => (is => 'ro', required => 1, handles => [qw(config)]);
-has 'gcodegen'                      => (is => 'ro', required => 1);
-has 'origin'                        => (is => 'ro', default => sub { Slic3r::Pointf->new(0,0) });
-
-has 'spiralvase'                    => (is => 'lazy');
-has 'vibration_limit'               => (is => 'lazy');
-has 'arc_fitting'                   => (is => 'lazy');
-has 'pressure_regulator'            => (is => 'lazy');
-has 'skirt_done'                    => (is => 'rw', default => sub { {} });  # print_z => 1
-has 'brim_done'                     => (is => 'rw');
-has 'second_layer_things_done'      => (is => 'rw');
-has '_last_obj_copy'                => (is => 'rw');
-
-sub _build_spiralvase {
-    my $self = shift;
-    
-    return $self->print->config->spiral_vase
-        ? Slic3r::GCode::SpiralVase->new(config => $self->print->config)
-        : undef;
-}
-
-sub _build_vibration_limit {
-    my $self = shift;
-    
-    return $self->print->config->vibration_limit
-        ? Slic3r::GCode::VibrationLimit->new(config => $self->print->config)
-        : undef;
-}
-
-sub _build_arc_fitting {
-    my $self = shift;
-    
-    return $self->print->config->gcode_arcs
-        ? Slic3r::GCode::ArcFitting->new(config => $self->print->config)
-        : undef;
-}
-
-sub _build_pressure_regulator {
-    my $self = shift;
-    
-    return $self->print->config->pressure_advance > 0
-        ? Slic3r::GCode::PressureRegulator->new(config => $self->print->config)
-        : undef;
-}
-
-sub process_layer {
-    my $self = shift;
-    my ($layer, $object_copies) = @_;
-    my $gcode = "";
-    
-    my $object = $layer->object;
-    $self->gcodegen->config->apply_object_config($object->config);
-    
-    # check whether we're going to apply spiralvase logic
-    if (defined $self->spiralvase) {
-        $self->spiralvase->enable(
-            ($layer->id > 0 || $self->print->config->brim_width == 0)
-                && ($layer->id >= $self->print->config->skirt_height && $self->print->config->skirt_height != -1)
-                && !defined(first { $_->config->bottom_solid_layers > $layer->id } @{$layer->regions})
-                && !defined(first { @{$_->perimeters} > 1 } @{$layer->regions})
-                && !defined(first { @{$_->fills} > 0 } @{$layer->regions})
-        );
-    }
-    
-    # if we're going to apply spiralvase to this layer, disable loop clipping
-    $self->gcodegen->enable_loop_clipping(!defined $self->spiralvase || !$self->spiralvase->enable);
-    
-    if (!$self->second_layer_things_done && $layer->id == 1) {
-        for my $extruder (@{$self->gcodegen->writer->extruders}) {
-            my $temperature = $self->config->get_at('temperature', $extruder->id);
-            $gcode .= $self->gcodegen->writer->set_temperature($temperature, 0, $extruder->id)
-                if $temperature && $temperature != $self->config->get_at('first_layer_temperature', $extruder->id);
-        }
-        $gcode .= $self->gcodegen->writer->set_bed_temperature($self->print->config->bed_temperature)
-            if $self->print->config->bed_temperature && $self->print->config->bed_temperature != $self->print->config->first_layer_bed_temperature;
-        $self->second_layer_things_done(1);
-    }
-    
-    # set new layer - this will change Z and force a retraction if retract_layer_change is enabled
-    $gcode .= $self->gcodegen->change_layer($layer);
-    $gcode .= $self->gcodegen->placeholder_parser->process($self->print->config->layer_gcode, {
-        layer_num => $layer->id,
-    }) . "\n" if $self->print->config->layer_gcode;
-    
-    # extrude skirt
-    if (((values %{$self->skirt_done}) < $self->print->config->skirt_height || $self->print->config->skirt_height == -1)
-        && !$self->skirt_done->{$layer->print_z}) {
-        $self->gcodegen->set_origin($self->origin);
-        my @extruder_ids = map { $_->id } @{$self->gcodegen->writer->extruders};
-        $gcode .= $self->gcodegen->set_extruder($extruder_ids[0]);
-        # skip skirt if we have a large brim
-        if ($layer->id < $self->print->config->skirt_height || $self->print->config->skirt_height == -1) {
-            # distribute skirt loops across all extruders
-            my @skirt_loops = @{$self->print->skirt};
-            for my $i (0 .. $#skirt_loops) {
-                # when printing layers > 0 ignore 'min_skirt_length' and 
-                # just use the 'skirts' setting; also just use the current extruder
-                last if ($layer->id > 0) && ($i >= $self->print->config->skirts);
-                my $extruder_id = $extruder_ids[($i/@extruder_ids) % @extruder_ids];
-                $gcode .= $self->gcodegen->set_extruder($extruder_id)
-                    if $layer->id == 0;
-                $gcode .= $self->gcodegen->extrude_loop($skirt_loops[$i], 'skirt', $object->config->support_material_speed);
-            }
-        }
-        $self->skirt_done->{$layer->print_z} = 1;
-        $self->gcodegen->avoid_crossing_perimeters->straight_once(1);
-    }
-    
-    # extrude brim
-    if (!$self->brim_done) {
-        $gcode .= $self->gcodegen->set_extruder($self->print->objects->[0]->config->support_material_extruder-1);
-        $self->gcodegen->set_origin($self->origin);
-        $gcode .= $self->gcodegen->extrude_loop($_, 'brim', $object->config->support_material_speed)
-            for @{$self->print->brim};
-        $self->brim_done(1);
-        $self->gcodegen->avoid_crossing_perimeters->straight_once(1);
-    }
-    
-    for my $copy (@$object_copies) {
