Add SVGPen

Copied and slightly adapted from:
https://github.com/typesupply/ufo2svg/blob/master/Lib/ufo2svg/svgPathPen.py

Lib/fontTools/pens/svgPen.py

@@ -0,0 +1,215 @@
+from __future__ import print_function, division, absolute_import
+from fontTools.misc.py23 import *
+from fontTools.pens.basePen import BasePen
+
+# Number to String Conversion
+
+def valueToString(v):
+    """
+    >>> valueToString(0)
+    '0'
+    >>> valueToString(10)
+    '10'
+    >>> valueToString(-10)
+    '-10'
+    >>> valueToString(0.1)
+    '0.1'
+    >>> valueToString(0.0001)
+    '0.0001'
+    >>> valueToString(0.00001)
+    '0'
+    >>> valueToString(10.0001)
+    '10.0001'
+    >>> valueToString(10.00001)
+    '10'
+    """
+    if int(v) == v:
+        v = "%d" % (int(v))
+    else:
+        v = "%.4f" % v
+        # strip unnecessary zeros
+        # there is probably an easier way to do this
+        compiled = []
+        for c in reversed(v):
+            if not compiled and c == "0":
+                continue
+            compiled.append(c)
+        v = "".join(reversed(compiled))
+        if v.endswith("."):
+            v = v[:-1]
+        if not v:
+            v = "0"
+    return v
+
+def pointToString(pt):
+    return " ".join([valueToString(i) for i in pt])
+
+class SVGPen(BasePen):
+
+    def __init__(self, glyphSet):
+        BasePen.__init__(self, glyphSet)
+        self._commands = []
+        self._lastCommand = None
+        self._lastX = None
+        self._lastY = None
+
+    def _handleAnchor(self):
+        """
+        >>> pen = SVGPen(None)
+        >>> pen.moveTo((0, 0))
+        >>> pen.moveTo((10, 10))
+        >>> pen._commands
+        ['M10 10']
+        """
+        if self._lastCommand == "M":
+            self._commands.pop(-1)
+
+    def _moveTo(self, pt):
+        """
+        >>> pen = SVGPen(None)
+        >>> pen.moveTo((0, 0))
+        >>> pen._commands
+        ['M0 0']
+
+        >>> pen = SVGPen(None)
+        >>> pen.moveTo((10, 0))
+        >>> pen._commands
+        ['M10 0']
+
+        >>> pen = SVGPen(None)
+        >>> pen.moveTo((0, 10))
+        >>> pen._commands
+        ['M0 10']
+        """
+        self._handleAnchor()
+        t = "M%s" % (pointToString(pt))
+        self._commands.append(t)
+        self._lastCommand = "M"
+        self._lastX, self._lastY = pt
+
+    def _lineTo(self, pt):
+        """
+        # duplicate point
+        >>> pen = SVGPen(None)
+        >>> pen.moveTo((10, 10))
+        >>> pen.lineTo((10, 10))
+        >>> pen._commands
+        ['M10 10']
+
+        # vertical line
+        >>> pen = SVGPen(None)
+        >>> pen.moveTo((10, 10))
+        >>> pen.lineTo((10, 0))
+        >>> pen._commands
+        ['M10 10', 'V0']
+
+        # horizontal line
+        >>> pen = SVGPen(None)
+        >>> pen.moveTo((10, 10))
+        >>> pen.lineTo((0, 10))
+        >>> pen._commands
+        ['M10 10', 'H0']
+
+        # basic
+        >>> pen = SVGPen(None)
+        >>> pen.lineTo((70, 80))
+        >>> pen._commands
+        ['L70 80']
+
+        # basic following a moveto
+        >>> pen = SVGPen(None)
+        >>> pen.moveTo((0, 0))
+        >>> pen.lineTo((10, 10))
+        >>> pen._commands
+        ['M0 0', ' 10 10']
+        """
+        x, y = pt
+        # duplicate point
+        if x == self._lastX and y == self._lastY:
+            return
+        # vertical line
+        elif x == self._lastX:
+            cmd = "V"
+            pts = valueToString(y)
+        # horizontal line
+        elif y == self._lastY:
+            cmd = "H"
+            pts = valueToString(x)
+        # previous was a moveto
+        elif self._lastCommand == "M":
+            cmd = None
+            pts = " " + pointToString(pt)
+        # basic
+        else:
+            cmd = "L"
+            pts = pointToString(pt)
+        # write the string
+        t = ""
+        if cmd:
+            t += cmd
+            self._lastCommand = cmd
+        t += pts
+        self._commands.append(t)
+        # store for future reference
+        self._lastX, self._lastY = pt
+
+    def _curveToOne(self, pt1, pt2, pt3):
+        """
+        >>> pen = SVGPen(None)
+        >>> pen.curveTo((10, 20), (30, 40), (50, 60))
+        >>> pen._commands
+        ['C10 20 30 40 50 60']
+        """
+        t = "C"
+        t += pointToString(pt1) + " "
+        t += pointToString(pt2) + " "
+        t += pointToString(pt3)
+        self._commands.append(t)
+        self._lastCommand = "C"
+        self._lastX, self._lastY = pt3
+
+    def _qCurveToOne(self, pt1, pt2):
+        """
+        >>> pen = SVGPen(None)
+        >>> pen.qCurveTo((10, 20), (30, 40))
+        >>> pen._commands
+        ['Q10 20 30 40']
+        """
+        assert pt2 is not None
+        t = "Q"
+        t += pointToString(pt1) + " "
+        t += pointToString(pt2)
+        self._commands.append(t)
+        self._lastCommand = "Q"
+        self._lastX, self._lastY = pt2
+
+    def _closePath(self):
+        """
+        >>> pen = SVGPen(None)
+        >>> pen.closePath()
+        >>> pen._commands
+        ['Z']
+        """
+        self._commands.append("Z")
+        self._lastCommand = "Z"
+        self._lastX = self._lastY = None
+
+    def _endPath(self):
+        """
+        >>> pen = SVGPen(None)
+        >>> pen.endPath()
+        >>> pen._commands
+        ['Z']
+        """
+        self._closePath()
+        self._lastCommand = None
+        self._lastX = self._lastY = None
+
+    def getCommands(self):
+        return "".join(self._commands)
+
+
+if __name__ == "__main__":
+    import sys
+    import doctest
+    sys.exit(doctest.testmod().failed)