A function to convert an SVG path into a QPainterPath

src/calibre/utils/speedups.py

@@ -43,4 +43,156 @@ class ReadOnlyFileBuffer(object):
     def close(self):
         pass
 
+def svg_path_to_painter_path(d):
+    '''
+    Convert a tiny SVG 1.2 path into a QPainterPath.
 
+    :param d: The value of the d attribute of an SVG <path> tag
+    '''
+    from PyQt5.Qt import QPainterPath
+    cmd = last_cmd = b''
+    path = QPainterPath()
+    moveto_abs, moveto_rel = b'Mm'
+    closepath1, closepath2 = b'Zz'
+    lineto_abs, lineto_rel = b'Ll'
+    hline_abs, hline_rel = b'Hh'
+    vline_abs, vline_rel = b'Vv'
+    curveto_abs, curveto_rel = b'Cc'
+    smoothcurveto_abs, smoothcurveto_rel = b'Ss'
+    quadcurveto_abs, quadcurveto_rel = b'Qq'
+    smoothquadcurveto_abs, smoothquadcurveto_rel = b'Tt'
+
+    # Store the last parsed values
+    # x/y = end position
+    # x1/y1 and x2/y2 = bezier control points
+    x = y = x1 = y1 = x2 = y2 = 0
+
+    data = d.replace(b',', b' ').replace(b'\n', b' ')
+    if isinstance(data, type('')):
+        data = data.encode('ascii')
+    end = len(data)
+    data = ReadOnlyFileBuffer(data)
+
+    def parse_float():
+        chars = []
+        while data.tell() < end:
+            c = data.read(1)
+            if c == b' ' and not chars:
+                continue
+            if c == b'-' or b'0' <= c[0] <= b'9' or c == b'.':
+                chars.append(c[0])
+            else:
+                break
+        if not chars:
+            raise ValueError('Premature end of input while expecting a number')
+        return float(b''.join(chars))
+
+    def parse_floats(num, x_offset=0, y_offset=0):
+        for i in xrange(num):
+            val = parse_float()
+            yield val + (x_offset if i % 2 == 0 else y_offset)
+
+    repeated_command = None
+
+    while data.tell() < end:
+        last_cmd = cmd
+        cmd = data.read(1) if repeated_command is None else repeated_command
+        repeated_command = None
+
+        if cmd == b' ':
+            continue
+        elif cmd == moveto_abs:
+            x, y = parse_float(), parse_float()
+            path.moveTo(x, y)
+        elif cmd == moveto_rel:
+            x += parse_float()
+            y += parse_float()
+            path.moveTo(x, y)
+        elif cmd == closepath1 or cmd == closepath2:
+            path.closeSubpath()
+        elif cmd == lineto_abs:
+            x, y = parse_floats(2)
+            path.lineTo(x, y)
+        elif cmd == lineto_rel:
+            x += parse_float()
+            y += parse_float()
+            path.lineTo(x, y)
+        elif cmd == hline_abs:
+            x = parse_float()
+            path.lineTo(x, y)
+        elif cmd == hline_rel:
+            x += parse_float()
+            path.lineTo(x, y)
+        elif cmd == vline_abs:
+            y = parse_float()
+            path.lineTo(x, y)
+        elif cmd == vline_rel:
+            y += parse_float()
+            path.lineTo(x, y)
+        elif cmd == curveto_abs:
+            x1, y1, x2, y2, x, y = parse_floats(6)
+            path.cubicTo(x1, y1, x2, y2, x, y)
+        elif cmd == curveto_rel:
+            x1, y1, x2, y2, x, y = parse_floats(6, x, y)
+            path.cubicTo(x1, y1, x2, y2, x, y)
+        elif cmd == smoothcurveto_abs:
+            if last_cmd == curveto_abs or last_cmd == curveto_rel or last_cmd == smoothcurveto_abs or last_cmd == smoothcurveto_rel:
+                x1 = 2 * x - x2
+                y1 = 2 * y - y2
+            else:
+                x1, y1 = x, y
+            x2, y2, x, y = parse_floats(4)
+            path.cubicTo(x1, y1, x2, y2, x, y)
+        elif cmd == smoothcurveto_rel:
+            if last_cmd == curveto_abs or last_cmd == curveto_rel or last_cmd == smoothcurveto_abs or last_cmd == smoothcurveto_rel:
+                x1 = 2 * x - x2
+                y1 = 2 * y - y2
+            else:
+                x1, y1 = x, y
+            x2, y2, x, y = parse_floats(4, x, y)
+            path.cubicTo(x1, y1, x2, y2, x, y)
+        elif cmd == quadcurveto_abs:
+            x1, y1, x, y = parse_floats(4)
+            path.quadTo(x1, y1, x, y)
+        elif cmd == quadcurveto_rel:
+            x1, y1, x, y = parse_floats(4, x, y)
+            path.quadTo(x1, y1, x, y)
+        elif cmd == smoothquadcurveto_abs:
+            if last_cmd in (quadcurveto_abs, quadcurveto_rel, smoothquadcurveto_abs, smoothquadcurveto_rel):
+                x1 = 2 * x - x1
+                y1 = 2 * y - y1
+            else:
+                x1, y1 = x, y
+            x, y = parse_floats(2)
+            path.quadTo(x1, y1, x, y)
+        elif cmd == smoothquadcurveto_rel:
+            if last_cmd in (quadcurveto_abs, quadcurveto_rel, smoothquadcurveto_abs, smoothquadcurveto_rel):
+                x1 = 2 * x - x1
+                y1 = 2 * y - y1
+            else:
+                x1, y1 = x, y
+            x, y = parse_floats(2, x, y)
+            path.quadTo(x1, y1, x, y)
+        elif cmd[0] in b'-.' or b'0' <= cmd[0] <= b'9':
+            # A new number begins
+            # In this case, multiple parameters tuples are specified for the last command
+            # We rewind to reparse data correctly
+            data.seek(-1, os.SEEK_CUR)
+
+            # Handle extra parameters
+            if last_cmd == moveto_abs:
+                repeated_command = cmd = lineto_abs
+            elif last_cmd == moveto_rel:
+                repeated_command = cmd = lineto_rel
+            elif last_cmd in (closepath1, closepath2):
+                raise ValueError('Extra parameters after close path command')
+            elif last_cmd in (
+                lineto_abs, lineto_rel, hline_abs, hline_rel, vline_abs,
+                vline_rel, curveto_abs, curveto_rel,smoothcurveto_abs,
+                smoothcurveto_rel, quadcurveto_abs, quadcurveto_rel,
+                smoothquadcurveto_abs, smoothquadcurveto_rel
+            ):
+                repeated_command = cmd = last_cmd
+        else:
+            raise ValueError('Unknown path command: %s' % cmd)
+    return path