-        $self->gcodegen->avoid_crossing_perimeters->new_object(1) if ($self->_last_obj_copy // '') ne "$copy";
-        $self->_last_obj_copy("$copy");
-        
-        $self->gcodegen->set_origin(Slic3r::Pointf->new(map $self->origin->[$_] + unscale $copy->[$_], X,Y));
-        
-        # extrude support material before other things because it might use a lower Z
-        # and also because we avoid travelling on other things when printing it
-        if ($layer->isa('Slic3r::Layer::Support')) {
-            if ($layer->support_interface_fills->count > 0) {
-                $gcode .= $self->gcodegen->set_extruder($object->config->support_material_interface_extruder-1);
-                $gcode .= $self->gcodegen->extrude_path($_, 'support material interface', $object->config->get_abs_value('support_material_interface_speed')) 
-                    for @{$layer->support_interface_fills->chained_path_from($self->gcodegen->last_pos, 0)}; 
-            }
-            if ($layer->support_fills->count > 0) {
-                $gcode .= $self->gcodegen->set_extruder($object->config->support_material_extruder-1);
-                $gcode .= $self->gcodegen->extrude_path($_, 'support material', $object->config->get_abs_value('support_material_speed')) 
-                    for @{$layer->support_fills->chained_path_from($self->gcodegen->last_pos, 0)};
-            }
-        }
-        
-        # tweak region ordering to save toolchanges
-        my @region_ids = 0 .. ($self->print->region_count-1);
-        if ($self->gcodegen->writer->multiple_extruders) {
-            my $last_extruder_id = $self->gcodegen->writer->extruder->id;
-            my $best_region_id = first { $self->print->regions->[$_]->config->perimeter_extruder-1 == $last_extruder_id } @region_ids;
-            @region_ids = ($best_region_id, grep $_ != $best_region_id, @region_ids) if $best_region_id;
-        }
-        
-        foreach my $region_id (@region_ids) {
-            my $layerm = $layer->regions->[$region_id] or next;
-            my $region = $self->print->regions->[$region_id];
-            $self->gcodegen->config->apply_region_config($region->config);
-            
-            # group extrusions by island
-            my @perimeters_by_island = map [], 0..$#{$layer->slices};   # slice idx => @perimeters
-            my @infill_by_island     = map [], 0..$#{$layer->slices};   # slice idx => @fills
-            
-            # NOTE: we assume $layer->slices was already ordered with chained_path()!
-            
-            PERIMETER: foreach my $perimeter (@{$layerm->perimeters}) {
-                for my $i (0 .. $#{$layer->slices}-1) {
-                    if ($layer->slices->[$i]->contour->contains_point($perimeter->first_point)) {
-                        push @{ $perimeters_by_island[$i] }, $perimeter;
-                        next PERIMETER;
-                    }
-                }
-                push @{ $perimeters_by_island[-1] }, $perimeter; # optimization
-            }
-            FILL: foreach my $fill (@{$layerm->fills}) {
-                for my $i (0 .. $#{$layer->slices}-1) {
-                    if ($layer->slices->[$i]->contour->contains_point($fill->first_point)) {
-                        push @{ $infill_by_island[$i] }, $fill;
-                        next FILL;
-                    }
-                }
-                push @{ $infill_by_island[-1] }, $fill; # optimization
-            }
-            
-            for my $i (0 .. $#{$layer->slices}) {
-                # give priority to infill if we were already using its extruder and it wouldn't
-                # be good for perimeters
-                if ($self->print->config->infill_first
-                    || ($self->gcodegen->writer->multiple_extruders && $region->config->infill_extruder-1 == $self->gcodegen->writer->extruder->id && $region->config->infill_extruder != $region->config->perimeter_extruder)) {
-                    $gcode .= $self->_extrude_infill($infill_by_island[$i], $region);
-                    $gcode .= $self->_extrude_perimeters($perimeters_by_island[$i], $region);
-                } else {
-                    $gcode .= $self->_extrude_perimeters($perimeters_by_island[$i], $region);
-                    $gcode .= $self->_extrude_infill($infill_by_island[$i], $region);
-                }
-            }
-        }
-    }
-    
-    # apply spiral vase post-processing if this layer contains suitable geometry
-    # (we must feed all the G-code into the post-processor, including the first 
-    # bottom non-spiral layers otherwise it will mess with positions)
-    $gcode = $self->spiralvase->process_layer($gcode)
-        if defined $self->spiralvase;
-    
-    # apply vibration limit if enabled
-    $gcode = $self->vibration_limit->process($gcode)
-        if $self->print->config->vibration_limit != 0;
-    
-    # apply pressure regulation if enabled
-    $gcode = $self->pressure_regulator->process($gcode)
-        if $self->print->config->pressure_advance > 0;
-    
-    # apply arc fitting if enabled
-    $gcode = $self->arc_fitting->process($gcode)
-        if $self->print->config->gcode_arcs;
-    
-    return $gcode;
-}
-
-sub _extrude_perimeters {
-    my $self = shift;
-    my ($island_perimeters, $region) = @_;
-    
-    return "" if !@$island_perimeters;
-    
-    my $gcode = "";
-    $gcode .= $self->gcodegen->set_extruder($region->config->perimeter_extruder-1);
-    $gcode .= $self->gcodegen->extrude($_, 'perimeter') for @$island_perimeters;
-    return $gcode;
-}
-
-sub _extrude_infill {
-    my $self = shift;
-    my ($island_fills, $region) = @_;
