1 files changed, 79 insertions, 0 deletions
diff --git a/lib/elements/gradient_fill.py b/lib/elements/gradient_fill.py
new file mode 100644
index 00000000..5ac49c4e
--- /dev/null
+++ b/lib/elements/gradient_fill.py
@@ -0,0 +1,79 @@
+from math import pi
+
+from inkex import DirectedLineSegment, Transform
+from shapely import geometry as shgeo
+from shapely.affinity import affine_transform, rotate
+from shapely.ops import split
+
+from ..svg import get_correction_transform
+
+
+def gradient_shapes_and_attributes(element, shape):
+    # e.g. url(#linearGradient872) -> linearGradient872
+    color = element.color[5:-1]
+    xpath = f'.//svg:defs/svg:linearGradient[@id="{color}"]'
+    gradient = element.node.getroottree().getroot().findone(xpath)
+    gradient.apply_transform()
+    point1 = (float(gradient.get('x1')), float(gradient.get('y1')))
+    point2 = (float(gradient.get('x2')), float(gradient.get('y2')))
+    # get 90° angle to calculate the splitting angle
+    line = DirectedLineSegment(point1, point2)
+    angle = line.angle - (pi / 2)
+    # Ink/Stitch somehow turns the stitch angle
+    stitch_angle = angle * -1
+    # create bbox polygon to calculate the length necessary to make sure that
+    # the gradient splitter lines will cut the entire design
+    bbox = element.node.bounding_box()
+    bbox_polygon = shgeo.Polygon([(bbox.left, bbox.top), (bbox.right, bbox.top),
+                                  (bbox.right, bbox.bottom), (bbox.left, bbox.bottom)])
+    # gradient stops
+    offsets = gradient.stop_offsets
+    stop_styles = gradient.stop_styles
+    # now split the shape according to the gradient stops
+    polygons = []
+    colors = []
+    attributes = []
+    previous_color = None
+    end_row_spacing = None
+    for i, offset in enumerate(offsets):
+        shape_rest = []
+        split_point = shgeo.Point(line.point_at_ratio(float(offset)))
+        length = split_point.hausdorff_distance(bbox_polygon)
+        split_line = shgeo.LineString([(split_point.x - length - 2, split_point.y),
+                                       (split_point.x + length + 2, split_point.y)])
+        split_line = rotate(split_line, angle, origin=split_point, use_radians=True)
+        transform = -Transform(get_correction_transform(element.node))
+        transform = list(transform.to_hexad())
+        split_line = affine_transform(split_line, transform)
+        offset_line = split_line.parallel_offset(1, 'right')
+        polygon = split(shape, split_line)
+        color = stop_styles[i]['stop-color']
+        # does this gradient line split the shape
+        offset_outside_shape = len(polygon.geoms) == 1
+        for poly in polygon.geoms:
+            if isinstance(poly, shgeo.Polygon) and element.shape_is_valid(poly):
+                if poly.intersects(offset_line):
+                    if previous_color:
+                        polygons.append(poly)
+                        colors.append(previous_color)
+                        attributes.append({'angle': stitch_angle, 'end_row_spacing': end_row_spacing, 'color': previous_color})
+                    polygons.append(poly)
+                    attributes.append({'angle': stitch_angle + pi, 'end_row_spacing': end_row_spacing, 'color': color})
+                else:
+                    shape_rest.append(poly)
+        shape = shgeo.MultiPolygon(shape_rest)
+        previous_color = color
+        end_row_spacing = element.row_spacing * 2
+    # add left over shape(s)
+    if shape:
+        if offset_outside_shape:
+            for s in shape.geoms:
+                polygons.append(s)
+                attributes.append({'color': stop_styles[-2]['stop-color'], 'angle': stitch_angle, 'end_row_spacing': end_row_spacing})
+            stitch_angle += pi
+        else:
+            end_row_spacing = None
+        for s in shape.geoms:
+            polygons.append(s)
+            attributes.append({'color': stop_styles[-1]['stop-color'], 'angle': stitch_angle, 'end_row_spacing': end_row_spacing})
+    return polygons, attributes