Add linear gradient fill (#2587)

8 files changed, 464 insertions, 41 deletions

diff --git a/lib/elements/element.py b/lib/elements/element.py
index 963653af..d6881955 100644
--- a/lib/elements/element.py
+++ b/lib/elements/element.py
@@ -526,6 +526,14 @@ class EmbroideryElement(object):
     def _get_guides_cache_key_data(self):
         return get_marker_elements_cache_key_data(self.node, "guide-line")
 
+    def _get_gradient_cache_key_data(self):
+        gradient = {}
+        if hasattr(self, 'gradient') and self.gradient is not None:
+            gradient['stops'] = self.gradient.stop_offsets
+            gradient['orientation'] = [self.gradient.x1(), self.gradient.x2(), self.gradient.y1(), self.gradient.y2()]
+            gradient['styles'] = [(style['stop-color'], style['stop-opacity']) for style in self.gradient.stop_styles]
+        return gradient
+
     def get_cache_key_data(self, previous_stitch):
         return []
 
@@ -535,6 +543,7 @@ class EmbroideryElement(object):
         cache_key_generator.update(self.get_params_and_values())
         cache_key_generator.update(self.parse_path())
         cache_key_generator.update(list(self._get_specified_style().items()))
+        cache_key_generator.update(self._get_gradient_cache_key_data())
         cache_key_generator.update(previous_stitch)
         cache_key_generator.update([(c.command, c.target_point) for c in self.commands])
         cache_key_generator.update(self._get_patterns_cache_key_data())
diff --git a/lib/elements/fill_stitch.py b/lib/elements/fill_stitch.py
index b20c2715..bc42163e 100644
--- a/lib/elements/fill_stitch.py
+++ b/lib/elements/fill_stitch.py
@@ -11,6 +11,7 @@ import numpy as np
 from inkex import Transform
 from shapely import geometry as shgeo
 from shapely.errors import GEOSException
+from shapely.ops import nearest_points
 from shapely.validation import explain_validity, make_valid
 
 from .. import tiles
@@ -18,8 +19,8 @@ from ..i18n import _
 from ..marker import get_marker_elements
 from ..stitch_plan import StitchGroup
 from ..stitches import (auto_fill, circular_fill, contour_fill, guided_fill,
-                        legacy_fill)
-from ..stitches.meander_fill import meander_fill
+                        legacy_fill, linear_gradient_fill, meander_fill)
+from ..stitches.linear_gradient_fill import gradient_angle
 from ..svg import PIXELS_PER_MM, get_node_transform
 from ..svg.clip import get_clip_path
 from ..svg.tags import INKSCAPE_LABEL
@@ -114,6 +115,7 @@ class FillStitch(EmbroideryElement):
                      ParamOption('guided_fill', _("Guided Fill")),
                      ParamOption('meander_fill', _("Meander Fill")),
                      ParamOption('circular_fill', _("Circular Fill")),
+                     ParamOption('linear_gradient_fill', _("Linear Gradient Fill")),
                      ParamOption('legacy_fill', _("Legacy Fill"))]
 
     @property
@@ -226,7 +228,8 @@ class FillStitch(EmbroideryElement):
            select_items=[('fill_method', 'auto_fill'),
                          ('fill_method', 'guided_fill'),
                          ('fill_method', 'meander_fill'),
-                         ('fill_method', 'circular_fill')])
+                         ('fill_method', 'circular_fill'),
+                         ('fill_method', 'linear_gradient_fill')])
     def expand(self):
         return self.get_float_param('expand_mm', 0)
 
