With the current code, scour could do a pointless remap of an ID,
where there is no benefit in it. Consider:
```xml
<?xml version="1.0" encoding="UTF-8"?>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<defs>
<rect id="a" width="80" height="50" fill="red"/>
<rect id="b" width="80" height="50" fill="blue"/>
</defs>
<use xlink:href="#a"/>
<use xlink:href="#b"/>
<use xlink:href="#b"/>
</svg>
```
In this example, there is no point in swapping the IDs - even if "#b"
is used more often than "#a", they have the same length. Besides a
performance win on an already scour'ed image, it also mean scour will
behave like a function with a fixed-point (i.e. scour eventually stops
altering the image).
To solve this, we no longer check whether an we find exactly the same
ID. Instead, we look at the length of the new ID compared to the
original. This gives us a slight complication as we can now "reserve"
a "future" ID to avoid the rename.
Thanks to Eduard "Ede_123" Braun for providing the test case.
Signed-off-by: Niels Thykier <niels@thykier.net>
* properly parse paths without space after boolean flags (fixes#161)
* omit space after boolean flag to shave off a few bytes when not using renderer workarounds
The bare "except" also catches exceptions like "NameError" and
"SystemExit", which we really should not catch. In scour.py, use the
most specific exception (NotFoundErr) and in the tests just catch any
"regular" exception.
Reported by flake8.
Signed-off-by: Niels Thykier <niels@thykier.net>
* Do not collapse straight path segments in paths that have intermediate markers (see #145). The intermediate nodes might be unnecessary for the shape of the path, but their markers would be lost.
* Collapse subpaths of moveto `m` and lineto `l` commands if they have the same direction (before we only collapsed horizontal/vertical `h`/`v` lineto commands)
* Attempt to collapse lineto `l` commands into a preceding moveto `m` command (these are then called "implicit lineto commands")
* Preserve empty path segments if they have `stroke-linecap` set to `round` or `square`. They render no visible line but a tiny dot or square.
When the preceeding path segment is a Bézier curve, too, the first control point of the shorthand defaults to the mirrored version of the second control point of this preceeding path segment. Scour always assumed (0,0) as the control point in this case which could result in modified path data (e.g. #91).
For example for `orient="auto"` SVGLength() returns (value=0, units=Unit.INVALID); since the default value for `orient` is zero it was removed as there was check for a valid unit.
- In text nodes quotes are fine
- In attributes quotes are fine if used reciprocally.
Escaping in the latter case often causes issues, e.g. with quoted font names (#21) or inline CSS styles (#56), while it probably does not gain anything (if quotes are wrongly used in attribute names the XML is most likely invalid to start with)
- Unused XML namespace declarations *are supposed* to be removed
- XML namespace declarations that are used as prefix for elements/attributes *must not* be removed