-    
-    return "" if !@$island_fills;
-    
-    my $gcode = "";
-    $gcode .= $self->gcodegen->set_extruder($region->config->infill_extruder-1);
-    for my $fill (@$island_fills) {
-        if ($fill->isa('Slic3r::ExtrusionPath::Collection')) {
-            $gcode .= $self->gcodegen->extrude($_, 'fill') 
-                for @{$fill->chained_path_from($self->gcodegen->last_pos, 0)};
-        } else {
-            $gcode .= $self->gcodegen->extrude($fill, 'fill') ;
-        }
-    }
-    return $gcode;
-}
-
-1;
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index dca82fc2b..88b527080 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -7,8 +7,7 @@ use File::Spec;
 use List::Util qw(min max first sum);
 use Slic3r::ExtrusionPath ':roles';
 use Slic3r::Flow ':roles';
-use Slic3r::Geometry qw(X Y Z X1 Y1 X2 Y2 MIN MAX PI scale unscale chained_path
-    convex_hull);
+use Slic3r::Geometry qw(X Y Z X1 Y1 X2 Y2 MIN MAX PI scale unscale convex_hull);
 use Slic3r::Geometry::Clipper qw(diff_ex union_ex intersection_ex intersection offset
     offset2 union union_pt_chained JT_ROUND JT_SQUARE);
 use Slic3r::Print::State ':steps';
@@ -456,243 +455,11 @@ sub write_gcode {
         binmode $fh, ':utf8';
     }
     
-    
-    # write some information
-    my @lt = localtime;
-    printf $fh "; generated by Slic3r $Slic3r::VERSION on %04d-%02d-%02d at %02d:%02d:%02d\n\n",
-        $lt[5] + 1900, $lt[4]+1, $lt[3], $lt[2], $lt[1], $lt[0];
-
-    print $fh "; $_\n" foreach split /\R/, $self->config->notes;
-    print $fh "\n" if $self->config->notes;
-    
-    my $first_object = $self->objects->[0];
-    my $layer_height = $first_object->config->layer_height;
-    for my $region_id (0..$#{$self->regions}) {
-        printf $fh "; external perimeters extrusion width = %.2fmm\n",
-            $self->regions->[$region_id]->flow(FLOW_ROLE_EXTERNAL_PERIMETER, $layer_height, 0, 0, -1, $first_object)->width;
-        printf $fh "; perimeters extrusion width = %.2fmm\n",
-            $self->regions->[$region_id]->flow(FLOW_ROLE_PERIMETER, $layer_height, 0, 0, -1, $first_object)->width;
-        printf $fh "; infill extrusion width = %.2fmm\n",
-            $self->regions->[$region_id]->flow(FLOW_ROLE_INFILL, $layer_height, 0, 0, -1, $first_object)->width;
-        printf $fh "; solid infill extrusion width = %.2fmm\n",
-            $self->regions->[$region_id]->flow(FLOW_ROLE_SOLID_INFILL, $layer_height, 0, 0, -1, $first_object)->width;
-        printf $fh "; top infill extrusion width = %.2fmm\n",
-            $self->regions->[$region_id]->flow(FLOW_ROLE_TOP_SOLID_INFILL, $layer_height, 0, 0, -1, $first_object)->width;
-        printf $fh "; support material extrusion width = %.2fmm\n",
-            $self->objects->[0]->support_material_flow->width
-            if $self->has_support_material;
-        printf $fh "; first layer extrusion width = %.2fmm\n",
-            $self->regions->[$region_id]->flow(FLOW_ROLE_PERIMETER, $layer_height, 0, 1, -1, $self->objects->[0])->width
-            if $self->regions->[$region_id]->config->first_layer_extrusion_width;
-        print  $fh "\n";
-    }
-    
-    # prepare the helper object for replacing placeholders in custom G-code and output filename
-    $self->placeholder_parser->update_timestamp;
-    
-    # estimate the total number of layer changes
-    # TODO: only do this when M73 is enabled
-    my $layer_count;
-    if ($self->config->complete_objects) {
-        $layer_count = sum(map { $_->total_layer_count * @{$_->copies} } @{$self->objects});
-    } else {
-        # if sequential printing is not enable, all copies of the same object share the same layer change command(s)
-        $layer_count = sum(map { $_->total_layer_count } @{$self->objects});
-    }
-    
-    # set up our helper object
-    my $gcodegen = Slic3r::GCode->new(
-        placeholder_parser  => $self->placeholder_parser,
-        layer_count         => $layer_count,
-        enable_cooling_markers => 1,
+    my $exporter = Slic3r::Print::GCode->new(
+        print   => $self,
+        fh      => $fh,
     );
-    $gcodegen->apply_print_config($self->config);
-    $gcodegen->set_extruders($self->extruders);
-    
-    print $fh $gcodegen->writer->set_fan(0, 1) if $self->config->cooling && $self->config->disable_fan_first_layers;
-    
-    # set bed temperature
-    if ((my $temp = $self->config->first_layer_bed_temperature) && $self->config->start_gcode !~ /M(?:190|140)/i) {
-        printf $fh $gcodegen->writer->set_bed_temperature($temp, 1);
-    }
-    
-    # set extruder(s) temperature before and after start G-code
-    my $print_first_layer_temperature = sub {
-        my ($wait) = @_;
-        
-        return if $self->config->start_gcode =~ /M(?:109|104)/i;
-        for my $t (@{$self->extruders}) {
-            my $temp = $self->config->get_at('first_layer_temperature', $t);
-            $temp += $self->config->standby_temperature_delta if $self->config->ooze_prevention;
-            printf $fh $gcodegen->writer->set_temperature($temp, $wait, $t) if $temp > 0;
-        }
-    };
-    $print_first_layer_temperature->(0);
-    printf $fh "%s\n", $gcodegen->placeholder_parser->process($self->config->start_gcode);
-    $print_first_layer_temperature->(1);
-    
-    # set other general things
-    print $fh $gcodegen->preamble;
-    
-    # initialize a motion planner for object-to-object travel moves
-    if ($self->config->avoid_crossing_perimeters) {
-        my $distance_from_objects = 1;
-        # compute the offsetted convex hull for each object and repeat it for each copy.
