Add transform extension which also transforms the fill angles (#3657)

1 files changed, 112 insertions, 0 deletions

diff --git a/lib/extensions/transform_elements.py b/lib/extensions/transform_elements.py
new file mode 100644
index 00000000..66d0ad82
--- /dev/null
+++ b/lib/extensions/transform_elements.py
@@ -0,0 +1,112 @@
+# Authors: see git history
+#
+# Copyright (c) 2025 Authors
+# Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.
+
+import json
+from typing import Optional
+
+from inkex import (Boolean, PathElement, ShapeElement, Transform, Vector2d,
+                   errormsg)
+
+from ..i18n import _
+from ..tartan.utils import get_tartan_settings
+from .base import InkstitchExtension
+
+
+class TransformElements(InkstitchExtension):
+    '''
+    This will apply transformations while also transforming fill angles.
+    '''
+    def __init__(self, *args, **kwargs):
+        InkstitchExtension.__init__(self, *args, **kwargs)
+        self.arg_parser.add_argument("--notebook")
+        self.arg_parser.add_argument("-r", "--rotate", type=float, default=0, dest="rotate")
+        self.arg_parser.add_argument("-f", "--flip-horizontally", type=Boolean, default=False, dest="horizontal_flip")
+        self.arg_parser.add_argument("-v", "--flip-vertically", type=Boolean, default=False, dest="vertical_flip")
+
+    def effect(self) -> None:
+        if not self.svg.selection:
+            errormsg(_("Please select one or more elements."))
+            return
+        selection_center = self.svg.selection.bounding_box().center
+
+        nodes = self.get_nodes()
+        for node in nodes:
+            parent_transform = node.composed_transform() @ -node.transform
+            if self.options.rotate != 0:
+                self.rotate_node(node, parent_transform, selection_center)
+            if self.options.horizontal_flip:
+                self.flip_node_horizontally(node, parent_transform, selection_center)
+            if self.options.vertical_flip:
+                self.flip_node_vertically(node, parent_transform, selection_center)
+
+            # Apply transform to path elements, simply because it's possible and nicer
+            if isinstance(node, PathElement):
+                node.apply_transform()
+
+    def flip_node_vertically(self, node: ShapeElement, parent_transform: Transform, center: Vector2d) -> None:
+        node.transform = (
+            -parent_transform @
+            Transform(f'translate({center[0], center[1]}) scale(1, -1) translate({-center[0], -center[1]})') @
+            node.composed_transform()
+        )
+        self.adapt_fill_angle(node, -1)
+
+    def flip_node_horizontally(self, node: ShapeElement, parent_transform: Transform, center: Vector2d) -> None:
+        node.transform = (
+            -parent_transform @
+            Transform(f'translate({center[0], center[1]}) scale(-1, 1) translate({-center[0], -center[1]})') @
+            node.composed_transform()
+        )
+        self.adapt_fill_angle(node, -1)
+
+    def rotate_node(self, node: ShapeElement, parent_transform: Transform, center: Vector2d) -> None:
+        node.transform = (
+            -parent_transform @
+            Transform(f'rotate({self.options.rotate}, {center[0]}, {center[1]})') @
+            node.composed_transform()
+        )
+        self.adapt_fill_angle(node, None, self.options.rotate)
+
+    def adapt_fill_angle(self, node: ShapeElement, multiplier: Optional[int] = None, rotation: Optional[float] = None) -> None:
+        if not node.style("fill", "black"):
+            return
+
+        self._apply_angle(node, "inkstitch:fill_underlay_angle", None, multiplier, rotation)
+        if node.get('inkstitch:fill_method', None) == "tartan_fill":
+            if rotation is None:
+                self._apply_angle(node, "inkstitch:tartan_angle", "-45", multiplier, rotation)
+            # Also rotate tartan pattern rotation setting
+            self._rotate_tartan_pattern(node, multiplier, rotation)
+        elif node.get('inkstitch:fill_method', None) == "meander_fill":
+            self._apply_angle(node, "inkstitch:meander_angle", "0", multiplier, rotation)
+        else:
+            self._apply_angle(node, "inkstitch:angle", "0", multiplier, rotation)
+
+    def _apply_angle(self, node: ShapeElement, attrib: str, default: Optional[str], multiplier: Optional[int], rotation: Optional[float]) -> None:
+        angle_string = node.get(attrib, default)
+        if angle_string is None:
+            return
+
+        try:
+            angle = float(angle_string)
+        except ValueError:
+            return
+
+        if multiplier is not None:
+            angle *= multiplier
+        elif rotation is not None:
+            angle -= rotation
+        node.set(attrib, str(angle))
+
+    def _rotate_tartan_pattern(self, node: ShapeElement, multiplier: Optional[int], rotation: Optional[float]) -> None:
+        settings = get_tartan_settings(node)
+        tartan_rotation = settings['rotate']
+
+        if multiplier is not None:
+            tartan_rotation *= multiplier
+        elif rotation is not None:
+            tartan_rotation += rotation
+        settings['rotate'] = tartan_rotation
+        node.set("inkstitch:tartan", json.dumps(settings))