@@ -254,6 +257,7 @@ class FillStitch(EmbroideryElement):
            select_items=[('fill_method', 'auto_fill'),
                          ('fill_method', 'contour_fill'),
                          ('fill_method', 'guided_fill'),
+                         ('fill_method', 'linear_gradient_fill'),
                          ('fill_method', 'legacy_fill')],
            default=3.0)
     def max_stitch_length(self):
@@ -270,6 +274,7 @@ class FillStitch(EmbroideryElement):
                          ('fill_method', 'contour_fill'),
                          ('fill_method', 'guided_fill'),
                          ('fill_method', 'circular_fill'),
+                         ('fill_method', 'linear_gradient_fill'),
                          ('fill_method', 'legacy_fill')],
            default=0.25)
     def row_spacing(self):
@@ -297,7 +302,10 @@ class FillStitch(EmbroideryElement):
                      'Fractional values are allowed and can have less visible diagonals than integer values.'),
            type='int',
            sort_index=25,
-           select_items=[('fill_method', 'auto_fill'), ('fill_method', 'guided_fill'), ('fill_method', 'legacy_fill')],
+           select_items=[('fill_method', 'auto_fill'),
+                         ('fill_method', 'guided_fill'),
+                         ('fill_method', 'linear_gradient_fill'),
+                         ('fill_method', 'legacy_fill')],
            default=4)
     def staggers(self):
         return self.get_float_param("staggers", 4)
@@ -310,7 +318,9 @@ class FillStitch(EmbroideryElement):
                   'Skipping it decreases stitch count and density.'),
         type='boolean',
         sort_index=26,
-        select_items=[('fill_method', 'auto_fill'), ('fill_method', 'guided_fill'),
+        select_items=[('fill_method', 'auto_fill'),
+                      ('fill_method', 'guided_fill'),
+                      ('fill_method', 'linear_gradient_fill'),
                       ('fill_method', 'legacy_fill')],
         default=False)
     def skip_last(self):
@@ -330,6 +340,20 @@ class FillStitch(EmbroideryElement):
         return self.get_boolean_param("flip", False)
 
     @property
+    @param(
+        'stop_at_ending_point',
+        _('Stop at ending point'),
+        tooltip=_('If this option is disabled, the ending point will only be used to define a general direction for '
+                  'stitch routing. When enabled the last section will end at the defined spot.'),
+        type='boolean',
+        sort_index=30,
+        select_items=[('fill_method', 'linear_gradient_fill')],
+        default=False
+     )
+    def stop_at_ending_point(self):
+        return self.get_boolean_param("stop_at_ending_point", False)
+
+    @property
     @param('underpath',
            _('Underpath'),
            tooltip=_('Travel inside the shape when moving from section to section.  Underpath '
@@ -353,7 +377,8 @@ class FillStitch(EmbroideryElement):
            select_items=[('fill_method', 'auto_fill'),
                          ('fill_method', 'guided_fill'),
                          ('fill_method', 'meander_fill'),
-                         ('fill_method', 'circular_fill')],
+                         ('fill_method', 'circular_fill'),
+                         ('fill_method', 'linear_gradient_fill')],
            sort_index=31)
     def running_stitch_length(self):
         return max(self.get_float_param("running_stitch_length_mm", 2.5), 0.01)
@@ -403,6 +428,12 @@ class FillStitch(EmbroideryElement):
         return self.get_style("fill", "#000000")
 
     @property
+    def gradient(self):
+        color = self.color[5:-1]
+        xpath = f'.//svg:defs/svg:linearGradient[@id="{color}"]'
+        return self.node.getroottree().getroot().findone(xpath)
+
+    @property
     @param('fill_underlay', _('Underlay'), type='toggle', group=_('Fill Underlay'), default=True)
     def fill_underlay(self):
         return self.get_boolean_param("fill_underlay", default=True)
@@ -427,6 +458,8 @@ class FillStitch(EmbroideryElement):
                     float(angle)) for angle in underlay_angles]
             except (TypeError, ValueError):
                 return default_value
+        elif self.fill_method == 'linear_gradient_fill' and self.gradient is not None:
+            return [-gradient_angle(self.node, self.gradient)]
         else:
             underlay_angles = default_value
 
@@ -704,10 +737,25 @@ class FillStitch(EmbroideryElement):
             return self.do_legacy_fill()
         else:
             stitch_groups = []
-            end = self.get_ending_point()
 