-        my @islands = ();
-        foreach my $obj_idx (0 .. ($self->object_count - 1)) {
-            my $convex_hull = convex_hull([
-                map @{$_->contour}, map @{$_->slices}, @{$self->objects->[$obj_idx]->layers},
-            ]);
-            # discard layers only containing thin walls (offset would fail on an empty polygon)
-            if (@$convex_hull) {
-                my $expolygon = Slic3r::ExPolygon->new($convex_hull);
-                my @island = @{$expolygon->offset_ex(scale $distance_from_objects, 1, JT_SQUARE)};
-                foreach my $copy (@{ $self->objects->[$obj_idx]->_shifted_copies }) {
-                    push @islands, map { my $c = $_->clone; $c->translate(@$copy); $c } @island;
-                }
-            }
-        }
-        $gcodegen->avoid_crossing_perimeters->init_external_mp(union_ex([ map @$_, @islands ]));
-    }
-    
-    # calculate wiping points if needed
-    if ($self->config->ooze_prevention) {
-        my @skirt_points = map @$_, map @$_, @{$self->skirt};
-        if (@skirt_points) {
-            my $outer_skirt = convex_hull(\@skirt_points);
-            my @skirts = ();
-            foreach my $extruder_id (@{$self->extruders}) {
-                push @skirts, my $s = $outer_skirt->clone;
-                $s->translate(map scale($_), @{$self->config->get_at('extruder_offset', $extruder_id)});
-            }
-            my $convex_hull = convex_hull([ map @$_, @skirts ]);
-            
-            $gcodegen->ooze_prevention->enable(1);
-            $gcodegen->ooze_prevention->standby_points(
-                [ map $_->clone, map @$_, map $_->subdivide(scale 10), @{offset([$convex_hull], scale 3)} ]
-            );
-        }
-    }
-    
-    # prepare the layer processor
-    my $layer_gcode = Slic3r::GCode::Layer->new(
-        print       => $self,
-        gcodegen    => $gcodegen,
-    );
-    
-    # set initial extruder only after custom start G-code
-    print $fh $gcodegen->set_extruder($self->extruders->[0]);
-    
-    # do all objects for each layer
-    if ($self->config->complete_objects) {
-        # print objects from the smallest to the tallest to avoid collisions
-        # when moving onto next object starting point
-        my @obj_idx = sort { $self->objects->[$a]->size->[Z] <=> $self->objects->[$b]->size->[Z] } 0..($self->object_count - 1);
-        
-        my $finished_objects = 0;
-        for my $obj_idx (@obj_idx) {
-            my $object = $self->objects->[$obj_idx];
-            for my $copy (@{ $self->objects->[$obj_idx]->_shifted_copies }) {
-                # move to the origin position for the copy we're going to print.
-                # this happens before Z goes down to layer 0 again, so that 
-                # no collision happens hopefully.
-                if ($finished_objects > 0) {
-                    $gcodegen->set_origin(Slic3r::Pointf->new(map unscale $copy->[$_], X,Y));
-                    print $fh $gcodegen->retract;
-                    print $fh $gcodegen->travel_to(
-                        $object->_copies_shift->negative,
-                        undef,
-                        'move to origin position for next object',
-                    );
-                }
-                
-                my $buffer = Slic3r::GCode::CoolingBuffer->new(
-                    config      => $self->config,
-                    gcodegen    => $gcodegen,
-                );
-                
-                my @layers = sort { $a->print_z <=> $b->print_z } @{$object->layers}, @{$object->support_layers};
-                for my $layer (@layers) {
-                    # if we are printing the bottom layer of an object, and we have already finished
-                    # another one, set first layer temperatures. this happens before the Z move
-                    # is triggered, so machine has more time to reach such temperatures
-                    if ($layer->id == 0 && $finished_objects > 0) {
-                        printf $fh $gcodegen->writer->set_bed_temperature($self->config->first_layer_bed_temperature),
-                            if $self->config->first_layer_bed_temperature;
-                        $print_first_layer_temperature->(0);
-                    }
-                    print $fh $buffer->append(
-                        $layer_gcode->process_layer($layer, [$copy]),
-                        $layer->object->ptr,
-                        $layer->id,
-                        $layer->print_z,
-                    );
-                }
-                print $fh $buffer->flush;
-                $finished_objects++;
-            }
-        }
-    } else {
-        # order objects using a nearest neighbor search
-        my @obj_idx = @{chained_path([ map Slic3r::Point->new(@{$_->_shifted_copies->[0]}), @{$self->objects} ])};
-        
-        # sort layers by Z
-        my %layers = ();  # print_z => [ [layers], [layers], [layers] ]  by obj_idx
-        foreach my $obj_idx (0 .. ($self->object_count - 1)) {
-            my $object = $self->objects->[$obj_idx];
-            foreach my $layer (@{$object->layers}, @{$object->support_layers}) {
-                $layers{ $layer->print_z } ||= [];
-                $layers{ $layer->print_z }[$obj_idx] ||= [];
-                push @{$layers{ $layer->print_z }[$obj_idx]}, $layer;
-            }
-        }
-        
-        my $buffer = Slic3r::GCode::CoolingBuffer->new(
-            config      => $self->config,
-            gcodegen    => $gcodegen,
-        );
-        foreach my $print_z (sort { $a <=> $b } keys %layers) {
-            foreach my $obj_idx (@obj_idx) {
-                foreach my $layer (@{ $layers{$print_z}[$obj_idx] // [] }) {
-                    print $fh $buffer->append(
-                        $layer_gcode->process_layer($layer, $layer->object->_shifted_copies),
-                        $layer->object->ptr . ref($layer),  # differentiate $obj_id between normal layers and support layers
-                        $layer->id,
-                        $layer->print_z,
-                    );
-                }
-            }
-        }
-        print $fh $buffer->flush;
-    }
-    
-    # write end commands to file
-    print $fh $gcodegen->retract;   # TODO: process this retract through PressureRegulator in order to discharge fully
-    print $fh $gcodegen->writer->set_fan(0);
-    printf $fh "%s\n", $gcodegen->placeholder_parser->process($self->config->end_gcode);
-    print $fh $gcodegen->writer->update_progress($gcodegen->layer_count, $gcodegen->layer_count, 1);  # 100%
-    
-    $self->total_used_filament(0);
-    $self->total_extruded_volume(0);
-    foreach my $extruder (@{$gcodegen->writer->extruders}) {
