Permalink
Fetching contributors…
Cannot retrieve contributors at this time
408 lines (348 sloc) 12 KB
"""
=========
PointPens
=========
Where **SegmentPens** have an intuitive approach to drawing
(if you're familiar with postscript anyway), the **PointPen**
is geared towards accessing all the data in the contours of
the glyph. A PointPen has a very simple interface, it just
steps through all the points in a call from glyph.drawPoints().
This allows the caller to provide more data for each point.
For instance, whether or not a point is smooth, and its name.
"""
from __future__ import absolute_import, unicode_literals
from fontTools.pens.basePen import AbstractPen
import math
__all__ = ["AbstractPointPen", "BasePointToSegmentPen", "PointToSegmentPen",
"SegmentToPointPen"]
class AbstractPointPen(object):
"""
Baseclass for all PointPens.
"""
def beginPath(self, identifier=None, **kwargs):
"""Start a new sub path."""
raise NotImplementedError
def endPath(self):
"""End the current sub path."""
raise NotImplementedError
def addPoint(self, pt, segmentType=None, smooth=False, name=None,
identifier=None, **kwargs):
"""Add a point to the current sub path."""
raise NotImplementedError
def addComponent(self, baseGlyphName, transformation, identifier=None,
**kwargs):
"""Add a sub glyph."""
raise NotImplementedError
class BasePointToSegmentPen(AbstractPointPen):
"""
Base class for retrieving the outline in a segment-oriented
way. The PointPen protocol is simple yet also a little tricky,
so when you need an outline presented as segments but you have
as points, do use this base implementation as it properly takes
care of all the edge cases.
"""
def __init__(self):
self.currentPath = None
def beginPath(self, **kwargs):
assert self.currentPath is None
self.currentPath = []
def _flushContour(self, segments):
"""Override this method.
It will be called for each non-empty sub path with a list
of segments: the 'segments' argument.
The segments list contains tuples of length 2:
(segmentType, points)
segmentType is one of "move", "line", "curve" or "qcurve".
"move" may only occur as the first segment, and it signifies
an OPEN path. A CLOSED path does NOT start with a "move", in
fact it will not contain a "move" at ALL.
The 'points' field in the 2-tuple is a list of point info
tuples. The list has 1 or more items, a point tuple has
four items:
(point, smooth, name, kwargs)
'point' is an (x, y) coordinate pair.
For a closed path, the initial moveTo point is defined as
the last point of the last segment.
The 'points' list of "move" and "line" segments always contains
exactly one point tuple.
"""
raise NotImplementedError
def endPath(self):
assert self.currentPath is not None
points = self.currentPath
self.currentPath = None
if not points:
return
if len(points) == 1:
# Not much more we can do than output a single move segment.
pt, segmentType, smooth, name, kwargs = points[0]
segments = [("move", [(pt, smooth, name, kwargs)])]
self._flushContour(segments)
return
segments = []
if points[0][1] == "move":
# It's an open contour, insert a "move" segment for the first
# point and remove that first point from the point list.
pt, segmentType, smooth, name, kwargs = points[0]
segments.append(("move", [(pt, smooth, name, kwargs)]))
points.pop(0)
else:
# It's a closed contour. Locate the first on-curve point, and
# rotate the point list so that it _ends_ with an on-curve
# point.
firstOnCurve = None
for i in range(len(points)):
segmentType = points[i][1]
if segmentType is not None:
firstOnCurve = i
break
if firstOnCurve is None:
# Special case for quadratics: a contour with no on-curve
# points. Add a "None" point. (See also the Pen protocol's
# qCurveTo() method and fontTools.pens.basePen.py.)
points.append((None, "qcurve", None, None, None))
else:
points = points[firstOnCurve+1:] + points[:firstOnCurve+1]
currentSegment = []
for pt, segmentType, smooth, name, kwargs in points:
currentSegment.append((pt, smooth, name, kwargs))
if segmentType is None:
continue
segments.append((segmentType, currentSegment))
currentSegment = []
self._flushContour(segments)
def addPoint(self, pt, segmentType=None, smooth=False, name=None, **kwargs):
self.currentPath.append((pt, segmentType, smooth, name, kwargs))
class PointToSegmentPen(BasePointToSegmentPen):
"""
Adapter class that converts the PointPen protocol to the
(Segment)Pen protocol.
"""
def __init__(self, segmentPen, outputImpliedClosingLine=False):
BasePointToSegmentPen.__init__(self)
self.pen = segmentPen
self.outputImpliedClosingLine = outputImpliedClosingLine
def _flushContour(self, segments):
assert len(segments) >= 1
pen = self.pen
if segments[0][0] == "move":
# It's an open path.
closed = False
points = segments[0][1]
assert len(points) == 1, "illegal move segment point count: %d" % len(points)
movePt, smooth, name, kwargs = points[0]
del segments[0]
else:
# It's a closed path, do a moveTo to the last
# point of the last segment.
closed = True
segmentType, points = segments[-1]
movePt, smooth, name, kwargs = points[-1]
if movePt is None:
# quad special case: a contour with no on-curve points contains
# one "qcurve" segment that ends with a point that's None. We
# must not output a moveTo() in that case.
pass
else:
pen.moveTo(movePt)
outputImpliedClosingLine = self.outputImpliedClosingLine
nSegments = len(segments)
for i in range(nSegments):
segmentType, points = segments[i]
points = [pt for pt, smooth, name, kwargs in points]
if segmentType == "line":
assert len(points) == 1, "illegal line segment point count: %d" % len(points)
pt = points[0]
if i + 1 != nSegments or outputImpliedClosingLine or not closed:
pen.lineTo(pt)
elif segmentType == "curve":
pen.curveTo(*points)
elif segmentType == "qcurve":
pen.qCurveTo(*points)
else:
assert 0, "illegal segmentType: %s" % segmentType
if closed:
pen.closePath()
else:
pen.endPath()
def addComponent(self, glyphName, transform, **kwargs):
self.pen.addComponent(glyphName, transform)
class SegmentToPointPen(AbstractPen):
"""
Adapter class that converts the (Segment)Pen protocol to the
PointPen protocol.
"""
def __init__(self, pointPen, guessSmooth=True):
if guessSmooth:
self.pen = GuessSmoothPointPen(pointPen)
else:
self.pen = pointPen
self.contour = None
def _flushContour(self):
pen = self.pen
pen.beginPath()
for pt, segmentType in self.contour:
pen.addPoint(pt, segmentType=segmentType)
pen.endPath()
def moveTo(self, pt):
self.contour = []
self.contour.append((pt, "move"))
def lineTo(self, pt):
self.contour.append((pt, "line"))
def curveTo(self, *pts):
for pt in pts[:-1]:
self.contour.append((pt, None))
self.contour.append((pts[-1], "curve"))
def qCurveTo(self, *pts):
if pts[-1] is None:
self.contour = []
for pt in pts[:-1]:
self.contour.append((pt, None))
if pts[-1] is not None:
self.contour.append((pts[-1], "qcurve"))
def closePath(self):
if len(self.contour) > 1 and self.contour[0][0] == self.contour[-1][0]:
self.contour[0] = self.contour[-1]
del self.contour[-1]
else:
# There's an implied line at the end, replace "move" with "line"
# for the first point
pt, tp = self.contour[0]
if tp == "move":
self.contour[0] = pt, "line"
self._flushContour()
self.contour = None
def endPath(self):
self._flushContour()
self.contour = None
def addComponent(self, glyphName, transform):
assert self.contour is None
self.pen.addComponent(glyphName, transform)
class GuessSmoothPointPen(AbstractPointPen):
"""
Filtering PointPen that tries to determine whether an on-curve point
should be "smooth", ie. that it's a "tangent" point or a "curve" point.
