py3: Full fix for svg2painterpath (I hope)

src/calibre/ebooks/covers.py

@@ -495,7 +495,11 @@ class Ornamental(Style):
     def __call__(self, painter, rect, color_theme, title_block, subtitle_block, footer_block):
         if not self.PATH_CACHE:
             from calibre.utils.speedups import svg_path_to_painter_path
-            self.__class__.PATH_CACHE['corner'] = svg_path_to_painter_path(self.CORNER_VECTOR)
+            try:
+                self.__class__.PATH_CACHE['corner'] = svg_path_to_painter_path(self.CORNER_VECTOR)
+            except Exception:
+                import traceback
+                traceback.print_exc()
         p = painter
         painter.setRenderHint(QPainter.Antialiasing)
         g = QRadialGradient(QPointF(rect.center()), rect.width())
@@ -503,7 +507,10 @@ class Ornamental(Style):
         painter.fillRect(rect, QBrush(g))
         painter.save()
         painter.setWindow(0, 0, *self.VIEWPORT)
-        path = self.PATH_CACHE['corner']
+        try:
+            path = self.PATH_CACHE['corner']
+        except KeyError:
+            path = QPainterPath()
         pen = p.pen()
         pen.setColor(self.ccolor1)
         p.setPen(pen)

src/calibre/utils/speedups.py

@@ -55,15 +55,15 @@ def svg_path_to_painter_path(d):
     from PyQt5.Qt import QPainterPath
     cmd = last_cmd = b''
     path = QPainterPath()
-    moveto_abs, moveto_rel = b'Mm'
+    moveto_abs, moveto_rel = b'M', b'm'
-    closepath1, closepath2 = b'Zz'
+    closepath1, closepath2 = b'Z', b'z'
-    lineto_abs, lineto_rel = b'Ll'
+    lineto_abs, lineto_rel = b'L', b'l'
-    hline_abs, hline_rel = b'Hh'
+    hline_abs, hline_rel = b'H', b'h'
-    vline_abs, vline_rel = b'Vv'
+    vline_abs, vline_rel = b'V', b'v'
-    curveto_abs, curveto_rel = b'Cc'
+    curveto_abs, curveto_rel = b'C', b'c'
-    smoothcurveto_abs, smoothcurveto_rel = b'Ss'
+    smoothcurveto_abs, smoothcurveto_rel = b'S', b's'
-    quadcurveto_abs, quadcurveto_rel = b'Qq'
+    quadcurveto_abs, quadcurveto_rel = b'Q', b'q'
-    smoothquadcurveto_abs, smoothquadcurveto_rel = b'Tt'
+    smoothquadcurveto_abs, smoothquadcurveto_rel = b'T', b't'
 
     # Store the last parsed values
     # x/y = end position
@@ -74,16 +74,21 @@ def svg_path_to_painter_path(d):
         d = d.encode('ascii')
     d = d.replace(b',', b' ').replace(b'\n', b' ')
     end = len(d)
-    data = ReadOnlyFileBuffer(d)
+    pos = [0]
+
+    def read_byte():
+        p = pos[0]
+        pos[0] += 1
+        return d[p:p+1]
 
     def parse_float():
         chars = []
-        while data.tell() < end:
+        while pos[0] < end:
-            c = data.read(1)
+            c = read_byte()
             if c == b' ' and not chars:
                 continue
-            if c == b'-' or b'0' <= c[0] <= b'9' or c == b'.':
+            if c in b'-.0123456789':
-                chars.append(c[0])
+                chars.append(c)
             else:
                 break
         if not chars:
@@ -97,16 +102,14 @@ def svg_path_to_painter_path(d):
 
     repeated_command = None
 
-    while data.tell() < end:
+    while pos[0] < end:
         last_cmd = cmd
-        cmd = data.read(1) if repeated_command is None else repeated_command
+        cmd = read_byte() if repeated_command is None else repeated_command
-        if isinstance(cmd, memoryview):
-            cmd = cmd.tobytes()
         repeated_command = None
 
         if cmd == b' ':
             continue
-        elif cmd == moveto_abs:
+        if cmd == moveto_abs:
             x, y = parse_float(), parse_float()
             path.moveTo(x, y)
         elif cmd == moveto_rel:
@@ -178,11 +181,11 @@ def svg_path_to_painter_path(d):
                 x1, y1 = x, y
             x, y = parse_floats(2, x, y)
             path.quadTo(x1, y1, x, y)
-        elif cmd[0:1] in b'-.0123456789':
+        elif cmd in b'-.0123456789':
             # 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)
+            pos[0] -= 1
 
             # Handle extra parameters
             if last_cmd == moveto_abs: