summaryrefslogtreecommitdiffstats
path: root/share/extensions/pixelsnap.py
diff options
context:
space:
mode:
Diffstat (limited to '')
-rwxr-xr-xshare/extensions/pixelsnap.py501
1 files changed, 501 insertions, 0 deletions
diff --git a/share/extensions/pixelsnap.py b/share/extensions/pixelsnap.py
new file mode 100755
index 0000000..e414af6
--- /dev/null
+++ b/share/extensions/pixelsnap.py
@@ -0,0 +1,501 @@
+#!/usr/bin/env python
+# coding=utf-8
+#
+# Copyright (c) 2009 Bryan Hoyt (MIT License)
+# 2011 Nicolas Dufour <nicoduf@yahoo.fr>
+# 2013 Johan B. C. Engelen <j.b.c.engelen@alumnus.utwente.nl>
+# 2019 Martin Owens <doctormo@gmail.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+"""
+TODO: mark elements that have previously been snapped, along with the settings
+ used, so that the same settings can be used for that element next time when
+ it's selected as part of a group (and add an option to the extension dialog
+ "Use previous/default settings" which is selected by default)
+
+TODO: make elem_offset return [x_offset, y_offset] so we can handle non-symetric scaling
+ => will probably need to take into account non-symetric scaling on stroke-widths,
+ too (horizontal vs vertical strokes)
+
+TODO: Transforming points isn't quite perfect, to say the least. In particular,
+ when translating a point on a bezier curve, we translate the handles by the same amount.
+ BUT, some handles that are attached to a particular point are conceptually
+ handles of the prev/next node.
+ Best way to fix it would be to keep a list of the fractional_offsets[] of
+ each point, without transforming anything. Then go through each point and
+ transform the appropriate handle according to the relevant fraction_offset
+ in the list.
+
+ i.e. calculate first, then modify.
+
+ In fact, that might be a simpler algorithm anyway -- it avoids having
+ to keep track of all the first_xy/next_xy guff.
+
+Note: This doesn't work very well on paths which have both straight segments
+ and curved segments.
+ The biggest three problems are:
+ a) we don't take handles into account (segments where the nodes are
+ aligned are always treated as straight segments, even where the
+ handles make it curve)
+ b) when we snap a straight segment right before/after a curve, it
+ doesn't make any attempt to keep the transition from the straight
+ segment to the curve smooth.
+ c) no attempt is made to keep equal widths equal. (or nearly-equal
+ widths nearly-equal). For example, font strokes.
+
+Note: Paths that have curves & arcs on some sides of the bounding box won't
+ be snapped correctly on that side of the bounding box, and nor will they
+ be translated/resized correctly before the path is modified. Doesn't affect
+ most applications of this extension, but it highlights the fact that we
+ take a geometrically simplistic approach to inspecting & modifying the path.
+"""
+
+from __future__ import division
+from __future__ import print_function
+
+import sys
+
+import inkex
+from inkex import PathElement, Group, Image, Rectangle, ShapeElement, Transform
+from inkex.localization import inkex_gettext as _
+
+Precision = 5 # number of digits of precision for comparing float numbers
+
+
+class TransformError(Exception):
+ pass
+
+
+def transform_point(transform, pt, inverse=False):
+ """apply_to_point with inbuilt inverse"""
+ if inverse:
+ transform = -transform
+ return transform.apply_to_point(pt)
+
+
+def transform_dimensions(transform, width=None, height=None, inverse=False):
+ """Dimensions don't get translated. I'm not sure how much diff rotate/skew
+ makes in this context, but we currently ignore anything besides scale.