"""
def __init__(self, outPen):
self._outPen = outPen
self._points = None
def _flushContour(self):
points = self._points
nPoints = len(points)
if not nPoints:
return
if points[0][1] == "move":
# Open path.
indices = range(1, nPoints - 1)
elif nPoints > 1:
# Closed path. To avoid having to mod the contour index, we
# simply abuse Python's negative index feature, and start at -1
indices = range(-1, nPoints - 1)
else:
# closed path containing 1 point (!), ignore.
indices = []
for i in indices:
pt, segmentType, dummy, name, kwargs = points[i]
if segmentType is None:
continue
prev = i - 1
next = i + 1
if points[prev][1] is not None and points[next][1] is not None:
continue
# At least one of our neighbors is an off-curve point
pt = points[i][0]
prevPt = points[prev][0]
nextPt = points[next][0]
if pt != prevPt and pt != nextPt:
dx1, dy1 = pt[0] - prevPt[0], pt[1] - prevPt[1]
dx2, dy2 = nextPt[0] - pt[0], nextPt[1] - pt[1]
a1 = math.atan2(dx1, dy1)
a2 = math.atan2(dx2, dy2)
if abs(a1 - a2) < 0.05:
points[i] = pt, segmentType, True, name, kwargs
for pt, segmentType, smooth, name, kwargs in points:
self._outPen.addPoint(pt, segmentType, smooth, name, **kwargs)
def beginPath(self):
assert self._points is None
self._points = []
self._outPen.beginPath()
def endPath(self):
self._flushContour()
self._outPen.endPath()
self._points = None
def addPoint(self, pt, segmentType=None, smooth=False, name=None, **kwargs):
self._points.append((pt, segmentType, False, name, kwargs))
def addComponent(self, glyphName, transformation):
assert self._points is None
self._outPen.addComponent(glyphName, transformation)
class ReverseContourPointPen(AbstractPointPen):
"""
This is a PointPen that passes outline data to another PointPen, but
reversing the winding direction of all contours. Components are simply
passed through unchanged.
Closed contours are reversed in such a way that the first point remains
the first point.
"""
def __init__(self, outputPointPen):
self.pen = outputPointPen
# a place to store the points for the current sub path
self.currentContour = None
def _flushContour(self):
pen = self.pen
contour = self.currentContour
if not contour:
pen.beginPath(identifier=self.currentContourIdentifier)
pen.endPath()
return
closed = contour[0][1] != "move"
if not closed:
lastSegmentType = "move"
else:
# Remove the first point and insert it at the end. When
# the list of points gets reversed, this point will then
# again be at the start. In other words, the following
# will hold:
# for N in range(len(originalContour)):
# originalContour[N] == reversedContour[-N]
contour.append(contour.pop(0))
# Find the first on-curve point.
firstOnCurve = None
for i in range(len(contour)):
if contour[i][1] is not None:
firstOnCurve = i
break
if firstOnCurve is None:
# There are no on-curve points, be basically have to
# do nothing but contour.reverse().
lastSegmentType = None
else:
lastSegmentType = contour[firstOnCurve][1]
contour.reverse()
if not closed:
# Open paths must start with a move, so we simply dump
# all off-curve points leading up to the first on-curve.
while contour[0][1] is None:
contour.pop(0)
pen.beginPath(identifier=self.currentContourIdentifier)
for pt, nextSegmentType, smooth, name, kwargs in contour:
if nextSegmentType is not None:
segmentType = lastSegmentType
lastSegmentType = nextSegmentType
else:
segmentType = None
pen.addPoint(pt, segmentType=segmentType, smooth=smooth, name=name, **kwargs)
pen.endPath()
def beginPath(self, identifier=None, **kwargs):
assert self.currentContour is None
self.currentContour = []
self.currentContourIdentifier = identifier
self.onCurve = []
def endPath(self):
assert self.currentContour is not None
self._flushContour()
self.currentContour = None
def addPoint(self, pt, segmentType=None, smooth=False, name=None, **kwargs):
self.currentContour.append((pt, segmentType, smooth, name, kwargs))
def addComponent(self, glyphName, transform, identifier=None, **kwargs):
assert self.currentContour is None
self.pen.addComponent(glyphName, transform, identifier=identifier, **kwargs)