Previously, annotation size and position always used pixel units. This
did not work well when exporting layouts, resulting in tiny annotations
(it also caused issues when moving projects between hidpi/non hidpi
displays).
Instead, use millimeters for annotation size and position so that the
appearance is consistent across displays and works correctly in layout
exports.
Add lots of unit tests covering this.
Fixes#18373
In OGC WMS standard, the empty string represents the default style.
QGIS Server when it parses the parameters, QGIS Server when it parses parameters it removes empty parts.
When all requested styles are default ones it's equal to an empty parameter STYLE, as defined in the standard.
When only one layer is requested, there is no issue with custom or default style.
When multiple layers are requested and some with custom styles, because QGIS Server does not retain empty strings, it loses the layer / style match.
To fix it, keeps empty parts for not empty styles parameters.
Previously, when marker or hash lines were rendered using interval
or center point place placement, the symbol angles were determined
by taking the exact line orientation at the position of the symbol.
This often leads to undesirable rendering effects, where little
jaggies or corners in lines which occur at the position of the
symbol cause the marker or hash line to be oriented at a very
different angle to what the eye expects to see.
With this new option, the angle is instead calculated by averaging
the line over a specified distance either side of the symbol. E.g.
averaging the line angle over 4mm means we take the points along
the line 2mm from either side of the symbol placement, and use these
instead to calculate the line angle for that symbol. This has the
effect of smoothing (or removing) any tiny local deviations from
the overall line direction, resulting in much nicer visual
orientation of marker or hash lines.
Like all symbol settings, the average angle smoothing distance
can be set using mm/pixels/map units/etc, and supports data-defined
values.
Closed rings also correctly consider wrapping around these average
angles from the start/end vertex.
(Sponsored by an anonymous corporate backer)
In QGIS 3.4, Selection can be printed in Image output and not in PDF or SVG output.
A fix has been done 2752f83 to fix inconsistent use of layout render context flags, and draw selection is activated with a flag.
In QGIS Server 2.* the WMS GetPrint request could genrate JPEG image. QGIS Server 3.4 has lost this capabilities.
```
<ServiceExceptionReport xmlns="http://www.opengis.net/ogc" version="1.3.0" capture-installed="true">
<ServiceException code="InvalidFormat">
Output format jpg is not supported by the GetPrint request
</ServiceException>
</ServiceExceptionReport>
```
To fix this regression, it is necessary to accept JPEG output format.
And to avoid this regression to come back, the QGIS Server tests has been updated to accept jpg image test.