-        my $used_filament = $extruder->used_filament;
-        my $extruded_volume = $extruder->extruded_volume;
-        
-        printf $fh "; filament used = %.1fmm (%.1fcm3)\n",
-            $used_filament, $extruded_volume/1000;
-        
-        $self->total_used_filament($self->total_used_filament + $used_filament);
-        $self->total_extruded_volume($self->total_extruded_volume + $extruded_volume);
-    }
-    
-    # append full config
-    print $fh "\n";
-    foreach my $config ($self->config, $self->default_object_config, $self->default_region_config) {
-        foreach my $opt_key (sort @{$config->get_keys}) {
-            next if $Slic3r::Config::Options->{$opt_key}{shortcut};
-            printf $fh "; %s = %s\n", $opt_key, $config->serialize($opt_key);
-        }
-    }
+    $exporter->export;
     
     # close our gcode file
     close $fh;
diff --git a/lib/Slic3r/Print/GCode.pm b/lib/Slic3r/Print/GCode.pm
new file mode 100644
index 000000000..c1b1a6813
--- /dev/null
+++ b/lib/Slic3r/Print/GCode.pm
@@ -0,0 +1,491 @@
+package Slic3r::Print::GCode;
+use Moo;
+
+has 'print'     => (is => 'ro', required => 1, handles => [qw(objects placeholder_parser config)]);
+has 'fh'        => (is => 'ro', required => 1);
+
+has '_gcodegen'                      => (is => 'rw');
+has '_cooling_buffer'                => (is => 'rw');
+has '_spiral_vase'                   => (is => 'rw');
+has '_vibration_limit'               => (is => 'rw');
+has '_arc_fitting'                   => (is => 'rw');
+has '_pressure_regulator'            => (is => 'rw');
+has '_skirt_done'                    => (is => 'rw', default => sub { {} });  # print_z => 1
+has '_brim_done'                     => (is => 'rw');
+has '_second_layer_things_done'      => (is => 'rw');
+has '_last_obj_copy'                 => (is => 'rw');
+
+use List::Util qw(first sum);
+use Slic3r::Flow ':roles';
+use Slic3r::Geometry qw(X Y scale unscale chained_path convex_hull);
+use Slic3r::Geometry::Clipper qw(JT_SQUARE union_ex offset);
+
+sub BUILD {
+    my ($self) = @_;
+    
+    {
+        # estimate the total number of layer changes
+        # TODO: only do this when M73 is enabled
+        my $layer_count;
+        if ($self->config->complete_objects) {
+            $layer_count = sum(map { $_->total_layer_count * @{$_->copies} } @{$self->objects});
+        } else {
+            # if sequential printing is not enable, all copies of the same object share the same layer change command(s)
+            $layer_count = sum(map { $_->total_layer_count } @{$self->objects});
+        }
+    
+        # set up our helper object
+        my $gcodegen = Slic3r::GCode->new(
+            placeholder_parser  => $self->placeholder_parser,
+            layer_count         => $layer_count,
+            enable_cooling_markers => 1,
+        );
+        $gcodegen->apply_print_config($self->config);
+        $gcodegen->set_extruders($self->print->extruders);
+        $self->_gcodegen($gcodegen);
+    }
+    
+    $self->_cooling_buffer(Slic3r::GCode::CoolingBuffer->new(
+        config      => $self->config,
+        gcodegen    => $self->_gcodegen,
+    ));
+    
+    $self->_spiral_vase(Slic3r::GCode::SpiralVase->new(config => $self->config))
+        if $self->config->spiral_vase;
+    
+    $self->_vibration_limit(Slic3r::GCode::VibrationLimit->new(config => $self->config))
+        if $self->config->vibration_limit > 0;
+    
+    $self->_arc_fitting(Slic3r::GCode::ArcFitting->new(config => $self->config))
+        if $self->config->gcode_arcs;
+    
+    $self->_pressure_regulator(Slic3r::GCode::PressureRegulator->new(config => $self->config))
+        if $self->config->pressure_advance > 0;
+}
+
+sub export {
+    my ($self) = @_;
+    
+    my $fh          = $self->fh;
+    my $gcodegen    = $self->_gcodegen;
+    
+    # write some information
+    my @lt = localtime;
+    printf $fh "; generated by Slic3r $Slic3r::VERSION on %04d-%02d-%02d at %02d:%02d:%02d\n\n",
+        $lt[5] + 1900, $lt[4]+1, $lt[3], $lt[2], $lt[1], $lt[0];
+
+    print $fh "; $_\n" foreach split /\R/, $self->config->notes;
+    print $fh "\n" if $self->config->notes;
+    
+    my $first_object = $self->objects->[0];
+    my $layer_height = $first_object->config->layer_height;
+    for my $region_id (0..$#{$self->print->regions}) {
+        my $region = $self->print->regions->[$region_id];
+        printf $fh "; external perimeters extrusion width = %.2fmm\n",
+            $region->flow(FLOW_ROLE_EXTERNAL_PERIMETER, $layer_height, 0, 0, -1, $first_object)->width;
+        printf $fh "; perimeters extrusion width = %.2fmm\n",
+            $region->flow(FLOW_ROLE_PERIMETER, $layer_height, 0, 0, -1, $first_object)->width;
+        printf $fh "; infill extrusion width = %.2fmm\n",
+            $region->flow(FLOW_ROLE_INFILL, $layer_height, 0, 0, -1, $first_object)->width;
+        printf $fh "; solid infill extrusion width = %.2fmm\n",
+            $region->flow(FLOW_ROLE_SOLID_INFILL, $layer_height, 0, 0, -1, $first_object)->width;
+        printf $fh "; top infill extrusion width = %.2fmm\n",
+            $region->flow(FLOW_ROLE_TOP_SOLID_INFILL, $layer_height, 0, 0, -1, $first_object)->width;
+        printf $fh "; support material extrusion width = %.2fmm\n",
+            $self->objects->[0]->support_material_flow->width
+            if $self->print->has_support_material;
+        printf $fh "; first layer extrusion width = %.2fmm\n",
+            $region->flow(FLOW_ROLE_PERIMETER, $layer_height, 0, 1, -1, $self->objects->[0])->width
+            if $region->config->first_layer_extrusion_width;
+        print  $fh "\n";
+    }
+    
+    # prepare the helper object for replacing placeholders in custom G-code and output filename
+    $self->placeholder_parser->update_timestamp;
+    
+    print $fh $gcodegen->writer->set_fan(0, 1)
+        if $self->config->cooling && $self->config->disable_fan_first_layers;
+    
+    # set bed temperature
+    if ((my $temp = $self->config->first_layer_bed_temperature) && $self->config->start_gcode !~ /M(?:190|140)/i) {
+        printf $fh $gcodegen->writer->set_bed_temperature($temp, 1);
+    }
+    
+    # set extruder(s) temperature before and after start G-code
+    $self->_print_first_layer_temperature(0);
+    printf $fh "%s\n", $gcodegen->placeholder_parser->process($self->config->start_gcode);
+    $self->_print_first_layer_temperature(1);
+    
+    # set other general things
+    print $fh $gcodegen->preamble;
+    
+    # initialize a motion planner for object-to-object travel moves
+    if ($self->config->avoid_crossing_perimeters) {
+        my $distance_from_objects = 1;
+        # compute the offsetted convex hull for each object and repeat it for each copy.
+        my @islands = ();
+        foreach my $obj_idx (0 .. ($self->print->object_count - 1)) {
+            my $convex_hull = convex_hull([
+                map @{$_->contour}, map @{$_->slices}, @{$self->objects->[$obj_idx]->layers},
+            ]);
+            # discard layers only containing thin walls (offset would fail on an empty polygon)
+            if (@$convex_hull) {
+                my $expolygon = Slic3r::ExPolygon->new($convex_hull);
+                my @island = @{$expolygon->offset_ex(scale $distance_from_objects, 1, JT_SQUARE)};
+                foreach my $copy (@{ $self->objects->[$obj_idx]->_shifted_copies }) {
+                    push @islands, map { my $c = $_->clone; $c->translate(@$copy); $c } @island;
+                }
+            }
+        }
+        $gcodegen->avoid_crossing_perimeters->init_external_mp(union_ex([ map @$_, @islands ]));
+    }
+    
+    # calculate wiping points if needed
+    if ($self->config->ooze_prevention) {
+        my @skirt_points = map @$_, map @$_, @{$self->print->skirt};
+        if (@skirt_points) {
+            my $outer_skirt = convex_hull(\@skirt_points);
+            my @skirts = ();
+            foreach my $extruder_id (@{$self->print->extruders}) {
+                push @skirts, my $s = $outer_skirt->clone;
+                $s->translate(map scale($_), @{$self->config->get_at('extruder_offset', $extruder_id)});
+            }
+            my $convex_hull = convex_hull([ map @$_, @skirts ]);
+            
+            $gcodegen->ooze_prevention->enable(1);
+            $gcodegen->ooze_prevention->standby_points(
+                [ map $_->clone, map @$_, map $_->subdivide(scale 10), @{offset([$convex_hull], scale 3)} ]
+            );
+        }
+    }
+    
+    # set initial extruder only after custom start G-code
+    print $fh $gcodegen->set_extruder($self->print->extruders->[0]);
+    
+    # do all objects for each layer
+    if ($self->config->complete_objects) {
+        # print objects from the smallest to the tallest to avoid collisions
+        # when moving onto next object starting point
+        my @obj_idx = sort { $self->objects->[$a]->size->z <=> $self->objects->[$b]->size->z } 0..($self->print->object_count - 1);
+        
+        my $finished_objects = 0;
+        for my $obj_idx (@obj_idx) {
+            my $object = $self->objects->[$obj_idx];
+            for my $copy (@{ $self->objects->[$obj_idx]->_shifted_copies }) {
+                # move to the origin position for the copy we're going to print.
+                # this happens before Z goes down to layer 0 again, so that 
+                # no collision happens hopefully.
+                if ($finished_objects > 0) {
+                    $gcodegen->set_origin(Slic3r::Pointf->new(map unscale $copy->[$_], X,Y));
+                    print $fh $gcodegen->retract;
+                    print $fh $gcodegen->travel_to(
+                        $object->_copies_shift->negative,
+                        undef,
+                        'move to origin position for next object',
+                    );
+                }
+                
+                my @layers = sort { $a->print_z <=> $b->print_z } @{$object->layers}, @{$object->support_layers};
+                for my $layer (@layers) {
+                    # if we are printing the bottom layer of an object, and we have already finished
+                    # another one, set first layer temperatures. this happens before the Z move
+                    # is triggered, so machine has more time to reach such temperatures
+                    if ($layer->id == 0 && $finished_objects > 0) {
+                        printf $fh $gcodegen->writer->set_bed_temperature($self->config->first_layer_bed_temperature),
+                            if $self->config->first_layer_bed_temperature;
+                        $self->_print_first_layer_temperature(0);
+                    }
+                    $self->process_layer($layer, [$copy]);
+                }
+                $self->flush_cooling_buffer;
+                $finished_objects++;
+            }
+        }
+    } else {
+        # order objects using a nearest neighbor search
+        my @obj_idx = @{chained_path([ map Slic3r::Point->new(@{$_->_shifted_copies->[0]}), @{$self->objects} ])};
+        
+        # sort layers by Z
+        my %layers = ();  # print_z => [ [layers], [layers], [layers] ]  by obj_idx
+        foreach my $obj_idx (0 .. ($self->print->object_count - 1)) {
+            my $object = $self->objects->[$obj_idx];
+            foreach my $layer (@{$object->layers}, @{$object->support_layers}) {
+                $layers{ $layer->print_z } ||= [];
+                $layers{ $layer->print_z }[$obj_idx] ||= [];
+                push @{$layers{ $layer->print_z }[$obj_idx]}, $layer;
+            }
+        }
+        
+        foreach my $print_z (sort { $a <=> $b } keys %layers) {
+            foreach my $obj_idx (@obj_idx) {
+                foreach my $layer (@{ $layers{$print_z}[$obj_idx] // [] }) {
+                    $self->process_layer($layer, $layer->object->_shifted_copies);
+                }
+            }
+        }
+        $self->flush_cooling_buffer;
+    }
+    
+    # write end commands to file
+    print $fh $gcodegen->retract;   # TODO: process this retract through PressureRegulator in order to discharge fully
+    print $fh $gcodegen->writer->set_fan(0);
+    printf $fh "%s\n", $gcodegen->placeholder_parser->process($self->config->end_gcode);
+    print $fh $gcodegen->writer->update_progress($gcodegen->layer_count, $gcodegen->layer_count, 1);  # 100%
+    
+    $self->print->total_used_filament(0);
+    $self->print->total_extruded_volume(0);
+    foreach my $extruder (@{$gcodegen->writer->extruders}) {
+        my $used_filament = $extruder->used_filament;
+        my $extruded_volume = $extruder->extruded_volume;
+        
+        printf $fh "; filament used = %.1fmm (%.1fcm3)\n",
+            $used_filament, $extruded_volume/1000;
+        
+        $self->print->total_used_filament($self->print->total_used_filament + $used_filament);
+        $self->print->total_extruded_volume($self->print->total_extruded_volume + $extruded_volume);
+    }
+    
+    # append full config
+    print $fh "\n";
+    foreach my $config ($self->print->config, $self->print->default_object_config, $self->print->default_region_config) {
+        foreach my $opt_key (sort @{$config->get_keys}) {
+            next if $Slic3r::Config::Options->{$opt_key}{shortcut};
+            printf $fh "; %s = %s\n", $opt_key, $config->serialize($opt_key);
+        }
+    }
+}
+
+sub _print_first_layer_temperature {
+    my ($self, $wait) = @_;
+    
+    return if $self->config->start_gcode =~ /M(?:109|104)/i;
+    for my $t (@{$self->print->extruders}) {
+        my $temp = $self->config->get_at('first_layer_temperature', $t);
