path: root/Lib/fontTools/pens/pointPen.py

"""
=========
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",
]


class AbstractPointPen:
	"""Baseclass for all PointPens."""

	def beginPath(self, identifier: Optional[str] = None, **kwargs: Any) -> None:
		"""Start a new sub path."""
		raise NotImplementedError

	def endPath(self) -> None:
		"""End the current sub path."""
		raise NotImplementedError

	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

	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


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, 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

	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)

	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))


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()

	def addComponent(self, glyphName, transform, identifier=None, **kwargs):
		del identifier  # unused
		del kwargs  # unused
		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):
		if self.contour is None:
			raise PenError("Contour missing required initial moveTo")
		self.contour.append((pt, "line"))

	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"))

	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"))

	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

	def endPath(self):
		if self.contour is None:
			raise PenError("Contour missing required initial moveTo")
		self._flushContour()
		self.contour = None

	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)


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)

	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)

	def endPath(self):
		self._flushContour()
		self._outPen.endPath()
		self._points = None

	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))

	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)


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):
		if self.currentContour is not None:
			raise PenError("Path already begun")
		self.currentContour = []
		self.currentContourIdentifier = identifier
		self.onCurve = []

	def endPath(self):
		if self.currentContour is None:
			raise PenError("Path not begun")
		self._flushContour()
		self.currentContour = None

	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))

	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)