Reworks the QgsLayoutItem API for handling multi-layered exports
to work as an iterator. The advantage with this is that it avoids
items needing to calculate in advance how many layers they require
in the output file.
exporting to a multi-layer format
Now, items are either
- placed onto the same layer as other items (simple items like labels, lines, pictures)
- placed onto the same layer as only other items of equal types (semi-complex items like scalebars or pages)
- placed onto their own unique layers (complex items like legends, maps)
Plus lots of tests covering this, where previously there was few
Adds a new visitor pattern API for creation of visitors which visit
all the style entities (symbols, color ramps, text formats, and
label styles) associated with different objects. Can be used on a
renderer, map layer, or project wide level.
E.g. on a project wide level, allows collection of ALL the style
symbols/color ramps/text settings inside a project, including those
in layouts or annotations!
This controls how close labels are permitted to the edges of the map
item. The labeling engine will then try other candidate positions
in order to avoid placing labels within this margin.
Instead, only rasterize that one item and pre-apply it's opacity
to the rasterized version. This keeps all the rest of the layout
content as vectors/text.
Sometimes, calling some layout methods, results in sip being inable
to downcast the items to their correct type, resulting only
in a QgsLayoutItem object.
This works around the problem, albeit in an incredibly hacky way.
Checks whether a function declaration has parameters that are
top level const.
const values in declarations do not affect the signature of a
function, so they should not be put there.
