Source code for fontTools.pens.pointPen

"""
=========
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.
"""

import math
from typing import Any, Optional, Tuple

from fontTools.pens.basePen import AbstractPen, PenError

__all__ = [
	"AbstractPointPen",
	"BasePointToSegmentPen",
	"PointToSegmentPen",
	"SegmentToPointPen",
	"GuessSmoothPointPen",
	"ReverseContourPointPen",
]


[docs]class AbstractPointPen: """Baseclass for all PointPens."""
[docs] def beginPath(self, identifier: Optional[str] = None, **kwargs: Any) -> None: """Start a new sub path.""" raise NotImplementedError
[docs] def endPath(self) -> None: """End the current sub path.""" raise NotImplementedError
[docs] def addPoint( self, pt: Tuple[float, float], segmentType: Optional[str] = None, smooth: bool = False, name: Optional[str] = None, identifier: Optional[str] = None, **kwargs: Any ) -> None: """Add a point to the current sub path.""" raise NotImplementedError
[docs] def addComponent( self, baseGlyphName: str, transformation: Tuple[float, float, float, float, float, float], identifier: Optional[str] = None, **kwargs: Any ) -> None: """Add a sub glyph.""" raise NotImplementedError
[docs]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
[docs] def beginPath(self, identifier=None, **kwargs): if self.currentPath is not None: raise PenError("Path already begun.") 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
[docs] def endPath(self): if self.currentPath is None: raise PenError("Path not begun.") 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)
[docs] def addPoint(self, pt, segmentType=None, smooth=False, name=None, identifier=None, **kwargs): if self.currentPath is None: raise PenError("Path not begun") self.currentPath.append((pt, segmentType, smooth, name, kwargs))
[docs]class PointToSegmentPen(BasePointToSegmentPen): """ Adapter class that converts the PointPen protocol to the (Segment)Pen protocol. NOTE: The segment pen does not support and will drop point names, identifiers and kwargs. """ def __init__(self, segmentPen, outputImpliedClosingLine=False): BasePointToSegmentPen.__init__(self) self.pen = segmentPen self.outputImpliedClosingLine = outputImpliedClosingLine def _flushContour(self, segments): if not segments: raise PenError("Must have at least one segment.") pen = self.pen if segments[0][0] == "move": # It's an open path. closed = False points = segments[0][1] if len(points) != 1: raise PenError(f"Illegal move segment point count: {len(points)}") movePt, _, _ , _ = 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, _, _ , _ = 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) lastPt = movePt for i in range(nSegments): segmentType, points = segments[i] points = [pt for pt, _, _ , _ in points] if segmentType == "line": if len(points) != 1: raise PenError(f"Illegal line segment point count: {len(points)}") pt = points[0] # For closed contours, a 'lineTo' is always implied from the last oncurve # point to the starting point, thus we can omit it when the last and # starting point don't overlap. # However, when the last oncurve point is a "line" segment and has same # coordinates as the starting point of a closed contour, we need to output # the closing 'lineTo' explicitly (regardless of the value of the # 'outputImpliedClosingLine' option) in order to disambiguate this case from # the implied closing 'lineTo', otherwise the duplicate point would be lost. # See https://github.com/googlefonts/fontmake/issues/572. if ( i + 1 != nSegments or outputImpliedClosingLine or not closed or pt == lastPt ): pen.lineTo(pt) lastPt = pt elif segmentType == "curve": pen.curveTo(*points) lastPt = points[-1] elif segmentType == "qcurve": pen.qCurveTo(*points) lastPt = points[-1] else: raise PenError(f"Illegal segmentType: {segmentType}") if closed: pen.closePath() else: pen.endPath()
[docs] def addComponent(self, glyphName, transform, identifier=None, **kwargs): del identifier # unused del kwargs # unused self.pen.addComponent(glyphName, transform)
[docs]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()
[docs] def moveTo(self, pt): self.contour = [] self.contour.append((pt, "move"))
[docs] def lineTo(self, pt): if self.contour is None: raise PenError("Contour missing required initial moveTo") self.contour.append((pt, "line"))
[docs] def curveTo(self, *pts): if not pts: raise TypeError("Must pass in at least one point") if self.contour is None: raise PenError("Contour missing required initial moveTo") for pt in pts[:-1]: self.contour.append((pt, None)) self.contour.append((pts[-1], "curve"))
[docs] def qCurveTo(self, *pts): if not pts: raise TypeError("Must pass in at least one point") if pts[-1] is None: self.contour = [] else: if self.contour is None: raise PenError("Contour missing required initial moveTo") for pt in pts[:-1]: self.contour.append((pt, None)) if pts[-1] is not None: self.contour.append((pts[-1], "qcurve"))
[docs] def closePath(self): if self.contour is None: raise PenError("Contour missing required initial moveTo") 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
[docs] def endPath(self): if self.contour is None: raise PenError("Contour missing required initial moveTo") self._flushContour() self.contour = None
[docs] def addComponent(self, glyphName, transform): if self.contour is not None: raise PenError("Components must be added before or after contours") self.pen.addComponent(glyphName, transform)
[docs]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, error=0.05): self._outPen = outPen self._error = error self._points = None def _flushContour(self): if self._points is None: raise PenError("Path not begun") 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, _, 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(dy1, dx1) a2 = math.atan2(dy2, dx2) if abs(a1 - a2) < self._error: points[i] = pt, segmentType, True, name, kwargs for pt, segmentType, smooth, name, kwargs in points: self._outPen.addPoint(pt, segmentType, smooth, name, **kwargs)
[docs] def beginPath(self, identifier=None, **kwargs): if self._points is not None: raise PenError("Path already begun") self._points = [] if identifier is not None: kwargs["identifier"] = identifier self._outPen.beginPath(**kwargs)
[docs] def endPath(self): self._flushContour() self._outPen.endPath() self._points = None
[docs] def addPoint(self, pt, segmentType=None, smooth=False, name=None, identifier=None, **kwargs): if self._points is None: raise PenError("Path not begun") if identifier is not None: kwargs["identifier"] = identifier self._points.append((pt, segmentType, False, name, kwargs))
[docs] def addComponent(self, glyphName, transformation, identifier=None, **kwargs): if self._points is not None: raise PenError("Components must be added before or after contours") if identifier is not None: kwargs["identifier"] = identifier self._outPen.addComponent(glyphName, transformation, **kwargs)
[docs]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()
[docs] def beginPath(self, identifier=None, **kwargs): if self.currentContour is not None: raise PenError("Path already begun") self.currentContour = [] self.currentContourIdentifier = identifier self.onCurve = []
[docs] def endPath(self): if self.currentContour is None: raise PenError("Path not begun") self._flushContour() self.currentContour = None
[docs] def addPoint(self, pt, segmentType=None, smooth=False, name=None, identifier=None, **kwargs): if self.currentContour is None: raise PenError("Path not begun") if identifier is not None: kwargs["identifier"] = identifier self.currentContour.append((pt, segmentType, smooth, name, kwargs))
[docs] def addComponent(self, glyphName, transform, identifier=None, **kwargs): if self.currentContour is not None: raise PenError("Components must be added before or after contours") self.pen.addComponent(glyphName, transform, identifier=identifier, **kwargs)