Using svg.draw(pen) and parse_path() from svgLib threw exception
ValueError: could not convert string to float: 'a'
on a SVG <path> string generated by Inkscape. Altering the path
string might object to other string bits like 'Z' or 'v', or
give even stranger exceptions.
Finally tracked it down to the path containing particular valid
numbers like "-4e-5" or "1e-4". Changing these to "-4.0e-5" or
"1.0e-4" would stop the exceptions. The parse_path() was not
accepting valid SVG real numbers.
The specification for real number formats is a bit of a mess in
CSS land right now, but the reassuringly concrete spec is:
https://www.w3.org/TR/css-syntax-3/#number-token-diagram
which allows a real number having an exponent but without having
a fractional part, such as the number "1e3".
This change updates an RE to make fractional parts optional,
and adds a test for this valid SVG number format.
Missed this test in previous commit.
Test is testing that parsing extraction of individual parameters
works as specified when spaces are omitted. Such as signaled when
a new number is specified with a leading sign +/-
Test previously used
"M1-2A3-4-1.0 01.5.7",
where the first arc radius value was '3' and the second was '-4'.
Now that we are forcing radius values to be non-negative using abs()
the value returned in the test is not
("arcTo", (3.0, -4.0, -1.0, False, True, (0.5, 0.7))),
but rather
("arcTo", (3.0, 4.0, -1.0, False, True, (0.5, 0.7))),
Changed to expect the positive value, nicely the test continues to
test omitting spaces, but now also tests that negative radius values
are forced non-negative.
* Replaced all from ...py23 import * with explicit name imports, or removed completely when possible.
* Replaced tounicode() with tostr()
* Changed all BytesIO ans StringIO imports to from io import ..., replaced all UnicodeIO with StringIO.
* Replaced all unichr() with chr()
* Misc minor tweaks and fixes
Some SVG authoring tool write arc commands without any space or comma around the boolean 'large-arc' and 'sweep' flags, leading our svg path parser to choke.
This makes the path parser smarter by special-casing arc command parsing so that it only consumes one character ('0' or '1') for these special boolean flags.