-            for shape in self.shape.geoms:
+            # start and end points
+            start = self.get_starting_point(previous_stitch_group)
+            final_end = self.get_ending_point()
+
+            # sort shapes to get a nicer routing
+            shapes = list(self.shape.geoms)
+            if start:
+                shapes.sort(key=lambda shape: shape.distance(shgeo.Point(start)))
+            else:
+                shapes.sort(key=lambda shape: shape.bounds[0])
+
+            for i, shape in enumerate(shapes):
                 start = self.get_starting_point(previous_stitch_group)
+                if i < len(shapes) - 1:
+                    end = nearest_points(shape, shapes[i+1])[0].coords
+                else:
+                    end = final_end
+
                 if self.fill_underlay:
                     underlay_shapes = self.underlay_shape(shape)
                     for underlay_shape in underlay_shapes.geoms:
@@ -724,10 +772,18 @@ class FillStitch(EmbroideryElement):
                         stitch_groups.extend(self.do_meander_fill(fill_shape, shape, i, start, end))
                     elif self.fill_method == 'circular_fill':
                         stitch_groups.extend(self.do_circular_fill(fill_shape, previous_stitch_group, start, end))
+                    elif self.fill_method == 'linear_gradient_fill':
+                        stitch_groups.extend(self.do_linear_gradient_fill(fill_shape, previous_stitch_group, start, end))
                     else:
                         # auto_fill
                         stitch_groups.extend(self.do_auto_fill(fill_shape, previous_stitch_group, start, end))
-                previous_stitch_group = stitch_groups[-1]
+                    if stitch_groups:
+                        previous_stitch_group = stitch_groups[-1]
+
+            # sort colors of linear gradient (if multiple shapes)
+            if self.fill_method == 'linear_gradient_fill':
+                colors = [stitch_group.color for stitch_group in stitch_groups]
+                stitch_groups.sort(key=lambda group: colors.index(group.color))
 
             return stitch_groups
 
@@ -746,10 +802,13 @@ class FillStitch(EmbroideryElement):
                             lock_stitches=self.lock_stitches) for stitch_list in stitch_lists]
 
     def do_underlay(self, shape, starting_point):
+        color = self.color
+        if self.gradient is not None and self.fill_method == 'linear_gradient_fill':
+            color = [style['stop-color'] for style in self.gradient.stop_styles][0]
         stitch_groups = []
         for i in range(len(self.fill_underlay_angle)):
             underlay = StitchGroup(
-                color=self.color,
+                color=color,
                 tags=("auto_fill", "auto_fill_underlay"),
                 lock_stitches=self.lock_stitches,
                 stitches=auto_fill(
@@ -763,7 +822,9 @@ class FillStitch(EmbroideryElement):
                     self.staggers,
                     self.fill_underlay_skip_last,
                     starting_point,
-                    underpath=self.underlay_underpath))
+                    underpath=self.underlay_underpath
+                )
+            )
             stitch_groups.append(underlay)
             starting_point = underlay.stitches[-1]
         return [stitch_groups, starting_point]
@@ -859,15 +920,9 @@ class FillStitch(EmbroideryElement):
                 starting_point,
                 ending_point,
                 self.underpath,
-                self.guided_fill_strategy,
-            ))
-        return [stitch_group]
-
-    def do_meander_fill(self, shape, original_shape, i, starting_point, ending_point):
-        stitch_group = StitchGroup(
-            color=self.color,
-            tags=("meander_fill", "meander_fill_top"),
-            stitches=meander_fill(self, shape, original_shape, i, starting_point, ending_point))
+                self.guided_fill_strategy
+            )
+        )
         return [stitch_group]
 
     @cache
@@ -882,6 +937,16 @@ class FillStitch(EmbroideryElement):
         else:
             return guide_lines['stroke'][0]
 
+    def do_meander_fill(self, shape, original_shape, i, starting_point, ending_point):
+        stitch_group = StitchGroup(
+            color=self.color,
+            tags=("meander_fill", "meander_fill_top"),
+            stitches=meander_fill(self, shape, original_shape, i, starting_point, ending_point),
+            force_lock_stitches=self.force_lock_stitches,
+            lock_stitches=self.lock_stitches,
+        )
+        return [stitch_group]
+
     def do_circular_fill(self, shape, last_patch, starting_point, ending_point):
         # get target position
         command = self.get_command('ripple_target')
@@ -893,24 +958,29 @@ class FillStitch(EmbroideryElement):
         else:
             target = shape.centroid
         stitches = circular_fill(
-                                 shape,
-                                 self.angle,
-                                 self.row_spacing,
-                                 self.end_row_spacing,
-                                 self.staggers,
-                                 self.running_stitch_length,
-                                 self.running_stitch_tolerance,
-                                 self.bean_stitch_repeats,
-                                 self.repeats,
-                                 self.skip_last,
-                                 starting_point,
-                                 ending_point,
-                                 self.underpath,
-                                 target
-                                )
+            shape,
+            self.angle,
+            self.row_spacing,
+            self.end_row_spacing,
+            self.staggers,
+            self.running_stitch_length,
+            self.running_stitch_tolerance,
+            self.bean_stitch_repeats,
+            self.repeats,
+            self.skip_last,
+            starting_point,
+            ending_point,
+            self.underpath,
+            target
+        )
 
         stitch_group = StitchGroup(
             color=self.color,
             tags=("circular_fill", "auto_fill_top"),
-            stitches=stitches)
+            stitches=stitches,
+            force_lock_stitches=self.force_lock_stitches,
+            lock_stitches=self.lock_stitches,)
         return [stitch_group]
+
+    def do_linear_gradient_fill(self, shape, last_patch, start, end):
+        return linear_gradient_fill(self, shape, start, end)
diff --git a/lib/stitches/__init__.py b/lib/stitches/__init__.py
index f77f16e7..ba56a0ec 100644
--- a/lib/stitches/__init__.py
+++ b/lib/stitches/__init__.py
@@ -7,6 +7,8 @@ from .auto_fill import auto_fill
 from .circular_fill import circular_fill
 from .fill import legacy_fill
 from .guided_fill import guided_fill
+from .linear_gradient_fill import linear_gradient_fill
+from .meander_fill import meander_fill
 
 # Can't put this here because we get a circular import :(
 # from .auto_satin import auto_satin
diff --git a/lib/stitches/auto_fill.py b/lib/stitches/auto_fill.py
index 83ff226b..24ce6610 100644
--- a/lib/stitches/auto_fill.py
+++ b/lib/stitches/auto_fill.py
@@ -78,7 +78,7 @@ def auto_fill(shape,
     segments = [segment for row in rows for segment in row]
     fill_stitch_graph = build_fill_stitch_graph(shape, segments, starting_point, ending_point)
 
-    if not graph_is_valid(fill_stitch_graph, shape, max_stitch_length):
+    if not graph_is_valid(fill_stitch_graph):
         return fallback(shape, running_stitch_length, running_stitch_tolerance)
 
     travel_graph = build_travel_graph(fill_stitch_graph, shape, angle, underpath)
@@ -269,7 +269,7 @@ def add_edges_between_outline_nodes(graph, duplicate_every_other=False):
         check_stop_flag()
 