+        $temp += $self->config->standby_temperature_delta if $self->config->ooze_prevention;
+        printf {$self->fh} $self->_gcodegen->writer->set_temperature($temp, $wait, $t) if $temp > 0;
+    }
+}
+
+sub process_layer {
+    my $self = shift;
+    my ($layer, $object_copies) = @_;
+    my $gcode = "";
+    
+    my $object = $layer->object;
+    $self->_gcodegen->config->apply_object_config($object->config);
+    
+    # check whether we're going to apply spiralvase logic
+    if (defined $self->_spiral_vase) {
+        $self->_spiral_vase->enable(
+            ($layer->id > 0 || $self->print->config->brim_width == 0)
+                && ($layer->id >= $self->print->config->skirt_height && $self->print->config->skirt_height != -1)
+                && !defined(first { $_->config->bottom_solid_layers > $layer->id } @{$layer->regions})
+                && !defined(first { @{$_->perimeters} > 1 } @{$layer->regions})
+                && !defined(first { @{$_->fills} > 0 } @{$layer->regions})
+        );
+    }
+    
+    # if we're going to apply spiralvase to this layer, disable loop clipping
+    $self->_gcodegen->enable_loop_clipping(!defined $self->_spiral_vase || !$self->_spiral_vase->enable);
+    
+    if (!$self->_second_layer_things_done && $layer->id == 1) {
+        for my $extruder (@{$self->_gcodegen->writer->extruders}) {
+            my $temperature = $self->config->get_at('temperature', $extruder->id);
+            $gcode .= $self->_gcodegen->writer->set_temperature($temperature, 0, $extruder->id)
+                if $temperature && $temperature != $self->config->get_at('first_layer_temperature', $extruder->id);
+        }
+        $gcode .= $self->_gcodegen->writer->set_bed_temperature($self->print->config->bed_temperature)
+            if $self->print->config->bed_temperature && $self->print->config->bed_temperature != $self->print->config->first_layer_bed_temperature;
+        $self->_second_layer_things_done(1);
+    }
+    
+    # set new layer - this will change Z and force a retraction if retract_layer_change is enabled
+    $gcode .= $self->_gcodegen->change_layer($layer);
+    $gcode .= $self->_gcodegen->placeholder_parser->process($self->print->config->layer_gcode, {
+        layer_num => $layer->id,
+    }) . "\n" if $self->print->config->layer_gcode;
+    
+    # extrude skirt
+    if (((values %{$self->_skirt_done}) < $self->print->config->skirt_height || $self->print->config->skirt_height == -1)
+        && !$self->_skirt_done->{$layer->print_z}) {
+        $self->_gcodegen->set_origin(Slic3r::Pointf->new(0,0));
+        my @extruder_ids = map { $_->id } @{$self->_gcodegen->writer->extruders};
+        $gcode .= $self->_gcodegen->set_extruder($extruder_ids[0]);
+        # skip skirt if we have a large brim
+        if ($layer->id < $self->print->config->skirt_height || $self->print->config->skirt_height == -1) {
+            # distribute skirt loops across all extruders
+            my @skirt_loops = @{$self->print->skirt};
+            for my $i (0 .. $#skirt_loops) {
+                # when printing layers > 0 ignore 'min_skirt_length' and 
+                # just use the 'skirts' setting; also just use the current extruder
+                last if ($layer->id > 0) && ($i >= $self->print->config->skirts);
+                my $extruder_id = $extruder_ids[($i/@extruder_ids) % @extruder_ids];
+                $gcode .= $self->_gcodegen->set_extruder($extruder_id)
+                    if $layer->id == 0;
+                $gcode .= $self->_gcodegen->extrude_loop($skirt_loops[$i], 'skirt', $object->config->support_material_speed);
+            }
+        }
+        $self->_skirt_done->{$layer->print_z} = 1;
+        $self->_gcodegen->avoid_crossing_perimeters->straight_once(1);
+    }
+    
+    # extrude brim
+    if (!$self->_brim_done) {
+        $gcode .= $self->_gcodegen->set_extruder($self->print->objects->[0]->config->support_material_extruder-1);
+        $self->_gcodegen->set_origin(Slic3r::Pointf->new(0,0));
+        $gcode .= $self->_gcodegen->extrude_loop($_, 'brim', $object->config->support_material_speed)
+            for @{$self->print->brim};
+        $self->_brim_done(1);
+        $self->_gcodegen->avoid_crossing_perimeters->straight_once(1);
+    }
+    
+    for my $copy (@$object_copies) {
+        $self->_gcodegen->avoid_crossing_perimeters->new_object(1) if ($self->_last_obj_copy // '') ne "$copy";
+        $self->_last_obj_copy("$copy");
+        
+        $self->_gcodegen->set_origin(Slic3r::Pointf->new(map unscale $copy->[$_], X,Y));
+        
+        # extrude support material before other things because it might use a lower Z
+        # and also because we avoid travelling on other things when printing it
+        if ($layer->isa('Slic3r::Layer::Support')) {
+            if ($layer->support_interface_fills->count > 0) {
+                $gcode .= $self->_gcodegen->set_extruder($object->config->support_material_interface_extruder-1);
+                $gcode .= $self->_gcodegen->extrude_path($_, 'support material interface', $object->config->get_abs_value('support_material_interface_speed')) 
+                    for @{$layer->support_interface_fills->chained_path_from($self->_gcodegen->last_pos, 0)}; 
+            }
+            if ($layer->support_fills->count > 0) {
+                $gcode .= $self->_gcodegen->set_extruder($object->config->support_material_extruder-1);
+                $gcode .= $self->_gcodegen->extrude_path($_, 'support material', $object->config->get_abs_value('support_material_speed')) 
+                    for @{$layer->support_fills->chained_path_from($self->_gcodegen->last_pos, 0)};
+            }
+        }
+        
+        # tweak region ordering to save toolchanges
+        my @region_ids = 0 .. ($self->print->region_count-1);
+        if ($self->_gcodegen->writer->multiple_extruders) {
+            my $last_extruder_id = $self->_gcodegen->writer->extruder->id;
+            my $best_region_id = first { $self->print->regions->[$_]->config->perimeter_extruder-1 == $last_extruder_id } @region_ids;
+            @region_ids = ($best_region_id, grep $_ != $best_region_id, @region_ids) if $best_region_id;
+        }
+        
+        foreach my $region_id (@region_ids) {
+            my $layerm = $layer->regions->[$region_id] or next;
+            my $region = $self->print->regions->[$region_id];
+            $self->_gcodegen->config->apply_region_config($region->config);
+            
+            # group extrusions by island
+            my @perimeters_by_island = map [], 0..$#{$layer->slices};   # slice idx => @perimeters
+            my @infill_by_island     = map [], 0..$#{$layer->slices};   # slice idx => @fills
+            
+            # NOTE: we assume $layer->slices was already ordered with chained_path()!