+ """
+ if inverse:
+ transform = -transform
+
+ if width is not None:
+ width *= transform.a
+ if height is not None:
+ height *= transform.d
+
+ if width is not None and height is not None:
+ return width, height
+ if width is not None:
+ return width
+ if height is not None:
+ return height
+
+
+class PixelSnap(inkex.EffectExtension):
+ """Snap objects to pixels"""
+
+ def add_arguments(self, pars):
+ """Add inx options"""
+ pars.add_argument(
+ "-a",
+ "--snap_ancestors",
+ type=inkex.Boolean,
+ default=True,
+ help="Snap unselected ancestors' translations "
+ "(groups, layers, document height) first",
+ )
+ pars.add_argument(
+ "-t",
+ "--ancestor_offset",
+ type=inkex.Boolean,
+ default=True,
+ help="Calculate offset relative to unselected ancestors' "
+ "transforms (includes document height offset)",
+ )
+ pars.add_argument(
+ "-g",
+ "--max_gradient",
+ type=float,
+ default=0.5,
+ help="Maximum slope to consider straight (%)",
+ )
+ pars.add_argument(
+ "-s",
+ "--snap_to",
+ default="tl",
+ choices=["tl", "bl"],
+ help="Origin of the coordinate system",
+ )
+
+ def vertical(self, pt1, pt2):
+ hlen = abs(pt1[0] - pt2[0])
+ vlen = abs(pt1[1] - pt2[1])
+ if vlen == 0 and hlen == 0:
+ return True
+ elif vlen == 0:
+ return False
+ return (hlen / vlen) < self.options.max_gradient / 100
+
+ def horizontal(self, pt1, pt2):
+ hlen = round(abs(pt1[0] - pt2[0]), Precision)
+ vlen = round(abs(pt1[1] - pt2[1]), Precision)
+ if hlen == 0 and vlen == 0:
+ return True
+ elif hlen == 0:
+ return False
+ return (vlen / hlen) < self.options.max_gradient / 100
+
+ def stroke_width_offset(self, elem, parent_transform=None):
+ """Returns the amount the bounding-box is offset due to the stroke-width.
+ Transform is taken into account.
+ """
+ stroke_width = self.stroke_width(elem)
+ if stroke_width == 0:
+ return 0 # if there's no stroke, no need to worry about the transform
+
+ transform = elem.transform @ Transform(parent_transform)
+
+ if abs(abs(transform.a) - abs(transform.d)) > (10**-Precision):
+ raise TransformError(
+ _("Selection contains non-symetric scaling")
+ ) # *** wouldn't be hard to get around this by calculating vertical_offset & horizontal_offset separately, maybe 1 functions, or maybe returning a tuple
+
+ stroke_width = transform_dimensions(transform, width=stroke_width)
+
+ return stroke_width / 2
+
+ def stroke_width(self, elem, setval=None):
+ """Get/set stroke-width in pixels, untransformed"""
+ style = elem.style
+ stroke = style("stroke")
+
+ stroke_width = 0
+ if stroke and setval is None:
+ stroke_width = self.svg.to_dimensionless(style("stroke-width").strip())
+
+ if setval:
+ style["stroke-width"] = setval
+ else:
+ return stroke_width
+
+ def transform_path_node(self, transform, path, i):
+ """Modifies a segment so that every point is transformed, including handles"""
+ segtype = path[i][0].lower()
+
+ if segtype == "z":
+ return
+ elif segtype == "h":
+ path[i][1][0] = transform_point(transform, [path[i][1][0], 0])[0]
+ elif segtype == "v":
+ path[i][1][0] = transform_point(transform, [0, path[i][1][0]])[1]
+ else:
+ first_coordinate = 0
+ if segtype == "a":
+ first_coordinate = 5 # for elliptical arcs, skip the radius x/y, rotation, large-arc, and sweep
+ for j in range(first_coordinate, len(path[i][1]), 2):
+ x, y = path[i][1][j], path[i][1][j + 1]
+ x, y = transform_point(transform, (x, y))
+ path[i][1][j] = x
+ path[i][1][j + 1] = y
+
+ def pathxy(self, path, i, setval=None):
+ """Return the endpoint of the given path segment.
+ Inspects the segment type to know which elements are the endpoints.
+ """
+ segtype = path[i][0].lower()
+ x = y = 0
+
+ if segtype == "z":
+ i = 0
+
+ if segtype == "h":
+ if setval:
+ path[i][1][0] = setval[0]
+ else:
+ x = path[i][1][0]
+
+ elif segtype == "v":
+ if setval:
+ path[i][1][0] = setval[1]
+ else:
+ y = path[i][1][0]
+ else:
+ if setval and segtype != "z":
+ path[i][1][-2] = setval[0]
+ path[i][1][-1] = setval[1]
+ else:
+ x = path[i][1][-2]
+ y = path[i][1][-1]
+
+ if setval is None:
+ return [x, y]
+
+ def snap_path_scale(self, elem, parent_transform=None):
+
+ path = elem.original_path.to_arrays()
+ transform = elem.transform @ Transform(parent_transform)
+ bbox = elem.bounding_box()
+
+ # In case somebody tries to snap a 0-high element,
+ # or a curve/arc with all nodes in a line, and of course
+ # because we should always check for divide-by-zero!