 
-def graph_is_valid(graph, shape, max_stitch_length):
+def graph_is_valid(graph):
     # The graph may be empty if the shape is so small that it fits between the
     # rows of stitching.  Certain small weird shapes can also cause a non-
     # eulerian graph.
diff --git a/lib/stitches/circular_fill.py b/lib/stitches/circular_fill.py
index 351f4cf4..959759dc 100644
--- a/lib/stitches/circular_fill.py
+++ b/lib/stitches/circular_fill.py
@@ -73,7 +73,7 @@ def circular_fill(shape,
             segments.append([(point.x, point.y) for point in coords])
 
     fill_stitch_graph = build_fill_stitch_graph(shape, segments, starting_point, ending_point)
-    if not graph_is_valid(fill_stitch_graph, shape, running_stitch_length):
+    if not graph_is_valid(fill_stitch_graph):
         return fallback(shape, running_stitch_length, running_stitch_tolerance)
 
     travel_graph = build_travel_graph(fill_stitch_graph, shape, angle, underpath)
@@ -124,7 +124,7 @@ def path_to_stitches(shape, path, travel_graph, fill_stitch_graph, running_stitc
 
     # If the very first stitch is travel, we'll omit it in travel(), so add it here.
     if not path[0].is_segment():
-        stitches.append(Stitch(*path[0].nodes[0]))
+        stitches.append(Stitch(*path[0].nodes[0], tags={'auto_fill_travel'}))
 
     for edge in path:
         if edge.is_segment():
diff --git a/lib/stitches/guided_fill.py b/lib/stitches/guided_fill.py
index 67ad4ccd..762515f6 100644
--- a/lib/stitches/guided_fill.py
+++ b/lib/stitches/guided_fill.py
@@ -39,7 +39,7 @@ def guided_fill(shape,
 
     fill_stitch_graph = build_fill_stitch_graph(shape, segments, starting_point, ending_point)
 
-    if not graph_is_valid(fill_stitch_graph, shape, max_stitch_length):
+    if not graph_is_valid(fill_stitch_graph):
         return fallback(shape, guideline, row_spacing, max_stitch_length, running_stitch_length, running_stitch_tolerance,
                         num_staggers, skip_last, starting_point, ending_point, underpath)
 
