Preemptively parse the necessary attributes in QSvgAttributes.

Previously, retrieving an attribute value requires a two-stage lookup,
first in the XML attributes and (if it is found there) in the CSS
attributes. Both look-ups requires a number of iterations and
comparisons, which have to be carried out for every value look-up.

This patch changes it so that iterations and comparisons need to be done
only once, namely at the beginning. This requires us to store several
SVG attributes needed by the parsing routine, but since they are just
QStringRefs, the increase in the heap usage is really minimal and even
not reported by Valgrind's Massif.

Also, now we don't need to hold the XML attributes anymore.

The loading of tiger.svg (tests/benchmarks/qsvgrenderer) is reduced from
101.2 millions instructions to 96.5. The biggest gain is however obvious
from the time spent in QSvgAttributes::parseStyle(QSvgNode*,
QSvgAttributes, QSvgHandler*) which goes down from 16.7 millions
instructions to 6.9 millions, i.e. 2.4x faster.

Even with the new extra overhead in the QSvgAttributes constructor,
QSvgAttributes::parseStyle(QSvgNode*, QXmlStreamAttributes,
QSvgHandler*) goes down from 23.5 millions instructions to 18.4 millions,
i.e. 1.3x faster.

Reviewed-by: Kim

0 files changed, 0 insertions, 0 deletions