+ if not bbox.width or not bbox.height:
+ return
+
+ width, height = bbox.width, bbox.height
+ min_xy, max_xy = bbox.minimum, bbox.maximum
+ rescale = round(width) / width, round(height) / height
+
+ min_xy = transform_point(transform, min_xy, inverse=True)
+ max_xy = transform_point(transform, max_xy, inverse=True)
+
+ for i in range(len(path)):
+ translate = Transform(translate=min_xy)
+ self.transform_path_node(-translate, path, i) # center transform
+ self.transform_path_node(Transform(scale=rescale), path, i)
+ self.transform_path_node(translate, path, i) # uncenter transform
+
+ elem.original_path = path
+
+ def snap_path_pos(self, elem, parent_transform=None):
+ path = elem.original_path.to_arrays()
+ transform = elem.transform @ Transform(parent_transform)
+ bbox = elem.bounding_box()
+ min_xy, max_xy = bbox.minimum, bbox.maximum
+
+ fractional_offset = (
+ min_xy[0] - round(min_xy[0]),
+ min_xy[1] - round(min_xy[1]) - self.document_offset,
+ )
+ fractional_offset = transform_dimensions(
+ transform, fractional_offset[0], fractional_offset[1], inverse=True
+ )
+
+ for i in range(len(path)):
+ self.transform_path_node(-Transform(translate=fractional_offset), path, i)
+
+ path = str(inkex.Path(path))
+ if elem.get("inkscape:original-d"):
+ elem.set("inkscape:original-d", path)
+ else:
+ elem.set("d", path)
+
+ def snap_transform(self, elem):
+ # Only snaps the x/y translation of the transform, nothing else.
+ # Doesn't take any parent_transform into account -- assumes
+ # that the parent's transform has already been snapped.
+ transform = elem.transform
+ # if we've got any skew/rotation, get outta here
+ if transform.c or transform.b:
+ raise TransformError(
+ _("TR: Selection contains transformations with skew/rotation")
+ )
+
+ trm = list(transform.to_hexad())
+ trm[4] = round(transform.e)
+ trm[5] = round(transform.f)
+ elem.transform @= Transform(trm)
+
+ def snap_stroke(self, elem, parent_transform=None):
+ transform = elem.transform @ Transform(parent_transform)
+
+ stroke_width = self.stroke_width(elem)
+ if stroke_width == 0:
+ return # no point raising a TransformError if there's no stroke to snap
+
+ if abs(abs(transform.a) - abs(transform.d)) > (10**-Precision):
+ raise TransformError(
+ _("Selection contains non-symetric scaling, can't snap stroke width")
+ )
+
+ if stroke_width:
+ stroke_width = transform_dimensions(transform, width=stroke_width)
+ stroke_width = round(stroke_width)
+ stroke_width = transform_dimensions(
+ transform, width=stroke_width, inverse=True
+ )
+ self.stroke_width(elem, stroke_width)
+
+ def snap_path(self, elem, parent_transform=None):
+ path = elem.original_path.to_arrays()
+
+ transform = elem.transform @ Transform(parent_transform)
+
+ if transform.c or transform.b: # if we've got any skew/rotation, get outta here
+ raise TransformError(
+ _("Path: Selection contains transformations with skew/rotation")
+ )
+
+ offset = self.stroke_width_offset(elem, parent_transform) % 1
+
+ prev_xy = self.pathxy(path, -1)
+ first_xy = self.pathxy(path, 0)
+ for i in range(len(path)):
+ segtype = path[i][0].lower()
+ xy = self.pathxy(path, i)
+ if segtype == "z":
+ xy = first_xy
+ if (i == len(path) - 1) or (
+ (i == len(path) - 2) and path[-1][0].lower() == "z"
+ ):
+ next_xy = first_xy
+ else:
+ next_xy = self.pathxy(path, i + 1)
+
+ if not (xy and prev_xy and next_xy):
+ prev_xy = xy
+ continue
+
+ xy_untransformed = tuple(xy)
+ xy = list(transform_point(transform, xy))
+ prev_xy = transform_point(transform, prev_xy)
+ next_xy = transform_point(transform, next_xy)
+
+ on_vertical = on_horizontal = False
+
+ if self.horizontal(xy, prev_xy):
+ # on 2-point paths, first.next==first.prev==last and last.next==last.prev==first
+ if len(path) > 2 or i == 0:
+ # make the almost-equal values equal, so they round in the same direction
+ xy[1] = prev_xy[1]
+ on_horizontal = True
+ if self.horizontal(xy, next_xy):
+ on_horizontal = True
+
+ if self.vertical(xy, prev_xy): # as above