diff --git a/lib/stitches/linear_gradient_fill.py b/lib/stitches/linear_gradient_fill.py
new file mode 100644
index 00000000..34f91d5a
--- /dev/null
+++ b/lib/stitches/linear_gradient_fill.py
@@ -0,0 +1,341 @@
+# Authors: see git history
+#
+# Copyright (c) 2023 Authors
+# Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.
+
+from math import ceil, floor, sqrt
+
+import numpy as np
+from inkex import DirectedLineSegment, Transform
+from networkx import eulerize
+from shapely import segmentize
+from shapely.affinity import rotate
+from shapely.geometry import LineString, MultiLineString, Point, Polygon
+
+from ..stitch_plan import StitchGroup
+from ..svg import get_node_transform
+from ..utils.threading import check_stop_flag
+from .auto_fill import (build_fill_stitch_graph, build_travel_graph,
+                        find_stitch_path, graph_is_valid)
+from .circular_fill import path_to_stitches
+from .guided_fill import apply_stitches
+
+
+def linear_gradient_fill(fill, shape, starting_point, ending_point):
+    lines, colors, stop_color_line_indices = _get_lines_and_colors(shape, fill)
+    color_lines, colors = _get_color_lines(lines, colors, stop_color_line_indices)
+    if fill.gradient is None:
+        colors.pop()
+    stitch_groups = _get_stitch_groups(fill, shape, colors, color_lines, starting_point, ending_point)
+    return stitch_groups
+
+
+def _get_lines_and_colors(shape, fill):
+    '''
+    Returns lines and color gradient information
+    lines:  a list of lines which cover the whole shape in a 90° angle to the gradient line
+    colors: a list of color values
+    stop_color_line_indices: line indices indicating where color changes are positioned at
+    '''
+    orig_bbox = shape.bounds
+
+    # get angle, colors, as well as start and stop position of the gradient
+    angle, colors, offsets, gradient_start, gradient_end = _get_gradient_info(fill, orig_bbox)
+
+    # get lines
+    lines, bottom_line = _get_lines(fill, shape, orig_bbox, angle)
+
+    gradient_start_line_index = round(bottom_line.project(Point(gradient_start)) / fill.row_spacing)
+    if gradient_start_line_index == 0:
+        gradient_start_line_index = -round(LineString([gradient_start, gradient_end]).project(Point(bottom_line.coords[0])) / fill.row_spacing)
+    stop_color_line_indices = [gradient_start_line_index]
+    gradient_line = LineString([gradient_start, gradient_end])
+    for offset in offsets[1:]:
+        stop_color_line_indices.append(round((gradient_line.length * offset) / fill.row_spacing) + gradient_start_line_index)
+
+    return lines, colors, stop_color_line_indices
+
+
+def _get_gradient_info(fill, bbox):
+    if fill.gradient is None:
+        # there is no linear gradient, let's simply space out one single color instead
+        angle = fill.angle
+        offsets = [0, 1]
+        colors = [fill.color, 'none']
+        gradient_start = (bbox[0], bbox[1])
+        gradient_end = (bbox[2], bbox[3])
+    else:
+        fill.gradient.apply_transform()
+        offsets = fill.gradient.stop_offsets
+        colors = [style['stop-color'] if float(style['stop-opacity']) > 0 else 'none' for style in fill.gradient.stop_styles]
+        gradient_start, gradient_end = gradient_start_end(fill.node, fill.gradient)
+        angle = gradient_angle(fill.node, fill.gradient)
+    return angle, colors, offsets, gradient_start, gradient_end
+
+
+def _get_lines(fill, shape, bounding_box, angle):
+    '''
+    To generate the lines we rotate the bounding box to bring the angle in vertical position.
+    From bounds we create a Polygon which we then rotate back, so we receive a rotated bounding box
+    which aligns well to the stitch angle. Combining the points of the subdivided top and bottom line
+    will finally deliver to our stitch rows
+    '''
+
+    # get the rotated bounding box for the shape
+    rotated_shape = rotate(shape, -angle, origin=(bounding_box[0], bounding_box[3]), use_radians=True)
+    bounds = rotated_shape.bounds
+
+    # Generate a Polygon from the rotated bounding box which we then rotate back into original position
+    # extend bounding box for lines just a little to make sure we cover the whole area with lines
+    # this avoids rounding errors due to the rotation later on
+    rot_bbox = Polygon([
+        (bounds[0] - fill.max_stitch_length, bounds[1] - fill.row_spacing),
+        (bounds[2] + fill.max_stitch_length, bounds[1] - fill.row_spacing),
+        (bounds[2] + fill.max_stitch_length, bounds[3] + fill.row_spacing),
+        (bounds[0] - fill.max_stitch_length, bounds[3] + fill.row_spacing)
+    ])
+    # and rotate it back into original position
+    rot_bbox = list(rotate(rot_bbox, angle, origin=(bounding_box[0], bounding_box[3]), use_radians=True).exterior.coords)
+
