Lib/fontTools/pens/recordingPen.py

"""Pen recording operations that can be accessed or replayed."""

from fontTools.pens.basePen import AbstractPen, DecomposingPen
from fontTools.pens.pointPen import AbstractPointPen


__all__ = [
    "replayRecording",
    "RecordingPen",
    "DecomposingRecordingPen",
    "RecordingPointPen",
    "lerpRecordings",
]


def replayRecording(recording, pen):
    """Replay a recording, as produced by RecordingPen or DecomposingRecordingPen,
    to a pen.

    Note that recording does not have to be produced by those pens.
    It can be any iterable of tuples of method name and tuple-of-arguments.
    Likewise, pen can be any objects receiving those method calls.
    """
    for operator, operands in recording:
        getattr(pen, operator)(*operands)


class RecordingPen(AbstractPen):
    """Pen recording operations that can be accessed or replayed.

    The recording can be accessed as pen.value; or replayed using
    pen.replay(otherPen).

    :Example:

            from fontTools.ttLib import TTFont
            from fontTools.pens.recordingPen import RecordingPen

            glyph_name = 'dollar'
            font_path = 'MyFont.otf'

            font = TTFont(font_path)
            glyphset = font.getGlyphSet()
            glyph = glyphset[glyph_name]

            pen = RecordingPen()
            glyph.draw(pen)
            print(pen.value)
    """

    def __init__(self):
        self.value = []

    def moveTo(self, p0):
        self.value.append(("moveTo", (p0,)))

    def lineTo(self, p1):
        self.value.append(("lineTo", (p1,)))

    def qCurveTo(self, *points):
        self.value.append(("qCurveTo", points))

    def curveTo(self, *points):
        self.value.append(("curveTo", points))

    def closePath(self):
        self.value.append(("closePath", ()))

    def endPath(self):
        self.value.append(("endPath", ()))

    def addComponent(self, glyphName, transformation):
        self.value.append(("addComponent", (glyphName, transformation)))

    def addVarComponent(self, glyphName, transformation, location):
        self.value.append(("addVarComponent", (glyphName, transformation, location)))

    def replay(self, pen):
        replayRecording(self.value, pen)

    draw = replay


class DecomposingRecordingPen(DecomposingPen, RecordingPen):
    """Same as RecordingPen, except that it doesn't keep components
    as references, but draws them decomposed as regular contours.

    The constructor takes a single 'glyphSet' positional argument,
    a dictionary of glyph objects (i.e. with a 'draw' method) keyed
    by thir name::

            >>> class SimpleGlyph(object):
            ...     def draw(self, pen):
            ...         pen.moveTo((0, 0))
            ...         pen.curveTo((1, 1), (2, 2), (3, 3))
            ...         pen.closePath()
            >>> class CompositeGlyph(object):
            ...     def draw(self, pen):
            ...         pen.addComponent('a', (1, 0, 0, 1, -1, 1))
            >>> glyphSet = {'a': SimpleGlyph(), 'b': CompositeGlyph()}
            >>> for name, glyph in sorted(glyphSet.items()):
            ...     pen = DecomposingRecordingPen(glyphSet)
            ...     glyph.draw(pen)
            ...     print("{}: {}".format(name, pen.value))
            a: [('moveTo', ((0, 0),)), ('curveTo', ((1, 1), (2, 2), (3, 3))), ('closePath', ())]
            b: [('moveTo', ((-1, 1),)), ('curveTo', ((0, 2), (1, 3), (2, 4))), ('closePath', ())]
    """

    # raises KeyError if base glyph is not found in glyphSet
    skipMissingComponents = False


class RecordingPointPen(AbstractPointPen):
    """PointPen recording operations that can be accessed or replayed.

    The recording can be accessed as pen.value; or replayed using
    pointPen.replay(otherPointPen).

    :Example:

            from defcon import Font
            from fontTools.pens.recordingPen import RecordingPointPen

            glyph_name = 'a'
            font_path = 'MyFont.ufo'

            font = Font(font_path)
            glyph = font[glyph_name]

            pen = RecordingPointPen()
            glyph.drawPoints(pen)
            print(pen.value)

            new_glyph = font.newGlyph('b')
            pen.replay(new_glyph.getPointPen())
    """

    def __init__(self):
        self.value = []

    def beginPath(self, identifier=None, **kwargs):
        if identifier is not None:
            kwargs["identifier"] = identifier
        self.value.append(("beginPath", (), kwargs))

    def endPath(self):
        self.value.append(("endPath", (), {}))

    def addPoint(
        self, pt, segmentType=None, smooth=False, name=None, identifier=None, **kwargs
    ):
        if identifier is not None:
            kwargs["identifier"] = identifier
        self.value.append(("addPoint", (pt, segmentType, smooth, name), kwargs))

    def addComponent(self, baseGlyphName, transformation, identifier=None, **kwargs):
        if identifier is not None:
            kwargs["identifier"] = identifier
        self.value.append(("addComponent", (baseGlyphName, transformation), kwargs))

    def addVarComponent(
        self, baseGlyphName, transformation, location, identifier=None, **kwargs
    ):
        if identifier is not None:
            kwargs["identifier"] = identifier
        self.value.append(
            ("addVarComponent", (baseGlyphName, transformation, location), kwargs)
        )

    def replay(self, pointPen):
        for operator, args, kwargs in self.value:
            getattr(pointPen, operator)(*args, **kwargs)

    drawPoints = replay


def lerpRecordings(recording1, recording2, factor=0.5):
    """Linearly interpolate between two recordings. The recordings
    must be decomposed, i.e. they must not contain any components.

    Factor is typically between 0 and 1. 0 means the first recording,
    1 means the second recording, and 0.5 means the average of the
    two recordings. Other values are possible, and can be useful to
    extrapolate. Defaults to 0.5.

    Returns a generator with the new recording.
    """
    if len(recording1) != len(recording2):
        raise ValueError(
            "Mismatched lengths: %d and %d" % (len(recording1), len(recording2))
        )
    for (op1, args1), (op2, args2) in zip(recording1, recording2):
        if op1 != op2:
            raise ValueError("Mismatched operations: %s, %s" % (op1, op2))
        if op1 == "addComponent":
            raise ValueError("Cannot interpolate components")
        else:
            mid_args = [
                (x1 + (x2 - x1) * factor, y1 + (y2 - y1) * factor)
                for (x1, y1), (x2, y2) in zip(args1, args2)
            ]
        yield (op1, mid_args)


if __name__ == "__main__":
    pen = RecordingPen()
    pen.moveTo((0, 0))
    pen.lineTo((0, 100))
    pen.curveTo((50, 75), (60, 50), (50, 25))
    pen.closePath()
    from pprint import pprint

    pprint(pen.value)