+ if len(path) > 2 or i == 0:
+ xy[0] = prev_xy[0]
+ on_vertical = True
+ if self.vertical(xy, next_xy):
+ on_vertical = True
+
+ prev_xy = tuple(xy_untransformed)
+
+ fractional_offset = [0, 0]
+ if on_vertical:
+ fractional_offset[0] = xy[0] - (round(xy[0] - offset) + offset)
+ if on_horizontal:
+ fractional_offset[1] = (
+ xy[1] - (round(xy[1] - offset) + offset) - self.document_offset
+ )
+
+ fractional_offset = transform_dimensions(
+ transform, fractional_offset[0], fractional_offset[1], inverse=True
+ )
+ self.transform_path_node(-Transform(translate=fractional_offset), path, i)
+
+ elem.original_path = path
+
+ def snap_rect(self, elem, parent_transform=None):
+ transform = elem.transform @ Transform(parent_transform)
+
+ if transform.c or transform.b: # if we've got any skew/rotation, get outta here
+ raise TransformError(
+ _("Rect: Selection contains transformations with skew/rotation")
+ )
+
+ offset = self.stroke_width_offset(elem, parent_transform) % 1
+
+ width = self.svg.to_dimensionless(elem.attrib["width"])
+ height = self.svg.to_dimensionless(elem.attrib["height"])
+ x = self.svg.to_dimensionless(elem.attrib["x"])
+ y = self.svg.to_dimensionless(elem.attrib["y"])
+
+ width, height = transform_dimensions(transform, width, height)
+ x, y = transform_point(transform, [x, y])
+
+ # Snap to the nearest pixel
+ height = round(height)
+ width = round(width)
+ x = (
+ round(x - offset) + offset
+ ) # If there's a stroke of non-even width, it's shifted by half a pixel
+ y = round(y - offset) + offset
+
+ width, height = transform_dimensions(transform, width, height, inverse=True)
+ x, y = transform_point(transform, [x, y], inverse=True)
+ y += self.document_offset / transform.d
+
+ # Position the elem at the newly calculate values
+ elem.attrib["width"] = str(width)
+ elem.attrib["height"] = str(height)
+ elem.attrib["x"] = str(x)
+ elem.attrib["y"] = str(y)
+
+ def snap_image(self, elem, parent_transform=None):
+ self.snap_rect(elem, parent_transform)
+
+ def pixel_snap(self, elem, parent_transform=None):
+ if not isinstance(elem, (Group, Image, Rectangle, PathElement)):
+ return
+
+ if isinstance(elem, Group):
+ self.snap_transform(elem)
+ transform = elem.transform * Transform(parent_transform)
+ for child in elem:
+ try:
+ self.pixel_snap(child, transform)
+ except TransformError as err:
+ raise inkex.AbortExtension(str(err))
+ return
+
+ # If we've been given a parent_transform, we can assume that the
+ # parents have already been snapped, or don't need to be
+ if self.options.snap_ancestors and parent_transform is None:
+ # Loop through ancestors from outermost to innermost, excluding this element.
+ for child in elem.ancestors():
+ self.snap_transform(child)
+
+ # If we haven't been given a parent_transform, then we need to calculate it
+ if self.options.ancestor_offset and parent_transform is None:
+ if isinstance(elem.getparent(), ShapeElement):
+ parent_transform = elem.getparent().composed_transform()
+
+ self.snap_transform(elem)
+ try:
+ self.snap_stroke(elem, parent_transform)
+ except TransformError as err:
+ raise inkex.AbortExtension(str(err))
+
+ if isinstance(elem, PathElement):
+ self.snap_path_scale(elem, parent_transform)
+ self.snap_path_pos(elem, parent_transform)
+ self.snap_path(
+ elem, parent_transform
+ ) # would be quite useful to make this an option, as scale/pos alone doesn't mess with the path itself, and works well for sans-serif text
+ elif isinstance(elem, Rectangle):
+ self.snap_rect(elem, parent_transform)
+ elif isinstance(elem, Image):
+ self.snap_image(elem, parent_transform)
+
+ def effect(self):
+ if self.options.snap_to == "bl":
+ self.document_offset = (
+ self.svg.to_dimensionless(self.svg.get_viewbox()[3]) % 1
+ )
+ else:
+ self.document_offset = 0
+ for id, elem in self.svg.selection.items():
+ try:
+ self.pixel_snap(elem)
+ except TransformError as err:
+ raise inkex.AbortExtension(str(err))
+
+
+if __name__ == "__main__":
+ PixelSnap().run()