Only create rules/categorized categories/graduated ranges if the
associated symbol could be converted to SLD, and is not an "empty"
symbol.
Otherwise we do not generate a rule, as SLD spec requires a
Symbolizer element to be present.
The old method was very inefficient, as it required a re-load and
re-parse of the associated SVG file content with every clone, only
for many of the parsed properties to be immediately overwritten.
Optimise by just directly copying members, avoiding all unnecessary
work.
This is frequently seen as a hotspot when profiling map renders,
as that involves cloning all symbol layers upfront.
Speeds up a benchtest cloning 100k markers from 4.3 seconds to
150ms.
Rework internals of QgsTextRenderer horizontal text rendering,
so that:
1. It's easier to read, cleaning up years of accumulated cruft
2. Split out bits into smaller functions
3. Reduce the amount of duplicate code for text layout, so that
there's only one function responsible for horizontal text layout
instead of multiple
4. Add shortcut optimisations for rendering text + buffer/shadow
at the same time, instead of always drawing these completely
independantly of each other and incurring the cost of text path
calculation multiple times for the same bit of text. In a simple
benchtest this reduces the time required for rendering many
text fragments with buffers from 40 seconds to 27 seconds.
There's still more we could do here, but it's a start...
This algorithm extracts point features corresponding to the minimum
and maximum pixel values contained within polygon zones.
The output will contain one point feature for the minimum and one
for the maximum raster value for every individual zonal feature
from a polygon layer.
Adds support for CSS margin properties for block elements in
the text renderer. Specifically:
- This is available for block type elements only, eg DIV, P, H1-H6.
- Margins are NOT available for spans or other non-block content (due to Qt
limitations)
- Margins can be specified in pt units only
- Margins can be specified either via "margin-left: 5pt; margin-right:
10pt" etc, or "margin: 5pt 0pt 10pt 0pt"
- Negative margins are supported for the bottom margin ONLY (due to Qt
limitations)