+    # segmentize top and bottom line to finally be ableto generate the stitch lines
+    top_line = LineString([rot_bbox[0], rot_bbox[1]])
+    top = segmentize(top_line, max_segment_length=fill.row_spacing)
+
+    bottom_line = LineString([rot_bbox[3], rot_bbox[2]])
+    bottom = segmentize(bottom_line, max_segment_length=fill.row_spacing)
+
+    lines = list(zip(top.coords, bottom.coords))
+
+    # stagger stitched lines according to user settings
+    staggered_lines = []
+    for i, line in enumerate(lines):
+        staggered_line = apply_stitches(LineString(line), fill.max_stitch_length, fill.staggers, fill.row_spacing, i)
+        staggered_lines.append(staggered_line)
+    return staggered_lines, bottom_line
+
+
+def _get_color_lines(lines, colors, stop_color_line_indices):
+    '''
+    To define which line will be stitched in which color, we will loop through the color sections
+    defined by the stop positions of the gradient (stop_color_line_indices).
+    Each section will then be subdivided into smaller sections using the square root of the total line number
+    of the whole section. Lines left over from this operation will be added step by step to the smaller sub-sections.
+    Since we do this symmetrically we may end one line short, which we an add at the end.
+
+    Now we define the line colors of the first half of our color section, we will later mirror this on the second half.
+    Therefor we use one additional line of color2 in each sub-section and position them as evenly as possible between the color1 lines.
+    Doing this we take care, that the number of consecutive lines of color1 is always decreasing.
+
+    For example let's take a 12 lines sub-section, with 5 lines of color2.
+    12 / 5 = 2.4
+    12 % 5 = 2
+    This results into the following pattern:
+    xx|xx|x|x|x| (while x = color1 and | = color2).
+    Note that the first two parts have an additional line (as defined by the modulo operation)
+
+    Method returns
+    color_lines: A dictionary with lines grouped by color
+    colors:      An updated list of color values.
+                 Colors which are positioned outside the shape will be removed.
+    '''
+
+    # create dictionary with a key for each color
+    color_lines = {}
+    for color in colors:
+        color_lines[color] = []
+
+    prev_color = colors[0]
+    prev = None
+    for line_index, color in zip(stop_color_line_indices, colors):
+        if prev is None:
+            if line_index > 0:
+                color_lines[color].extend(lines[0:line_index + 1])
+            prev = line_index
+            prev_color = color
+            continue
+        if prev < 0 and line_index < 0:
+            prev = line_index
+            prev_color = color
+            continue
+
+        prev += 1
+        line_index += 1
+        total_lines = line_index - prev
+        sections = floor(sqrt(total_lines))
+
+        color1 = []
+        color2 = []
+
+        c2_count = 0
+        c1_count = 0
+        current_line = 0
+
+        line_count_diff = floor((total_lines - sections**2) / 2)
+
+        stop = False
+        for i in range(sections):
+            if stop:
+                break
+
+            c2_count += 1
+            c1_count = sections - c2_count
+            rest = c1_count % c2_count
+            c1_count = ceil(c1_count / c2_count)
+
+            current_line, line_count_diff, color1, color2, stop = _add_lines(
+                current_line,
+                total_lines,
+                line_count_diff,
+                color1,
+                color2,
+                stop,
+                rest,
+                c1_count,
+                c2_count
+            )
+
+        # mirror the first half of the color section to receive the full section
+        second_half = color2[-1] * 2 + 1
+
+        color1 = np.array(color1)
+        color2 = np.array(color2)
+
+        c1 = np.append(color1, second_half - color2)
+        color2 = np.append(color2, second_half - color1)
+        color1 = c1
+
+        # until now we only cared about the length of the section
+        # now we need to move it to the correct position
+        color1 += prev
+        color2 += prev
+
+        # add lines to their color key in the dictionary
+        # as sections can start before or after the actual shape we need to make sure,
+        # that we only try to add existing lines
+        color_lines[prev_color].extend([lines[x] for x in color1 if 0 < x < len(lines)])
+        color_lines[color].extend([lines[x] for x in color2 if 0 < x < len(lines)])
+
+        prev = np.max(color2)
+        prev_color = color
+
+        check_stop_flag()
+
+    # add left over lines to last color
+    color_lines[color].extend(lines[prev+1:])
+
+    # remove transparent colors (we just want a gap)
