# filterPen

class fontTools.pens.filterPen.ContourFilterPen(outPen)

  A “buffered” filter pen that accumulates contour data, passes it through a `filterContour` method when the contour is closed or ended, and finally draws the result with the output pen.

  Components are passed through unchanged.

  addComponent(glyphName, transformation, **kwargs)

    Add a sub glyph. The ‘transformation’ argument must be a 6-tuple containing an affine transformation, or a Transform object from the fontTools.misc.transform module. More precisely: it should be a sequence containing 6 numbers.

  closePath()

    Close the current sub path. You must call either pen.closePath() or pen.endPath() after each sub path.

  curveTo(*points)

    Draw a cubic bezier with an arbitrary number of control points.

    The last point specified is on-curve, all others are off-curve (control) points. If the number of control points is > 2, the segment is split into multiple bezier segments. This works like this:

    Let n be the number of control points (which is the number of arguments to this call minus 1). If n==2, a plain vanilla cubic bezier is drawn. If n==1, we fall back to a quadratic segment and if n==0 we draw a straight line. It gets interesting when n>2: n-1 PostScript-style cubic segments will be drawn as if it were one curve. See decomposeSuperBezierSegment().

    The conversion algorithm used for n>2 is inspired by NURB splines, and is conceptually equivalent to the TrueType “implied points” principle. See also decomposeQuadraticSegment().

  endPath()

    End the current sub path, but don’t close it. You must call either pen.closePath() or pen.endPath() after each sub path.

  filterContour(contour)

    Subclasses must override this to perform the filtering.

    The contour is a list of pen (operator, operands) tuples. Operators are strings corresponding to the AbstractPen methods: “moveTo”, “lineTo”, “curveTo”, “qCurveTo”, “closePath” and “endPath”. The operands are the positional arguments that are passed to each method.

    If the method doesn’t return a value (i.e. returns None), it’s assumed that the argument was modified in-place. Otherwise, the return value is drawn with the output pen.

  lineTo(p1)

    Draw a straight line from the current point to ‘pt’.

  moveTo(p0)

    Begin a new sub path, set the current point to ‘pt’. You must end each sub path with a call to pen.closePath() or pen.endPath().

  qCurveTo(*points)

    Draw a whole string of quadratic curve segments.

    The last point specified is on-curve, all others are off-curve points.

    This method implements TrueType-style curves, breaking up curves using ‘implied points’: between each two consequtive off-curve points, there is one implied point exactly in the middle between them. See also decomposeQuadraticSegment().

    The last argument (normally the on-curve point) may be None. This is to support contours that have NO on-curve points (a rarely seen feature of TrueType outlines).

  replay(pen)

class fontTools.pens.filterPen.FilterPen(outPen)

  Base class for pens that apply some transformation to the coordinates they receive and pass them to another pen.

  You can override any of its methods. The default implementation does nothing, but passes the commands unmodified to the other pen.

      >>> from fontTools.pens.recordingPen import RecordingPen
      >>> rec = RecordingPen()
      >>> pen = FilterPen(rec)
      >>> v = iter(rec.value)

      >>> pen.moveTo((0, 0))
      >>> next(v)
      ('moveTo', ((0, 0),))

      >>> pen.lineTo((1, 1))
      >>> next(v)
      ('lineTo', ((1, 1),))

      >>> pen.curveTo((2, 2), (3, 3), (4, 4))
      >>> next(v)
      ('curveTo', ((2, 2), (3, 3), (4, 4)))

      >>> pen.qCurveTo((5, 5), (6, 6), (7, 7), (8, 8))
      >>> next(v)
      ('qCurveTo', ((5, 5), (6, 6), (7, 7), (8, 8)))

      >>> pen.closePath()
      >>> next(v)
      ('closePath', ())

      >>> pen.moveTo((9, 9))
      >>> next(v)
      ('moveTo', ((9, 9),))

      >>> pen.endPath()
      >>> next(v)
      ('endPath', ())

      >>> pen.addComponent('foo', (1, 0, 0, 1, 0, 0))
      >>> next(v)
      ('addComponent', ('foo', (1, 0, 0, 1, 0, 0)))

  addComponent(glyphName, transformation, **kwargs)

    Add a sub glyph. The ‘transformation’ argument must be a 6-tuple containing an affine transformation, or a Transform object from the fontTools.misc.transform module. More precisely: it should be a sequence containing 6 numbers.

  closePath()

    Close the current sub path. You must call either pen.closePath() or pen.endPath() after each sub path.

  curveTo(*points)

    Draw a cubic bezier with an arbitrary number of control points.

    The last point specified is on-curve, all others are off-curve (control) points. If the number of control points is > 2, the segment is split into multiple bezier segments. This works like this:

    Let n be the number of control points (which is the number of arguments to this call minus 1). If n==2, a plain vanilla cubic bezier is drawn. If n==1, we fall back to a quadratic segment and if n==0 we draw a straight line. It gets interesting when n>2: n-1 PostScript-style cubic segments will be drawn as if it were one curve. See decomposeSuperBezierSegment().

    The conversion algorithm used for n>2 is inspired by NURB splines, and is conceptually equivalent to the TrueType “implied points” principle. See also decomposeQuadraticSegment().

  endPath()

    End the current sub path, but don’t close it. You must call either pen.closePath() or pen.endPath() after each sub path.

  lineTo(pt)

    Draw a straight line from the current point to ‘pt’.

  moveTo(pt)

    Begin a new sub path, set the current point to ‘pt’. You must end each sub path with a call to pen.closePath() or pen.endPath().

  qCurveTo(*points)

    Draw a whole string of quadratic curve segments.

    The last point specified is on-curve, all others are off-curve points.

    This method implements TrueType-style curves, breaking up curves using ‘implied points’: between each two consequtive off-curve points, there is one implied point exactly in the middle between them. See also decomposeQuadraticSegment().

    The last argument (normally the on-curve point) may be None. This is to support contours that have NO on-curve points (a rarely seen feature of TrueType outlines).

class fontTools.pens.filterPen.FilterPointPen(outPointPen)

  Baseclass for point pens that apply some transformation to the coordinates they receive and pass them to another point pen.

  You can override any of its methods. The default implementation does nothing, but passes the commands unmodified to the other pen.

      >>> from fontTools.pens.recordingPen import RecordingPointPen
      >>> rec = RecordingPointPen()
      >>> pen = FilterPointPen(rec)
      >>> v = iter(rec.value)
      >>> pen.beginPath(identifier="abc")
      >>> next(v)
      ('beginPath', (), {'identifier': 'abc'})
      >>> pen.addPoint((1, 2), "line", False)
      >>> next(v)
      ('addPoint', ((1, 2), 'line', False, None), {})
      >>> pen.addComponent("a", (2, 0, 0, 2, 10, -10), identifier="0001")
      >>> next(v)
      ('addComponent', ('a', (2, 0, 0, 2, 10, -10)), {'identifier': '0001'})
      >>> pen.endPath()
      >>> next(v)
      ('endPath', (), {})

  addComponent(glyphName, transformation, **kwargs)

    Add a sub glyph.

  addPoint(pt, segmentType=None, smooth=False, name=None, **kwargs)

    Add a point to the current sub path.

  beginPath(**kwargs)

    Start a new sub path.

  endPath()

    End the current sub path.