+            
+            PERIMETER: foreach my $perimeter (@{$layerm->perimeters}) {
+                for my $i (0 .. $#{$layer->slices}-1) {
+                    if ($layer->slices->[$i]->contour->contains_point($perimeter->first_point)) {
+                        push @{ $perimeters_by_island[$i] }, $perimeter;
+                        next PERIMETER;
+                    }
+                }
+                push @{ $perimeters_by_island[-1] }, $perimeter; # optimization
+            }
+            FILL: foreach my $fill (@{$layerm->fills}) {
+                for my $i (0 .. $#{$layer->slices}-1) {
+                    if ($layer->slices->[$i]->contour->contains_point($fill->first_point)) {
+                        push @{ $infill_by_island[$i] }, $fill;
+                        next FILL;
+                    }
+                }
+                push @{ $infill_by_island[-1] }, $fill; # optimization
+            }
+            
+            for my $i (0 .. $#{$layer->slices}) {
+                # give priority to infill if we were already using its extruder and it wouldn't
+                # be good for perimeters
+                if ($self->print->config->infill_first
+                    || ($self->_gcodegen->writer->multiple_extruders && $region->config->infill_extruder-1 == $self->_gcodegen->writer->extruder->id && $region->config->infill_extruder != $region->config->perimeter_extruder)) {
+                    $gcode .= $self->_extrude_infill($infill_by_island[$i], $region);
+                    $gcode .= $self->_extrude_perimeters($perimeters_by_island[$i], $region);
+                } else {
+                    $gcode .= $self->_extrude_perimeters($perimeters_by_island[$i], $region);
+                    $gcode .= $self->_extrude_infill($infill_by_island[$i], $region);
+                }
+            }
+        }
+    }
+    
+    # apply spiral vase post-processing if this layer contains suitable geometry
+    # (we must feed all the G-code into the post-processor, including the first 
+    # bottom non-spiral layers otherwise it will mess with positions)
+    # we apply spiral vase at this stage because it requires a full layer
+    $gcode = $self->_spiral_vase->process_layer($gcode)
+        if defined $self->_spiral_vase;
+    
+    # apply cooling logic; this may alter speeds
+    $gcode = $self->_cooling_buffer->append(
+        $gcode,
+        $layer->object->ptr . ref($layer),  # differentiate $obj_id between normal layers and support layers
+        $layer->id,
+        $layer->print_z,
+    ) if defined $self->_cooling_buffer && defined $layer;
+    
+    print {$self->fh} $self->filter($gcode);
+}
+
+sub _extrude_perimeters {
+    my $self = shift;
+    my ($island_perimeters, $region) = @_;
+    
+    return "" if !@$island_perimeters;
+    
+    my $gcode = "";
+    $gcode .= $self->_gcodegen->set_extruder($region->config->perimeter_extruder-1);
+    $gcode .= $self->_gcodegen->extrude($_, 'perimeter') for @$island_perimeters;
+    return $gcode;
+}
+
+sub _extrude_infill {
+    my $self = shift;
+    my ($island_fills, $region) = @_;
+    
+    return "" if !@$island_fills;
+    
+    my $gcode = "";
+    $gcode .= $self->_gcodegen->set_extruder($region->config->infill_extruder-1);
+    for my $fill (@$island_fills) {
+        if ($fill->isa('Slic3r::ExtrusionPath::Collection')) {
+            $gcode .= $self->_gcodegen->extrude($_, 'fill') 
+                for @{$fill->chained_path_from($self->_gcodegen->last_pos, 0)};
+        } else {
+            $gcode .= $self->_gcodegen->extrude($fill, 'fill') ;
+        }
+    }
+    return $gcode;
+}
+
+sub flush_cooling_buffer {
+    my ($self) = @_;
+    print {$self->fh} $self->filter($self->_cooling_buffer->flush);
+}
+
+sub filter {
+    my ($self, $gcode) = @_;
+    
+    # apply vibration limit if enabled;
+    # this injects pauses according to time (thus depends on actual speeds)
+    $gcode = $self->_vibration_limit->process($gcode)
+        if $self->print->config->vibration_limit != 0;
+    
+    # apply pressure regulation if enabled;
+    # this depends on actual speeds
+    $gcode = $self->_pressure_regulator->process($gcode)
+        if $self->print->config->pressure_advance > 0;
+    
+    # apply arc fitting if enabled;
+    # this does not depend on speeds but changes G1 XY commands into G2/G2 IJ
+    $gcode = $self->_arc_fitting->process($gcode)
+        if $self->print->config->gcode_arcs;
+    
+    return $gcode;
+}
+
+1;