+    color_lines.pop('none', None)
+
+    # remove empty line lists and update colors
+    color_lines = {color: lines for color, lines in color_lines.items() if lines}
+    colors = list(color_lines.keys())
+
+    return color_lines, colors
+
+
+def _add_lines(current_line, total_lines, line_count_diff, color1, color2, stop, rest, c1_count, c2_count):
+    for j in range(c2_count):
+        if stop:
+            break
+        if rest == 0 or j < rest:
+            count = c1_count
+        else:
+            count = c1_count - 1
+        if line_count_diff > 0:
+            count += 1
+            line_count_diff -= 1
+        for k in range(count):
+            color1.append(current_line)
+            current_line += 1
+            if total_lines / 2 <= current_line + 1:
+                stop = True
+                break
+        color2.append(current_line)
+        current_line += 1
+    return current_line, line_count_diff, color1, color2, stop
+
+
+def _get_stitch_groups(fill, shape, colors, color_lines, starting_point, ending_point):
+    stitch_groups = []
+    for i, color in enumerate(colors):
+        lines = color_lines[color]
+
+        multiline = MultiLineString(lines).intersection(shape)
+        if not isinstance(multiline, MultiLineString):
+            if isinstance(multiline, LineString):
+                multiline = MultiLineString([multiline])
+            else:
+                continue
+        segments = [list(line.coords) for line in multiline.geoms if len(line.coords) > 1]
+
+        fill_stitch_graph = build_fill_stitch_graph(shape, segments, starting_point, ending_point)
+
+        if not graph_is_valid(fill_stitch_graph):
+            # try to eulerize
+            fill_stitch_graph = eulerize(fill_stitch_graph)
+            # still not valid? continue without rendering the color section
+            if not graph_is_valid(fill_stitch_graph):
+                continue
+
+        travel_graph = build_travel_graph(fill_stitch_graph, shape, fill.angle, False)
+        path = find_stitch_path(fill_stitch_graph, travel_graph, starting_point, ending_point)
+        stitches = path_to_stitches(
+            shape,
+            path,
+            travel_graph,
+            fill_stitch_graph,
+            fill.running_stitch_length,
+            fill.running_stitch_tolerance,
+            fill.skip_last,
+            False  # no underpath
+        )
+
+        stitches = _remove_start_end_travel(fill, stitches, colors, i)
+
+        stitch_groups.append(StitchGroup(
+            color=color,
+            tags=("linear_gradient_fill", "auto_fill_top"),
+            stitches=stitches,
+            force_lock_stitches=fill.force_lock_stitches,
+            lock_stitches=fill.lock_stitches,
+            trim_after=fill.has_command("trim") or fill.trim_after
+        ))
+
+    return stitch_groups
+
+
+def _remove_start_end_travel(fill, stitches, colors, color_section):
+    # We can savely remove travel stitches at start since we are changing color all the time
+    # but we do care for the first starting point, it is important when they use an underlay of the same color
+    remove_before = 0
+    if color_section > 0 or not fill.fill_underlay:
+        for stitch in range(len(stitches)-1):
+            if 'auto_fill_travel' not in stitches[stitch].tags:
+                remove_before = stitch
+                break
+        stitches = stitches[remove_before:]
+    remove_after = len(stitches) - 1
+    # We also remove travel stitches at the end. It is optional to the user if the last color block travels
+    # to the defined ending point
+    if color_section < len(colors) - 2 or not fill.stop_at_ending_point:
+        for stitch in range(remove_after, 0, -1):
+            if 'auto_fill_travel' not in stitches[stitch].tags:
+                remove_after = stitch + 1
+                break
+        stitches = stitches[:remove_after]
+    return stitches
+
+
+def gradient_start_end(node, gradient):
+    transform = Transform(get_node_transform(node))
+    gradient_start = transform.apply_to_point((float(gradient.x1()), float(gradient.y1())))
+    gradient_end = transform.apply_to_point((float(gradient.x2()), float(gradient.y2())))
+    return gradient_start, gradient_end
+
+
+def gradient_angle(node, gradient):
+    if gradient is None:
+        return
+    gradient_start, gradient_end = gradient_start_end(node, gradient)
+    gradient_line = DirectedLineSegment(gradient_start, gradient_end)
+    return gradient_line.angle
diff --git a/lib/svg/tags.py b/lib/svg/tags.py
index 5713c399..e3d336df 100644
--- a/lib/svg/tags.py
+++ b/lib/svg/tags.py
@@ -97,6 +97,7 @@ inkstitch_attribs = [
     'staggers',
     'underlay_underpath',
     'underpath',
+    'stop_at_ending_point',
     'flip',
     'clip',
     # stroke